BANCROFT LIBRARY ♦ THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA WALTER WADSWORTH BRADLEY 1878-1950 Walter W. Bradley was born in San Jose and received the degrees of B.S. and E.M. from the University of California. From 1912 to 1946 he was associated with the California Division of Mines, serving as State Mineral- ogist for the last eighteen years of that period. His published works relate to mining, proc- essing, and geology. This book is from his private collection, presented to the Bancroft Library by Mrs. Alice Roberts Bradley. "^ A.' A ,>•/ Qfsiajj:y7r^i, : 'i/&. ''/. »f Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/depositsoforeuniOOkemprich THE ORE DEPOSITS OF THE UNITED STATES AND CANADA BY JAMES FURMAN KEMP, A.B., E.M., PROFESSOR OF GEOLOGY IN THE SCHOOL OF MINES, COLUMBIA. UNIVERSITY. FOLRTH LDJTIOK ENTIRELY REWRITTEN AND ENLARGED. NEW YORK AND LONDON: THE SCIENTIFIC PUBLISHING COMPANY, 1901. FSV mi Copyright, 1893 and 1900, BY The Scientific Publishing Company. PREFACE. The following pages presuppose for their apprehension some acquaintance with geology and mineralogy. The mate- rials for them tiave been collected and arranged in connection with lectures on economic geology, first at Cornell University and later at the School of Mines, Columbia College, To the descriptions of others the author has endeavored to add, as far as possible, observations made by himself in travel during the last ten years. The purpose of the book is twofold, and this fact has been conscientiously kept in view. It is, on the one hand, intended to supply a condensed account of the metallifer- ous resources of the country,, which will be readable and serv- iceable as a text- book and work of reference. For this rea- son every effort has been put forth to make the bibliography complete, so that, in cases where fuller accounts of a region are desired, the original sources may be made available in any good library. But, on the other hand, it has also been the hope and ambition of the author to treat the subject in such a way as to stimulate investigation and study of these interesting phenomena. If, by giving an extended view over the field, and by making clear what our best workers have done in late years toward explaining the puzzling yet vastly important questions of origin and formation, some encouragement may be afforded those in a position to observe and ponder, the second aim will be fulfilled. In carrying out this purpose, the best work of recent investigators on the origin and changes of rocks, espe- cially as brought out by microscopic study, has been kept con- stantly in mind, and likewise in the artificial production of the ore and gangue minerals. So much unsound and foolish theo> rizing has been uttered and believed about ores, that too much care cannot be exercised in basing explanations on reasonable and right foundations. vi PREFACE, Acknowledgments are due to many friends for encourage- ment, suggestion, and criticism. To Prof. Henry S. Williams, now of Yale, but late of Cornell, whose interest made the book possible, these are especially to be made. On particular regions much advice has been obtained from Dr. W. P. Jenney, for which the author is grateful. In the same way Prof. H. A. Wheeler, of St. Louis, Prof. R. A. F. Penrose, of Chicago, and several other friends have contributed. Dr. R. W. Raymond suggested the method of enumerating the paragraphs. It has the advantages of being elastic and of showing at once in what part of the book any paragraph is situated. The geologists of the United States Geological Survey, who have been engaged in the study of our great mining regions, especially in the West, have laid the whole scientific world un- der a debt of gratitude, and in this country have probably been the most potent influences toward right geological conceptions regarding ores. Of authors abroad, Von Groddeck has been a means of inspiration to all readers of German who have inter- ested themselves in this branch of geology. The writer cannot well forbear acknowledging their influence. Should errors be noted by any reader, the writer will be very appreciative of the kindness if his attention is called to them. J. F. Kemp. Columbian College, in the City of New York, 1892. PREFACE TO THE SECOND EDITION, In the second edition many pages have been rewritten and ex- panded. The endeavor has been also made to introduce into the body of the work the new materials that have become avail- able in the last year. This is especially true of iron ores, of the geology of the Sierras, and of nickel and cobalt. In all some fifty pages of new matter have been added, and fifteen cuts. Acknowledgments are herewith made to Professors W. H. Pettee, of Ann Arbor; H. S. Munroe, of New York; and C. H. Smyth, Jr., of Hamilton College; and to Mr. now Prof. H. L, Smyth, of Cambridge, and Prof. W. C= Knight, of Laramie, for suggestions, as requested in the preface to the first edition. 1895,' J. F. K. PREFACE TO THE THIRD EDITION, In the third edition the title has been expanded so as to in- clude Canada, since the nature of the contents now justifies this change. About one hundred pages of new matter have been added, and considerable portions of the former text have been rewritten. The figures have been doubled in number, and many maps have been introduced. The writer's thanks are due for advice and assistance to Messrs. W. H. Weed, H. Wo Turner and John D. Irving, of the United States Geological Survey, to Mr. H. F. Bain, of the Iowa Geological Survey, to Mr. S. S. Fowler, of Nelson, B, C, and to many of his students, now in the active practice of the profession of mining engi- neering. J. F. K. December, 1899. ERRATA. Page 320, line 28, " 30 miles east," not "20 miles west." Page 241, fig. 78, and text p. 243, line 12 and following. In connection with the diagram and its intei'pvetation, it should be stated thatin.preparing chart proper allowance has not been made for the varying heights of the loca- tions of the bore-holes and for their stratigi'aphical positions. The chart shows therefore actual depths not stratigraphical distribution. ^ <:':M'^^-^->^mj^)^'^'^^^ im mi tr^ „,,, i»^ ■■?!?■•.: J.- ■:• « ^li TABLE OF CONTENTS. PAGS Preface , . , v List of Illustrations o . xv List of Abbreviations xxi PART I.— INTRODUCTOEY. CHAPTER I.— General Geological Facts and Principles. The two standpoints of geology, 3, 4 ; the scheme of classificar tion, 4, 5 ; classification of rocks, 6 ; brief topographical survey of the United States, 7, 8; brief geological outline, 8-11; forms as- sumed by rock masses, 11, 12 1-12 CHAPTER n. — The Formation of Cavities in Rocks. Tension joints, 13, 14; cleavage, fissility, and compression joints, 14-16 ; by more extensive movements, 16-31 ; faults, 21-25 ; zones of possible fracture in the earth's crust, 25, 26 ;• secondary modifications of cavities, 26-32. lS-32 CHAPTER in. — The Minerals Important as Ores; the Gangue Minerals, and the Sources whence both are Derived. The minerals, 32; source of the metals, 32-38 .82-38 CHAPTER IV.— On the Filling of Mineral Veins. Resume, 39 ; methods of filling, 39, 40 ; lateral secretion, 40 ; ascension by infiltration, 40-44; replacement, 44-46 39-46 CHAPTER V. — On Certain Structural Features of Mineral Veins. Banded structure, 47-49; clay selvage, 49; pinches, swells, lateral enrichments, 49, 50 ; changes in character of vein filling, 50 ; secondary alteration of the minerals in veins, 50-52 : electrical activity, 52, 53 , . .47-53 CHAPTER VI.— The Classification of Ore Deposits, a Review and a Scheme Based on Origin. Statement of principles, 54, 55 ; principal schemes, 55 ; scheme entirely based on origin, 55-59 ; remarks on the above, and dis- cussion of methods of formation, 59-73; fahlbands, 73; phrase- ology used, 73 ; character of the rocks containing the deposits, 73 ; general bibliography of ore deposits, 74-79 .... 54-79 X TABLE OF CONTENTS. PART II.— THE ORE DEPOSITS. PAGE CHAPTER I. — The Iron Series (in Part). — Introductory Remarks ON Iron Ores. — Limonite.^^iderite. General literature, 83, 84; table of analyses, 84; general re- marks on composition and occurrence, 85-87 ; Limonite, Example 1, bog-ore, 87-92; Examples, brown hematite not Siluro-Cambrian, 92-100; Example 2a, Siluro-Cambrian brown hematites, 100-104; origin of same, 104, 105; analyses of limonites. 106; siderite or spathic ore, introductory, 106; Example 3, clay ironstone, 106, 107; Example 3a, black-band, 107-110; Example 4, Burden Mines, 110, 111; Example 5, Roxbury, Conn., 112; genetic discussion of siderite, 112, 113 83-113 CHAPTER II. — The Iron Series, Continued— Hematites, Red and Specular. Introductory remarks, 114 ; Example 6, Clinton ore, 114-121 ; Greenbrier Co., W. Va., 121; Mansfield ores, Penn., 121, 152; Ex- ample 7, Crawford Co., Mo., 122, 123; Example 8, Jefferson Co., N. Y., 123-125; Example 9, Lake Superior hematites, 125; intro- ductory, 125-129; Marquette district, 129-136; Menominee dis- trict, 136-139; Penokee-Gogebic district, 139-143; Vermilion Lake and range, 144-150 ; Mesabi, 150-154 ; Example 10, James River, Va., 154, 155; Example 11, Pilot Knob, Mo., 155-157; Example 11a, Iron Mountain, Mo., 157, 158; analyses of hematites, 159.. 114-159 Chapter hi.— Magnetite and Pyrite. Example 12, Magnetite beds, 160; Adirondack region, 160- 166; New York and New Jersey Highlands, 166-169; South Moun- tain, Penn., 169; Western North Carolina and Virginia, 169, 170; Colorado, 170, 171 ; California, 171 ; Example 13, titaniferous mag- netites, 171-175; Example 14, Cornwall, Pa., 175-180; Example 14a, Iron Co., Utah, 180; Example 15, magnetite sands, 180, 181; origin of magnetite deposits, 181-183 ; analyses of magnetites, 183 ; pyrite, 184-186; Example 16, pyrite beds, 184-186; statistics, 186; remarks on Cuban and Mexican iron ores, 18S-188. ... 160-188 CHAPTER IV.— Copper. Table of analyses of copper ores, 189 ; Example 16, continued, pyrite beds, 189-194; Spenceville, Cal., 195, 196; Example 17, Butte, Mont., 197-203; Gilpin Co., Colo., 203, 204; Llano Co., Texas, 204; Example 18, Keweenaw Point, Mich., 204-209; origin of the copper, 209-212; Example 19, St. Genevieve, Mo., 313, 214; Example 20, Arizona Copper, 214, 215; Morenci, 215, 216; classi- fication of ores by Henrich, 216, 217; Bisbee, 217, 218; Globe, 218, 219; Santa Rita, N. M., 219; Black Range, 220; Copper Basin, 220; Crismon-Mammoth, Utah, 221, 222; Wyo., Idaho, Wash., 222; Example 21, copper ores in Triassic or Permian sandstone, 222-224; Eastern States, 323, 334; Western States, 334; statistics of copper, 225 189-225 TABLE OF CONTENTS. xi CHAPTER V.—Lead Alone. Introductory and analyses of lead ores, 226 ; Example 22, At- lantic border, St. Lawrence Co., N. Y., 226, 227; Mass., Conn., and Eastern K Y., 227; Southeastern Penn., 227; Davison Co., N. C, 228; Sullivan and Ulster Counties, N. Y., 228; Example 23, Southeastern Missouri, 228-231 ; statistics of lead, 232 .226-233 CHAPTER VI.— Lead and Zinc. Example 24, Upper Miss. Valley, 233-237; Washington Co., Mo., 238, 239; Livingston Co., Ky., 239; Example 25, Southwest Missouri, 240-245; Example 26, Wythe Co., Va., 247-249 233-249 CHAPTER VII. — Zinc Alone, or with Metals other than Lead. Introduction : Tables of analyses of zinc ores, 250 ; Example 27, Saucon Valley, Penn., 250, 251; Example 28, Franklin Fur- nace and Sterling, N. J., 251-257; Zinc in the Rocky Mountains, 258, 259; in New Mexico, 259 250-259 CHAPTER VIII.— Lead and Silver. Introduction, 260; Rocky Mountain region and the Black Hills, 260, 274; New Mexico, 260-262; Example 29, Kelley Lode, 260; Lake Valley, 260-262; Colorado, 262-272; Example 30, Lead- ► ville, 262-266; Example 30a, Ten Mile, Summit Co., 266, 267; Ex- ample 305, Monarch District, ChaifeeCo., 268; Example 30c, Eagle River, Eagle Co., 268; Example 30d, Aspen, Pitkin Co., 268-271; Example 30e, Rico, Dolores Co., 271, 272; Example 31, Red Moun- tain, Ouray Co., 272; South Dakota, Example 30/, 272; Montana- Idaho, Example 32, Glendale, 273; Example 32a, Wood River, 273; Example 33, Wickes, Jefferson Co., 273; Example 34, Coeur d'Alene, 274; Region of the Great Basin, 274-279; Utah, Exam- ple 35, Bingham and Big and Little Cottonwood Canons, 274, 275 ; Example 35a, Tooele Co,, 275; Example 355, Tintic District, 275; Example 30gr, Hornsilver Mine, 275, 276; Example 33a, Car- bonate Mine, Beaver Co., 276; Example 326, Cave Mine, Beaver Co., 276; Nevada, Example 26, Eureka, 277, 278; Arizona; CaU- fornia, 279 260-279 CHAPTER IX. — Silver and Gold. — Introductory : Eastern Silver Mines and the Rocky Mountain Region of New Mex- ico AND Colorado. Introduction, 280; Examples 37-42, defined, 280, 281; silver and gold ores, 281-283; Example 22a, Atlantic Border, 283; Ex- ample 42, Silver Islet, Lake Superior, 283, 284; Thunder Bay, Canada, 284 ; region of the Rocky Mountains and the Black Hills, 284-307; New Mexico, geology, 284, 285; mines, 285, 286; Colorado, geology, 286, 287; San Juan region, 287-293; Creede region, 293; Gunnison region, 294; Eagle Co., 294; Summit Co., 294, 295; Park, Chaffee, Rio Grande Counties, 295; Conejos Co., 296; Cus- ter Co., 296; Example 39, Bassick Mine. 296, 297; Example 39a, xii TABLE OF CONTENTS. PAGE Bull Domingo Mine, 297-299; Humboldt-Pocahontas, 299; Silver 'Cliff, 299, 300; Teller Co., 300-305; Gilpin Co., 305, 306; Clear Creek Co., 306; Boulder Co., 306, 307 280-307 CHAPTER X.— Silver and Gold, Continued.— Rocky Mountain Region, Wyoming, the Black Hills, Montana, and Idaho. Wyoming, geology, 308; South Dakota, geology, 309; the Black Hills, 309-314; Montana, geology, 314-316; Madison Co., 316, 317; Beaverhead Co., 317; Jefferson Co., 317, 318; Silver Bow Co., 318, 319; Broadwater Co., 319; Deer Lodge Co., 319; Lewis and Clarke Counties, 320; Meagher Co., 320,321; Cascade Co., 321; Flathead, Choteau, and Fergus Counties, 322, 323; Idaho, geology, 323; Kootenai and Lemhi Counties, 324; Custer, Boise, Alturas, and other counties, 324-327 308-327 CHAPTER XI.— Silver and Gold, Continued.— The Region of the Great Basin, in Utah, Arizona, and Nevada. Utah, geology, 328; Ontario and other mines, 329, 330; Ex- ample 41, Silver Reef, 333, 334; Arizona, geology, 334; Apache, Yavapai, Mohave, Yuma, Maricopa, and Pinal Counties, 335; Silver King mine, 335, 336; Graham and Cochise Counties, 336; Tombstone, 336; Pima and Yuma Counties, 336, 337; Nevada, geology, 337; Lincoln, Ney, and White Pine Counties, 338, 339; Lander and other counties, 339, 340; the Comstock Lode, 340- 345 328-345 CHAPTER XIL— The Pacific Slope— Washington, Oregon and California. Washington, geology, 346; mines, 347; Oregon geology, 347, 348; Example 44a, Port Orford, 348, 349; California, geology, 349, 350; Calico District, 351-353; Example 44, auriferous gravels, 353-362; river gravels, 353, 354; high or deep gravels, 354-360; general resume of geological history of gravels, 360-362 ; Example 45, gold-quartz veins, 362-375 .„....,,,......, 346-375 CHAPTER XIII.— Gold Elsewhere in the United States and Canada. Example 45a, Southern Appalachians, 376-378 ; Alabama, 378, 379; Georgia, 379; South Carolina, 380; North Carolina, 380, 381; Virginia, Maryland and the Northern States, 381-383; Example 45&, Ishpeming, Mich., 383; the Rainy River District, 383-385; Alaska and the Canadian Northwest, geology, 385-389 ; Example 38, Douglass Island, 390-393; Yukon Basin, 393-397; Example 45c, Nova Scotia, 397-399; gold elsewhere in Canada, 400, 401; sta- tistics, 401, 402 376-400 CHAPTER Xrv.— The Lesser Metals— Aluminum, Antimony, Ar- senic, Bismuth, Chromium, Manganese. Aluminum, 403-410; antimony, 410, 411; Example 47, includ- ing California, Nevada, Arkansas, New Brunswick, 410, 411 r Ex- TABLE OF CONTENTS. xiii PAoa ample 48, Iron Co., Utah, 411; arsenic, 413; bismuth, 412* chro- mium, 415, 416; Example 49, chromite in serpentine, 414, 415; California, 415, 416; Quebec, 416; manganese, 416-423; Exam pie 50, manganese ores in residual clay, 418-423 ; Batesville, Ark. 420-422; Panama, 423 403-433 CHAPTER XV.— The Lesser Metals, Continued.— Mercury, Nickel and Cobalt, Platinum, Tin. Mercury, ores, 424, 425 ; Example 50, New Almaden, 425, 426 ; Example 50a, Sulphur Bank, 427; Example 50&, Steam^ 3at Springs, Nev., 427; resume regarding mercuiy, 428; nickel and cobalt, 428-441 ; introductory, 428-430 ; Example 16c, pyrrhotite beds or veins, 430, 431; Example 13a, Gap mine, Penn., Sudbury, Ont., 431-438; Example 49a, Riddle's, Oregon, 438-440; Example 23a, Mine la Motte, Mo., 440; other occurrences of nickel ores, 440, 441; platinum, 441; tin, 441, 442; Example 51, Black Hills, 442, 443; other occurrences of tin, 443, 444; Mexico, 444 434-444 CHAPTER XVI.— Concluding Remarks. Summation of such general geological relations among North American ore deposits as can be detected 445-447 APPENDIX I, — A Review of the Schemes for the Classification OF Ore Deposits. General remarks, 447, 448; schemes involving only the classification of veins, 448-451 ; general schemes based on forms, 451-453 ; schemes, partly based on form, partly on origin, 453-455; schemes largely based on origin, 455-457 ; schemes entirely based on origin, 457-459 ; remarks on schemes and classification of ore deposits, 459-462. . .447-463 LIST OF ILLUSTRATIONS FiaS. PAOB 1. Illustration of rifting in granite at Cape Ann, Mass. After R. S. Tarr 13 2. Open fissure in the Aubrey limestone (Upper Carboniferous), 25 miles north of Canon Diablo Station, on the A. & P. R.R., Arizona. Photographed by G. K. Gilbert, 1892 0pp. 20 3. Normal fault at Leadville, Colo. After A. A. Blow 20 4. Reversed fault at Holly Creek, near Dalton, Ga. After C. W. Hayes 22 5. Illustration of an older vein, the Jiunbo faulted by a later one (cross vein) at Newman Hill, Rico, Colo. After T. A. Rickard. 24 6. Banded vein at Newman Hill, near Rico, Colo. After J. B. Farish 36 7. Map showing the distribution of iron ores in North America 88 8. Cross-section of the Prosser iron mine near Portland, Ore., show- ing the bed of limonite between two flows of basalt. After B. T. Putnam 91 9. Section of the Hurst limonite bank, Wj^the Co., Va., illustrating the replacement of shattered limestone with limonite and the formation of geodes of ore. After E. R. Benton 93 10. View of the Low Moor limonite mines, Virginia. After a photo- graph by J. F. Kemp 0pp. 95 11. Geological section of the Low Moor, Va., iron ore bed. After B. S. Lyman 96 12. Ideal cross-section of Iron Hill near Waukon, Allamakee Co., Iowa 99 13. Geological section of the Amenia mine, Dutchess Co., N. Y. After B. T. Putnam 100 14. View of the Siluro- Cambrian, brown hematite bank at Baker Hill, Ala. From the Engineering and Mining Journal. . .0pp. 103 15. Map and sections of the Burden spathic ore mines. After J. P. Kimball. 110 16. Clinton ore, Ontario, Wayne Co., N. Y. After C. H. Smyth, Jr. 115 17. Clinton ore, CUnton, N. Y. After C. H. Smyth, Jr 116 18. Clinton ore. Eureka mine, Oxmoor, Ala. After C. H. Smyth, Jr. 117 xvi LIST OF ILLUSTRATIONS. FIG. PAGE 19. Cross-section of the Sloss mine, Red Mountain, Ala. From the Engineering and Mining Journal 117 20. Map of the vicinity of Birmingham, Ala. From the Transac- tions of the American Institute of Mining Engineers 119 21. View of Cherry Valley mine, showing sandstone with underly- ing cherty clay. After F. L, Nason Opp. 122 22. Section of the northern end of the Cherry Valley mine. After F. L. Nason Opp. 122 23. Cross-section of the Cherry Valley mine. After F. L. Nason . Opp. 122 24. Map of the Lake Superior region, showing the location of the iron-ore districts. From U. S. Geological Survey 126 25. Generalized section across Marquette iron range, to illustrate the type of folds. After C. R. Van Hise 129 26. Geological map of the western portion of the Marquette iron range. After Van Hise and Bayley 130 27. Geological map of the eastern portion of the Marquette iron range. After Van Hise and Bayley 131 28. Cross-section to illustrate the occurrence and associations of iron ore in the Marquette district, Michigan. After C. R. Van Hise = . 133 29. Open cut in the Republic mine, Marquette range, showing a horse of jasper. After H. A. Wheeler Opp. 133 30. Plan of the Ludington ore body, Menominee district, Michigan. After P. Larsson 137 31. Geological map of the Penokee-Gogebic iron range. After Irving and Van Hise 140 32. Longitudinal and cross-section of the Ashland mine, Ironwood, Mich., re-drawn from mine maps 142 33. Cross-section of the Colby mine, Penokee-Gogebic district, Michi- gan, to illustrate oocurrence and origin of the ore. After C. R. Van Hise 143 34. Map of the Minnesota iron ranges. After F. W. Denton 145 85. Geological map of the vicinity of Tower and Soudan, Minn. After Smyth and Finlay 147 36. Cross-sections of the ore bodies at Soudan, Vermilion Range, ' Minn. After Smyth and Finlay 149 37. Open cut at Minnesota Iron Co.'s mine, Soudan, near Tower, in south vein, looking west. After J. F. Kemp OpP- 148 38. Horizontal and vertical cross-section of the Chandler ore body at Ely, Minn. After Smyth and Finlay 150 39. View of Chandler mine, showing sinking of ground. After J. F. Kemp Opp. 149 40 General cross-section of ore body at Biwabik, Mesabi Range, Minn. After H. V. Winchell IM 41. View of the Mesabi Mountain or Oliver mine, Virginia, Minn., looking southeast. After J. F. Kemp Opp. 153 42. Cross-section of Pilot Knob, Mo. From drawing by W. B. Potter 156 LIST OF ILLUSTRATIONS. xvii FIG. PAGE 43. View of open cut at Pilot Knob, Mo., showing the bedded char- acter of the iron ore. After J. F. Kemp 0pp. 157 44. View of Iron Mountain, Mo., from the east. After H. A. Wheeler 0pp. 158 45. Cross-section of Iron Mountain, Mo. By W. B. Potter: 156 46. View of open cut and underground work in mine 21, Mineville, near Port Henry, N. Y. After J. F. Kemp 0pp. 163 47. Cross-section of the Cheever iron mine, near Port Henry, N. Y, After J. F. Kemp 163 48. Geological map of the iron mines at Mineville, near Port Henry, N. Y. After J. F. Kemp .163 49. Cross-section of ore-bodies at Mineville, near Port Henry, N. Y., to accompany map, Fig. 48. After J. F. Kemp 164 50 and 51. Model of the Tilly Foster ore body. After F. S. Rutt- mann and J. F. Kemp 166 52. Sketch map illustrating the geological structure of the Hibernia magnetite beds, Hibernia, N. J. After J. E. Wolff 168 53. Section along Cornwall Railroad from Lebanon to Miner's Vil- lage. After E. V. dlnvilHers 176 54. Map of Cornwall mines. After E. V. d'Invilliers 177 55. Map of Ducktown, Tenn., copper mines, showing the relations and extent of the veins. After Carl Henrich 191 56. Cross-section, shaft 3, Old Tennessee mine, Ducktown, lenn. After Carl Henrich 193 57. View of the Mary Mine, Ducktown, Tenn. , from the west. From a photograph by J. F. Kemp 0pp. 194 58. Geological map of the western half of Butte district, Montana, reproduced from map of U. S. Geological Survey 198 59. Geological map, eastern half, Butte district, Montana. Idem 199 60. View of the Big Butte, Butte City, Mont., looking northwest across Missoula Gulch. From photograph by J. F. Kemp.. 0pp. 200 61. View of the Anaconda mine, Butte, Mont. From photograph by Alexander Brown Opp- 200 62. View of the larger copper mines, Butte, Mont., looking nearly due east from the roof of the Hotel Butte. From photograph by J. F. Kemp .0pp. 201 63. Contact of the older Butte granite and the later intruded Blue- bird granite as exposed in a cut on the Butte, Anaconda, Pacific R. R. Photographed by J. F. Kemp 0pp. 202 64. Cross-section of the Bob-tail mines, Central City, Colo. After F. M. Endlich 204 65. Geological section of Keweenaw Point, Mich. , near Portage Lake and through Calumet. After R. D. Irving 206 66. Map of the Portage Lake district, Keweenaw Point, Mich 207 67. Cross-section in the St. Genevieve copper mine, illustrating the relations of the ore. After F. Nicholson 213 68. Section at the St. Genevieve mine, illustrating the intimate re- lations of ore and chert. After F. Nicholson 213 xviii LIST OF ILLUSTRATIONS. no. PAGE 69. Geological map of the Morenci or Clifton copper district of Arizona. After A. F. Wendt 214 70. Vertical section of Longfellow Hill, Clifton district, Arizona. After A. F. Wendt 215 71. Horizontal section of Longfellow ore body. After A. F. Wendt. 215 72. Geological section of the Metcalf mine, Clifton district, Arizona. After A. F. Wendt 216 73. View of the Copper Queen mine, Bisbee district, Arizona. From photograph by James Douglass 0pp. 218 74. Cross-section of the Schuyler copper mine, New Jersey. After N. H. Darton 223 75. Geological map of the Southeastern Missouri disseminated lead ore sub-district. After Arthur Winslow 229 76. Gash veins, fresh and disintegrated. After T. C. Chamberlin . . 234 77. Idealized section of "flats and pitches," forms of ore bodies in Wisconsin. After T. C. Chamberlin 235 78. Chart showing the results of deep borings in the Joplin district. Mo. From Engineering and Mining Journal -. 241 79. Vertical section of a typical zincblende ore body, near Webb City, Mo. After C. Henrich 243 80. Geological section of the Bertha zinc mine, Wythe Co., Va. After W. H. Case 246 81. Geological section, Altoona coal mines to Bertha zinc mines. After W. H. Case 248 82. View of open cut in Bertha zinc mine, Va. Photographed by J. F. Kemp 0pp. 248 83. View of open cut in the Wythe zinc mines, Va. Photographed by J. F. Kemp Opp. 248 84. Cross-section at Franklin Furnace, N. J. , corresponding to AA, of map (Fig. 88). At the left is blue limestone and quartzite. After J. F. Kemp 252 85. View of the w^est vein at Franklin Furnace, looking south. The two shafts are at the Trotter mine. Photographed by J. F. Kemp Opp. 252 86. View of the open cut at south end of Mine Hill, Franklin Fur- nace, N. J., exposing the syncline of ore. Photographed by J. F. Kemp Opp. 253 87. View of Sterling Hill, Ogdensburgh, N. J. From photograph by J. F. Kemp. Opp. 253 88 and 89. Geological map of Mine Hill and Sterling Hill, showing the relations of the ore bodies. After J. F. Kemp 255 90 and 91. Stereograms of the ore bodies at Mine Hill and Sterling Hill. After J. F. Kemp 256 92. Geological cross-section at Lake Valley, New Mexico, to show the relations of the ore. After Ellis Clark 261 93. Section of the White Cap chute, Leadville, showing the geo- logical relations of the ore, and its passage into unchanged sulphides in depth. After A. A. Blow 264 LIST OF ILL U8TBA TIONS. xix FIG. PAGE 94. Section through the No. 2 ore chute of the Robinson mine, Ten- mile district, Colo. After S. F. Emmons 267 95. Cross-section, Queen of the West mine, Ten-mile district, Colo. After S. F. Emmons 267 96. Geological section at the Eagle River mines, Colo. After E. E. Olcott 269 97. A — Cross-section of the Delia S. mine. Smuggler Mt. , Aspen, Colo. After J. E. Spurr 270 B — Section through the Durant and Aspen mines. By D. Rohlfing 270 98. View of the Bunker Hill and Sullivan mines, Wardner, Idaho. Photographed by E. E. Olcott 0pp. 274 99. View of town of Mammoth, Tintic district, Utah. Photographed by L. E. Riter, Jr 0pp. 275 100. Bullion and Beck mine and mill. Eureka, Tintic district, Utah. Photographed by L. E. Riter, Jr 0pp. 275 101. Section at Eureka, Nev. After a plate by J. S. Curtis 278 102. Geological sketch map of the Telluride district, Colo. After Arthur Winslow 289 103. Geological cross-sections of strata and veins at Newman Hill, near Rico, Colo. After J. B. Farish 291 104. Geological cross-sections of strata and veins at Newman Hill, near Rico, Colo. After J. B. Farish 292 105. Cross-section of the Bassick mine, near Rosita. After S. F. Emmons 298 106. Cross-section of the Bull-Domingo mincj, near Silver Cliff, Colo. After S. F. Emmons 298 107. Cross-section of the Humboldt-Pocahontas vein, near Rosita, Colo. After S. F. Emmons 299 108. Geological map of Cripple Creek, Colo. U. S. Geological Survey. Geology by Cross and Mattliews 301 109. View of Cripple Creek, Colo., from Mineral Hill; Gold Hill in background. Photographed by J. F. Kemp 0pp. 302 110. View of Battle Mt., Victor, Colo., Portland group of mines and Independence mine. Photographed hy J. F. Kemp 0pp. 802 111. Map of the Independence and Washington claims. Cripple Creek, Colo. After R. A. F. Penrose 303 112. Stereogram of the Annie Lee ore-chute, Victor, Colo. After R. A. F. Penrose 304 113. Geological section of the Black Hills. After Henry Newton 309 114. Geological section of the strata in the Northern Black Hills, S. D. After John D. Irving 310 115. Plan and crosssection of the Cambrian, siliceous gold-ore de- posits in the Black Hills, S. D. After John D. Irving 311 116. Plan and section. Mail and Express mine, to illustrate the sili- ceous gold ores of the Black Hills, S. D. After John D. Irving. 312 117. View of Green Mt., Black Hills, S. D., a laccolite of phonolite. XX LIST OF ILLUSTRATIONS. FIG. PA6B with the mines of siliceous ore on the so-called "upper con- tact," around the foot. Photographed by John D. Irving. .0pp. 312 118. View of the Union mine in siliceous ore, near Terry, Black Hills, S. D. Photographed by John D. Irving 0pp. 312 119. Cross-section of a siliceous gold ore-body lying next to a porphyry dike. Black Hills, S. D. After John D. Irving 313 120. Prospective cross-section of siliceous gold ore-body, in Carbonif- erous limestone, Dacy Flat, Black Hills, S. D. After John D. Irving 0pp. 313 121. View of the Golden Star open cut. Lead City, S. D. Photo- graphed by J. F. Kemp 0pp. 313 122. View of the outcrop of the Wabash silver lode projecting above the granite, Butte, Mont. Photographed by A. C. Beatty . .0pp. 318 123. View of weathered granite, Butte, Mont. Photographed by J. F. Kemp Opp. 318 124. Cross-section of vein of the Alice mine, Butte, Mont. After W. P. Blake 318 125. The old gold diggings on Napias Creek, Leesburg, Idaho. Illus- trating an abandoned placer camp. Photographed by J. F. Kemp Opp. 324 126. View of Napias Creek, below California Bar, after a fre^et. Photographed by J. F. Kemp Opp. 324 127. Sections to illustrate typical gold veins in the Boise granite "region, Idaho. After W. Lindgren. 326 128. Geological cross-section at Mercur, Utah. After J. E. Spurr. . . . 330 129. Diagram showing relations of ore to fault in Tunnel No. 3, Mar- ion mine, Mercur, Utah. After J. E. Spurr 331 130. Section along the Geyser mine tunnel, Mercur, Utah. After J. E. Spurr : 331 131. View of open cut, showing pay streak at Mercur, Utah. From a photograph by P. K. Hudson Opp. 332 132. The Golden Gate cyanide mill, Mercur, Utah. From a photo- graph by L. E. Eiter, Jr Opp. 332 133. Two sections of the argentiferous sandstone of Silver Reef, Utah. After C. M. Rolker 333 134. Section of the Comstock Lode on the line of Sutro tunnel. After G. F. Becker 341 135. Geological section of the Calico district, California. After W. Lindgren 351 136. View of the Randsburg, California, looking southeast. Schists underlie the town, but the hills are eruptive. From a photo- graph by H. A. Titcomb Opp. 350 137. View of the Stevens hydraulic placer mine, Auro City, Colo. From a photograph Opp- 350 138. View in the Malakoff hydraulic placer mine, North Bloomfield, Calif. From a photograph Opp. 351 139. View of the Malakoff hydraulic placer mine. North Bloomfield, Calif. From a photograph OpP- ^51 LIST OF ILLUSTRATIONS. xxi FIG, PAGE 140. Generalized section of a deep gravel bed, with technical terms. After R. E. Browne = 355 141. Section of Forest Hill Divide, Placer Co., Calif., to illustrate the relations of old and modern lines of drainage. After R. E. Browne - • 356 142. North Star vein. Grass Valley, Calif., showing quartz vein in brecciated and altered diabase. After W. Lindgren 0pp. 363 143 and 144. Ore shoots of Nevada City and Grass Valley mines, Calif. After W. Lindgren. 364 145. Section of the Pittsburg vein, ninth level, Nevada City district, Calif. From U. S. Geological Survey 365 146. Geological section at Merrifield vein. Providence claim, Nevada City district, Cahf. After W. Lindgren. 366 147. Cross-section of vein in St. John mine, fifth level, Nevada City district, Calif. After W. Lindgren. , . „ 366 148. Cross-section of the Maryland vein, in slope above 1500-foot level. Grass Valley district, Calif. After W. Lindgren , . . 367 149. Cross-section of the Brunswick vein, on the 700-foot level. Grass Valley district, Calif. After W. Lindgren 368 150. Western half of Geological map of the Yukon Gold Belt, and ad- jacent regions. (See Fig. 151) 386 151. Eastern half of Geological map of the Yukon Gold Belt, and ad- jacent regions. After J. E, Spurr 387 152. Map of the Juneau mining district, Southeast Alaska. After G. F. Becker 392 153. Sketch map of Nova Scotia Gold Fieldc. After E. Gilpin. 398 154. Cross-section of a Bauxite deposit in Georgia. After C. Willard Hayes , » 405 155. Sections of the Crimora manganese mine, Virginia. After C. E. Hall 418 156. Geological sections illustrating the formation oi manganese ores in Arkansas. After R, A. F. Penrose 419 157. The Turner mine, Batesville region, Arkansas. After R. A. F Penrose « . = . . 420 158. Section of the Great Western cinnabar mine. After G. F Becker , . , , . 426 159. Map and section of Gap Nickel mine, Lancaster Co., Penn. After J. F. Kemp , 433 160. Geological section-map of the Sudbury .district, Ontario. After by T. L. Walker. , , 435 161 and 162. View of Copper Cliff mine, Sudbury, Ontario. Photo- graphs by T. G. White 0pp. 436 163. Horizontal section of the Etta granite knob, Black Hills, S. D. After W. P. Blake , 442 ABBREVIATIONS Amen Assoc. Adv. Sci., or A. A. A. >S.— Proceedings of the American As- sociation for the Advancement of Science. Amer. Geol. — American Geologist. Minneapolis, Minn. Amer. Jour. Sci. — American Journal of Science, also known as Silliman's Journal. Fifty half- yearly volumes make a series. The Journal is now (1893) in the third series. In the references the series is given first, then the volume, then the page. Ann. des Mines — Annales des Mines. Paris, France. Bost. Soc. Nat. Hist. — See Proceedings of same. Bull. Geol. Soc. Amer. — Bulletin of the Geological Society of America. Bidl. Mus. Comp. Zool. — Bulletin of the Museum of Comparative Zoology, Harvard University. Cambridge, Mass. B. und H. Zeitung. — Berg- und Huettenmdnnische Zeitung. Leipzig, Germany. Neues Jahrb. — Neues Jahrbuch fiir Mineralogie, Geologie und Palseon- tologie, often called Leonhard's Jahrbuch. Stuttgart, Germany. Oest. Zeit. f. Berg. u. Huett. — Oesterreichische Zeitschrift fur Berg- und Huettenwesen. Vienna, Austria. Philos. Mag. — Philosophical Magazine. Edinburgh, Scotland. Proc. Amer. Acad. — Proceedings of the American Academy of Arts and Sciences. Boston, Mass. Proc. and Trans. N. S. Inst. Nat. Sci. — Proceedings and Transactions of the Nova Scotia Institute of Natural Science. Halifax, Nova Scotia. Proc. Bost. Soc. Nat. Hist. — Proceedings of the Boston Society of Natural History. Boston, Mass. Proc. Colo. Sci. Soc. — Proceedings of the Colorado Scientific Society. Denver, Colo. Raymond's Reports. — Mineral Resources West of the Rocky Mountains, Washington, 1867-1876. The fij'st two volumes were edited by J. Ross Browne, the others by R. W. Raymond. Trans. Amer. Inst. Min. Eng. — Transactions of the American Institute of Mining Engineers. Trans. Min. Assoc, and Inst., Cornwall. — Transactions of the Mining As- sociation and Institute of Cornwall. Tuckingmill, Camborn, England. xxiv ABBRE VIA TIONS. Trans. N. Y. Acad, of Sci. — Transactions of the New York Academy of Sciences, formerly the Lyceum of Natural History. Zeit. d. d. g. Ges. — Zeitschrift der deutschen geologischen Gesellschaft. Berlin, Germany. Zeitsch. f. B., H. und S. im. P. St. — Zeitschrift fur Berg-, Huetten-, und Salinenwesen im Preussischen Staat. Berlin, Germany. Zeitschr. f. Krys. — Zeitschrift fiXr KrystallograpMe. Munich, Germany. Zeitsch f. prakt. Geol. — Zeitschrift fiir praktische Geologie. Berlin, Ger- many. The remaining abbreviations are deemed self-explanatory. The num- bering of the paragraphs is on the following principle: The first digit refers invariably to the part of the book, the second digits to the chapter, and the last two to the paragraph of the chapter. PART I. INTRODUCTORY. CHAPTER I. GENERAL GEOLOGICAL FACTS AND PRINCIPLES. 1.01.01/ In the advance of geological science the stand- points from which the strata forming the earth's crust are re- garded necessarily change, and new points of view are estab- lished. In the last few years two have become especially prominent, and there are now two sharply contrasted positions from which to obtain a conception of the structure and develop- ment of the globe. The first is the physical, the second the biological. For example, we consider the surface of the earth as formed by rocks, differing in- one part and another, and these different rocks or groups of rocks are known by different names. The names have no special reference to the animal remains found in them, but merely indicate that series of re- lated strata form the surface in particular regions. On the other hand, the rocks are also regarded as having been formed in historical sequence, and as containing the remains of organ- isms characteristic of the period of their formation. They illus- trate the development of animal and vegetable life, and in this way afford materials for historical-biological study. In the original classification, the biological and historical considera- tions are all-important. But when once the rocks are placed in their true position in the scale, and are named, these considera- tions, for many purposes, no longer concern us. The forma- tions are regarded simply as members in the physical constitu- tion of the outer crust. The International Geological Congress held in Berlin in 1885 expressed these different points of view in two parallel and equivalent series of geological terms, which ^ The numbers at the b^inning of the paragraphs are so arranged that the first figure denotes the part of the book, the next two figures the chap- ter, and the last two the paragraph. Thus 1.06.21 means Part I., Chapter VI., Paragraph 21 under Chapter VI. KEMP'S ORE DEPOSITS. are tabulated on p. 4. They are now very generally adopted. For clearness in illustration, the equivalent terms employed by Dana are appended. Biological Terms. Physical Terms. Dana's Terms. niustrations. Era. Group. Time. Paleozoic. Period. System. Age. Devonian. Epoch. Series. Period. Hamilton. Age. Stage. Epoch. Marcellus. The United States Geological Survey divides as follows : Era and System, Period and Group, Epoch and Formation. In considering the ore deposits of the country, we employ only the physical terms. We understand, of course, the chronological position of the systems in historical sequence, but it is of small moment in this connection what may be the forms of life in- closed in them. The purely physical character of the rocks — .whether crystalline or fragmental; whether limestone, sand- stone, granite or schists; whether folded, faulted, or undis- turbed — are the features on which we lay especial stress. In all the periods the same sedimentary rocks are repeated, and in the hand specimen it is almost always impossible to distin- guish those of different ages from one another. The classifi- cation, briefly summarized, is as follows : 1.01.02. Archean Group.— I. Laurentian System. II. Huronian System. Additional subdivisions have been intro- duced by Canadian and Minnesota geologists (Animikie, Mont- alban, etc.), and it is a growing custom to call all those which are sediments or later than sediments, especially in the region of the Great Lakes, by the name of Algonkian. (See discus- sion under Example 9.) Paleozoic Group. — III. Keweenawan System. (This may belong with the Archean.) IV. Cambrian System: (a) Georgian Stage; (6) Acadian Stage; (c) Potsdam Stage. V. Lower Silurian System. (A) Canadian Series: (a) Calcifer- ous Stage; (b) Chazy Stage. (This will probably experience revision.) (B) Trenton Series: (a) Trenton Stage; (b) Utica Stage; (c) Cincinnati or Hudson River Stage. VI. Upper Silurian System. (J.) Niagara Series: (a) Medina Stage; (b) Clinton Stage; (c) Niagara Stage. (B) Salina Series. (C) Lower Helderberg Series. VII. Devonian System. (A) Oris- kany Series. (B) Corniferous Series; (a) Cauda-Galli Stage. GENERAL QEOLOGIGAL FACTS AND PRINCIPLES. 5 (h) Schoharie Stage; (c) Corniferous Stage. ((7) Hamilton Series: (a) Marcellus Stage; (6) Hamilton Stage; (c) Genesee Stage. (Z>) Chemung Series: (a) Portage Stage; (6) Chemung Stage. VIII. Carboniferous System. {A) Sub-carboniferous or Mississippian Series. {B) Carboniferous Series. (C) Permian Series. Mesozoic Group. — IX. Triassic Sj'stem. X. Jurassic Sys- tem. IX. and X. are not sharply divided in the United States, and we often speak of Jura-Trias. A stratum of gravel and sand, along the Atlantic coast, that contains Jurassic fossils has been called the Potomac formation by McGee. XI. Cre- taceous System. Subdivisions differ in different parts of the country. Atlantic Border: (a) Karitan Stage; (6) New Jer- sey Greensand Stage, Gulf States: (a) Tuscaloosa Stage; (6) Eutaw Stage; (c) Rotten Limestone Stage ; (d) Ripley Stage. Rocky Mountains: {a) Comanche Stage; {h) Dakota Stage; (c) Benton Stage; (d) Niobrara Stage; (e) Pierre Stage; (/) Fox Hills Stage; {g) Laramie Stage, Stages (c) and (d) are sometimes collectively called the Colorado Stage; while (e) and (/)are grouped as the Montana Stage. Pacific Coast: (a) Shasta Stage ; (6) Chico Stage, Cenozoic Group. — XII. Tertiary System. Gulf States. {A) Eocene Series: Midway, Lignitic, Lower Claiborne, Clai- borne, Jackson and Vicksburg Stages. (J5) Oligocene, want- lug. (C) Miocene Series, Chattahoochee, Chipola and Chesa- peake Stages. {!)) Pliocene Series: Floridian Stage. Interior Region. {A) Eocene Series : Puerco, Torrejon, Wasatch, Wind River, Bridger and Uinta Stages. {B) Oligocene Series: White River Stage. (C) Miocene Series: John Day, Deep River, and Loup Fork Stages. {D) Pliocene Series: Good-night (Palo Duro) and Blanco Stages. Pacific Coast. The Eocene is called the Tejon. Miocene and Pliocene are used for the others. XIII. Quaternary System. {A) Glacial Series. {B) Champlam Series. (C) Terrace Series. (X)) Recent Series, Pleistocene is sometimes employed as a name for the early Quaternary, especially south of the Glacial Drift. In accord witb the practice of the U. S. Geological Survey, the Tertiary is now generally divided into the Eocene and the Neocene (in- cluding Ohgocene' Miocene and Pliocene) series. 6 KEMP'S ORE DEPOSITS. Other terms are also often used, especially when we do not wish to speak too definitely. ** Formation" is a word loosely employed for any of the above divisions. ''Terrane" is used much in the same way, but is rather more restricted to the lesser divisions. A stratum is one of the larger sheet- like masses of sedimentary rock of the same kind; a bed is a thinner subdivision of a stratum. **Horizon" serves to indi- cate a particular position in the geological column; thus, speaking of the Marcellus Stage, we say that shales of this horizon occur in central New York. 1.01.03. The rock species themselves are classified into three great groups — the Igneous, the Sedimentary, and the Metamorphic. The Igneous (synonymous terms, in whole or in part : massive, eruptive, volcanic, plutonic) include all those which have solidified from a state of fusion. They are marked by three types of structure — the granitoid, the porpbyritic, and the glassy, depending on the circumstances under which they have cooled. Under the first type of structure come the granites, syenites, diorites, gabbros, diabases, and peri- dotites; under the second, quartz-porphyries, rhyolites, por- phyries, trachytes, porphyrites, andesites, and basalt; under the third, pitchstone, obsidian, and other glasses. The Sedimentary rocks are those which have been deposited in water. They consist chiefly of the fragments of pre-existing rocks and the remains of organisms. They include gravel, conglomerate, breccia, sandstone — both argillaceous and cal- careous—shales, clay, limestone, and coal. In volcanic dis- tricts, and especially where the eruptions have been subma- rine, extensive deposits of volcanic lapilli and fine ejectments have been formed, called tuffs. With the sedimentary rocks we place a few that have originated by the evaporation of solu- tions, such as rock salt, gypsum, etc. The Metamorphic rocks are usually altered and crystallized members of the sedimentary series, but igneous rocks are known to be subject to like change, especially when in the form of tuffs. They are all more or less crystalline, more or less distinctly bedded or laminated, of ancient geological agec or in disturbed districts. They include gneiss, crystalline schists, quartzite, slate, marble, and serpentine. GENERAL GEOLOGICAL FACTS AND PRINCIPLES. 7 After a brief topographical survey, we shall employ the above terms to summarize the geological structure of the United States. The several purely artificial territorial divi- sions are made simply for convenience. Nothing but intelli- gent travel will perfectly acquaint one with the topographical and geological structure of the country, and in this connection Macfarlane's "Geological Railway Guide" and a geological map are indispensable. 1.01.04. On the east we note the great chain of the Appa- lachians, with a more or less strongly marked plain between it and the sea. This is especially developed in the south, and is now generally called the Coastal Plain. It is of late geologi- cal age, and contains the pine barrens and seacoast swamps. The Appalachians themselves consist of many ridges, running on the north into the White Mountains, the Green Mountains, and the Adirondacks. Farther south the Highlands of New York and New Jersey, the South Mountain of Pennsylvania, the Alleghenies,the Blue Ridge, and the other southern ranges make up the great eastern continental mountain system. In western New York and Ohio we find a rolling, hilly country; in Kentucky and Tennessee, elevated tableland, with deeply worn river valley's. Indiana, Illinois, Iowa, and Missouri con- tain prairie and rolling country, more broken in southern Mis- souri by the Ozark uplift. In Michigan, Wisconsin, and Minne- sota, the surface is rolling and hilly with numerous lakes. In Arkansas, Louisiana, and Mississippi there are bottom lands along the Mississippi and Gulf with low hills back in the interior. Across Arkansas and Indian Territory runs the east and west Ouachita uplift. West of these States comes the region of the great plains, and then the chain of the Rocky Mountains, consisting of high, dome-shaped peaks and ridges, with ex- tended elevated valleys (the parks) between the ranges. Some distance east of the main chain are the Black Hills, made up of later concentric formations around a central, older nucleus. To the east lies also the extinct volcanic district of the Yellowstone National Park. In western Colorado, Utah, and New Mexico, between the Rocky Mountains and the Wasatch, is the Colorado plateau, an elevated tableland. This is terminated by the north and south Wasatch range, and is traversed east and west by the Uintah range. To the 8 KEMP'S ORE DEPOSITS. west lies the region called the Great Basin, characterized by- alkaline deserts, and subordinate north and south ranges of mountains. Next comes the chain of the Sierra Nevada, and lying between it and the Coast range is the great north and south valley of California. This rises in the comparatively low Coast range, which slopes down to the Pacific Ocean. To the north, these mountains extend into eastern Oregon and Washington, with forests and fertile river valleys. These topographical features are important in connection with what follows, for the reason that the ore deposits especially favor mountainous regions. Mountains them- selves are due to geological disturbances — upheaval, folding, faulting, etc. — and are often accompanied by great igneous outbreaks. They therefore form the topographical surround- ings most favorable to the development of cavities, waterways, and those subterranean, mineral-bearing circulations which would fill the cavities or replace the rock with useful min- erals. 1.01.05. Geological Outline, I. New EnglancL, New York, New Jersey, and Eastern Pennsylvania District. — In New England and northern New York the Archean is espe- cially developed, forming the White Mountains, the Adiron- dacks, and the Highlands of New York and New Jersey. These all consist of granite and other igneous rock, of gneiss, and of crystalline schists. There are also great areas of meta- morphic rocks whose true age may be later. The Green Moun- tains are formed of such, and were elevated at the close of the Lower Silurian. In New England there are small, scattered exposures of the undoubted Paleozoic (Devonian, Carbonif- erous). In eastern New York, and to some extent in New Jer- sey and eastern Pennsylvania, the entire Paleozoic, except the Carboniferous, is strongly developed. Up and down the coast there are narrow north and south estuary deposits of red Jura- Trias sandstone, which are pierced by diabase eruptions. The Cretaceous clays are strong, and the Tertiary strata occur at Martha's Vineyard, in Massachusetts, while over all, as far south as Trenton, is found the glacial drift. Between the Archean ridges of the Highlands, and the first foldings of the Paleozoic on the west is found the so-called Great Valley, which also runs to the south and is a very important topo- GENERAL GEOLOGICAL FACTS AND PRINCIPLES. 9 graphic and geologic feature. It follows the outcrop of the Siluro-Cambrian limestones, to whose erosion it is due. II. Eastern -Middle and Southeastern Coast District. — The low plains of the coast are formed by Quaternary, Terti- ary, and Cretaceous, consisting of gravel, sand, shell beds, and clay. Inland there are exposures of Jura- Trias, as in the north. The Archean crystalline rocks are also seen at numer- ous points not far from the ocean. Florida is largely made up of limestones, with a mantle of calcareous sand. III. Allegheny Region and the Central Plateau. — The Appalachian mountain system, from New York to Alabama, consists principally of folded Paleozoic (largely Carboniferous), with Archean ridges on its eastern flank. There is an enor- mous development of folds, with northeast and southwest axes. On the west they are succeeded by the plateau region of Ken- tucky and Tennessee, chiefly Paleozoic. Along central latitudes the Archean does not appear again east of the Mississippi. IV. Region of the Great Lakes. — In Michigan, Wiscon- sin, and Minnesota the Archean rocks are extensively devel- oped, both Laurentian and Huron ian. Around Lake Superior are found the igneous and sedimentary rocks of the Keweena- wan, followed by the lower Paleozoic. Lake Michigan and Lake Huron are surrounded by Silurian, Devonian, and Car- boniferous; Lake Erie by Devonian; Lake Ontario, by Silu- rian. Running south through Ohio, we find an important fold known as the Cincinnati uplift, with a north and south axis. It was elevated at the close of the Lower Silurian. In the lower peninsula of Michigan and in eastern Ohio and western Pennsylvania the Carboniferous is extensively developed. V. Mississippi Valley. — The headwaters of the Mississippi are in the Archean, It then passes over Cambrian and Silu- rian strata in Minnesota. Wisconsin, northern Iowa, and Illi- nois, which in these States lie on the flanks of the Archean ''Wisconsin Island" of central Wisconsin. These are suc- ceeded by subordinate Devonian, and in Southern Iowa, Illi- nois, and Missouri by Carboniferous. In southern Missouri the Lower Silurian forms the west bank. Thence to the Gulf the river flows on estuary deposits of Quaternary age, with Tertiary and Cretaceous farther inland. VI. The Gulf Region. — The Gulf States along the water 10 KEMP'S ORE DEPOSITS. front are formed by the Quaternary. This is soon succeeded inland by very extensive Tertiary beds, which are the princi- pal formation represented. VII. The Great Plains. — West of the Paleozoic rocks of the States bordering on the Mississippi is found a broad strip of Cretaceous running from the Gulf of Mexico to and across British America, and bounded on the west by the foothills of the Rocky Mountains. A few Tertiary lake deposits are found in it. Quite extensive Triassic rocks are developed on the south. The surface is a gradually rising plateau to the Rocky Mountains. VIII. Region of the Rocky Mountains^ the Black Hills, and the Yellowstone National Park, The Rocky Mountains rise from the prairies in long north and south ranges, consist- ing of Archean or Algonkian axes with the Paleozoic in relatively small amount in Colorado, but present in a large cross- section in Montana. There is abundant Mesozoic on the east and west flanks. In the parks are found lake deposits of Ter- tiary age. There are also great bodies of igneous rocks, which attended the various upheavals. The principal upheavals began at the close of the Cretaceous. The outlying Black Hills consist of an elliptical Archean core, with concentric Paleozoic and Mesozoic strata laid up around it. The National Park consists chiefly of igneous (volcanic) rocks in enormous development. IX. Colorado Plateau, — The Rocky Mountains shade out on the west into a great elevated plateau, extending to central Utah, where it is cut off by the north and south chain of the Wasatch. The Uintah Mountains are an east and west chain in its northern portion. The rocks on the north are chiefl}^ Terti- ary, with Mesozoic and Paleozoic in the mountains. To the south are found Cretaceous and Triassic strata, with igneous rocks of great extent. The principal upheaval of the Wasatch began at the close of the Carboniferous, and seems still to be in progress. X. Region of the Great Basin, — Between the Wasatch and the Sierra Nevada ranges is found the Great Basin region, once lake bottoms, now very largely alkaline plains of Qua- ternary age. The surface is diversified by subordinate north and south ranges, formed by great outflows of eruptive rocks, GENERAL GEOLOGICAL FACTS AND PRINCIPLES. H and by tilted Paleozoic. The ranges are extensively broken and the stratified rocks often lie in confused and irregular positions. There is no drainage to the ocean. XI. Region of the Pacific Slope. — The depression of the Great Easin is succeeded by the heights of the Sierra Nevada. On the west the Sierras slope down into the Central Valley of California. The flanks are largely nietamorphosed Jurassic and Cretaceous rocks with great developments of igneous out- flows. The surface rises again in the Coast ranges, which slope away farther west to the ocean. In addition to the Jurassic and Cretaceous, the Tertiary and Quaternary are also devel- oped, and in the Coast ranges are many outflows of igneous rock. The principal upheaval of the Sierra Nevada began at the close of the Jurassic, that of the Coast range at the close of the Miocene Tertiary. XII. Region of the Northwest. — Washington and Oregon, along the coast, are formed by Cretaceous and Tertiary strata similar to California. But inland, immense outpourings of igneous rocks cover the greater portion of both States and ex- tend into Idaho. On the north the Carboniferous is extensive, running eastward into Montana. Quaternary and Tertiary lake deposits are also not lacking. 1.01.06. On the Forms Assumed by Rock Masses. — All sedimentary rocks have been orginally deposited in beds, ap- proximately horizontal. They are not of necessity absolutely horizontal, because they may have been formed on a sloping bot- tom, or in a delta, in both of which cases an apparent dip ensues. We find them now, however, in almost all cases changed from a horizontal position by movements caused primarily by the compressive strain in the earth's crust. Beds thus assume folds known as monoclines, anticlines, and synclines. A monocline is a terrace-like dropping of a bed without changing the direction of the dip. There is usually a zone, more or less shattered, along the folded portion, and such a zone may become a storage receptacle. Monoclines of a gentle character in Ohio, which have been detected by Orton in stud- ies of natural gas, have been called **arrested anticlines." An anticline is a convex fold with opposing dips on its sides, while a syncline is a concave fold with the dips on its sides coming together. We speak of the axis of a fold, and this 12 KEMP'S ORE DEPOSITS, marks the general direction of the crest or trough. The axis is seldom straight for any great distance. Folds are often broken and faulted across the strike of their axes, and this causes what is called a ** pitch" of the axes and makes the original dips run diagonally down on the final one. Folds are the primary cause of the phenomena of dip and strike. Hori- zontal beds have neither. A dome-like elevation of the beds, with dips radiating in every direction from its summit, is called a quaquaversal, but it is a rare thing. An anticline or syncline with equal dips on opposite sides of its axis is called a normal fold. If the dip is steeper on one side than on the other, it is an overthrown fold ; if the sides are crushed to- gether, it is a collapsed, or sigmoid fold. Igneous rocks are in the form of sheets (the term **bed" should be restricted to sedimentary rocks), knobs or bosses, necks, laccolites, and dikes. A sheet is the form naturally as- sumed by surface- flows, and by an igneous mass which has been intruded between beds. It has relatively great length and breadth as compared with its thickness, and coincides with its walls in dip and strike. A knob, or boss, is an irregu- lar mass, of approximately equal length and breadth, which may be related in any way to the position of its walls. Such masses are often left projecting by erosion. A neck is the filled conduit of a volcano, which sometimes remains after the over- lying material has been denuded. A laccolite is a lenticular sheet which has spread between beds laterally from its conduit, and thus has never reached the surface, unless revealed by sub- sequent erosion. A dike is a relatively long and narrow body of igneous rock which has been intruded in a fissure. It is analogous to a vein, but the term "vein" ought not to be ap- plied to an undoubtedly igneous rock. Some granitic mixtures, however, of quartz, feldspar, and mica, leave us yet in uncer- tainty as to whether they are dikes or veins. (See Example 51.) From the above it will be seen at once that bosses, knobs, and necks may be practically indistinguishable. CHAPTER IL THE FORMATION OF CAVITIES IN ROCKS AND THEIR SECOND- ARY MODIFICATION — SUBTERRANEAN WATERS. 1.02.01. Tension Joints. — In the contraction caused by cool- ing, drying, or hardening, both igneous and sedimentary rocks break into more or less regular masses along division planes, called joints, or diaclases. Numerous cracks and small cavities result. Basaltic columns, or the prismatic masses, formed by the separation, in cooling and consolidating, of the heavier basic rocks, along planes normal to the cooling surface, are good illustrations of the first. Larger manifestations of them often become filled with zeolites, calcite, and other secondary Fig. 1. — Illustration of rifting in granite at Cape Ann, Mass. After R. S. Tarr. Amer. Jour, of Sci., April, 1891. minerals. Granitic rocks and porphyries break up less regu- larly from the same cause, but still exhibit prismoids and polygonal blocks and benches.^ Large cracks have been re- ferred to this cause, which have afterward formed important receptacles for ores. (See Example 11a.) The nature of the strain which produces the Assuring makes * J. P. Iddings' paper on "The Columnar Structure in the Igneous Rocks on Orange Mountain, N. J.," Amer. Jour. Sci., III., xxxi. 320, is an excel- lent discussion. 14 KEMP'S ORE DEPOSITS. the term *' tension joint'' an excellent name for them. ^ There are, however, other varieties of tension joints. Sedimentary rocks, that contain a large quantity of water when first formed, may lose it in whole or in part, and may shrink and crack for this reason, precisely as does the mud on the bottom of a dried puddle. Ledges in many parts of the world are exposed during the day to a hot sun, and during the night cool down to a com- paratively low temperature. The alternate expansion and con- traction may produce tensional stresses leading to the produc- tion of joints. The concentric surfaces of parting which are so often displayed in granite quarries, and which resemble the coats of an onion, have been referred to this cause. When stratified rocks become folded into anticlines and synclines, tensional strains are developed in the upper laj'ers of the anti- cline, and the lower layers of the syncline, respectively above and below the surface of no strain. Rupture almost always results, and cracks or joints are produced, which nm parallel with the axis of the fold. Cross-folding may then develop an- other series at an angle with the first. 1.02.02. Cleavage, Fissility and Compression Joints. — In speaking of the effects of pressure upon rocks, it is in many respects convenient to follow again the nomenclature of Van Hise, as established in the paper last cited, ^ and to distinguish at the outset between cleavage and fissility. Cleavage is the **capacity present in some rocks to break in some directions more easily than in others;" whereas fissility is *'a structure in rocks by virtue of which they are already separated into paral- lel laminae in a state of nature." Fissility is therefore practi- cally a development of joints on a very extensive and closely set scale, and chiefly in one direction. Cleavage, on the other hand, does not necessarily imply cavities and has not a very important bearing on the present discussion. A case has been met in the granites of Cape Ann, however, that deserves men- tion. The granites are known to possess a tendency to split along certain planes that greatly facilitates the operations of the workmen. R. S. Tarr discovered by microscopic study, * C. R. Van Hise, "Principles of North American Pre-Cambrian Geol- ogy," XVI Annual Report Director U. S. Geological Survey, Part I., p. 668. 2 Op. dt, p. 633. ON THE FORMATION OF CAVITIES IN ROCKS. 15 that coincident with this * 'rifting" there was a minute breccia- tion that had no connection with the cleavage of the component minerals or their bounding surfaces. The brecciation has manifestly resulted from compression, and it is obvious that its presence made the granite much more permeable to water. A rock of this character, if in a region of ore deposition, would quite readily become Impregnated. Both the joints produced by cooling and those formed by drying and consolidation may be afterward modified or increased by rock movements, and still different ones may be brought about independently of either. Indeed, it is a growing belief among observers, that even the joints in- sedi- mentary strata, which have been usually referred to contrac- tional strains during consolidation, are the products of pressure or of other dynamical causes, external to the rock mass itself. It may be a very difficult matter to differentiate the effect of one from that of the other, but pressure and torsion would naturally occasion displacement, if only on a microscopic scale. W. O. Crosby has suggested the undulatory tremor of an earthquake as of possible importance. The experiments of Daubree indicated that pressure would produce joints, and that in a homogeneous medium two sets would result at right an- gles with each other, and each at 45° with the direction of the pressure. This theoretical regularity is not met in nature, alike from the heterogeneous character of rocks and from the complexity of the strains to which they are subject. G. F. Becker has sought in the several recent papers cited below to analyze in a mathematical way the theoretical application and effects of such strains. Torsional stresses referred to above have been suggested as having important bearings on natural phenomena, and especially since the experimental work of Daubree along these lines, but Becker is led to question their extended application to rocks. As regards the finer textural characteristics of certain joint surfaces, J. B. Woodworth has contributed some very interesting observations, which, it is to be hoped, will be ex- tended to a wide series of rocks. In certain slaty rocks near Boston, the joint surfaces for a limited area exhibited small undulations, which diverge from a central axis, like the branches of a feather, but which then bend in curved surfaces 16 KEMP'S ORE DEPOSITS. of much larger development, so as to form somewhat extended corrugations. The author remarks the resemblance which the distribution of certain great fractures in the earth's crust bears to these hand specimens, a suggestion that might be tested in fractured areas containing veins. It is manifest that the passage from joints, properly speaking, and as outlined above, to slaty cleavage, schistosity and dy- namic effects, that are the results of many small fractures and shearing surfaces, is a gradual one, and that the two are inti- mately connected. The references below, therefore, embrace both, although schistosity is but briefly referred to here, as its connection is not particularly close with the origin of ore bodies, however much it may afterward affect them.^ 1.02.03. Cavities Formed by More Extensive Movements in the Earth* s Crust, — The strains produced by compression in the outer portion of the earth are by far the most important causes of fractures. The compression develops a tangential stress which is resisted by the archlike disposition of the crust. (By the term "crust" is simply meant the outer portion of the 1 G. F. Becker on the production of fissures. See paper on "The Struc- ture of a Portion of the Sierra Nevada of California," Bulletin Geological Society of America, II. 49, 1891; also "Finite Homogenous Strain, Flow andEupture of Rocks," Idem., IV. 13, 1893; "The Finite Elastic Stress- strain Function," Amer. Jour. Sci., Nov., 1893, p. 337. The above are rather mathematical for the general reader and the following are less so. " The Torsional Theory of Joints," Trans. Amer. Inst. Min. Eng., XXIV. 130, 1894; "Schistosity and Slaty Cleavage," Journal of Geology, IV. 429, 1896; " Reconnoissance of the Gold Fields of the Southern Appalachians," XVI Ann. Rep. Dir. U. S. Geol. Survey, Part III., 265-272; W. C. Crosby, "Absence of the Joint Structure at Great Depths," Geol. Maga- zine, Sept., 1881, p. 416; "Classification and Origin of Joint Structures," Proc. Boston Soc. Nat. Hist., XXII. 72, 1882; "On the Joint Stmcture of Rocks," Technology Quarterly, 1890; "The Origin of Parallel and Inter- secting Joints, Idem. , VI. 230, 1898 ; also in Amer. Geologist, Dec. , 1893, 368; G. K. Gilbert, "On the Origin of Jointed Sti-ucture," Amer. Jour. Sci., July, 1882, 50; J. Le Conte, " Origin of Jointed Structure in Undis- turbed Clay and Marl Deposits," Amer. Jour. Sci., III., xxiii. 238; W. J McGee, " On Jointed Structure, " Amer. Jour. Sci., III. xxv. 152, 476. An excellent bibliography on slaty cleavage up to 1885 will be found in a paper by Alfred Harker, in Rep. British Assoc, for the Advancement of Science, 1885, 813, and upon this and other kindred subjects, Daubree's Etudes Synthetiques de Geologie Experimentale, 1879, Part I. ; Sub Part II., Chaps. I. -IV. ' ON THE FORMATION OF CAVITIES IN ROCKS. 17 globe without reference to the character of the interior. ) Where there is insufficient support, gravity causes a sagging of the material into synclinals, which leave salient anticiinals be- tween them. "Where the tangential strain is also greater than the ability of the rocks to resist, they are upset and crumpled into folds from the thrust. Both kinds of folds are fruitful causes of fissures, cracks, and general shattering, and every slip from yielding sends its oscillations abroad, which cause breaks along all lines of weakness. The simplest result, either from sagging or from thrust, is a fissure, on one of whose sides the wall has dropped, or on the other of which it has risen, or both, as will be more fully described under "Faults." If the rocks are firm and quite thicklj^ bedded, as is the case with lime- stones and quartzites, the separation is cleanly cut ; but if they are softer and more yielding, they are sheared downward on the stationary or lifting side, and upward on the one which relatively sinks. Such fissures may pass into folds along their strike, as at Leadville, Colo. 1.02.04. A phenomenon which is especially well recognized in metamorphic regions, and which is analogous to those last cited, is furnished by the so-called '* shear zones." A faulting movement, or a crush, may be made apparent in rocks of this character by changes in mineralogical composition and structure, as well as by clearly fractured rocks. Massive diabases, for in- st-ance, pass into hornblende schists or amphibolites for limited stretches. Garnets and other characteristically metamorphic minerals appear, and pyroxenes alter to amphiboles. Strains are manifested in the optical behavior of the minerals in thin sections of specimens taken from such localities. These crushed strips, or shear zones, may be formed with very slight displacement, but they afford favorable surroundings for the formation of ore bodies. This conception of the original condi- tion of a line of ore deposition is a growing favorite with recent writers, and combined with the idea of replacement is often applicable. Fahlbands, which are very puzzling prob- lems, may have originated as shear zones. 1.02.05. A more extended effect is produced by the mono- cline, which has a double line of shattered rock marking both the crest and foot of its terrace. Anticlines and synclines occasion the greatest disturbances. Comparatively brittle 18 KEMP'S OBE DEPOSITS. materials like rocks cannot endure bending without suffering extended fractures. When strained beyond their limit of resist- ance, along the crest of an anticline, and in the trough of a syn- cline, cracks and fractures are formed which radiate from the axis of each fold. As these open upward and outward in anti- clines, they become the easiest points of attack for erosion, so that it is a very common thing to find a stream flowing in a gorge, which marks the crest of an anticline, while synclinal basins are frequently left to form the summits of ridges, as is so markedly the case in the semi-bituminous coal basins of Pennsylvania. It is quite probable, however, that the anti- cline may have been leveled off at this fissured crest because it was upheaved under water and became exposed at its vulner- able summit to wave action. Ore deposits may collect in these fissured strips, of which the lead and zinc mines of the upper Mississippi Valley (Example 24) are illustrations. Such fissures are peculiar in that they exhibit no displacement. The accompanying figure is from a photograph of a gaping crack in the Aubrey (Upper Carbonif- erous) limestone, twenty-five miles north of Canon Diablo sta- tion, Ariz., on the Atlantic and Pa<^ific Railroad. It was caused by a low anticlinal roll and contained water about one hundred feet below the top. Its reproductions of the condi- tions of a vein, with horse, pinches and swells, devious course, and all, is striking. The photograph was made by Mr. G. K. Gilbert, of the United States Geological Survey, and to his courtesy its use is due. While it is true that in many regions the folds and fractures have resulted in this simple way, and exhibit tbe unmistaka- ble course through which they have passed, yet geological structure is by no means always so clear. Extended disturb- ances, great faults and displacements, combined with folds and the intrusion of igneous rocks, have often so broken up a dis- trict that it is a matter of much difficulty to trace out the course through which it has passed. Subsequent erosion, or the superposition of heavy beds of gravel or forest growths, etc., may so obstruct observation even of the facts as to add to* the obscurity. The expense of making and the consequent scarcity of accurate contour maps to assist in such work are other obstacles. The profound dynamic effects wrought by ON THE FORMATION OF CAVITIES IN BOCKS. 19 mountain-making processes, although in individual cases pro- ducing only the simpler phenomena already cited, yet in gen- eral are much more extensive, and must be considered in the study of many large districts. When folds are the result of compression or thrust, the dynamic effects are more marked than in those formed by sagging. Faults are larger and more abundant. When sedimentary beds have been laid down along an older axis of granite or some equally resistant rock and the thrust crowds the beds against this axis, the conditions are eminently favorable to great fracturing and disturbance. The flanks of the Rocky Mountains furnish such examples. 1.02.06. There are also great lines of weakness in the outer portion of the earth, which seem to have been the scene of faulting movements from a very early period. Thus, on the western front of the Wasatch Mountains, in Utah, is a great line of weakness, that was first faulted, asnearlj^as we can dis- cover, in Archean times, and has suffered disturbances even down to the present. A few instances of actual movements within recent years have been recorded. In 1889 a sudden small fold and fissure developed under a paper mill near Ap- pleton. Wis., and heaved the building four and a half inches. (See F. Cramer, "Recent Rock Flexure," Amer. Jour. Sci., III., xxxix. 220.) This occurred in what was regarded a set- tled region, and one not liable to disturbance. 1.02.07. Wherever igneous rocks form relatively large por- tions of the globe they necessarily share extensively in ter- restrial disturbances. Not being often in sufficiently thin sheets, they rarely furnish the phenomena of dip and strike. Folds are largely wanting. Thej^ are replaced by faults and shattering. The fissures thus formed are at times of great size and indicate important movements. The Comstock Lode fis- sure is four miles long and in the central part exhibits a vertical displacement of three thousand feet. (See 2.11.21.) Such fissures seldom occur alone, but minor ones are found on each side and parallel with the main one. 1.02.08. The intrusion of igneous dikes may start earth- quake vibrations which fracture the firm rock masses. Fis- sures caused in this way radiate from the center of disturbance or else appear in concentric rings. The violent shakings which so often attend great volcanic eruptions, and the sinking of 20 KEMP'S ORE DEPOSITS. the surface from the removal of underlying molten material, all tend to form cracks and cavities. They are possible causes which may well be borne in mind in the study of an igneous district. 1.02.09. Faults. — When fractures have been formed by any of the means referred to above, and the opposite w^alls slip past each other, so as not to correspond exactly at all horizons, they are called "faults," a term which indicates this lack of correspondence. The separation is chiefly due to the relative slipping down or sinking of one side. The distance through which this has taken place is called the amount of displacement, or throw. Fig. 3. — Normal fault, Leadville, Colo. After A. A. Blow. Trans. Amer. Inst Min. Eng., XVIII, 180. Plate IV. Faults are most commonly inclined to the horizon, so that there is both a vertical and a horizontal displacement. The in- clination of a fault plane to the horizontal is called the dip, just as in the case of stratified rocks. Its inclination to the vertical is the hade. Faults most commonly run parallel with the strike of inclined rocks, and are then called *' strike-faults.'* When they cut across the strike and are in the direction of the dip they are called '* dip- faults." Experience has shown that Fia. 2. — Open fissure in the Aubrey limestone (Upper Carboniferous) miles north of Canon Diablo Station, Ariz., on the A. & P. R. R. Reproduced from a photograph by G. K. Gilbert, 1892. (Science, August 2. 1895, 118.) ON THE FORMATION OF CAVITIES IN ROCKS. 21 where beds or veins encounter faults and operations are brought to a standstill, the continuation is usually found as follows, according to Schmidt's law. If the fault dips or hades away from the workings, the continuation is down the hade; if it dips toward the workings, it should be followed upward. Such a fault is called a normal, or gravity fault, and is illustrated in the figure on p. 20, after A. A Blow. This is a natural result of the drawing apart of the two sides. The least supported mass would slip down on the one which has the larger base. Less commonly the opposite movement results. Thus, when the fault is due to compression, the beds pass each other in the reverse direction, and what is called a reverse fault results. The accompanying cut illustrates a very extended one in the SECT/ON f. Cohuttu^ ContjlomevaU ^^^ Ocoee Slate Knox Dolomite ^^^^^^^^I^^Z^rzI^^^^^^-^y^ Coimasauga SfialeS StCTlON S Fig. 4. Reversed Fault at Holly Creek, near Dalton, Qa. After C. W, Hayes, Bull G. S. A., Vol. II., PI 3, p. 152 southern Appalachians. While we would naturally think of a reversed fault as resulting from a compressive strain, in that in this case the lower wedge-shaped portion would be forced under the upper one, yet normal faults can likewise, in in- stances, be explained by compression. If we consider the fault to be caused by the vertical thrust or component, that would al- ways be present in the compression of a completely supported arch, this would tend to heave upward the portion next the fissure that had the larger base. Along an inclined fracture such portion is manifestly the under one. Again, if the com- pressive strain is applied in a direction parallel w^ith the fissure, and not at right angles to it, the hanging wall might be forced to bulge downward and the footwall upward, thus 22 KEMP'S ORE DEPOSITS. yielding a normal fault by compression. It is important to note whether the fault plane, both in normal and in reversed faults, cuts inclined beds in the direction of the dip or across it, because the relative amount of vertical and lateral displace- ment is much affected by these considerations. (See Margerie and Heim, Dislokation der Erdrinde, Zurich, 1888.) 1.02.10. The movement of the vv^alls on each other produces grooves and polished surfaces called slickensides, or slips. They are usually covered with a layer of serpentine, talc, or some such secondary product. The strain caused by the move- ment may in rare instances leave the slips in such a state of tension that when, from any cause, such as excavation, the pressure is relieved, they will scale off with a small explosion.^ Observations on the directions of slips may, in cases of doubt, throw some additional light on the direction of the movement which occasioned the fault. Some particular and recognizable bed or vein may be crushed and dragged down by the faulting movement, and afford the so-called *Hrail of the fault," which will indicate the direction of movement and direct the miner. But the best guide in stratified rocks is a knowledge of the suc- cession of the beds as revealed by drill cores or excavations. Attempts have been made to deduce mathematical formulas for the calculation of the amount of downthrow or upthrow, and when sufficient data are available, as is often the case in coal seams, this may be done. The methods depend on the projection of the planes in a drawing, on the principles of ana- lytical geometry, and on the calculation of the displacements by means of spherical trigonometry.^ Prof. Hans Hoefer has called attention to the fact that in faulting there is frequently a greater displacement in one por*^ion of the fissure than in a neighboring part, and even a difference of hade. This causes a twisting, or circular movement of one wall on the other, and 1 See A. Strahan, "On Explosive Slickensides," Geological Magazine, IV. 401, 522. 2 See G. Koehler, Die Storungen der Gunge, Flotze und Lager, Leijjzig, 1886 ; William Englemann. A translation by W. B. Phillips, entitled, "Ir- regularities of Lodes, Veins and Beds," appeared in the Engineering and Mining Journal, June 25, 1887, p. 454, and July 2, 1887, p. 4. A very ex- cellent paper, having a quite complete bibliography, is F. T. Freeland's "Fault Rules." Trans. Amer. Inst. Min. Eng., XXI. 491, 1892. OlS" THE FOBMATION OF CAVITIES IN ROCKS. 23 needs to be allowed for in some calculations/ In the Engineer- ing and Mining Journal for April and May, 1892, a quite extended discussion of faults by several prominent American mining engineers and geologists is given, apropros of the ques- tion raised by Mr. J. A. Church as to whether fissure veins are more regular on the dip or on the strike. In a relatively uniform massive rock the regularity should be greater on the dip, but in inclined and diversified stratified rocks too many variables enter to warrant any sweeping assertions. In soft rocks like shales the fissure may become so split into small stringers as to be valueless. Again, in very firm rock, where there is little drawing apart, the fissure may be very tight. Fig. 5. Illustration of an older vein, the Jurribo, faulted by a later one, (cross-vein) at Newman Hill, near Rico, Colo. After T. A. Rickard, Trans. Amer. Inst. Min. Eng., XXVI., 951. In the veins of Newman Hill, near Eico, Colo, (see 2-09.11), the fissure is so narrow above a certain statum as practically to fail. Quartzite is a favorable rock for such effect. Despite all rules, faults are often causes of great uncertainty, annoy- ance, and expensive exploration. 1.02.11. If a number of faults succeed one another in a short distance, they are called ''step faults." An older and completed vein may also be faulted by one formed and filled later. In such a case the continuous one is the younger. Figure 5 above will illustrate each case. At the intersection of the two, the later vein is often richer than in other parts. 1.02.12. If a faulted series of rocks is afterward tilted and eroded, so as to expose a horizontal section across the strike of the faulting plane, an apparent horizontal fault may result; or * Oesterreiches Zeitschrift fiir Berg-und Hilttemvesen, Vol. XXIX. An abstract in English is given by R. W. Raymond, Titans. Amer. Inst. Min. Eng., X. 456, 1882. 24 KEMP'S ORE DEPOSITS. if the erosion succeeds normal faulting and lays bare two un- conformable beds each side of the fissure, a lack of correspond- ence in plan as well as in section may be seen. Faulting frac- tures are seldom straight; on the contrary, they bend and cor- rugate. When the walls slip past each other, they often stop with projection opposite projection, and depression opposite depression. These irregularities cause pinches and swells in the resulting cavity, and constitute one of the commonest phe- nomena of veins. Fisij^ures also gradually pinch out at their extremities, or break up into various ramifications that finally entirely cease. They may pass into folds, as stated above. It is not surprising, therefore, that in stratified rocks, the largest faults, as a matter of observation, are usually parallel w4th the general strike. They cross the strike or run in the sense of the dip much less frequently. 1.02.13. Zones of Possible Fracture in the Earth's Crust. — In a discussion of the deformation of rocks C. R. Van Hise^ has recently established the conception of three zones in the earth's crust, which are intimately connected in a large way with the subjects just discussed. They are (1) an upper zone of fracture; (2) a middle zone of combined fracture and plas- ticity; (3) a lower zone of plasticity. (1) Rocks under less weight than their ultimate strength, when rapidly deformed, are in the zone of fracture. This is manifestly incontroverti- ble and the conception adds to the points touched on in preced ing paragraphs the important further one of the load under which the rocks stand at the time of experiencing the strain. As alreadj" pointed out, the character of the wall rock will influence the resulting fissure, firm rocks giving clean-cut fissures, while soft rocks, such as shales, will more readily break along multitudes of small cracks. The amount of load is also important, for with its increase even the firmest rock could not fracture, as is shown in describing the next two zones. It is also manifest that the depths of the zones are vari- able in different regions, on account of local differences of rocks, and that they are not to be too sharply viewed in a quan- titative way. ^ Principles of North American Pre Cambrian Geology, XVI. Annual Rep Dir U. S Geol. Survey, Part 1 , 589, 1896. See also Journal of Geology, IV. 195, 312, 449, 593. ON TEE FORMATION OF CAVITIES IN ROCKS. 25 In round numbers the maximum depths at which cavities can exist varies from 500 meters (1,625 ft.) for soft shales to 10,000 meters (32,500 ft.) for firm granites. These maximum depths introduce zone (3), or the zone of flowage, wherein the load is so excessive that the yielding to deformation comes in the wa}' of a viscous flow, or plastic yielding, evidences of which are visible in many gneisses. That such a zone exists will appear to any one who reflects upon the necessary behavior and yield- ing of rocks, which are confined on all sides and yet are com- pressed beyond their limits of resistance. The second or inter- mediate zone embraces the border region between (1) and (3), or the region of combined fracture and flowage. These considerations have an important bearing on the forma- tion of veins, because they indicate that veins must be limited to the outer portions of the globe and must have always formed in such surroundings. The considerations as regards their practical bearing are largely theoretical, it must be admitted, because even moderate estimates of the depth of zone (1) soon reach below the limit of possible mining,^ but in their broad scientific bearings they are a valuable aid to the formation of correct views on the necessary place of origin of veins. The "ewige Teufe" of the earlier miners is therefore quite limited. 1.02.14. Secondm^y Modifications of Cavities. — Fractures and cavities of all sorts speedily become lines of subterranean drainage. The dissolving power of water, and to a much smaller degree its eroding power, serve to modify the walls very greatly. An enlargement may result, and what was per- haps a small joint or fissure may become a waterway of con- siderable size. This is especially true in limestones, in which great caverns (like tbe Mammoth Cave and Luray's Cave) are excavated. Caves are, however, almost always due to surface water, and do not extend below the permanent water level un- less they have been depressed after their formation.^ 1.02.15. The subterranean movements of water are of prime importance in connection with so many aspects of the subject of ore deposits that it is necessary to have a fairly definite con- * See in this connection A. C. Lane, "How Deep Can we Mine?" The Mineral Industry, IV. 767. 10,000 ft. is placed as a general limit, with possibilities as far as 15,000, but probably not much beyond. ' See J. S. Curtis, Monograph VII, U. S. Geol. Survey, Chap. VIII. 26 KEMP'S ORE DEPOSITS. caption of their nature and causes. Water falling on the sur- face as rain in part runs off at once, in part evaporates, at least before it has gone far, and in part sinks into the ground. With the last named we are especially concerned. World-wide experience long ago demonstrated that under all portions of the land, unless possibly in excessively arid and exceptional districts, there is a body of almost stationary water, that main- tains a very constant level and that will fill a well if one is sunk sufficiently deep. Where the rainfall is heavy this *' per- manent water level" or "ground water" stands only a short distance below the surface, it may be only a few feet ; but in regions of slight rainfall, it is correspondingly depressed. It varies also, more or less, with the nature of the local rocks, with the nearness or remoteness of low-lying valleys and with the geological structure.^ The "ground water" that stands at this level is to be distinguished from the actively circulating water above it — the "vadose" circulation of Posepny,^ whose recent treatise has served to focus attention upon this phase of the subject — and is not itself without motion, because where it is situated above some more or less remote and lower lying outlet it passes toward it by a slow, gradual flow, or sinks downward, moves laterally and rises again by a siphonic ac- tion. Cracks and clefts are the chief lines of movement in both these circulations, and instances are known of communi- cations across wide intervals. Capillary circulations are also not lacking but are of less quantitative moment. As solvents of rocks the ground-water circulations are not comparable with the vadose, for, as already remarked, caves, the chief results of such solution and removal, are essentially products of the latter. 1.02. 16. The ground-water stands between the motive power of the overlying hydrostatic column and the further motive power of the underlying heated zones of the earth, to which some of the surface water attains, more or less by capillary movements. Daubree has shown that capillary attraction is 1 See, in this connection, T. C. Chamberlin, "The Requisite and Qualify- ing Conditions of Artesian Weils," Fifth Annual Rep. Dir. U. S. Geol. Survey, 131, 1885. ^Transactions Amer. Inst. Min. Eng., XXIII. 313,1893. Reissued as *' Genesis of Ore Deposits," in which see p. 17. ON THE FORMATION OF CAVITIES IN BOCKS. 27 ■effective even against steam pressure/ Cooling but still heated intrusions of igneous rocks, which may not necessarily reach the surface, are doubtless the most serious of all these internal stimulators, and furnish us with the most reasonable cause for those active circulations, that have led to ore-deposi- tion in regions of extended mineral veins. They are at once localized, of relatively abrupt development, and the}^ bring great stores of heat within the conceivable zones of the ground- water's existence. It is also quite probable that waters and other fluid or vaporous substances are emitted and driven out- ward, which are not derived from infiltrations from the surface, but which have been involved in the substance of igneous mag- mas since their derivation from the original nebula. All these circulations from deep-seated sources are more likely to be fillers than enlargers of cavities in the upper portions of the zone of fracture. It is conceivable that the heat necessarily developed in the crushing and fracture of rocks on a large scale may also be an important local stimulus and in this way contribute in no small degree to the final results. 1.02.17. The solvent action of water is vastly augmented by the carbonic acid which it gathers from the atmosphere, and this is the chief cause of the excavations wrought by it in lime- stones. Pure cold water has comparatively small dissolving and almost no eroding power. It has also been advocated that various acids which result from the decay of vegetable matter aid in such results.^ This may be true, but in general carbonic acid is the chief agent. Iron in minerals falls an easy prey, as does calcium, and both are dissolved out in large amount. (See Example 1.) When charged with alkaline carbonates, water has the power to attack other less soluble minerals, such as quartz and silicates, and by such action the walls of a cavity in the crystalline rocks may be much affected. ^ The most important works bearing on this entire question of under- ground waters are those of Daubree, viz. : "Etudes Synthetiques de Geologie Experimental e," 1879. "Les Eaux Souterraines aux Epoques anciennes," 1887. "Les Eaux Souterraines a I'Epoque actuelle," 1887, 3 vols. Suggestive reading will also be found in C. R. Van Hise, ' ' Metamorph- ism of Rocks and Rock-flowage, Bull. Geol. Soc. Amer., IX. 269. ' A. A. Julien, Amer. Asso. Adv. Sci., 1879, p. 311. 2S KEMP'S ORE DEPOSITS. 1.02. 18. As has been set forth in a previous paragraph, waters percolating to great depths in the earth, or circulating in re- gions of igneous disturbances, become highly heated, and this too at great pressure. Under such circumstances the solvent action, is very strongly increased, and all the elements present in the rock-making minerals are taken into solution. Alka- line carbonates are formed in quantity; silica is easily dis- solved; alkaline sulphides result in less amount; and even the heaviest and least tractable metals enter into solution, either in the heated v^aters themselves, or in the alkaline liquors formed by them. The action on the walls of cavities and courses of drainage is thus profound, and accounts for the fre- quent decomposed character of the walls and the general lack of sharpness in their definition. The vast amount of siliceous material deposited by hot springs and geysers is additional evi- dence of its importance. When the uprising solutions reach the regions of diminished temperature and pressure they con- tribute their burden of dissolved minerals to veins and surface accumulations. 1.02.19. The composition of mineral springs is of the great- est interest in this connection, and is a subject that has received much attention in recent years. ^ The vast majority of those recorded contain chiefly silica and salts of alkalies and alkaline earths, of which a few represent the gangue minerals. Here and there, however, examples with metallic contents have been detected, and in several instances springs have been met in deep mines and the waters have been analyzed. Often the ore deposition, as indicated by these, seems to have ceased, but again either in the waters themselves or in crusts formed by them, metallic minerals have been detected. In the table be- low the first seven relate to American cases, the last three to ^ R. N. Brackett, " Mineral Waters of Arkansas," Geological Survey of Arkansas, 1891, I. Gooch and Whitfield, "Analyses of Waters of the Yellowstone National Park," Bulletin 4:1, U. S. Geol. Survey. A. C. Peale, "Lists and Analyses of the Mineral Springs of the United States, Bulletin 32, Idem. F. Posepny, "Genesis of Ore Deposits," pp. 26-48. J. Roth, " Allgemeine und Chemische Geologic," I. Chap, x., 407. P. Schweitzer, "The Mineral Springs of Missouri," Mo. Geol Survey,* m. 1892. ON THE FORMATION OF CAVITIES IN ROCKS. 29 European. All the amounts are expressed in parts per mil- lion, i. e., grams per 1,000 liters. 1.02.20. In analyses I. and II. metallic salts were not them- selves detected, but ammonium carbonate was, and on its presence, as well as the results of experiment, Becker bases his explanation of the introduction of the cinnabar. Cinnabar is found to be soluble in ammoniacal liquors under pressure and heat, but to precipitate again as the pressure and temperature fall. The water from Steamboat Springs did yield traces of quicksilver, but the crusts which had been precipitated at the surface of the ground in past time afforded in this order: sul- phides of arsenic and antimony, ferric hydrate, lead sulphide, copper sulphide, mercuric sulphide, gold and silver, and traces of zinc, manganese, nickel and cobalt.^ The waters from the Geyser mine were of exceptional interest. When compared with each other it is noticeable that the vadose waters (IV.) have much less metallic matter than the deep-water (V.), and that in the latter the metals appear in much the same relative abundance as in the ore (VI. and VIL). In the "Genesis of Ore Deposits," from which analyses VIII. , IX. and X. have been taken, Posepny has collected many more, and cites some in- stances abroad in which the metals have also been noted. An- timony, arsenic, bismuth, iron, manganese, copper, tin, cobalt, nickel, lead, zinc and uranium are to be numbered among them. So far as the metals are concerned all the analyses in- dicate extremely dilute solutions, and the waters must have required a very long period of time to yield the ore bodies. The dissolved content of alkaline salts must have flowed away on the surface and have disappeared. I. Water from the Hermann shaft at Sulphur Bank, Califor- nia, from a quicksilver mine. Monograph XIII., U, S. Geol. Survey, p. 259. W. H. Melville, Analyst. II. Parrott shaft, same locality. Idem. III. Steamboat Springs, Nev. Idem. p. 349. IV. Calculated composition of the vadose water at the 500- ft. level of the Geyser silver mine, Silver Cliff, Colo., in rhyo- lite tuff. The analysis is made up from analyses of the water and of the sediment that settled from it, chiefly by precipita- ^ Monograph XIIL, U. S. Geol. Survey, 343. 30 KEMP'S ORE DEPOSITS. I. II. III. IV. V. SiOj 37.15 41.85 25.90 24 42 AIqOs 0.25 1.06 A1..0,, PoOr 0.80 1.50 1.70 93.50 FeCOo •. 0.98 0.29 7 25 MnCOg 1.19 CaCOg 35.20 23.40 50.55 15.77 366 03 CaS04 CaoPoOfi 1.37 caS :!.... ...... ... ......: :.::.. Trace SrCO. 3.29 i^';-;:--:::;;::::::::::::: 18.90 5.55 0.99 42.85 4.20 16.60 621.84 19 18 K&i^*........::::::::;:::::::::: 47.05 74.70 197.35 361.34 KBr, KI Trace Na^COa . . . 1,946.75 322.60 689.05 1,039.75 43.14 111.47 1,411.75 38.70 60.50 1,489.67 223.53 NaoSOi NaCl .......................... 1,102.70 NaNOg 2.1» Na2b407 1,8/8.40 2,404.35 313.6a 390.90 290. 2:^ 3.58 8.66 1.00 56.50 NanSi^Oo SaHcfi;;::::;;;::;;::;;;:::;::: NaHS NAoAsSg Na^SbSa LLSO4 LiCl.. 17.30 (NH^UCOo 6.64 4.55 262.41 5.00 2.82 0.74 1,751.31 7.6 HoS cot 37.20 1,418.61 Orcranic matter ..•• HerS, nNaoS Trace. PbCO...... Trace. Trace. 0.40 1.74 CuCOa 0.04 ZnCOa 0.66 Gold Silver Lead Zinc Copper Iron... — Manganese Lime Sulphur Silica Total.... VI. VII. Trace. Trace. 1.05 1.27 23.80 17.60 14.00 11.10 1.50 2.30 2.30 2.00 1.20 0.80 1.70 12.60 9.50 33.60 46.90 91.75 91.47 Alk. Carbonates — Earthy Carbonates Alk. Sulphates Earthy Sulphates... Chlorides Silica Others vm. 352.00 55.00 12.00 6.00 51.00 IX. 1,150.00 510.00 82.00 1.00 2,eo 00 00 37.00 6.00 .58.00 72.00 6.00 tion mthecarbo}^ XVII. Ann. Rep. Dir. U. S. Oeol. Surv., Part II., p. 463. W. F. Hillebrand, Analyst. V. Calculated composition of deep v^aters, 2,000-ft. level, same place and conditions. Idem. VI., VII. Analyses of two carload lots of ore from same mine, made at Arkansas Valley smelter, Leadville. Idem, p. 457. The gangue was chiefly barite, calcite and chalcedony. VIII. Water from the Einigkeit's shaft, Joachimsthal, Bo- hemia, presumably at a depth of .533 meters (1,774 ft.), as stated on p. 27 of citation. Analysis on p. 38, ' ' Genesis of Ore Deposits. ' ' ON THE FORMATION OF CAVITIES IN ROCKS. 31 Analyst, J. Seifert. The table of equivalent temperatures on p. 37 of original is incorrect. IX. Gottesgeschick mine, Schwarzenberg, Saxony. Idem. Analyst, R. Richter. X. "Sprudel" spring in a colliery at Brux, Bohemia. Idem. Analyst, J. Gintl. 1.02.20* Magnesia is one of the alkaline earths readily taken into solution by carbonated waters, and when such wa- ters again meet limestone the effect is often very great, and constitutes one of the most important methods of the formation of cavities. Solutions of magnesium carbonate, on meeting calcium carbonate, effect a partial exchange of the former for the latter. This leaves the rock a double carbonate of calcium and magnesium, which is the composition of the mineral and rock dolomite. The process is therefore called dolomitization. (See Example 25.) It may bring about a general shrinkage of eleven or twelve per cent. In any extended thickness of strata this would cause vast shattering and porosity. As an illus- tration of its residts, the following analysis of normal, un- changed Trenton limestone of Ohio, and of well drillings from the porous, gas-bearing, dolomitized portions of the same, are given. They are taken from a paper by Edward Orton. (Amer. Manuf. and Iron Worlds Pittsburg, Dec. 2, 1887.) CaC03. MgCOa. Fe203,Al203. SiO^. Unchanged Trenton limestone. .79.30 0.92 7.00 12.00 ..82.36 1.67 0.58 12.34 Dolomitized *' " . .53.50 43.50 1.25 1.70 ..51.78 36.80 1.02.21. Recent studies in ore deposits by Posepny, Curtis and Emmons indicate also that solutions of metallic ores may affect an interchange of their contents with the carbonate of calcium or magnesium in limestones and dolomities, leaving an ore body in place of the rocks. This change is effected molecule by molecule, and is spoken of as a metasomatic inter- change or replacement. (See Example 30.) By "metasoma- tic" is meant an interchange of substance without, as in pseu- domorphs, an imitation of form. Alteration of the metallic ores may follow and occasion cavities from shrinkage. (See Example 36, and Curtis, on Eureka, Nev., Monograph VIII, U. S. Geol. Survey, Chap. VIII.) CHAPTER III. THE MINERALS IMPORTANT AS ORES; THE GANGUE MINER- ALS, AND THE SOURCES WHENCE BOTH ARE DERIVED. 1.03.01. The minerals which form the sources of the metals are almost without exception included in the following com- pounds: the sulphides and tellurides, the arsenides and antimo- nides, the oxides and oxidized compounds such as hydrous oxides, carbonates, sulphates, phosphates, and silicates, and one or two compounds of chlorine. A few metals occur in the native state. All the other mineral compounds such as a chromateor two, a bromide or iodide, etc., are rarities. It may be said that nine-tenths of the productive ores are sulphides, oxides, hydroxides, carbonates, and native metals. The ores of each metal are subsequently outlined before its particular deposits are described. 1.03.02. The most common gangue mineral is quartz, while in less amount are found calcite, siderite, barite, fluorite, and in places feldspar, pyroxene, hornblende, rhodonite, etc. The silicates are chiefly present where the gangue is a rock and the ore is disseminated through it. All the common rocks serve in this capacity in one place or another. 1.03.03. Source of the Metals. — The metallic contents of the minerals which constitute ores must logically be referred to a source, either in the igneous rocks, or in the ocean. If the nebular hypothesis expresses the truth — and it is the best formulation that we have — all rocks, igueous, sedimentary, and metamorphic, must be traced back to the original nebulao This, in cooling, afforded a fused magma, w^hich chilled and assumed a structure analogous to the igneous rocks with which we are familiar. Igneous rocks must thus necessarily be con- sidered to have furnished by their erosion and degradation the materials of the sedimentary rocks; while igneous and sedi= THE MINERALS IMPORTANT AS ORES, ETC. 33 mentary alike have afforded the substances whose alterations have produced the metamorphic rocks. It may also be true that eruptive rocks, especially when basic, have been formed, by the oxidation and combination with silica, of inner metallic portions of the earth, for this is one of our most reasonable explanations of volcanic phenomena, suggested alike by the composition of basalts, by the high average specific gravity of the globe, and by analogy with meteorites. 1.03.04. As opposed to this conception, there are those who would derive the metallic elements of ores from the ocean, in which they have been dissolved from its earliest condensation. Thus it is said that substantially all the metals are in solution in sea water. From the sea they are separated by organic creatures, it may be, through sulphurous precipitation, attend- ant on the decay of dead bodies. The accumulations of the remains of organisms bring the metals into the sedimen- tary strata. Once thus entombed, circulation may concentrate them in cavities. When present in igneous rocks, the latter are regarded as derived from fused sediments. If the metallic contents of sedimentary rocks do not come from the ocean in this way, the igneous rocks as outlined above are the only pos- sible source. No special mention is here made of the meta- morphic rocks, because in their original state they are refera- ble to one or the other of the two remaining classes. But it is not justifiable in the absence of special proof to consider them altered sediments, any more than altered igneous rocks, and it is doubtless true that the too generally and easily admitted sedimentary origin for our gneisses and schists has materially hindered the advance of our knowledge of them in the last forty years. 1.03.05. Microscopic study of the igneous rocks has shown that, with few exceptions, the rock-making minerals separate from a fused magma on cooling and crystallizing, in a quite definite order. ^ Thus the first to form are certain oxides, mag- netite, specular hematite, ilmenite, rarely chromite and pico- tite, a few silicates, unimportant in this connection (zircon, titanite), and the sulphides pyrite and pyrrhotite. Next after these metallic oxides, etc., the heavy, dark-colored, basic sili- * H. Rosenbusch, "Ueber das Wesen der koernigen und porphyrischen Stnictur bei Massengesteine," Neues Jahrhuch, 1882, ii., 1. 34 KEMP'S ORE DEPOSITS. cates, olivine, biotite, augite, and hornblende are formed. All these minerals are characterized by high percentages of iron, magnesium, calcium, and aluminum. They are very gener- ally provided with inclusions of the first set. Following the bisilicates in the order of crystallization, come the feldspars, and after these the residual silica, which remains uncombined, separates as quartz. 1.03.06. If we regard the igneous rocks as the source, the metallic elements are thus to be ascribed to the first and sec- ond series of crystallizations, while the elements of the gangue minerals are derived from the last three. It is a doubtful point whether the less common metals, such as copper, silver and nickel, enter into the composition of the dark silicates as bases, replacing the iron, alumina, lime, etc., or whether they are present in them purely as inclusions of the first series. F. Sandberger^ argues in support of the first view, but his critics, notably A. W. Stelzner, cast doubt upon his conclusions on the ground that his chemical methods were indecisive. The case is briefly this: Sandberger, as an advocate of views which will be subsequently outlined, separated the dark silicates of a great many rocks. By operating on quantities of thirty grams he proved the presence in them of lead, copper, tin, antimony, arsenic, nickel, cobalt, bismuth, and silver, and considered these metals to act as bases. The weak point of the demonstra- tion consists in dissolving out from the powdered silicate any possible inclusions. There seems to be no available solvent which will take the inclusions and be without effect on the silicates. This is the point attacked by the critics, and appa- * rently with reason. It is, however, important to have shown the presence of these metals, even though their exact relations be thus doubtful. Quite recently in a series of "Notes on Chil- ean Ore Deposits." Dr. Moricke^ mentions native gold in pearlstone (obsidian) from Guanaco, in skeleton crystals in the ^ The principal paper of Professor Sandberger is his "Untersuchungen fiber Erzgange," 1882, abstracted in the Engineering and Mining Journal, March 15, 22, and 29, 1884; but a long series of others might be cited in which the investigations, notably at Pribram, Bohemia, are in- terpreted as indicated above A. W. Stelzner, B. and H. Zeit. , xxxix. , No. 3, Zeitsch. d. d. a. G^eseZZ. , xxxi. 644. "Die Lateral-secretions-Theorie, etc. " Reprint Freiberg, 1889. ^ Tschermaks Min. and Petrog. Mitth. , XII. , p. 195. THE MINERALS IMPORTANT A8 ORES, ETC. 35 glass, as inclusions in perfectly fresh plagioclase and sanidine crystals, and in spherulites. G. P. Merrill has recorded gold as an original mineral in biotite-granite from Sonora, Mexico.^ A. Simundi reported years ago the existence of gold in the gran- ites of Owyhee Co., Idaho, far from any vein, to an amount equal to 25 cents per ton.^ The existence of silver in quartz- porphyry has been demonstrated in this country by J. S. Curtis, at Eureka, Nev. f both the precious metals have been shown by G. F. Becker to be in the diabase near the Comstock Lode;^ and, by the same investigator, antimony, arsenic, lead and copper, were proved to be contained in the granite near Steam- boat Springs, Nov.* S. F. Emmons has also shown that the porphyries at Leadville contain appreciable, though small, amounts of silver/ Of forty-two specimens tested, thirty -two afforded it ; of seventeen tested for lead, fourteen yielded results. Emmons has also recorded determinations of silver by L. G. EakijDs in the eruptive rocks of Custer Co,, Colo., in connection with investigations upon the interesting ore-bodies of the dis- trict. Nine rocks were assayed, embracing trachytes, an ande- site-breccia, a different andesite, rhyolite, red granite, black granite, the separated bisilicates of the last-named, and diorite. Five out of the nine contained appreciable amounts, viz., one trachyte, the rhyolite, the diorite, and both granites. The amounts vary from 0.005 to 0.402 of an ounce per ton. The separated bisilicates yielded 0.045 per cent, lead and 0.04 of an ounce of silver.^ Undoubtedly the multiplication of tests will show similar metallic contents in other regions. Thus the augite of the eastern Triassic diabase will pmbably yield cop- per, for this metal is abundant in connection with the outflows. 1.03.07. Among the igneous rocks certain metals seem to be characteristically associated with some varieties, others again with a different series, while to many no generalizations apply. The basic rocks are the richest in iron, but the metal is not lacking in the most acidic. Copper in association with ^ G. P. Merrill, Gold in Granite, Amer. Jour. Sci., April 1896, 309, Si- mundi's results are given by G. F. Becker. — Tenth Census, XIII. 52. ^ Monograph VIL, U.S. Geol. Survey, p. 80. ^ Monograph III. , U. S. Geol. Survey. " Monograph XIIL, U. S. Geol. Survey, p. 350. ^ Monograph XII., U. S. Geol. Survey, p. 569. * XVII Annual Rep. Director U. S. Geol. Survey, Part II., 471. 36 KEMP'S ORE DEPOSITS. nickel and some cobalt is found in widely separated parts of the world in basic gabbros, but other cases are equally pro- nounced in which it seems connected with igneous rocks of medium acidity, or with sediments having no visible connec= tion with igneous rocks at all. The greatest copper district now productive, Butte, Mont., has only granites and rhyolites (quartz- porphyries) exposed for miles around. Lead and zinc are more commonly associated with limestones than with any other one rock, but the precipitating action of this rock, rather than any original content of the metals in it, is probably responsible for the association. In other respects no generalizations are possiblOo Gold and silver are cosmopolitan in their relations. The former has been found in the native state in igneous granite and perlite, and with pyrrhotite in basic gabbros, aside from its occurrence in veins. Silver in one locality and another is a companion of almost all types of rock ; chromium and plati- num are certainly at home in the basic peridotites and -their serpentinous alteration products, and tin is seldom seen except in connection with granite. The other lesser metals that are of serious, practical importance admit of no general statements that are not largely speculative.^ The rarer elements do, however present some striking associations. The ''rare earths" seldom if ever occur in notable amount except in pegmatites and gran- itic rocks. Vanadium finds its peculiar home in titaniferous mag- netite, but it is of remarkably wide distribution in basic rocks in general, as shown by over sixty analyses by Hillebrand and Stokes.^ The amounts are small, in only one case reaching a tenth of one per cent., and the vanadium favors the dark sili- cates, especially biotite. It has also been detected in surpris- ing quantities in the ashes of coals in Argentina and Peru.^ ^ These questions have been discussed at length by L. De Launay, "Contribution a I'Etude des Gites Metallif eres, " Annalesdes Mines, 'Kil,, 1897, 119-228. J. H. L. Vogt, "Ueber die relative Verbreitung der Elemente, besonders der Schwermetalle und ueber die Concentration des urspriinglich fein vertheilten Metallgehaltes zu Erzlagerstatten. Zeitsch. fur praktisehe Geologie, August, 1898, to January, 1899. 2 W. F. Hillebrand, " Distribution and Quantitative Occurrence of Vana- dium and Molybdenum in Rocks of the United States," Amer. Jour, Sci. September, 1898, 209. ' W. P. Blake, Engineering and Mining Journal, Aug. 11, 1894, p. 128. Vanadium has been detected by R. S. McCaffery, E. M., in coals used at Casapalca, Peru. \* THE MINERALS IMPORTANT A8 ORES, ETC. 37 Molybdenum is much rarer and appears to be limited to the acidic rocks. The mineral molybdenite is seldom met except in pegmatites. Tungsten has practically the same associa- tions as tin. 1.03.08. That the metals are so generally combined with sulphur in ore deposits seems to be due to the extended distri- bution of this element, and to its vigorous precipitating action on nearly all the metals at the temperatures and pressures Avhich prevail near the earth's surface. Sulphur is widespread in pyrrhotite and pyrite, original minerals in many igneous rocks, and ones much subject to alteration; while sulphuretted hydrogen is common in waters from sedimentary rocks, and is a very general result of organic decomposition. Natural gas and petroleum from limestrne receptacles almost always con- tain it.^ Many sulphides, too, are soluble under the pressures and temperatures prevailing at great depths, but are deposited spontaneously at the pressures and temperatures prevailing at or near the surface. 1.03.09. Where veins occur in igneous rocks the bases for gangue minerals have been obtained from the rock-making silicates. Calcium is afforded by nearly all the important ones ; silicon is everywhere present ; barium has been proved in many feldspars, in small amount; and magnesia is present in many pyroxenes and amphiboles. Of the sedimentary rocks, limestone of course affords unlimited calcium, and recently Sandberger reports that he has identified microscopic crystals of barite in the insoluble residues of one.^ This is of interest, as barite is such a common gangue in limestone. 1.03.10. It may be remarked that the natural formation of both ore and gangue minerals has doubtless proceeded in na- ture with great slowness, and from very dilute solutions. Both classes exhibit a tendency to concentrate in cavities, even from a widely dispersed condition through great masses of compara- tively barren rock. The formation may have proceeded when the walls were far below their present position with regard to ^ See, in this connection, J. F.Kemp, "The Precipitation of Metallic Sulphides by Natural Gas, ''jEJ^igrmeermg and JtfimngrJbi p. 151. THE IRON SERIES {IN PART). 97 amounts of iron ore. Such deposits as have been found are practically all limonite (brown hematite) and are generally very low in iron. The ores occur in five districts, viz. : North- eastern Arkansas, northwestern Arkansas, the valley of the Arkansas River, the Ouachita Mountains, and southern Arkan- sas. They are generally associated with sandstones or cherty limestones. The first-named district makes the best showing. In it the ores are in Lower Silurian (Calciferous or lower) sandstones, cherts and limestones. In the second district they are in Lower Silurian cherts, and Lower Carboniferous sand- stones. In the third they occur with Carboniferous and Lower Carboniferous strata, but are also in the form of recent spring deposits. In the Ouachita Mountains they are with Lower Silurian shales and novaculites. In this district the magne- tite or natural lodestone of Magnet Cove occurs, but it is only an interesting mineral, and of no practical importance. The last district has the ores in sands and clays of the Eocene, Its continuation in Texas and Louisiana is referred to below. In eastern Texas, along the latitude of the northern boundary of Louisiana, extended beds of limonite are found capping the mesas or near their tops, and associated with glauconitic sands of Tertiary age. They are described by Penrose^ as (1) brown laminated ores, (2) nodular or geode ores, (3) conglom €rate ores. The first form extended beds whose firmness has prevented the erosion of the hills, and which are thought to have originated by the weathering of the pyrites in the greensands and from the iron of the glauconite itself. The second group occur just north of the last, and have probably resulted from the alteration of clay ironstone nodules (Cf, Example 5), while the third has formed in the streams by the erosion of the first two and from the smaller ore-streaks and segregations. Limonite also occurs in northwestern Louis- iana.^ Lawrence C. Johnson has also written of these ores,^ but the most complete account has been given by W. Ken- nedy.* Mr. Kennedy speaks of the available ores as the •'Laminated Ores" and the "Nodular Ores," both belong- ^ First Ann. Rep. Texas Geol. Survey, p. 66 ; also Bull. Oeol. Soc. Amer., III., 44. ^ Mineral Resources, 1887, p. 51. ^ Fiftieth Congress, First Session, Exec. Doc. No. 195. * 'Iron Ores of East Texas," Trans. Amer. Inst. Min. Eng., XXIV., 258, 862. 98 EEMrS OBE DEPOSITS. ing, in serious amount, to the greensand beds of the upper Eocene. An abundant series of analyses is given which shows the ores to be in general rather rich for limon- ites, and not high in sulphur or phosphorus. Accord- ing to the grade of ore now demanded and obtained on Lake Superioj, they are seldom Bessemer ores, but ought to yield excellent foundry irons. While the quantity is large, the situation precludes the use of any fuel but charcoal, and the remoteness of markets will mostly restrict the output to the comparatively limited local demand. The ore can be won by shallow stripping or from exposed beds, up to two feet or so in thickness. The geological relations of these ores are inter- esting and important in that they are derived from greensands, which consist so largely of glauconite, the double silicate of iron and potassium, and which are comparatively deep-sea deposits. The formation of glauconite ' by precipitation from sea- water, and as a filling of the small chambers in minute shells and organisms indicates^ a marine method for the concentration of iron oxide. It is significant that J. E. Spurr has lately advo- cated a similar source for the ores of the Mesabi range, Minn. (See Example 9e.) Limonite is known in a number of locali- ties in Colorado. The chief productive mines lie in Saguache County, near Hot Springs. They furnish a most excellent ore from cavities in limestones, which are generally, but with no great certainty, considered Lower Silurian. R. Chauvenet states that the ores yield about 43% Fe in the furnace.^ In Allamakee County, in the extreme northeastern corner of Iowa, important deposits of rich limonites have been dis- covered on Iron Hill near the town of Waukon^ and elsewhere, * On the formation of greensands, see W. B. Clark, Journal of Geology, II., 161, 1894. * R. Chauvenet, " Preliminary Notes on the Iron Resources of Col- orado," ^?m. Rep. Colo. State School of Mines, 1885, p. 21; " Iron Re- sources of Colorado," Trans. Amer. hist. Min. Eng., XVIII., 266. F. M. Endlich, Hayden's Reports, 1^73, p. 333. B. T. Putnam, Tenth Census, Vol. XV., p. 483. C. M. Rolker, "Notes on Certain Iron Ore Deposits in Colorado," Trans. Amer. Inst. Min. Eng., XIV., 266. Rec. ' E. Orr, "Brown Hematite in Allamakee County, Iowa,*' Amer. Ge- ologist, I., 129, 1888. W. J. McGee, "The Pleistocene History of Northeast Iowa," Eleventh Ann. Rep. Dir. U. S. Geol. Siirvey, 548, 1891. Samuel Calvin, " Geology of Allamakee Co.," Fourth Ann. Rep. Geol. Surv, Iowa, 97, 1894 Rec. THE IRON SEBIE8 {IN PART). 99 The superficial decay of the rocks in this unglaciated region has been extensive and has left a thick mantle of residual mate- rial. Calvin estimates that a total of about 800 feet of Tren- ton and Galena limestones, Maquekota shales and Niagara limestone have disappeared, leaving behind them the usual clays and the iron ore. The latter is in the form of nodules, pipes and pots, and is as much as 30 feet thick. It has less ocher and clay than is usual in residual deposits, and this fact, together with the amount of iron oxide, leads Calvin to infer more of concentration than would result by simple weathering,. The known chemical composition of the beds which have dis- appeared indicates that the strata which were formerly over the area of the ore would have furnished but a fraction of it. Fig. 13. — Ideal cross-section of Iron Hill, near Waukon, Allamakee Co., Iowa. For explanation of letters, see text. Fourth Annual Report Iowa Oeol. Survey, p. 101, 1894. Professor Calvin therefore suggests, as shown in the accom- panying figure, that a depression first formed, into which the iron oxide drained from a wide area. Having once been con- centrated, it then settled down and rested like a mantle upon the hilltop, which now stands in relief although it represents the rock formerly under the depression. In the accompanying Fig. 12, A is the St. Peter's sandstone; J5the remaining Tren- ton limestone; the black area, the present ore; CCC the origi- nal geological section ; HJE the depressed outline after consid- erable weathering and erosion, with the production of the ore at D, FF is the present outline. Much limonite occurs at Leadville in connection with the lead -silver ores, and is used as a flux by the lead smelters. Some grades low in silver and rich in manganese have even 100 KEMP'S ORE DEPOSITS. beeD used for spiegel at Pueblo. For the geological relations, see Example 30. 2.01.16. Limonites in supposed Carboniferous limestone occur in the East Tintic mining district in Utah, and seem to be associated with a decomposed eruptive rock, somewhat as at Leadville. The limonite is chiefly used as a flux by lead- silver smelters.^ 2.01.17. Example 2a. Siluro- Cambrian Limonites. — Beds of limonite in so-called hydromica (talcose, damourite), slates and schists, often also with limestones of the Cambrian and Lower Silurian systems of the Appalachians. The great extent, the geological relations and the importance of these deposits warrant their being grouped in a subtype by themselves. They extend along the Appalachians from Vermont to Alabama, and are in the ** Great Valley," as it was early termed, which A Ssr.^ . « I Engine House vr^nofand Gra vel ^ 1 _ Probably Limestone Slate Limestone (Micaceous) Fig. 13. — Geological Section of the Amenia Mine, Dutchess County, New York, Ulustratiug a Siluro-CamhHaii limonite deposit. After B^ T. Putnam, Tenth Census, Vol. XV., p. 133. marks the trough between the Aichean on the east and the first corrugations of the Paleozoic rocks, often metamorphosed, on the west. The masses of limonite are buried in ochreous clay, and the whole often preserves the general structure of the schistose rocks which they have replaced. The original string- ers of quartz remain, following the original folds. Dolomitic limestone often forms one of the walls, and still less often (but especially in New England) masses of siderite are found inclosed. Manganese is at times present, and in Vermont is of some importance of itself. 2.01.18. The deposits begin in Vermont, where in the vicinity of Brandon they have long been ground for paint. A curious pocket of lignite occurs with them, and affords Ter- tiary fossils. This prompted President Edward Hitchcock, about 1850, to refer all the limonites to the Tertiary, making » B. T. Putnam, Tenth Census, Vol. XV., p. 490. THE IRON SERIES (IN PART). 101 an instructive example of the occasional hasty generalizations of the early days. Lignite has also been found at Mont Alto, Pa. In northwestern Massachusetts, at Richmond and West Stockbridge; and just across the State line, in Columbia and Dutchess counties, New York, and at Salisbury, Conn., the mines are large, and were among the first worked in the United States. The limonite forms geodes, or *'pots," pipes, stalactitic masses, cellular aggregates, and smaller lumps from which the barren clays and ochers are removed by washing. The ore is but a fraction of the material mined and occurs in irregular streaks through the clays, etc. It is mostly obtained by stripping and open cuts, and only rarely by underground mining, which would present difficulties with such poor ma- terial for walls. ^ A gap occurs in the succession of the deposits across south- ern New York and New Jersej^ although a few minor ones are known in the western part of the latter State, in the mag- nesian limestone of the valleys between the hills of gneiss.^ 2.01.19. In Lehigh County and to the southwest through York County, in eastern Pennsylvania, the limonites are again ' J. D. Dana, " Occurrence and Origin of the New York and New Eng- land Limonites, 'i^mer. Jour. Scl, iii., XIV., 133, and XXVIII., 398. Rec. E. Hitchcock, "Description of a Brown Coal Deposit at Brandon, Vt., with an Attempt to Determine the Geological Age of the Principal Ore Beds of the United States," Amer. Jour. Sci., ii., XV., 95; Hist. Geol. Sur- vey of Vermont, I., 233. See also Lesley, below. A. L. Holley, "Notes on the Salisbury (Conn. ) Iron Mines and Works," Trans. Amer. Inst. Min. Eng., VI., 220. J. P. Lesley, "Mont Alto (Pa.) Lignites," Proc. Amer. Acad. Scl, 1864, 463-482; Amer. Jour. Scl, ii., XL., 119. L. Lesque- reux, "On the Fossil Fruits Found in Connection with the Lignite at Brandon, Vt.," Amer. Jour. Scl, ii., XXXII. , 355. H. Carvill Lewis, " The Iron Ores of the Brandon Period," Proc. ^mer. Assoc. Adv. Scl, XXIX., 427, 1880. J. F. Lewis, "The Hematite (Brown) Ore Mines, etc.. East of the Hudson River," Trans. Amer. Inst. Min. Eng., V., 216. J. G, Percival, Rep. on the Geol. of Conn., p. 132; also, Amer. Jour. Scl, ii., II., 268. R. A. F. Penrose, "Report on Manganese Ores," Geol. Survey Ark., 1890, Vol. I. (Contains many valuable descriptions of Vermont limonites.) B. T. Putnam, Tenth Census, Vol. XV. C. U. Shepherd, "Notice, etc., of the Iron Works of Salisbury, Conn.," Amer. Jour. Scl, i., XIX., 311. J. C. Smock, Bull. VII Neiv York State Museum, pp. 12, 52. N. H. and H. V. WMnchell, "Taconic Ores of Minnesota and Western New England," Amer. Geol, VI., 263. 1890. '^ B. T. Putnam, Tenth Cenms, Vol. XX., p. 176. See also Geol. Survey New Jersey, 1880. 103 KEMP'S ORE DEPOSITS. developed iD great amount, and rim southwesterly, with few gaps, to Alabama. It is in this portion that the ** Great Val- ley" (called also the Cumberland Valley, or Valley of Vir- ginia) is especially marked. Wherever the great limestone formation. No. II. of Rogers, is developed the ores are found. Thi3 corresponds to the Calciferous, Chazy, and Trenton of New York. Limonites also occur still lower in the Cambrian at about the horizon of the Potsdam sandstone or in the over . lying slates. According to McCreath, they are divisible in Pennsylvania into ores at the top, ores in the middle, and ores at the bottom of the great limestone No. II. Those at the top form the belt along the central part of the valley where the Trenton limestone underlies the Utica or Hudson River slates. Those in the middle are connected with various horizons of fer- ruginous limestones in the Chazy and Calciferous. Those at the bottom along the north or west part of the South Mountain- Blue Ridge range are geologically connected with the Potsdam sandstone, or the slates which intervene between it and the base of the Calciferous.^ Cobalt has been detected on those of Chester Ridge by. Boye, but it is a rare and unique discovery.^ 2.01.20. The Siluro-Cambrian limonites run across Mary- land in Carroll and Frederick counties, and arerdfined to a small extent.^ These limonites are again strongly developed in the Shenan- doah Valley along the western base of the Blue Ridge, and in southwestern Virginia in the Cripple Creek and New River * Second Pemi. Survey, Rep. MM, p. 199. 2 Dr. Boye, "Oxyd of Cobalt with the Brown Hematite of Chester Ridge, Penn., Amer. Phil. Soc., January, 1846. P. Fraser, Second Geol. Survey Penn., Reps. C and CC; " Origin. of the Lower Silurian Limonites of York and Adams Counties," Proc. Amer. Phil. Soc, March. 1875. See also, "Remarks on a Paper of F. Prime," Idem, December 21, 1877, 255. J. W. Harden, "The Brown Hematite Ore Deposits of South Mountain between Carlisle, Waynesborough, and the Southeast Edge of the Cum- berland Valley," Trails. Amer. Inst. Min. Eng., I., 136. J. P. Lesley, Summary, Final Report, Vol. I., 1892, pp. 205, 341. Rec. A. S. McCreath Second Geol. Survey Penn., Vol. MM, 199. F. Prime, Second Geol. Suiwey Penn., Reps. D and DD; "On the Occurrence of the Brown Hematite Deposits of the Great Valley," Trans. Amer Inst. Min. Eng., III., 410; Amer. Jour. Sci., ii., IX., 433; also, XL, 62, and XV., 261. Rec. B. T. Putnam, Tenth Census, Vol. XV., p. 181. ^ E. R. Benton, Tenth Census, Vol., XV., p.. 254. m s •a •5 ^^^ •8? •■si 'E^ THE IRON SERIES {IN PART). 103 belt. The ores occur in connection with calcareous shales, cal- careous sandstones, and impure limestones, but have not justi- fied the expectations formed of them. The geological relations are similar to those of the zinc ores described under Example 26, and the pictures of the zinc mines will answer for those worked for limonite. In Carroll County, Virginia, the gossan of the great deposit of pyrite is dug for iron ore. The walls, however, are older than the Cambrian.^ 2.01.21. The limonites of eastern Tennessee are the southern prolongation of the area of southwest Virginia. They lie bet wen the Archean of the Unaka range on the east, and the Upper Silurian strata in the foot of the Cumberland tableland on the west. The ores outcrop in the longitudinal valleys or '*coves." The bottoms of these valleys, according to Safford (p. 449), are formed by the shales, slates, and magnesian lime- stones of the Knox group, and in the residual clay left by their alteration the ore is found. The gossan of the neighboring veins of Cjppper pyrites, best known at Ducktown (see Example 16), was originally exploited for iron.^ The Tennessee limon- ite extends across northwestern Georgia, and still farther east ' E. R. Benton, Tenth Cenms, Vol. XV., p. 361. J. L. Campbell, "Re port on the Mineral Prospects of the St. Mary Iron Property," etc. , The Vir ginias, February, 1883, p. 19. See also The Virginias, January, 1880, p. 4; March, p. 43. F. P. Dewey, "The Rich Hill Iron Ores," Trans. Amer. Inst. Min. Eng., X., 77. W. M. Fontaine, " Notes on the Mineral Deposits of Certain Localities in the Western Part of the Blue Ridge," The Vir ginias, March, 1883, p. 44; April, p. 55; May, p. 73; June, p. 93. B. S Lyman, "On the Lower Silurian Brown Hematite Beds of America,' Proc. Amer. Assoc. Adv. Sei., XVII., 114. A. S. McCreath, "The Iron Ores of the Valley of Virginia," Trans. Amer. Inst. Min. Eng., XII., 103 Engineering and Mining Journal, June, 1883, p. 334. E. C. Moxham "The Great Gossan Lead of Virginia," Trans. Amer. Inst. Min. Eng. XXL, 133. E. C. Pechin, "The Iron Ores at Buena Vista, Rockbridge County, Virginia." Engineering and Mining Journal, Aug. 3, 1889, p. 92 "Mining of Potsdam Brown Ores in Virginia," Engineering and Mining Journal, Sept. 19, 1891, p. 337; "Iron Ores of Virginia and their Develop- ments," Trans. Amer. Inst. Min. Eng., XIX., 101; "Ore Supply for Vir- ginia Furnaces," Engineering and Mining Journal, Vol. LI., 1891, pp. 323, 349. Rec. ' J. M. Safford, Geol. of Tenn., p. 448, 1869. B. Willis, Tenth Census, Vol. XV., p. 331. The best works of reference are the recent folios of the U. S. Geological Survey, which cover a large part of southeastern Ten- nessee and the neighboring parts of Alabama and Georgia, 104 KEMP'S ORE DEPOSITS. the so-called Huronian limestones of North Carolina also enter the State. But as even these so-called Huronian schists and associated marbles have been considered by F. P. Bradley to be metamorphosed Silurian (Cambrian), the ores may also be- long under Example 2a. The well-determined Siluro-Cambrian rocks form but a narrow belt of no great importance in North Carolina.^ The limonites are again strongly developed in Alabama and furnish a goodly proportion of the ore used in the State. They form a belt lying east of the Clinton ores (Example 6), later described. As in Tennessee, they are associated with strata of the Knox group. ^ 2.01.23. Origin of the . Siluro- Cambrian Limonites. — Dr. Jackson, of the First Pennsylvania Survey, argued in 1839^ that they originated in situ; that is, by the alteration of the rocks in and with which they occur. Percival, in his report on the Geology of Connecticut in 1842 (p. 132), attributed them to the alteration of pyrite in the neighboring mica-slate. Prime, in Pennsylvania, in 1875 and 1878 (Reports D and DD), considers that the iron has been obtained by the leaching of the neighboring dolomites and slates, it being in them either as silicate, carbonate or sulphide; that the ore has reached its position associated with the slates, because, being impervious, they retained the ferruginous solutions; and that the potash abundantly present in the slates probably assisted in precipita- ting it.* Frazer, in 1876,^ in studying the beds of York and Adams counties, Pennsylvania, found the hydromica slates filled with the casts of pyrite crystals, and held these to have been the sources of the iron, because they would afford ferrous sul- phate and sulphuric acid. The latter reacted on the alkali of the ^ F. P. Bradley, "The Age of the Cherokee County Rocks, North Car- olina," Amer. Jour. Set, iii., IX., 279, 320; B. Willis, Tenth Census, Vol. XV., p. 367. "" W. M. Chauvenet, Tenth Census, Vol. XV., p. 383. H. McCalley, " Li- monites of Alabama Geologically Considered," Engineering and Mining Journal, Dec. 19, 1896, 583. For other references to Alabama iron ore deposits, see under Example 6. The fohos of the U. S. Geological Survey bearing on this region should be consulted. • Ann. Rep. First Pa. Survey, 1839. * Trans. Amer. Inst. Min. Eng., II. 410. " Second Pa. Survey, Rep. C, p. 136. THE IRON SERIES {IN PART). 105 slates, producing sodium sulphate. This, meeting calcium car- bonate afforded calcium sulphate and sodium carbonate, which latter precipitated the iron. Calcium carbonate alone is, how- ever, abundantly able to precipitate iron carbonate and ox ide from both ferrous and ferric sulphate solutions (even when neutral) without the introduction of the alkali, although this might account for the alteration of the slates.^ 2.01.24. J. D. Dana has written at length on the New England and New York deposits, and finds them always at or near the junction of a stratum of limestone, proved in many cases to be ferriferous, and sometimes entirely siderite, and one of hydromica slate or mica schist. In several mines bodies of unchanged spathic ore are embedded in the limonite. Hence Professor Dana explains the limonite as derived by the weath- ering of a highly ferruginous limestone, from which the limon- ite has been left behind by the removal of the more soluble elements, so as practically to replace the limestone in connec- tion with other less soluble matter. The limonite has also at times replaced the schists, probably deriving its substance in part from iron-bearing minerals in them, and changing these rocks to the ochers and clays now found with the ores. These views are undoubtedly very near the truth for the region stud- ied, and have been corroborated by observations of the writer. (Cf. also Example 4.) Weathering limestones do furnish residual clay, ocher, etc., as is shown by the deposits of western Kentucky and Tennessee under Example 2. 2.01.25. Another hypothesis early formulated and advo- cated by many is that the limonites have been derived from the surface drainage of the old Appalachian highlands, then have been precipitated in still water and have been buried up where they are now found. A precipitation around the shores of a ferruginous sea has also been urged on the analogy of certain explanations of the Clinton ore. (Example 6.) Their supposed Tertiary age has already been remarked. All these views are essentially hypothetical and have no good foundation.^ * See F. P. Dunnington, "On the Formation of Deposits of Manganese," Amer. Jour. Sci., iii., XXXVI., p. 175, (Experiments 10 and 11.) "" See H. D. Rogers, Trans. Asso. Amer. Geol. and Nat., 1842, p. 345; E. Hitchcock, Geol. Vt., Vol. I., p. 233; J. P. Lesley, Iron Manufacturers* Guide, p. 501; Rep. A, Second Pa. Surrey, p. 83; J. S. Newberry, International Review, November and December, 1874. 106 KEMP'S ORE DEPOSITS. ANALYSES OF LIMONITES. 2.01.26. All published analyses, except when forming a sufficiently large and continuous series from the output of any one mine, are to be taken with caution. Ores necessarily vary much, and a single analysis or a selected set may give a very wrong impression. The percentage in iron is different for dif- ferent parts of the same ore body. The few that follow have been selected to show the range and the average. The highest are exceptionally good, the lowest less than the average, and the medium values indicate approximately the general run. Limonites afford from 40 to 50% Fe as actually exploited, but it is not difficult to find individual analyses that run higher. They are not, generally speaking, Bessemer ores. ANALYSES OF LIMONITES. Fe. P. S. SiO, AlaOg H,0. Berkshire County, Mass '. . 47.52 50.48 46.45 39.72 0.187 0.353 0.370 0.059 Connecticut Dutchess County, New York Staten Island 0.391' 0.020 14.100 14.190 5.165 3.056 3.590 12.41 Pennsylvania 56.30 0.125 Virginia (Low Moor) 43.34 50.91 50.89 0.636 0.237 225 Tennessee (Lagrange Furnace) . . Alabama 0.200 20.000 0.700 Colorado 53.37 0.034 Colorado, average 43.00 44.71 59.92 0.030 0.666 18 00 Prosser mine, Oregon. Pure mineral 14.40 SIDERITE OR SPATHIC ORE. 2.01.27. Siderite is the protocarbonate of iron. As a min- eral it often contains more or less calcium, magnesium, and manganese. When of concretionary structure, embedded in shales and containing much clay, the ore is called clay iron- stone. -When the concretions enlarge and coalesce, so as to form beds of limited extent, generally containing much bitumi- nous matter, they are called black-band, and are chiefly devel- oped in connection with cpal seams. 2.01.28. Examples. C/az/Jron5^07ie.— The name is applied to isolated masses of concretionary origin (kidneys, balls, etc.) THE IRON 8EBIE8 {IN PART). 107 which may at times coalesce to form beds of considerable extent. They are usually distributed through shales, and on the weathering of the matrix are exposed and concentrated. They are especially characteristic of Carboniferous strata and differ from black-band only in the absence of bituminous mat- ter and in the consequent drab color. They weather to limon- ite, generally in concentric shells with a core of unchanged carbonate within. Fossil leaves or shells often furnish the nucleus for the original concretion, and are thus, as at Mazon Creek, 111., beautifully preserved. When in beds the ore is sometimes called flagstone ore; when broken into rectangular masses by joints, it is called block ore. 2.01.29. Example 3a. jB/acA;-6and— The name is applied to beds consisting chiefly of carbonate of iron with more or less earthy and bituminous matter. They are of varying thickness, thoiigh rarelj" more than six feet, and are almost invariably associated with coal seams. They are thus especially found in the Carboniferous system, and to a far less degree in the east- ern Jura-Trias. They are also recorded with the Cretaceous coals of the West. It is not possible to separate the two varie- ties in discussing their distribution. The various productive areas are taken up geographically, beginning with the Appa- lachian region. 2.01.30. The carbonate ores are of great importance in the Carboniferous of western Pennsylvania and in the adjacent parts of Ohio, West Virginia and Kentucky. In these States the system is subdivided in connection with the coal, from above downward, as follows : I. The Upper Barren Measures, Permo-Carboniferous, or Dunkard's Creek Series; II. The Upper Productive Coal Measures, or Monongahela River Series; III. The Lower Barren Measures, or Elk River Series; IV. The Lower Productive Coal Measures, or Allegheny River Series; V. The Great or Pottsville Conglomerate. In the Upper Barren Measures of Pennsylvania, according to McCreath, there is hardly a stratum of shale or sandstone without clay ironstone nodules, but no continuous beds are known.* The deposits are not of great actual importance, and are worthy of only passing mention. In the Upper Productive Coal Measures some ore occurs associated with the Waynes- ^ Second Pa. Survey, Rep. K, p. 386; MM, p. 159. 108 KEMP'S ORE DEPOSITS. burg coal seam, and again, just under the Pittsburg seam, there is considerable known as the Pittsburg Iron Ore Group. This latter ore becomes of great importance in Fayette County, and extends through several beds/ The Lower Barren Meas ures in Pennsylvania also contain carbonate ore in a number of localities. The most persistent is the Johnstown ore bed, near the base of the series. There are two additional beds just over the Mahoning sandstone. The Lower Coal Measures are the chief ore producers in all the States. They furuish balls of clay ironstone in very many localities in western Pennsylvania, which will be found recorded with many additional references in Report MM, p. 174, Pa. Qeol. Survey. The nodules are scattered through clay and shales. The so-called Ferriferous limestone, which lies a few feet below the Lower Kittanning coal seam, affords in its upper portion varying thicknesses of carbonate ore,known as **buhrstone ore," which is altered in large part to limonite. Some little carbonate ore was found in the early days in the anthracite measures of eastern Pennsylvania. Sevei'al beds of the same occur in the Great Conglomerate and its underlying (Mauch Chunk) shales. They are chiefly developed in south- western Pennsylvania (Report KK), and may form either entire beds or disseminated nodules. The limonites of the Marcellus stage that pass into carbonates in depth in Perry and the neighboring counties have already been mentioned under Example 2. In West Virginia both Upper and Lower Meas- ures afford the ore. From the latter black-band is extensively mined on Davis Creek, near Charleston.^ 2.01.31. In Ohio a number of nodular deposits are known, but practically no ore is produced above the Mahoning sand- stone of the Lower Coal Measures. Below this sandstone the ores are extensively developed. They extend up and down the eastern part of the State, and are both black- band and cla}^ ironstone. Orton identifies twelve different and well-marked horizons distributed through the Lower Measures. He distin- guishes the stratified ores, mostly black-band, and the concre- » Rep. MM, p. 162; KK, p. Ill; L, p. 98. ^ M. F. Maury and W. M. Fontaine, Resources of West Virginia, 1876, p. 247. THE IRON SERIES {IN PART). 109 tionary ores, including kidney ores, block ores, and limestone ores.^ 2.01.32. The general distribution of the iron ores of Ken- tucky has already been outlined under Example 2. The Hang- ing Rock region is a southern prolongation of the Ohio district of the same geological horizon. P. N. Moore has classified the local ores as limestone ores, which are associated with lime- stone, block ores, and kidney ores. The last two names refer to the fracture or shape of the masses. They occur associated with the usual clay and shale. Farther west, between the Ken- tucky and Red rivers, are the other deposits, the principal one of which comes low in the series, just over the Subcarbonifer- ous limestone.'' 2.01.33« Small quantities of black-band have been found in the Deep River coal beds, in North Carolina, associated with the Triassic coals. ^ A large bed, or series of beds, has recently been reported from Enterprise, Miss., in strata of the Claiborne stage. They run from ten to eighteen feet in thickness, and extend for miles.* Scattered nodules have been noted at Gay Head, Martha's Vine- yard.^ Carbonate ores are as yet of no importance in the coal measures of the Mississippi Valley. They have been found associated with the Cretaceous coals of Wyoming and Colo- rado — and indeed the first pig iron of the latter State was made from them in Boulder County — but they are not an important source of ore." An extended bed of very excellent carbonate has recently been discovered with coal near Great Falls, in the Sand Coulee region of Montana. Being near coal, limestone, ^ Geol. of Ohio, V., p. 378, and supplemental report on the Hanging Rock region in Vol. III. "^ P. N. Moore, " On the Hanging Rock District in Kentucky," Kentucky Oeol. Survey, Vol. I., Part 3. " B. Willis, Tenth Census, Vol. XV., p. 306; W, C. Kerr, Geology of North Carolina, 1875, p. 225. * A. F. Brainard, " Spathic Ore at Enterprise, Miss.," Trans. Amer. Inst. Min. Eng., XIV., 146. * W. P. Blake, "Notes on the Occurrence of Siderite at Gay Head, Mass.," Trans. Amer. Inst. Min. Eng., IV., 113. ® R. Chauvenet, "Notes on the Iron Resources of Colorado," Ann. Rep. Colo. School of Mines, 1885, 1886; Trans. Amer. Inst. Min. Eng., XVIIL, 110 KEMP'S ORE DEPOSITS. and other iron ores, it promised to be of considerable impor- tance/ 2.01.34. Example 4. Burden Mines, near Hudson, N. Y. Elongated lenticular beds of clay ironstone, passing into sub- crystalline siderite, enclosed conformably between underlying slates, and overlying calcareous sandstone, of the Hudson River stage. The ore occurs in four "basins,'* which outcrop * O. C. Mortson, Mineral Resources U. S., 1888, p. 34. THE IRON SERIES {IN PART). HI along the western slope of a series of moderate hills, just east of the Hudson River. The hills have been shown by Kimball to be the eastern halves of anticlinal folds now reduced by ero- sion to easterly dipping monoclines. The western half of the ore bodies has been eroded away, leaving an outcrop 44 feet thick as a maximum, which pinches out along the strike and dip. The basins extend from southwest to northeast, parallel to the trend of the hills. The beds are more or less faulted. The southern part of the second basin affords Bessemer ores, but the others are too high in phosphorus. At this point the principal mining has been done. According to Olmstead, some varieties are richer in phosphorus than others, but they are so intimately mixed as not to be practicably separated. Up to 1889 the mines had produced 450,000 tons of roasted Bessemer ores. 2.01.35. In their geological relations the ores are of the greatest interest, as they occur in the western limit of the metamorphic belt, which forms the basis of the Taconic con- troversy, yet in strata which have been identified by fossils. Beds of limonite hitherto regarded as Siluro Cambrian occur to the* east; and should further study, on the lines developed chiefly by J. D. Dana, W. B. Dwight, and C. D. Walcott, clear up their stratigraphical relations, the work done in devel- oping the structure of the siderite basins, as pointed out by Kimball, may be of great aid in explaining them. Very similar bodies of siderite occur with these limonites. (Exam- ple 2a.) The Burden ores are relatively high in magnesia, and this leads Kimball to suggest their original deposition from the off-shore drainage of the basic rocks of the Archean highlands. Further, it may be added that the ores in their lenticular shape are highly suggestive of a possible origin for magnetite deposits, and they are again referred to under "Mag- netite." Other deposits of siderite in the shales of the Marcel- lus stage are known and were formerly worked at Wawar- sing, Ulster County, across the Hudson River.^ ' J. P. Kimball, "Siderite Basins of the Hudson River Epoch," Amer. Jour. Set, III., xl. 155. I. Olmstead, "Distribution of Phosphorus in the Hndson River Carbonate," Trans. Amer. Inst. Min. Eng., XVIII., 252. R W. Raymond, "The Spathic Ores of the Hudson River," Trans. Amer. Inst. Min. Eng., IV., 309. J. C. Smock, Bulletin VII of New York State Mus eum on Iron Ores, p. 62. 112 KEMP'S ORE DEPOSITS. 2.01.36. Example 5. Roxbury, Conn. A fissure vein in gneiss, six to eight feet wide, of crystalline siderite,with which are asociated quartz and a variety of metallic sulphitles, galena, chalcopyrite, zinc blende, etc. Although productive in former years, it is no longer worked, and is of scientific more than economic interest, being a unique deposit. It has fur- nished many fine cabinet specimens.^ 2.01.37. The spathic ores are the lowest in iron of all, and in the raw state are often, if not always, far below the limit of profitable treatment. Calcination, however, drives off the carbonic acid and moisture and brings the percentage of iron up to a merchantable grade. The later development of the iron industry in this country has been unfavorable to spathic ores, and year by year their amount has decreased until now it is nearly obliterated, being only about one per cent of the total. 2.01.38. The subjects of limonite and siderite cannot well be passed without further reference to their genetic relations as connected with limestone. The processes involved concern not alone these ores, but also the more metamorphic forms — hema- tite and magnetite — into which they may pass by reasofi of subsequent changes. It was stated earlier (2.01.05) that cal- cium carbonate precipitated from ferric salts, ferric hydrate, and from ferrous salts, ferrous carbonate, which in the presence of oxygen quickly changed to ferric hydrate. Jo P. KimbalP has recently added a note on the chemistry of the process which modifies it somewhat. He brings out the fact that it is the hydrous carbonate of iron which is precipitated from ferrugi- nous salts by the various alkaline carbonates, and that, being an unstable salt, it quickly oxidizes to a hydrous oxide. From this the argument is made that bodies of siderite, or anhydrous ferrous carbonate, could not have originated by direct precipi- tation, but must have done so by pseudomorphous replacement of limestone. Dr. Kimball then follows out the possible meta- morphism or changes of these bodies to other forms of iron ore, ^ J. P. Lesley, Iron Manufacturers' Guide, p. 649. C. U. Shepherd, ''Report on the Geology of Connecticut," 1837, p. 30, Amer. Jour. Sci., I., xix. 311. ' J. P. Kimball, ' ' Genesis of Iron ores by Isomorphous and Pseudomor- phous Replacement of Limestone," A7ner. Jour. Sci., September, 1891, p 231, and conclusion in the ^?/ier. Geol., December, 1891. THE IRON SERIES {IN PART). 113 citing, however, among many that are unexceptionable, some instances as possible examples for which the field relations give but slight justification. The specular ores with the porphyries of Missouri are of this latter character, and the work of C. H. Smyth, Jr., later cited, on the oolitic Clinton hematites gives strong ground for thinking them accumulations in shallow waters as concentric layers upon original nuclei of quartz. 2.01.39. While the importance of limestone as a cause of the formation of bodies of iron ore cannot be too highly empha- sized, and it is quite possible that some puzzling ones, such as many magnetite beds, have originated in this way, and that the limestone has so entirely disappeared as to give slight clue to its original presence; yet it must not be overlooked that siderite often does form in nature quite independently of cal- cite, and that conditions must be often such as to make this possible. If vuggs with free crystals, or if cleavage masses with the proper angle occur in a deposit, we must admit that the siderite is produced under circumstances not different from those which prevailed during the formation of the walls or of the massive mineral. Repeated experience indicates that these are not extraordinary. CHAPTER II. THE IRON SERIES CONTINUED— HEMATITE, RED AND SPECULAR. 2.02.01. The sesquioxide of iron, F2O3, is always of a red color when in powder. If it is of earthy texture, this color shows in the mass, and the ore is called red hematite ; if the ore is crystallized, the red color is not apparent, and the bril- liant luster of the mineral gives it the name specular hematite. The red hematites are first treated. 2.02.02. Example 6. Clinton Ore.— Wherever the Clinton stage of the Upper Silurian outcrops, it almost invariably con- tains one or more beds of red hematite, interstratified with the shales and limestones. These ores are of extraordinary persist- ence, as they outcrop in Wisconsin, Ohio and Kentucky in the interior, and then beginning in New York, south of Lake Ontario, they run easterly across the State. Again in Penn- sylvania they follow the waves of the Appalachian folds and extend south into West Virginia and Virginia in great strength. They are found in eastern Tennessee and northwest- ern Georgia, and finally in Alabama are of exceptional size and importance. The structure of the ore varies somewhat. At times it is a replacement of fossils, such as crinoid stems, molluscan remains, etc. (fossil ore) ; again as small oolitic con- cretions, like flaxseed (flaxseed ore, oolitic ore, lenticular ore); while elsewhere it is known as dyestone ore. The ore in many places is really a highly ferruginous limestone, and below the water level in the unaltered portion it often passes into lime- stone, while along the outcrop it is quite rich. 2.02.03. In Dodge County, southeastern Wisconsin, the ore in 14 to 26 feet thick, and consists of an aggregate of small lenticular grains.^ In Ohio it outcrops in Clinton, Highland ^ T. C. Chamberlin, Geol. Survey Wis., Vol. I., p. 179. R. D. Irving, " Mineral Resources of Wisconsin," Trans. Amer. Inst. Min. Eng., VIII. 478; Geol. Survey Wis., Vol. I., p. 625. TEE IRON SERIES CONTINUED. 115 and Adams counties, in the southwestern portion of the State along the flanks of the Cincinnati Arch, but it is thin and poor in iron, although rich in fossils.^ A small area of the Clinton has furnished considerable ore in Bath County, Kentucky, where it is altered to limonite.^ 2.02.04. Coming eastward, the limestones and the shales of the Clinton outcrop in the Niagara River gorge in New York, but show no ore. This appears first in quantity in Wayne County, a hundred miles east and just south of Lake Ontario. One bed reaches 20 to 22 inches. Farther east are the Sterling ~ ' ' ~ jlZ ! ^ i ~ I ' ~ I li J L_ _ . LJ I _ Till loi Limestone 0-6 '_ J I _J _L_ LI _J I I i ' -' l_J_ I _ ^ — ; - --I- i—ir ' V — r!;=^-T-' -n '-^ Fig. 16. — Clinton Ore, Ontario, Wayne County, New York. After C. H. Smyth, Jr. mines, in Cayuga County ; and again near Utica, in the town of Clinton, which first gave the ore its name, it is of great eco- nomic importance. There are two workable beds, the upper of which, with a thickness of about two feet, is the only one now exploited. Beneath this are 12 or 15 inches of shale, and then the second bed of 8 inches of ore.^ Some 25 feet over the upper bed is still a third, which is too low grade for mining. It is four to six feet thick, and is locally called red flux. It consists of pebbles and irregular fragments of fossils, which are coated with hematite and cemented with calcite. • J. S. Newberry, Geol. of Ohio, Vol III., p. 7. E. Orton, Geol. of Ohio, Vol v., p. 371. » N. S. Shaler, Geol. of Ky., Vol. III., 163. ' A. H. Chester, " The Iron Region of Central New York," address be- fore the Utica Merchants and Manufacturers' Association, Utica, 1881. J. C. Smock, Bull. VII of N. Y. State Museum, June 1889. C. H. Smyth, Jr., "On the Clinton Iron Ore," Arner. Jour. Sci., June, 1892, p. 487. Zeitschr. fiir prakt. Geologie, ISM, ^04. 116 KEMP'S ORE DEPOSITS. 2.02.05. The rocks of the Clinton thicken greatly in Penn- sylvania and run south westward through the central part of the State. Six different ore beds have been recognized, of which the lower are probably equivalent to the Southern dyestone ores. Calcareous Sandstonie and I thin Shale layers CO* Non-Oolitic Ore i (Red Flux) 6 Calcareous , Sandstone 6 Blue Shale and thin f Sandstone layers 16' Oolitic Ore 2 Shale 2' , Oolitic Ore 1 Blue Shale and thin , Sandstone layers 100 X Fig. 17.— Clinton Ore, Clinton, New York. After C. H. Smyth, Jr. The ores are of chief importance in the Juniata district. The belt extends southwestward across Maryland and eastern West Virginia, where the beds are quite thick, although as yet not much developed, and appears in the extreme southwest corner of Virginia. Thence it runs across eastern Tennessee, and is of very great importance. The lines of outcrop aje ^ J. H. Dewees, "Fossil Ores of the Juniata Valley," Perm. Geol. Sur- vey, Rep. F. E. d'lnvilliers, Ibid., Rep. F3 (Union, Snyder, Mifflin, and Juniata counties). A. S. McCreath, Ibid., Rep. MM, p. 23i. J. J. Stevenson, Ibid., Reps. MM and T2 (Bedford and Fulton counties). I. C. White, Ibid., Reps. MM and T3 (Huntingdon County) . H. H. Stoek, "Ores at Danville, Montour County," Trans. Amer. Inst. Min. Eng., XX., 369. THE IRON SERIES CONTINUED, 117 known as **dyestone ranges." They lie west of the Siluro-Cam- brian limestones (Example 2a) and in the edges of the Cum- berland tableland. Four or five are known, of which the largest extends across the State. This ore is more fossiliferous Fig. 18. — Clinton Ore, Eureka Mine, Oxmoor, Ala. After C. H. Smyth, Jr. toward the south and more oolitic toward the north. It is very productive in the Chattanooga region.^ 2.02.06. The Clinton just appears in northwestern Georgia, and continues thence into Alabama, where it is again of great Fig. 19. — Cross-section of the Sloss Mine, Red Mountain, Ala. importance, and, with the less productive Siluro-Cambrian limonites, furnishes practically all the ore of the State. The outcrop can be traced almost continuously for 130 miles. The ore is rich in fossils and occurs in several beds, which, although averaging much less, may aggregate, as at the Eureka furnace, as much as 34 to 37 feet. The chief mines are in Red Mountain, ^ Killebrew and Safford, Resources of Tennessee. E. C. Pechin, "The Iron Ores of Virginia, " etc., Trans. Amer. Inst. Min. Eng., XIX., 1016. J. B. Porter, "Iron Ores, Coal, etc., in Alabama, Georgia, and Tennessee," Trans. Amer. Inst. Min. Eng., XV., 170. J. M. Safford, Geol. of Tenn. P. N. Moore, Virginias, May, 1880, p. 78. 118 KEMP'S ORE DEPOSITS. a local name for the northeast and southwest ridges, in which the ore outcrops, east and south of Birmingham. Folds and faults have brought the beds into close proximity with the coal and limestone of the region, and thus into a position very favorable for economic working.^ The accompanying map, Fig. 20, illustrates the geography and economic geology of the Birmingham district. In expla- nation it may be said that the three coal fields, the Warrior, the Cahaba, and the Coosa, make three elevated basins, formed in part by synclinal foldings and in part by faulting. The intervening strips are relatively depressed and constitute the so-called valleys, each of which has its own name. Thus there is a long valley in which Birmingham is situated and which forks at the northeast corner of the map. The central portion of it consists of Cambrian and Lower Silurian rocks, which yield brown hematite ores, as indicated on the map. They, however, are a miner feature and do not form over 10% of the total furnace supply. On each side of the valley there is a ridge called Red Mountain, mostly formed by Clinton strata, with Trenton limestone beneath and black Devonian shale above. The Clinton reaches a thickness of 150 feet, but is quite variable in character. It may contain as many as five or more beds of ore of differing thicknesses and somewhat con- trasted composition and structure. The best of these are worked. The Clinton beds in Red Mountain dip on each side awaj^ from the center of the valley, and really are the remains of an anticline eroded at its crest. The anticline is of the usual Appalachian type with steeper dips on one flank, in this case the northwestern, than on the other, and the crest is nearer the northwest side than the northeast. The dip at one important mine is shown in Fig. 18. The most productive points are east and south of Birmingham, and along this line the largest mines are situated. The ore is chiefly won hy open cuts, and. is laid bare by stripping off the banging. Curiously enough, * A. F. Brainerd, "On the Iron Ores, Fuels, etc., of Birmingham, Ala.," Trans. Amer. Inst. Min. Eng., XVII., 151. "TheSloss Iron Ore Mines," Engineering and Mining Journal, Oct. 1, 1892, p. 318. T. S. Hunt, "Coal and Iron in Alabama," Trans. Amer. Inst. Min. Eng., XI., 236. J. B. Porter, "Iron Ores, Coal, etc., in Alabama, Georgia, and Tennessee, " Trans. Amer. Inst. Min. Eng., XV., 170. E. A. Smith, Alabama Geol. Survey, 1876; also Proc. Amer. Assoc. Adv. Sci., XXVII., 246, THE IRON SERIES CONTINUED. 119 3y Bangor V N*^ Reids Blount Sprs. \ 4"^ Jasper hJlUberry COXi. l^lNp ^V^ Connellsville i^^^Tvto/ ivicuaua/ /^n 6?C-;'-^Jiroo|fs STANDARD V^ r-^^S^ 4/ Milldale 1 *^>^, X .m^^ c,Wm^\.M-'^ O EUREKA/CCWf^Oj Fig. 20. — 1' a?) of the Vicinity of Birmingham, Ala. From the Transactions of the American Institute of Mining Engineers, Vol. XIX., Plate IV. 120 KEMP'S ORE DEPOSITS. for an ore in the midst of limestone and limey shales, it is pre- vailingly siliceous, so that non-siliceoua or calcareous varieties are much -sought- for mixtures. The red hematites are also exposed in Murphrees Valley and are developed in some large and productive openings. While on the west this valley has the normal and anticlinal flank, it is faulted along the east so that the Clinton measures lie against the Cambrian shales and are overthrown to a steep northwesterly dip. 2.02.07, Red hematite, supposed to be of the Clinton stage, occurs in Nova Scotia in very considerable amount, in Pictou and Antigonish counties.^ 2.02.08. In general the Clinton ore is characterized by a high percentage of phosphorus, and is seldom, if ever, available for Bessemer pig. It is chiefly employed for ordinary foundry irons. The percentage in iron varies much. Experience at Clinton, N. Y., shows that it averages about 44% Fe in the fur- nace. These hematites have undoubtedly originated in some cases by the weathering of ferruginous limestones above the water level. I. C. Russell has shown that the unaltered lime- stones at the bottom of a mine in Atalla, Ala., 250 feet from the surface, contained but 7.75% Fe, while the outcrop afforded 57.52%. J. B. Porter has recorded the gradual increase of lime also in another Alabama mine from a trace at the outcrop to 30.55% at 135 feet. Other writers have explained these beds as due to the bringing of iron in solution into the sea of the Clinton age and to its deposition as small nodules, etc., or as ferruginous mud (Roger, Lesley, Newberry). In this way an oolitic mass has originated, as in the modern Swedish lakes (Newberry). (See Example 1. ) N. S. Shaler has argued, on the basis of the Kentucky betls, that the iron has been derived from the overlying shales, and descending in solution has been precipitated by the lower-lying limestones. As the shales are themselves calcareous, this seems improbable. A. F. Foerste has shown that the ore is very often deposited either in the interstices of fragments of bryozoans or as replacing their sub- stance. The rounded, water-worn character of the original fragments is regarded as occasioning the apparent concretion- ary character. Admirable work upon the origin of the ore has ^ Sir J. W. Dawson, Acadian Geology, p. 591. Fletcher, Can. Geol Survey, 1886. THE IRON SERIES CONTINUED. lt\ also been done by C. H. Smyth, Jr. He finds that the small oolites, or concretions, as they occur at Clinton, N. Y., and many other localities, have a water- worn grain of quartz as a nucleus. The character of the grain is such that it has evi- dently been derived from granitoid or schistose rocks. The hematite comes off at times in concentric layers, when tapped gently. It may also be dissolved away so as to leave a sili- ceous cast or skeleton of the spherule. Dr. Smyth thus makes a strong argument that the ores in such cases are concretion- ary, and that they were formed in shallow waters around the nuclei of sand. But he also admits, as others quoted above have indicated, that the replacement of brj'ozoa and the weath- ering of ferruginous limestone have in many localities played their part. The iron ore is in the latter case a residual prod- uct, but now the mine waters are depositing calcium carbonate rather than removing it.^ 2.02.09. Glenmore Estate, Greenbrier County, West Vir- ginia. A bed of red hematite in Oriskany sandstones. Limon- ites are abundant in the Oriskany of Virginia, and the hema- tite may have been derived from some such original.^ 2.02.10. Mansfield Ores, Tioga County, Pennsylvania. Three beds of ore are found in the strata of the Chemung stage of Tioga County, Pennsylvania. They are known as (1) the Upper or Spirifer Bed, (2) the Middle or Fish Bed, and (3) the Lower Ore Bed. No. 1 is full of shells and is about 200 feet below the Catskill red sandstones, and at Mansfield is two to three feet thick. No. 2 is oolitic, resembles the Clinton ore, and affords fish remains. It lies about 200 feet below No. 1 * A. F. Foerste, ''Clinton Group Fossils, with Special Reference to Col- lections from Indiana, Tennessee, and Georgia," Amer. Jour. Sci., iii., XL., 252. (Abstract; original not cited.) "Clinton Oolitic Iron Ores," Amer. Jour. Sci., iii., XLI., 28. Rec. "Notes on Clinton Group Fossils, with Special Reference to Collections from Maryland, Tennessee, and Georgia," Proc. Bost. Soc. Nat. Hist., XXIV., 263. J. P. Lesley, Iron Man- ufacturers' Guide, p. 611. J. S. Newberry, "Genesis of the Ores of Iron," School of Mines Quarterly, November, 1880, p. 13. Rec. H. D. Rogers, Geol of Penn., Vol. II., p 127. N. S. Shaler, Geol of Ky., Vol. III., p. 163. C. H. Smyth, Jr., "On the Clinton Iron Ore," ^mer. Jour. Sci., June, 1892, p. 487. Rec. " Die Haematite von Clinton in den oestlichen Vereinigten Stachin," Zeitscher. fur prakt. Geologic, 1894, 304. "^ W. N. Page, "The Glenmore Iron Estate, Greenbrier County, West Virginia," Trans. Amer. Inst. Min. Eng., XVII., 115. 122 KEMP'S ORE DEPOSITS. and varies up to six or seven feet thick. -No. 3 is 100 to 200 foet lower, and contains small quartz pebbles.* The ore is not rich, and but little has been mined. It is a brownish red hema- tite.' 2.02.11. Beds of red hematite are reported by Schmidt in the Lower Carboniferous of western central Missouri.^ 2.02.12. Example 7. Crawford County, Missouri. Bodies of finely crystalline specular hematite, associated with chert, sandstone fragments, residual clays and some pyrite in conical or rudely cylindrical depressions in the Cambrian (Ozark) Series. A broad area of upheaval runs across central Missouri from the east, near St. Louis, to the south- western part of the State. In the eastern and central portions it is chiefly composed of Cambrian and Silurian strata, but to the southwest Lower Carboniferous come in (see 2.06.06). The hematites here considered belong in the Cambrian. In the region of the mines there is a heavy sandstone stratum, earlier called the '* Second Sandstone," but in the later reports described as the Roubidoux. It is underlain by a heavy limestone stra- tum locally called the Gasconade. The Ozark uplift was formed at the close of the Lower Carboniferous and has remained exposed to atmospheric agencies ever since. Their effects are shown in the great mantles of residual clay, which are widely distributed, and in the phenomena of the hematite deposits. Dr. A. Schmidt, of the Missouri Survey of 1872 (Report on Iron Ores. p. QQ), wrote that these had replaced the pre-existing rock, or had been deposited in hollows in the then existing sur- face. Pumpelly, however, in 1885,* advanced a more probable hypothesis, which is strongly supported by F. L. Nason. The region is and has long been one of sink-holes caused by sub- terranean drainage through the Gasconade limestone and the caving in, at times, of the overlying sandstone. Cavities were thus afforded in which ferruginous waters might stand and precipitate their dissolved burden of ore. Nason shows that ^ A. S. McCreath, Rep. MM, Second Penn. Survey, p. 231. ^ J. P. Lesley, Geol. of Penn., 1888, Vol. I., p. 311. A. Sherwood, Rep. G, Second Penn. Survey, pp. 33, 37, 41, 42, 67. A. S. McCreath, Rep. MM, Second Penn. Survey, p. 251. ^ A. Schmidt, "Iron Ores and Coal Fields," Missouri Oeol Survey, 1872, p. 169. * Tenth Cenms, Vol. XV. . p. 12. ^mii-m^^^^^^^^^'mmw^r^^m^M^^m^m.'i ■®ca*'»^***r" x.'A Z'ni-js^ Fig. 21.— View in Cherry Valley Mine, showing sandstone with under- lying cherty clay. The sandstone dips southeast inward toward the ores. After F. L. Nason, Report on Iron Ores of Missouri, p. 125. Plate VI. Fig. 23. — Section of the northern end of the Cherry Valley Mine. 1, Clay detritus; 2, Sandstone; 3, Chei'ty and slaty clay; 4, Ores; 5, Blocks of sandstone. After F. L. Nason, Re- port on Iron Ores of Missouri, p. 131. F'G. 23.— Cross section of the Cherry Valley Mine. 1. Sandstone; 2, Clay and chert; 3, Sandstone dipping inward; 4, Magnesian limestone. After F. L. Nason, Report on the Iron Ores of Missouri, p. 134. THE litON SERIES CONTINUED. 123 several of the largest mines are along lines of old drainage valle3^s. The edges or walls of the pits are formed by the sandstone which dips inward, as shown in the accompanying figures. Just how much overlying rock has washed away does not appear with all desirable certainty, but the presence 01 large amounts of chert mixed with the ore indicates that the cap must have been to a great extent limestone with interbedded layers of this rock. As Nason states^ the limestone that fell into the cavities has been replaced with ore. It is very proba- ble that the former was an important precipitating agent to the latter. A fossil crinoid was found at Cherry Valley, replaced by hematite, giving evidence that even Lower Carboniferous strata had been present. The leaching of these old, overlying beds and the superficial drainage seem to indicate the method of derivation of the ore. The most productive counties are Crawford, Phelps and Dent, but smaller deposits occur in several others. The largest mines are the Cherry Valley, with a total product of over half a million tons, the Simmons Mountain, which has yielded about half as much, and the Meramec with 375,000. The total product of all the mines is computed by Nason at about two and one-quarter millions of tons. A sample from a stockpile made up at St. Louis furnaces from several mines, yielded Fe 56.43, P 0.065 (Nason, /. c. p. 157), but many are much lower in iron. In former years 100,000 to 200,000 tons were annually produced ; recently, however, much less. Some anomalous features are presented by these ores in that they are specular hematite in a practically unmetamorphosed sandstone, whereas some less crystalline form would naturally be expected. Nason believes that they were originally sulphides, and that the heat generated by the decomposition of this mineral has effected the change to specular.^ 2.02.13. Examples. Jefferson County, New York. Large buf irregular bodies of red hematite associated with crystalline ' "Iron Ores of Missouri," p. 138, Mo. Geol. Sur., 1892. ^ W. M. Chauvenet, Tenth Cenms, Vol. XV., 1885, p. 403. F. L. Nason. " Report on Iron Ores," pp. 119-156, 218-231. Missouri Oeol. Survey, 1892. Rec. R. Pumpelly "On the Origin of the Ore," Tenth Census, Vol. XVI., p. 12. Rec. A. Schmidt, "Iron Ores and Coal Yields," Missouri Geol. ■Survey, 1872, p. 124. 124 KEMP'S ORE DEPOSITS. limestone, serpentine, and pyritous gneiss and overlain by Pots- dam sandstone. The crystalline limestone is certainly pre- Cambrian, and would be called Algonkian in the later use of this term„ and later Laurentian in the earlier nomenclature.^ In a recently issued report to James Hall, State Geologist, C. H. Smyth, Jr., has named the limestone series the Oswe- gatchie. The ore bodies occur along a northeast belt, from Philadelphia, Jefferson County, to Gouverneur, St. Lawrence County. They range up to 30 or 40 feet in thickness and con- sist of red, earthy hematite in porous or cellular masses, with some specular. Many interesting minerals, including siderite, millerite, chalcodite, quartz, etc., are found in cavities,, The alignment of the mines along a marked belt has given some ground for thinking them interbedded deposits, and their asso- ciation with Potsdam sandstone has created the impression that they are of Cambrian (or as it was then called, Lower Silu- rian) age.^ J= P. Kimball has stated that they are replace- ments of Calcif erous limestone. * E. Emmons in the * ' Report on the Second District" of the early New York Survey, regarded the associated crystalline limestone as an intruded igneous mass, and the same method of origin was applied to the ores and accompanying so-called serpentine. The latter was called rensselaerite by Emmons. Brooks gave the following section, taken at the Caledonia Mine: 1 Potsdam sandstone, 40 feet. 2. Hematites, 40 feet. 3. Soft, schistose, slaty, green, magne- sian rock with pyrite and graphite, 90 feet plus. 4. Granular, crystalline limestone, with phlogopite and graphite. 5. Sand- stone (like 1), 15 feet. 6. Crystalline limestone with beds and veins of granite. C. H. Smyth, Jr., has recorded the strati - graphical observations, cited earlier, and has formulated the following explanation of origin. The lineal arrangement of the ore-bodies is referred to their association with a great stra- tum of pyritous gneiss belonging to the Oswegatchie Series. This weathers deeply and becomes light and porous (constitut- * C. H. Smyth, Jr., "Geological Reconnaissance in the Vicinity of Gouverneur, N. Y.," Trans. N. Y. Acad. Sci., XII., 97, 1893. "Report on Jefferson and St. Lawrence Counties, " i^ep. of N. Y. State Geol., 1893, 493. Also 1895, 481. 2 See T. B. Brooks, Amer. Jour. Sci., iii., IV., 22. ^ J P. Kimball, Amer. Geologist, December, 1891, p. 368. THE IRON SERIES (JuNTINUED. 125 ing thus a "fahlband"). It coBtains considerable dissemi- nated magnetite. The so-called serpentine or reusselaerite only occurs in association with ore, and itself varies in character, so that one is justified , in regarding it as an altered form of several different kinds of rocks. Smyth infers that the decay of the ferruginous minerals, but especially of pyrite in the pyritous gneiss, has furnished the iron- bearing solutions, which following down the dip have replaced the crystalline limestone where the presence of intruded granites or the flattening of the dip checked the circulations. The action of the acidulated fer- ruginous waters has altered the granites and gneisses in the limestone series to the so-called serpentine.^ These views are fortified by microscopic study of the rocks, and though advanced only as an hypothesis are worthy of great confidence. The mines have afforded in the past a moderately rich (50 to bb% Fe), non-Bessemer ore. The best known and largest producers are the Old Sterling, the Caledonia and Kearney properties, but they are not now operated and are not likely to be reopened in the immediate future. 2.02.14. Example 9. Lake Superior Hematites. Bodies of hematite, both red and specular, soft and hard, anhydrous and somewhat hydrated, associated with jaspers and cherts, and deposited by the replacement of cherty iron carbonate with iron oxide, in troughs, formed by some relatively impervious rock. The impervious rock is usually a decidedly altered igne- ous dike, now hornblendic and dioritic, but one that has been originally diabase. The trough may be formed by a folded dike ; by two or more intersecting dikes; by the intersection of a dike and a compact, sedimentary stratum ; or less commonly by a folded bed of slate. All of these varieties are known in one place and another. Increasing study has shown that the paral- lelism in the structure of the several districts, in the associates of the ore, and in the geological horizons at which the ore / T. B. Brooks, "On Certain Lower Silurian Rocks in St. Lawrence Co., New York," Amer. Jour. Sci., iii., IV., p. 22. Rec. G. S. Colby, Jour U. S. Assoc. Charcoal Iron Workers, XL, p. 263. E. Emmons; iV. Y. Geol. Survey, Second District, p. 93. T. S. Hunt, " Mineralogy of the Lauren- tian Limestones of North America," 21st Ann. Rep. Regents N. Y. State Univ., 1871, p. 88. J. C. Smock, Bull. N. Y. State Mus., No. 7, 1889, p. 44. Rec. C. H. Smyth, Jr., in Report of N. Y. State Geologist for 1894. and Journal of Geology, IL, 678, 1894. Rec. s ? \ ^ f ^ // BO _ ^-^^ ''«l^ r^^b.o^e ^^ ,J^^ *-N_ J ^ k ^: >— ^ cXg" ^♦'TM+t ©g / ^^~>/ J > If ^^^W^ ^^ j 1 l^-'^^ 1" O -J- Jo oJ r! s \ \| :(&'=/ ^' .^ fl? t4 ^,^ i "o \ ^ B^ M ^ <| 5 l^ro*i- 4^^W >i^ ^iwpvj^l '^^-^^^ i \ " ^n z o 1 ^ \" - r " 1 ^ < i^ \ ^ ^ > A ^ ,^* ..VrV^ \ ; O ^* \ \ '4^%% % (J^tv**^ ^ V, V ^v ^ '4. ^"^Sr*" \\/\i ^ \ ^ |7\ o ^ \ \ r *"%. cTP^ J^ r^' n jiV o. \ / 5. -f .i****"**^ '4 |W;-^ '"^^Cj" / ".^' \^#f^ ~"> ^ Jv / ^^ .1 s 7^ r -^^^^^Cs N 3 /^ 5 / I ^ ^\ r^x^^^^^ • s 1 r- _r~v \ J j^o^'f -tS' J \^ '^'^^X^^'WJ \ ^.4.=^r/ ^ "^ cl ^ ^ ^^ Ch s: ^ ^ 1 ^ ci ■^ ^ »~^ 'Vv ^ ^. ^ ^ ^ ts c^ rC 5^ OB ^ 'S, !?» ?- <^ !1~ a. ^ ^^ r^ ?J s <;^ ^ "S> a. 1 '^ Cl 6 fe THE IRON SERIES CONTINUED. 127 occurs, is pronounced. Magnetite is at times present and limo- nites have been mined to a limited degree. There are five principal ore-producing belts or districts, which are also called in instances** ranges," as they follow ranges of low hills. They are, in the order of their chronological exploitation, the Mar- quette, just south of Lake Superior, in Michigan; the Menomi- nee, on the southern border of the Upper Peninsula and partly in Wisconsin; the Gogebic or Penokee-Gogebic, on the north- western border between Michigan and Wisconsin; the Vermil- ion Lake, in Minnesota, northwest of Lake Superior; and the Mesabi (Mesaba), in the same general region as the last. 2.02.15. The geology of these districts has been a subject of much controversy, not alone in the relations of the separate areas, but in the subdivisions of a single one. The ever-pres- ent difficulty of classifying and correlating metamorphic rocks has here been very great. Moreover, there are other separate districts, of related geological structure, which ought also to be brought into harmony, and only at a very recent date has this been even partially attained. 2.02.16. The ores and their inclosing rocks have usually been called Hurouian, as this is the name formerly applied to the schistose and metamorphic rocks overlying what was con- ceived to be the basal, gueissic Laurentian. The geologists of the United States Geological Survej^ have essentially modified this nomenclature, and have restricted Archean to the earliest crystalline or metamorphosed, igneous rocks that precede the first sediments. Algonkian is then employed for the first and subsequent sedimentary rocks, and for the igneous intrusions that followed the first sediments up to the opening of the fos- siliferous Cambrian. The difficulty of correctly correlating these strata with the original Huronian prompted the step, but Huronian is still in very general use and Algonkian and the new meaning of Archean have received but moderate support outside of the Survey. In later years, however, the excep- tionally difficult geological problems in the iron ore districts on the south side of Lake Superior have been especially solved by the geologists of the U. S. Survey^ Irving, Van Hise, Bayley, H. L. Smyth, and others, and it is upon their work that the following descriptions for the- three districts in question are based. The references in the footnote following will place any 128 KEMP'S ORE DEPOSITS. reader in touch with the earlier literature, reviews of which will be found in the citations from Van Hise, A. Winchell and Wads worth. ^ The north shore districts are also closely related , and as a geological problem account must be taken as well of the original Huronian area, north of Lake Huron, and of the Kaministiquia and Rainy Lake regions north of Lake Supe- rior, although they contain no iron ores.^ 2.02.1?. The oldest or pre-sedimentary rocks (Archean) consist of massive granites, gneissoid granites, syenites, perido- tites, greenstone schists, and other schists that are sheared and metamorphosed igneous rocks and tuffs of various kinds. They were called the *' Fundamental Complex" by Irving, and the name in the form of "Basement Complex" has been retained in the later work. Further investigation maj^ clear up its stratigraphical relations to a certain extent. The Archean is succeeded by the formations of the Algonkian, which involve or succeed undoubted sediments. In the south shore iron ranges the Algonkian has been quite uniformly found to be divisible into two series, which are separated by an unconform- ity and a considerable period of erosion. The lower is called Lower Huronian, Lower Marquette, Keewatin, Lower Vermil- ion, and Menominee proper in the different exposures, and prob- ably the great cherty limestone of the Penokee-Gogebic series is its local equivalent. In the Marquette district Wadsworth has recently divided it still further into the Republic and Mes- nard formations. The upper part follows an unconformity and is called in the different regions L^pper Huronian, Animikie, Upper Vermilion, Upper Marquette, Western Menominee, and * C. R. Van Hise, "An Attempt to Harmonize Some Apparently Con- flicting Views on Lake Superior Stratigraphy, Amer. Jour. Sci., ii., XLI., 117; Tenth Annual Report Director U. S. Geol. Survey. Van Hise, Bayley and Smyth, Monograph XXVIII. of U. S. Geological Survey on the Geology of the Marquette Iron District. A. Winchell, ' ' A Last Word with the Huronian," Bull. Geol. Soc. Amcr., XL, 85. M. E. Wadsworth, " Notes on the Geology of the Iron and Coi)per Districts," 1880. ^ The following papers deal with the ores in general: D. N. Bacon, "The Development of Lake Superior Iron Ores," Trans. Amer. Inst. Min. Eng., XXVII., 841; John Birkinbine, "The Resources of the Lake Superior Region," Idem, XVL, 168, 1887; "The Iron Ore Supply," Idem, XXVIL, 519: H. V. Winchell, "Historical Sketch of the Discovery of Mineral De- posits in the Lake Superior Basin," Proc. Lake Superiar Min. Inst., IL, contains a bibliography. See also Amer. Geologist, XIII. , 164. THE IRON SERIES CONTINUED. 129 Penokee-Gogebic proper. For the Marquette region this has also been further divided by Wadsworth into two, the Holj'oke and the Negaunee formations. It is much less metamorphosed than the lower member, and in the Marquette district contains some ore. In the Menominee region of Wisconsin it affords the deposits there wrought and carries the ore in the Gogebic range. Higher in the section, after another unconformity fol- lows the Keweenawan (Keweenian) or Nipigon. This closes the Algonkian. Still above is the Cambrian (Eastern, West- ern or Potsdam) sandstone. 2.02.18. Example 9a. Marquette District. The Marquette Fig. 25. — Oeneralized section across the Marquette Iron Range, to illustrate the type of folds. After C. R. Van Rise, Fifteenth Ann. Rep. Dir. U. 8. Geological Survey, p. 485. district was earliest known and has been most thoroughly stud- ied ; but owing to the confused geological structure, there has been, as already remarked, much discordance of interpretation. The remarkably careful and systematic work of Van Hise and Bayley^ has, however, cleared up the greatest difficulties. In the Marquette district the Algonkian (or Huronian) rocks form a synclinorium or synclinal trough, resting in the older Archean crystallines and extending from Marquette on Lake Superior, westward in a nearly east and west line. While the axis of the main syncline runs east and west, there are many minor folds parallel with this, which are overturned outwardly from the ' C. R. Van Hise and W. S. Bay ley, "Preliminary Report on the Marquette Iron-bearing District of Michigan," with a Chapter on the Republic Trough, by H. L. Smyth, Fifteenth Annual Report Director U. S. Geol. Survey, 485-650. This report should be in the hands of every one interested in the region. See also Monograph XXVIII., which with its atlas is the fullest exposition of the subject. ^ § a 2* o <5> o v> E^ %> '^ g 11 « ,^ >> 15 m ^R «l o . ^ i v:;^;; § ^ P C- CQ = ?0 f^ < ^ '^ ll i-l ! I 132 KEMP'S ORE DEPOSITS. ceDter as in the accompanyiDg figure, after Van Hise. Some marked folding has also occurred at right angles to the east and west axis. Faulting is almost entirely lacking, and the topographic relief is quite entirely due to the relative resist- ances presented by the several rocks to erosion. Al] are more or less metamorphosed and have evidently suffered severely from pressure and shearing stresses. The Lower Marquette is chiefly developed at the eastern end and around the rims of the synclinorium, as it was from this end that the shore-line seems to have advanced upon the ancient land. It begins with the Mesnard quartzite, 110 to 6 70 feet thick. Above come in order the Kona dolomite, 42^ to 1,375 feet; the Wewe slate, 550 to 1,050 feet; the Ajibik quartzite, 700 to 900 feet; the Siamo slate, 200 to 625 feet; and the Negaunee iron formation, 1,000 to 1,500 feet. In Figs. 26 and 27 all these except the Negaunee are grouped under one sign. The total thickness varies from 2,975 to 6,120. The Upper Marquette includes from below upward, the Ishpeming formation, including the Goodrich quartzite and the Bijiki schist; the Michigamme formation of slates and mica schist; and the Clarksburg formation of more or less altered volcanic rocks. Upon Figs. 26 and 27 the Ishpeming has one sign and the Michigamme and Clarksburg another. In the mining district the total thick- ness of the Upper Marquette is less than 5,000 feet. Except as regards the Goodrich quartzite of the Ishpeming and some small limonite deposits in the Michigamme formation the divisions have no economic importance. In the Lower Marquette the economic interest centers in the Negaunee formation, which is much the most important of alL Later than all these just cited are intrusions of basic dikes that have been prime factors in the ore deposition. The Negaunee formation in its completest section consists from below upward of sideritic slate and griinerite-magnetite^ slate; ferruginous slate; ferruginous chert ; and at the top of jasperite or jasper- rock; but not all of these are necessarily present in any one section. The ores are either "soft ores" or *' hard ores." The former are blue, red or brown, earthy and somewhat hydrated varieties of hematite, and resemble ordi- * Griinerite is a variety of amphibole or hornblende. It is an iron amphibole. ¥ ¥ -W^~ry- / Fig. 29. — Open cut in the Republic mine, Marquette range, showing a. horse of jasper. From a photograph hy H. A. Wheeler. THE IRON SERIES CONTINUED. 133 nary dirt of these colors, with small lumps of ore scattered throughout. They strongly simulate, limonite but are not so hydrated. The soft ores are now the main object of mining, but they were earlier looked upon with disfavor and only the hard ores were sought. The hard ores are mas- FlG. 28. — Cross-ftections to illustrate the occurrence and asfonations of iron ore in the Marquette district, Michigan. After 0. E. Van Rise, Amer. Jour. Sci., Febrvary, 1892; Engineering and Mining Journal, July 9, 1892. sive or micaceous specular hematite, rarely magnetite, and are blasted out in lumps. Van Hise makes three classes of depos- its: (1) Thoseat the bottom of the iron- bearing formation; (2) those within it; and (3) those at its top, including also some that run up into the Goodrich quartzite, the lowest stratum of 134 KEMP'S ORE DEPOSITS. the overlying Ishpeming formation. The hard ores belong to the third class. All these classes rest upon an impervious rock of some sort, and lie in a pitching trough formed by it. The trough may be a fold in the Siamo slate, and often is for ores of the first class. It may be a single folded dike, v^^hich is an altered diabase, now called soapstone or paint-rock by the miners. These are shown in the cuts of Fig. 28. The trough may result from the intersection of two or rnore dikes, as is more fully illustrated under the Vermilion district. In all cases it seems evident that after the close of the time-period rep- resented by the Upper Marquette, and after the intrusion of the basic dikes, the overlying ferruginous rocks were subjected to extensive leaching of their iron, by descending atmospheric waters, charged with carbonic acid. When these came to rest in the troughs, or met other descending currents, which were charged with oxygen, and which had percolated downward along the dikes, the dissolved proto-salt of iron was oxidized and precipitated as ferric oxide, replacing the cherts or other siliceous rock that had previously filled the trough. The sil- ica is thought to have been in large part removed by alkaline solutions emanating from the diabase. These changes were facilitated by the fact that the brittle cherts had been much shattered during the folding, and this condition contributed to the formation of the soft ores in their fragmental condition. The hard ores appear to owe their condition to the dynamic metamorphism that has been particularly strong along the con- tact line of the Upper and Lower Marquette. The micaceous ores certainly owe their structure to shearing. The magne- tites are supposed to be former hematites, that have suffered partial reduction \yy infiltrating solutions charged with organic matter. They are best developed in the Republic tongue of the main trough. 2.02.21. The origin of these ore bodies has been a subject of much controversy. A review of the various hypotheses up to 1880 is given in Wadsworth's monograph^ and a still later one is given in the monograph of Van Hise,Bayley and Smyth. ^ * M. E. Wadsworth, "Notes on the Iron and Copper Districts of Lake Superior," Bull. Mus. Comp. Zool., Vol. VII., No. 1. July, 1880. " Van Hise, Bay ley and Smyth, "The Marquette Iron-bearing District of Michigan," Monograph XXVIII. U. S. Geological Survey, pp. 3-148. 1897. THE IRON SERIE8 CONTINUED. 135 The early survey of Foster and Whitney (1851) attributed an eruptive origin to them and the same difficult thesis has been supported by Wadsworth (1880). Others formerly regarded them as old limonite beds in a sedimentary series that was subsequently metamorphosed. Credner (1869), Brooks (1873), and others saw reason for it; but there is little doubt that the origin outlined above is correct. While the present text follows the recent work of the U. S. Geological Survey, be- cause it is more detailed, comprehensive and really accurate than any other available, and because space is necessarily limited, yet the reader who would thoroughly acquaint him- self with the questions under discussion should consult the citations given below, especially those from Brooks, Irving, Wadsworth and Rominger. 2.02.22. It was in the forties that the importance and extent of the ore bodies were first vaguely suspected. The trouble that they made with the compasses of the early land surveyors indicated their existence. Important mining began in 1854. Somewhat over 100,000 tons were produced in 1860, over 800,- 000 in 1870, nearly 1,500,000 in 1880. In 1877 the Menominee region was opened, and in 1885 the Penokee-Gogebic and Ver- milion districts began to ship. The total shipments from the Lake Superior region in 1890 were 8,982,531 tons. The total production through 1897 of the Marquette district was 49,253,- 222 tons. A quite complete citation of the literature is to be found in Wadsworth's monograph, already referred to; in Irv- ing's *' Copper-bearing Rocks of Lake Superior," Monograph v., U. S. Geol. Survey; and in Van Hise, Bay ley and Smyth, Monograph XXVIII. See also under Examples 9b, 9c, and 9d. Only the most important or most recent papers are mentioned here.^ * J. Birkinbine, "Resources of the Lake Superior District," M. E., July. 1887. T. B. Brooks, Oeol Survey of Michigan, Vol. I., 1878; Geol. Survey of Wisconsin, Vol. III., p. 450. H. Credner, "Die vorsilurischen Gebilde der oberen Halbinsel von Michigan in Nord Amerika," Zeitsch. d. d. Geol Ges., 1869, XXI.. 516; also Berg- und HiXtt. Zeit., 1871, p. 369. Foster and Whitney, Geol. of the Lake Superior District, Vol. I., "Iron Lands." 1851. R. D. Irving, " On the Origin of the Ferruginous Schists and Iron Ores of the Lake Superior Region," ^7?ier. Jour. Sci., iii., XXXIL, 263; ''Preliminary Paper on an Investigation of the Archean of the North- western States," Fifth Ann. Rep. Director U. S. Geol. Survey, p. 131; 136 K..MP'S ORE DEPOSITS. 2.02.23. Example 96. Menominee District. The Menomi- nee River, which gives the district its name, forms the south- easterly boundary between the Upper Peumsula of Michigan and Wisconsin. The mines are situated about forty miles south of the Marquette group, and the same distance west of Lake Michigan. The larger number are in Michigan, but the productive bolt extends also into Wisconsin. They lie along the south side of an east and west range of hills, which rises from 200 to 300 feet above the surrounding swampy land. Begin- ning with the base and included in the lower Menominee accord- ing to H. L. Smj^th, the geological section is as follows, all of Seventh Ann. Rep., p. 431; also Administrative Reports in subsequent volumes. J. E. Jopling, "The Marquette Range: Its Discovery, Devel- opment, and Resources," Titans. Amer. Inst. Min. Eng., XXVII., 541. J. P. Kimball, "The Iron Ore of the Marquette District," Amei\ Jour, of Sci., ii., XXXIX., 290. H. S. Munroe, School of Mines Quarterly, II., p. 43. E. Reyer, " Geologie der Anierikanischen Eisenerzlagerstatten (insbe- sonden Michigan)." Oest. Zeitsch. f. Berg- u. Hutt., Vol. XXXV., pp. 120, 181, 1887. C. Rominger, Geol. Survey of Michigan, Vol. IV., 1884. "Re- port on the Iron and Copper Regions, 1881-84, Idem, Vol. V., 1895. C. R. Van Hise, "An Attempt to Harmonize Some Apparently Conflicting Views of Lake Superior Stratigraphy," Ainer. Jour. Sci., iii., XLI., p. 117, Feb- ruary, 1891 ; Tenth Ann. Rep. Director U. S. Geol. Survey ; ' The Iron Ores of the Marquette District of Michigan," Amer. Jour. Sci., February, 1892, p. 115. 15th Annual Report Director U. S. Geol. Survey, pp. 485- 657. Van Hise, Bayley and Smyth. " The Marquette Iron-bearing District of Michigan," Mono. XXVIII. and Atlas U. S. Geol. Survey. M. E. Wadsworth, • ' Notes on the Iron and Copper Districts of Lake Superior, " Bull. Mus. Comp. Zool., VIL, 1, 1880; "On the Origin of the Iron Ores of the Marquette District, Lake Superior," Proc. Bost. Soc. Nat. Hist., Vol. XX., p. 470; Engineering and Mining Journal, Oct. 29, 1881, p. 286; Ann. Rep. Mich. State Geologist, 1891-92. "The Geology of the Lake Superior Region," in a pamphlet issued by the Duluth, South Shore & Atlantic R. R., 1892. Dr. Wadsworth announces a new subdivision of Formations in this and in Amer. Jour. Sci., January. 1893, p. 73. H. Wedding, Zeitsch. f. Berg-, Hiitt-, und Salinemvesen in Preus. Staat. , XXIV. , p. 339. C. E. Wright and C. D. Lawton, Reps, of the Commissioners of Mineral Statistics of Michigan, 1880, and annually to date. G. H. Williams, ' ' Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan," introduction by R. D. Irving, Bull. 63, U. S. Geol. Survey. H. V. Winchell, "Historical Sketch of the Discovery of Mineral Deposits in the Lake Superior Region, Proc. Lake Superior Mining Inst., II. 3. A careful compilation of analyses of ores from all the larger mines of the four older ranges is given by Geo.W. Goetz, Trans. Amer. Inst. Min. Eng., XIX., 59, 1890. THE IRON SERIES CONTINUED. 137 which rests on the Archean crystallines: 1. A basal quartzite, rarely conglomeratic, 1,000 feet thick as a maximum, and at least 700 feet over wide areas. 2. A crystalline limestone, 700 to 1,000 feet thick, and possibly reaching 1,500 to 2,000 on the Fence River. This was earlier called by Rominger the Norway limestone. 3. Red, black and green slates that are not known to exceed 200 to 300 feet. The slates here and there contain the iron formation that affords the rich ores of Iron Mountain and Nor- way. In the southern portion the horizon of the slates is in part occupied by altered eruptives, which may thicken up to 2,000 feet on the Fence River. 4. . The Michigamme jasper, a greatly altered ferruginous rock, usually carrying apparently Fig. 30. — Plan of the Ludington ore body, Menominee district, Michigan. After P. Larsson, Trans. Amer. Inst. Min. Eng., XVI., 119. fragmental quartz grains. The rock is best developed at Michi- gamme Mountain, S. 4, T. 43 N., R. 31 W. It is variable but appears to have originally been, in part at least, a clastic sedi- ment. Infiltrating iron salts and the formation of cherty sil- ica have brought about the alteration of the rock. Iron ores are met at three horizons in this section. The low- est is in the quartzite, No. 1, not far from its junction with the limestone. It has yielded but one workable deposit The great majority of the ore bodies is in the slates, No. 3. They occur as local concentrations in a ferruginous rock composed of banded jasper and iron ore. The ferruginous rock is met at various horizons in the slates. The third ore-bearing forma- tion is the Michigamme jasper, but the ore bodies are small. ^ * The above is condensed from H. L. Smyth, "Relations of the Lower Menominee and Lower Marquette Series in Michigan (Preliminary)," Amer. Jour Sci. , March, 1894, 216. Further correlative notes are given in 138 KEMP'S ORE DEPOSITS. The Michigamme jasper is correlated by Smyth with the Negaunee formation of the Marquette district, and this brings the principal ore bearing stratum of the Menominee range below the ore-bearing formations in the Marquette. In the black slates of the Upf)er or Western Menominee there are still other ore bodies, such as those of the Common- wealth and Florence mines, and at the Quinnesec mines. A goodly mass of soft blue ore was obtained in the Potsdam sand- stone, which had evidently been eroded from the older ores during the deposition of the Potsdam. Great geologic interest has been felt in the metamorphism of the eruptive rocks in the Menominee district, and although remotely related to the geology of the ores, attention should be directed to the valua- ble paper of G. H. Williams cited below. Since 1890 W. S. Gresley of Erie, Pa., has been collecting from the ore piles in that city most extraordinary slabs of ore, chiefly from the Chapin mine, of the Menominee range, that contain impressions bearing the closest resemblance to algse, or other low forms of plant life. They may be the long-sought fossils of Huronian times. ^ The Menominee ores are generally soft, blue-earthy hema- tites, which give a red powder and consist of finely divided particles of specular. Brown hematites are very limited. A lenticular shape is more pronounced than in the Marquette district and the concentration of the ore has not been shown to be connected with intruded dikes as elsewhere, although the chemical reactions involved are doubtless the same. The gen- eral strike is about N. 75° W., and the dip 70° to 80° N. They also pitch diagonally down on the dip. (Of. New Jersey Mag- netites, Example Vdd.) There has been produced including 1897 a grand total of 24,931,441 tons since mining began. ^ C. R. Van Hise's paper on the Marquette range, in 15th Ann. Rep. Dir. U. S. Geol. Survey, p. 647. Smyth has also given an excellent short sketch at the close of his paper on "Magnetic Observations in Geological Mapping," Trans. Amer. Inst. Min. Eng., XXVI., 640-709, 1896. ^ W. S. Gresley, "Traces of Organic Remains from the Huronian (?) Series at Iron Mountain, Mich.," etc., Trans. Amer. Inst. Min. Eng., XXVI. , 527. See also Science, April 24, 1896, 522 ; Amer. Geologist, August, 1896, 123. "" T. B. Brooks, Geol. Survey of Wisconsin, Vol. III., 430-663. D. H. Brown, " Distribution of Phosphorus in the Ludington Mine, " M. E., XVI. THE IRON SERIES CONTINUED. 139 Some fifteen miles north of the Menominee range, and between it and Negaunee in the Marquette range, is a narrow, closely folded syncline, called the Felch Mountain district. It contains a series of strata closely parallel to the Lower Menomi- nee, and apparently an outlier cut off by erosion. H. L. Smyth has also traced out by means of magnetic observations a northwesterly extension of the Menominee range, in a drift- covered district, so as almost to connect with the Marquette area west of the Republic trough. From 20 to 30 miles of con- cealed rocks have thus been shown that may prove productive, although the cheap ores of the Mesabi range have made their immediate future uncertain.^ 2.02.24. Example 9c. Penpkee-Gogebic District. This lies in an east and west range of hills which crosses the westerly boundary of the Upper Peninsula and Wisconsin, and is from ten to twenty miles south of Lake Superior, and eighty to one hundred miles west of the Marquette mines. The rocks are less metamorphosed than in the previous two districts. The strata Tun east and west with a northerly dip of 60° to 80° (65° in the larger mines), and with no subordinate folds. The geological series is now generally called the Penokee, following the usage of Irving and Van Hise, to whose labors we owe our accurate knowledge of the district and from whose papers the following is taken. It rests upon the southern complex of Archean crys- tallines and forms a narrow belt, over 70 miles long, and from half a mile to three miles broad. The geological structure and relations are much simpler than in the other districts, and have afforded the key for the solution of problems elsewhere. The strata are divided into an upper and a lower series, of which the former is much the larger in amount, but the latter is the 525. J. Fulton, "Mode of Deposition of the Iron Ores of the Menominee Range, Michigan," Trans. Amer. Inst. Min. Eng., XVI., 525. N. P. Hulst, "The Geology of that Portion of the Menominee Range East of the Me- nominee River, Proc. Lake Superior Mining Institute, March, 1893, p. 19. Per Larsson, " The Chapin Mine, " Trans. Amer. Inst. Min. Eng., XVI., 119. C. E. Wright, Geol Survey Wisconsin, III. ,666-734. G. H. Williams, " Greenstone Schist Areas of the Menominee and Marquette Regions of Michigan, with an Introduction by R. D. Irving," Bull. 62, U. S. Oeol. Survey. ' H. L. Smyth, "Magnetic Observations in Geological Mapping." Trans, Amer. Inst. Min. Eng., XXVI., 640. 189 6. THE IRON SElilES CONTINUED. J41 one that is of economic importance. At the base is a cherty (lolomitic limestone 300 feet and less thick. It outcrops chief!}" at the extreme west and the extreme east, and has no immedi- ate connection with the ores. Over this lies a quartz-slate or quartzite that is extremely persistent throughout the entire area. It is 500 feet and less thick, and forms the usual foot- wall of the large ore bodies. Above the quartz slate is the iron-bearing member, 800 to 1,000 feet thick. It is not clastic, but consists of cherty carbonates of iron, with some magnesium and calcium, or of derivatives from these carbonates and cherts. Three types of rock have been established: (1) The slaty and often cherty iron carbonate, more or less analogous to siliceous iron carbonates in the Carboniferous and other later systems. It is regarded as of organic origin. (2) Ferruginous slates and cherts. The iron of the siderite in type one has been more or less moved and redeposited as oxides, and rearrange- ment and recrystallization of the silica have also transpired. (3) Actinolite and magnetite schists have resulted by the change of much of the iron carbonate to magnetite and by the combination of the remainder with lime, magnesia and silica to yield actinolite. This last-named type is especially abun- dant west of Tyler's Fork, i.e.^ in the western third and beyond the productive mining region. The upper Penokee consists of slate, with quartzites, graywackes and schists, 12,800 feet thick and less. It has no connection with the ores, and is suc- ceeded by the Keweenawan traps and sandstones on the north. All the Penokee strata are cut by dikes and sheets of diabase, some of which in the iron-bearing formation have plaj^ed an important part in the production of the ore bodies. The ores are found in the lower portion of the iron-bearing member, and either on or near the underlying quartz-slate. The northerly dipping quartz-slate with the overlying cherty carbonates and ferruginous slates is cut by southerly dipping diabase dikes, so as to form a trough with sides nearly at right angles. The troughs themselves pitch downward to the west, and in them, as illustrated by the accompanying figures (Figs. 32 and 33) are found the ore bodies. The ores are soft blue, brown and black earthy hematites, and often contain notable percentages of manganese. There is little doubt that they have been derived from the cherty carbonates in the overlying iron- 142 KEMP'S ORE DEPOSITS. 1^ _J Ul c^i^^;' > A>-;i-j < o THE IRON SERIES CONTINUED 143 bearing formation, which in the long run of weathering and erosion has yielded its iron oxide to descending atmospheric waters, more or less charged with carbonic acid. The iron- bearing solutions filtering downward have come to comparative rest in the troughs, where they have met other waters, presumablj^ charged with oxygen. The iron oxide has been precipitated and at the same time the silica has been removed by carbonated waters or by those which have been rendered alkaline by the leaching of the neighboring dikes. The latter are excessively alterec^and are locally called soapstone or soap-rock in description of their condition. It is impossible to state how much of the iron-bear- FlGo SS.—Cross-section of the Colby mine, Penokee-Gogebic district, Mich- igan, to illustrate occurrences and origin of the ore. After C. R. Van Hise, Amer. Jour. Sci., January, 1891. ing formation has disappeared in the protracted process of super- ficial erosion, but probably some thousands of feet. The depth to which the ore will be found in the troughs is also problemati- cal. It is now known to extend to 800 feet on the dip. The solution of the question of the origin of these ores has been one of the most valuable of the additions to our knowledge in recent years, and has proved suggestive and fruitful for all the other Lake Superior districts. The range became productive in 1885, and including 1897 there has been shipped a total of 23,047,023 tons of ore.^ ^ C. M. Boas, Some Dike Features of the Gogebic Iron Range," Trans. Amer. Inst. Min. Eng., XXVIL, 556 R. D. Irving, Geol. Survey of Wis- 144 KEMP'S ORE DEPOSITS. 2.02.25. Example 9d. Vermilion Range, Minnesota. Bodies of hard specular ores at Vermilion Lake, and soft ores at Ely, deposited in troughs as in the preceding examples, formed by folded or intersecting dikes, which penetrate the iron- bearing formation. The district is situated in north- eastern Minnesota, and lies northwest from Lake Superior. Two Harbors, the shipping point, is twenty-six miles east of Dulutb, and from Tower, the principal town near the Vermil- ion Lake mines, it is sixty- seven miles to the docks. Ely is twenty- three miles northeast of Tower. Leaving the lake the railroad first crosses with heavy grades the northwestern flank of the Lake Superior synclinal, chiefly consisting of the south- easterly dipping trap sheets of the Keweenawan. Underlying these is a series of gabbros and augite syenites — the former of which contain some titan if erous magnetites, similar to those in the Adirondacks. The Mesabi range of hills succeeds on the north, but although ore-bearing further west, as described under the next example, it is barren at this point, and consists chiefly of black slates, referred to the Animikie. Sedimen- tary, gneissic and eruptive rocks, regarded as Laurentian by the Minnesota geologists, succeed, and give place finally to the metamorphic rocks of the Vermilion range, that contain the ore. Still further north are the Laurentian rocks again. This whole region needs further and very detailed mapping to accu- rately bring out its geological structure, although the main points mentioned above serve to outline it. The immediate geological relations of the ores have been elucidated, however, by the recent careful work of H. L. Smyth and J. R. Fin lay, consin, III., pp. 100-167, 1880. "Origin of the Ferruginous Schists and Iron Ores of the Lake Superior Region," ^mer. Jour. Sci., iii., XXXII., 263, 365; see also under Van Hise. C. D. Lawton, " Gogebic Iron Mines, " Engineering and Mining Journal, Jan 15, 1887, p. 42. C. R. Van Hise, " On the Origin of the Mica Schists and Black Mica Slates of the Penokee- Gogebic Iron-bearing Series," Amer. Jour. Sci.., iii., XXXI., 453-459. ''The Iron Ores of the Penokee-Gogebic Series in Michigan and Wisconsin, Amer. Jour. Sci. , iii. , XXXVII. , 32. Irving and Van Hise, ' ' The Penokee Iron-bearing Series of Northern Michigan and Wisconsin," Monograph XIX. , U. S. Geological Survey, 1892. Rec. An abstract of the monograph will be found in the Tenth Annual Rep. Director U. S. Geol. Survey, 341. Rec. C. Whittlesey, "The Penokee Mineral Range, Wisconsin," Proc. Bost. Soc. Nat. Hist., IX., July, 1863. C. E. Wright, Geol. Survey of Wisconsin, III., pp. 239-301. TEE IRON 8EBIE8 CONTINUED. 145 Fig. 34. — Map of the Minnesoto. Iron Ranges. After F. W. Denton, I Amer. Inst Min. Eng., XXVII., 344. 146 KEMP'S CRE DEPOSITS. to which the subsequent description is chiefly due. For a thorough reading up upon the district, the references given below will suffice.^ The Vermilion Lake mines are situated on the top of an abrupt hill above the town of Soudan. Some ore appears in Lee Hill, a mile or two southeast, near Tower, but the depos- its are not known to be large. The mines at Soudan extend for about a mile along a main belt in a direction a little north of east, and upon a more or less parallel minor belt that lies a short distance north. This alignment is due to the intrusion of a great mass of greenstone, with many ramifying dikes, but all on this general line, which is also the strike of the jasper. On the northern side of the mines the surface slopes some- what sharply to Vermilion Lake. The general relations are illustrated by the accompanying Fig. 35. Smyth and Finlay have shown that stratigraphically there are two series of sedi- mentary rocks, both of which have been penetrated by abun- dant intrusions of quartz porphyry and diabase. The lower series consists of slates and graj^wackes, not excessively meta- morphosed. The slates are at times carbonaceous and occa- sionally charged with pyrites. Above the slates lies the iron- bearing formation, consisting of quartz, variously intermingled with hematite or magnetite, or quite free from either. The ^ A. H. Chester, Eleventh Ann. Rep. Minn. Oeol. Survey, 155, 167. T. B. Comstock, " Vermilion Lake District in British America," Trans. Amer. Inst. Min. Eng., July, 1887. F. W Denton, " Methods of Iron Mining in Northern Minnesota,'' Idem, XXVII., 344. R. D. Irving, Seventh Ann. Rep. U. S. Geol. Survey, 1885-86, 435. H. L. Smyth and J. R. Finlay. " The Geological Structure of the Western Part of the Vermilion Range, Minnesota," Trans. Amer. Inst. Min. Eng., XXV., 595-645, 1895. Rec. C. R. Van Hise, Bull. 86, U. S. Geol. Survey. Various references in chap- ter ii. Bailey Willis, Tenth Census, XV. , 457. Alexander Winchell, Fif- teenth Ann. Rep. Minn. Geol. Survey, 174. Also "Some Results of Archean Studies," Bull. Geol. Soc. Amer., I, 357. H. V. Winchell, "Diabasic Schists, Containing the Jaspilyte Beds of Northeastern Minnesota, " Amer. Geol. , II. , 18. "The Iron Ranges of Minnesota," Proc. Lake Superior Mining Inst., III., 1895. Rec. N. H. Winchell: Many references to the region by N. H. Winchell are to be found in the reports of the Minn. Geol. Survey. They are practically summarized in the next reference. N. H. and H. V. Winchell, " The Iron Ores of Minnesota," Bull. 6, Geol. Survey of Minn. Rec. * ' On a Possible Chemical Origin of the Iron Ores of the Kewatin in Minnesota," ^wer. Geol., TV., 291, 389. "The Taconic Iron Ores of Minnesota and Western New England," Amer. Geol., VI., 263. 148 KEMP'S ORE DEPOSITS. varieties occur in parallel but narrow bands, never over three or four inches across, and doubtless represent the original beds of the sediment, but just what the character of the origi- nal sediment was, whether the cherty carbonates of the south shore or the probable glauconites of the Mesabi range is hope- lessly destroyed b^^ metamorphism. These sediments each form three belts, as shown in Fig. 35, which are repeated because of sharply compressed and pitching folds. After the formation of the sediments, but before the folding, intrusions of quartz porphyry and diabase took place, as dikes and sheets, some large, others of excessive thinness. Subsequently all suffered severely from compression. A larger series of folds was developed along an east and west line, and a smaller series at right angles to this. This severe compression and shearing changed the quartz porphyries in large part to conglomerate breccias, and to sericite schists, while the diabases passed into chlorite or actinolite schists or conglomerate breccias. The breccias first resulting from the crushing have had their frag- ments so rubbed upon one another that they are stretched and rounded and have their interstices filled with sericite schist or chlorite schist, as the case may be. The brecciationtook place on the anticlinal crests, but in the synclinal troughs schists resulted. These foldings also formed troughs especiallj" from the corrugated greenstone dikes and from the intersections of the same, and when the iron- bearing formation stood over such a trough, it passed through the same series of changes that have been earlier outlined under the Marquette range, so that the iron oxide became concentrated along the sides and on the bot- toms, while the silica was removed. The accompanying fig- ures exhibit cross-sections in all respects like those on the south shore. The ores are all hard, dense, specular, and are about half of bessemer and half oi nou-bessemer grade. 2.02.26. The geological relations at Ely are practically the same, but the ore body as displayed in the Chandler and Pioneer mines is larger than at Vermilion Lake. It rests, however, on a greenstone dike, which is folded into a syncline with a minor roll in the bottom of the trough which, as shown in Fig. 38, makps it a double one. The ores are soft hematites of extraor- dinary richness and purity, and are all of very high bessemer grade. Indications of ore are strong still further east, and Fi«. 37. — Open ciO at Minnesota Iron Company's Mine, Soudan, near Tower, in south view looking west. Photograph by J. F. Kemp, 1894. Ph •*5'-''* t SI ^^ 150 KEMP'S ORE DEPOSITS. developments have now proved important. The combined output of the mines at Ely and Vermilion Lake is from 800,000 to over 1,000,000 tons annually, about equally divided between them. The total shipments up to the close of 1897 have been 10,498,716 tons. The work of H. L. Smyth and Finlay has demonstrated what many observers have felt from more cursor}^ examination — that the geological relations of these ores are essentially the same as those on the south shore. Different explanations have, however, been advanced, and great uncertainty has surrounded the geology, on account of the excessively metamorphosed and Fig. JjS. — Horizontal and vertical cross-sections of the Chandler ore body at Minn. After Smyth and Finlay, Trans Amer. Inst. Min. Kng., XXV., 595, 1895. obscure igneous rocks. N. H. and H. V. Winchell have argued that the ores were submarine precipitates from volcanic lapilli, furnished by submarine eruptions. From the lapilli the sea water was thought to have extracted the iron and silica. There seems, however, little reason to question the results of Smyth and Finlay. 2.02.27. Example 9e. Mesabi Range. Of much more recent development than the other districts is the Mesabi range of Minnesota. The mines began to make important shipments of ore in 1893. The indications are that the depos- its are not less extensive than those in any other of the Lake THE IRON SERIES CONTINUED. 151 Superior localities, and that they are even larger and of a char- acter to be more easily mined. The present developments are situated southwest of Vermilion Lake, and nearer Duluth and Lake Superior. They cover a stretch of about 30 miles, from Biwabik on the east, through McKinley, Virginia, Eveleth, Mountain Iron and smaller towns to Hibbing on the west. Little ore is known beyond Hibbing. The ore bodies are all south of the granite ridge. The ore lies under the black slates called Animikie in the section given in Paragraph 2.02.2$, and over the quartzite, there called the Pewabic; but they are situated twenty miles or so west of the line of that section. The G R E Fig. 40. — General cross-section of ore body at Biwabik, Mesabi Range, Minn. After H. V. Winchell, Twentieth Ann. Rep. Minn. State Geologist. ore bodies are all south of the granite ridge called the Giants' Range. Upon the southern slopes of this range lie the green schists of the Keewatin, which are unconformably overlain by the Pewabic quartzite. On this rests the ore-bearing rock, which is a jaspery or cherty siliceous variety called taconyte by H. V. Winchell. Over this, in order, come greenish siliceous slates and cherts, black slates (referred to the Animikie), and great masses of gabbro. On the flanks of the Giants' Range the dip is steep, but it flattens out nearly to horizontality away from the granite. All the formations above the Keewatin are called Taconic by the Winchells. 152 KEMP'S ORE DEPOSITS. 2.02.28. The ore bodies lie on the southerly slopes of low hills, and are found immediately below the mantle of glacial drift, which varies up to 200 feet in thickness. Ore indications have long been known on the range, and various reports have been made in former years, although always unfavorably. The indications then available showed only siliceous limonites of low grade. Deep test pits, however, which penetrated these caps and the drift, have revealed enormous ore bodies and have rewarded persistent prospecting. The ores are blue and brown and of soft, earthy texture, with occasional hard streaks. They lie from 10 to as much as 180 feet below the surface a& now mined, and where the stripping is sufficiently thin it is removed with steam shovels, and then after being shaken up with black powder the ore is excavated in the same way. The ore bodies are lenses, which at times, as at the Mesaba Mountain or Oliver mine in Virginia, appear to form a basin. In the central part of this mine a drill hole is stated to have shown 335 feet of ore, but the general run is less. The ore bodies have usually a southeasterly trend, and are longer than wide. The blue ores are richest in iron and purest as regards phosphorus, and they are the ones specially desired. Ores for foundry iron also occur in large amount, but are at present less sought for. The rock most intimately associated with them all is the chert, called taconyte. The underlying quartzite is occasionally shown in the mines as well as the overlying slates, but the whole region is so completely buried in drift that outcropping rock is a rare thing. The ores are thought by H. V. Winchell to have originated b}^ replacement of the taconyte. The rock contains calcareous streaks which have perhaps aided in furnishing the carbonic acid, which, it is thought, has dissolved the silica of the taconyte in the replacement process. Recently, valuable observations on the geology of the ores have been accumulated by J. E. Spurr, while in the field for the Minnesota Geological Survey, in whose Bulletin X. the detailed report has appeared. A preliminary paper in the American Geologist for May, 1894, gives an abstract of the results. As in the Penokee-Gogebie and Marquette districts, the western end of the Mesaba range is least disturbed and metamorphosed. The stratigraphy is the same as that already outlined in preceding paragraphs, but the 05 GO si ?= s 1 1 THE IRON SEUIE8 CONTINUED. 153 quartzite is simply called by Spurr, Animikie, and not Pewa- bic. The iron-bearing series is stated to be from 500 to 1,000 feet thick, with an average of 800 feet. The unaltered rock is described as consisting of **cryptocrystalline, chalcedonic or finely phenocrystalline silica" thickly "strewn with rounded or subangular bodies made up chiefly of a green mineral," regarded as glauconite, the hydrated silicate of protoxide of iron and potash. Analyses of the rock corroborate this deter- mination, because they indicate a constant but small percent- age of potash. Layers of the rock, rich in calcite (probably magnesian) also occur. Spurr is thus led to regard the rock as an altered greensand, to which view similar conclusions regard- ing the much more recent and unmetamorphosed ores of Texas and Louisiana (see 2.01.15) give support. The chemistry of the deposition is considered by Spurr to be the following: Atmospheric waters, with dissolved carbonic acid, and some alkaline salts have filtered into the cracks and become charged with ferrous carbonate, where the conditions prevented oxidation. The greater solubility of the ferrous salt led to its solution before the alkali attacked the silica. Later, reaching more open and fissured portions, the ferrous salt was oxidized and deposited, while the silica was attacked and removed by the alkali. In time, thus the iron oxide was concentrated along fissured strips, near faults, and the like, whereas the silica was removed. It is recognized as well that the ferrous salt was precipitated as carbonate, amid deoxidiz- ing conditions. The change from silicate or carbonate to hydrous oxide of iron led to shrinkage and shattering, and the passage from hydrous oxide to carbonate, where such occurred, to expansion and shattering. It follows from the explanation that the regions of rich ore bodies would be those of notable geological disturbances, so that faults are presumed near Vir- ginia, Biwabik and elsewhere.^ ^ C. E. Bailey, "Mining Methods on the Mesabi Range," Trans. Amer. Inst. Min. Eng., XXVII., 529. F. W. Denton, "Open-pit Mining with Special Reference to the Mesabi," Proc. Lake Superior Mining Inst., III., 1896. "Methods of Iron Mining in Northern Minnesota," Trans. Amer. Inst. Min. Eng., XXVII., 344. E. P. Jennings, "The Mesabi Range," Sci- ence, XXIII., 73. E. J. Longyear, "Explorations on the Mesabi Range,' Trans. Amer. Inst. Min. Eng., XXVII., 537. J. E. Spurr, " The Mesabi 154 KEMP'S OBE DEPOSITS. 2.02.29. Hematites apparently much like those of Lake Superior have been reported from the Hartville iron district in Laramie County, Wyoming. The ores, according to W. C. Knight, constitute irregular zones in Carboniferous rocks and are associated in many cases with copper deposits. (See 2.04.28.) The published analyses show rich ores of bessemer grade. ^ 2.02.30. The explorations of Mr. A. P. Low, of the Geologi- cal Survey of Canada, have shown extensive developments of iron carbonates, and magnetite and hematite, associated with jasper, and with cherty carbonate of lime, along the east side of Hudson Bay, and in the valleys of the Koksoak (called also Ungava) and Hamilton rivers. Mr. Low describes the enclos- ing strata as Cambrian. The samples brought back proved rather low in iron (30 to 54% Fe), but the geological relations are extraordinarily' like those of Lake Superior.^ 2.02.31. Example 10. James River, Virginia. Specular hematite in narrow beds (lenses), interstratified with quartzites and slates of metamorphic character and Archean age. They run four to six feet, or less, in thickness, with prevailingly vertical dip, but they also pitch diagonally down on the dip like the lenses of magnetite, later described. They furnish a very excellent grade of ore. The ore bodies are found along both sides of the James River, a few miles above Lynchburg. Some magnetite also occurs in the region, and some limonite. More or less clay accompanies the ore.^ Iron-bearing Rocks, " Bulletin 10, Minn. Geol. Survey, 1894. Rec. ' * The Iron Ores of the Mesabi Range," Amer. Geologist, XIII., May, 1894, 335. H. V. Winchell, Twentieth Ann. Rep. Minn. State Geol., 112, 1892. "Iron Ores of Minnesota," Bull. 6, Minn. Geol. Survey. H. V. Winchell and J. T. Jones, "The Biwabik Mine," Trans. Amer. Inst. Min. Eng., XXI., 951. For an early account of the Mesabi Range see New York Times, December 14, 1892. * W. C. Knight, Bulletin U, Wyoming Experiment Station, Laramie, Wyo., pp. 135 and 176. A large series of analyses appears in the prospec tus of the Wyoming Railway and Iron Co. E. P. Snow, " The Hartville Iron Ore Deposits in Wyoming," Engineering and Mining Journal, Octo- ber 5, 1895, p. 320. ^ The above note is due to the courtesy of Dr. George M. Dawson, Di rector of the Geological Survey of Canada, who kindly gave the writer an abstract of Mr. Low's report in advance of its publication. ' E. B. Benton, Tenth Cenms, Vol. XL, p. 363 (on Virginia). J. L. Campbell, Geology and Resources of the James River Valley, p. 49, Nei^ THE IRON SERIES CONTINUED. 155 2.02.32. Similar lenses of specular ore and magnetite are found in central North Carolina, in schistose rocks, which have been referred to the Huronian. As stated under 2.02.29, lenses of specular hematite of very excellent quality are found also in metamorphic rocks, north of Fort Laramie, Wyoming, which may prove productive in time. 2.02.33. Example 11. Pilot Knob, Missouri. Two beds of hard specular hematite separated by a thin seam of so-called slate (possibly volcanic tuff), and interstratified with breccias and sheets of porphyry. Along the eastern limit of the Ozark uplift of Missouri and Arkansas a series of knobs of granite and porphyritic rocks project through the Cambrian limestones and sandstones. They are older than the limestones, and clearly were not intruded through them. The limestones and sandstones lie up against the porphyry and in the valleys between. The underlying porphyry has been found in the val- ley near Pilot Knob, after penetrating four hundred feet of sedimentary rocks. The porphyry and ores have often been called Huronian, but in view of the recent reorganization of the Huronian (see Example 9), this is not done, nor ever has been, on any accurate grounds. Pilot Knob is formed by one of these eruptive knobs. It consists of sheets of porphyries that are capped by porphyry breccia, and two ore beds, and the in- tervening slaty rock which may be a tuff. The beds strike and dip 13° S. S. W. The hill is over 600 feet high. The lower bed has furnished most of the ore, running from 25 to 40 feet thick, and affording a dense bluish, specular hematite of from 50 to 60% Fe, siliceous and very low in phosphorus. The upper bed is irregular and of lower grade, and runs from 6 to 10 feet thick. The Pilot Knob mines in this solid ore are DOW substantially exhausted. Recent drill holes on the northerly slope and below the out- cropping face of ore have shown that under the Cambrian strata of the valley there is a great bed of ore boulders or breccia in clay, much as is the case at Iron Mountain, later described. Analyses of these latter ores were not, however, York, 1882. H. B. C. Nitze, "On North Carolina," Bulletin No. 1, North Carolina Geol. Survey, 1893. B. Willis, Te^ith Census, Vol. XV., p. 301. The Virginias, a monthly, formerly published by Jed. Hotchkiss, at Staun- ton, contains much information on Virginia in general. TT 'l.l»li!?W. ^ ^ ^ s * ^ ^ ^ Ci- THE IRON SERIES CONTINUED. 157 sufficiently encouraging for development during the recent low prices for iron. Doubtless the bed will afford important re- serves. 2.02.34. Near Pilot Knob are two other hills of porphyry, Shepherd Mountain and Cedar Mountain, whose ores are structurally more related to Example 11a. The first contains three veins, the Champion, the North, and the South. They are long and narrow (4 to 10 feet) strike north 60° to 70° east, and dip 70° north. The Champion vein contained a little streak of natural lodestone, but the ore is mostly specular. The North vein ^hows a good breast of ore five feet wide, but too full of pyrite to be available. Cedar Mountain has a vein of specular ore. Neither hill has been an important pro- ducer. Minor veins have been found on neighboring porphyry hills (Buford, Hogan, and Lewis mountains), some of which contain much manganese. 2.02.35. Example 11a. Iron Mountain, Missouri. Veins of hard, specular hematite irregularly seaming a knob of por- phyry. Iron Mountain is five or six miles north of Pilot Knob, and is a low hill with a westerly spur called Little Mountain. It has also a northerly spur. It consists of feldspar porphy- ries, more or less altered. These are seamed with one large, and on the west somewhat dome-shaped, parent mass of ore and innumerable minor veins that radiate into the surrounding rock. Upon the flanks of the porphyrj^ hill rests a mantling succession of sedimentary rocks, that dip away on all sides. The lowest member is a conglomerate of ore fragments, weath- ered porphyry, and residual clay left by its alteration. It is regarded by Pumpellyas formed by pre-Silurian, surface disin- tegration and not by shore action, inasmuch as sand does not fill the interstices, while white clay from decomposed porphyry does. It is, however, overlain by a thin bed of coarse, friable sandstone, which marks the advance of the sea, and whose formation preceded the limestones. This conglomerate was in later years the principal source of the ore, but the mines are now considered to be worked out. It was mined underground, hoisted and washed by hydraulic methods, like those employed in the auriferous gravels of California, and then jigged. The apatite has largely weathered out of it. The rock of the mountain itself, in the cuts of the mines, is largely kaolinized. 158 KEMP'S ORE DEPOSITS. and exhibits everywhere the effects of extreme alteration. The smaller veins that penetrate the porphyry show at times casts or much altered cores of apatite crystals. 2.02.36. The porphyries of Pilot Knob and Iron Moun- tain, in thin section, are seen to belong to quartz porphyries, feldspar porphyries, and porphyrites. Both orthoclase and plagioclase are present in them, and many interesting forms of structure. One significant fact is that they are everywhere filled with dusty particles of iron oxide, probably magnetite. An eruptive origin was originally assigned to these ores by J. D. Whitney {Metallic Wealth of the United States, p. 479, 1854), just as to the Lake Superior hematites. The later in- vestigations of Adolph Schmidt for the Missouri Survey in 1871 arrived at a different conclusion. Dr. Schmidt considered them, whether occurring in an apparent bed, as at Pilot Knob, or in various more or less irregular veins, as at Iron Mountain, to have been formed either by a replacement of the porphyries with iron oxide deposited from solution, or by a filling in the same way of fissures, probably formed by the contraction of the porphyry in cooling. In the valuable report on iron ores by F. L. Nason in the Missouri Geological Survey a sedimentary origin is advocated for the Pilot Knob beds. They are con- ceived to have been deposited in a body of water in a hollow, between formerly existing porphyry hills, which rose above. In the course of weathering, the hills became the valleys, and the early sedimentary beds the hilltop. It is, however, some- what difficult to understand how the more or less incoherent sediments withstood degradation better than the hard, firm, porphyry hills. Some such origin as sedimentation or replace- ment is, however, the only reasonable one. It is not improba- ble that the Pilot Knob ores originated in the saturation and more or less complete replacement of layers of tuffs with in- filtrating iron oxide. An extended table of analyses of Iron Mountain ores will be found in Mineral Resources of the United States, 1889-90, p. 47.' ^ G. C. Broadhead, "The Geological History of the Ozark Uplift, "^me?*. Geol. , III. , 6. J. R. Gage, ' * On the Occurrence of Iron Ores in Missouri, " Trans. St. Louis Acad. Sci., 1873, Vol. III., p. 181. E. Harrison, " Age of the Porphyry Hills, Ibid., Vol. II., p. 504. E. Ha worth, "A Contribu- Fig. 43. — View of ojjen cut at Pilo^ Knob, Mo., aJiowing the bedded char- acter of the iron ore. From v photograi^h by J. F. Kemp, 1888. f O THE IRON SERIES CONTINUED. 159 ANALYSES OP HEMATITES, RED AND SPECULAR. (The same discrimination must be employed in looking over these anal- yses that was emphasized under limonite. ) Fe. P. S. SiO^. Al,03 H,0. Clinton, N. Y. (fossil ore) Wisconsin (fossil ore) 44.10 51.75 44.40 51.63 ■ 56.40 0.650 1.392 0.115 0.345 0.230 12.63 5.45 2.77 Pennsylvania (Mifflin ore) 0.028 Tennessee (Meigs County) 0.340 0.883 0.085 0.530 0.067 0.009 0.040 0.015 0.139 0.020 16.80 0.50 ■ \: \ • • Antwerp, N. Y 46.32 59.41 68.40 64.83 60.47 65.50 59.15 49.89 61.81 70.00 Missouri (Crawford County) Marquette dist., Mich, (specular) 6. bio' 2.07 3.60 3.38 5.75 13.27 Menominee district, Michigan. . . 2.03 Iron Mountain, Mo Pilot Knob, Mo 2.19 James River (Maud vein) Elba 0.170 5.97 3.47 Pure mineral These analyses are mostly taken from State reports and from Mineral Resources of the United States. They are intended to illustrate he general run of compositions, but for Birming- ham and Marquette are high. Analyses vary widely. tion to the Archaean Geology of Missouri," Amer. Geol, I., 280-363; "Age and Origin of the Crystalline Rocks of Missouri," Bull. 5, Mo. Geol. Sur- vey, 1891. A. V. Leonhard, "Notes on the Mineralogy of Missouri," Trans. St. Louis Acad. Sci., Vol. IV., p. 440. F. L. Nason, "Report on the Iron Ores of Missouri," Mo. Geol. Survey, II. Rec. R. Pumpelly, "Geology of Pilot Knob and Vicinity," ilfo. Geol. Survey, 1872, p. 5; see also remarks on Iron Mountain, Bull. Geol. Soc. Amer., Vol. II., p. 220. Rec. W. B. Potter, "The Iron Ore Regions of Missouri," Journal U. S. Asso. Charcoal Iron Workers, Vol. VI., p. 23. Rec. F. A. Sampson, "A Bibliography of the Geology of Missouri, ' Bull. 2, Mo. Geol. Survey, 1890. (This is a valuable book of reference. ) F. Shepherd, Ann. Rep. Mo. Geol. Survey, 1853-54. Hist. A. Schmidt, "Iron Ores of Missouri," ilfo. Geol. Survey, 1872, p. 45, and especially p. 94. Rec. J. D. Whitney, Metallic Wealth of the U. S., p, 479. Of more recent issues are the following: E. Ha worth, "The Crystalline Rocks of Missouri," Eighth Ann. Rep. Mo. Geol. Survey, 1894, p. 81. C. R. Keyes, "Geographic Relations of the Granites and Porphyries in the Eastern Part of the Ozarks, " J5«*/Z. Geol. Soc. Amer., VII., 363, 1896. "Report on the Mine la Motte Sheet," Geol. Survey of Mo., IX., Sheet Report 4. Arthur Winslow, E. Haworth and F. L. Nason, "Report on the Iron Mountain Sheet," Idem, Sheet Report 3. Rec. This last is the best work of reference as regards the mines. Further details will be found in Winslow's Bulletin 132 of the U. S. Geol. Survey, on "The Disseminated Lead Ores of Southeastern Missouri." CHAPTER III. MAGNETITE AND PYRITE. 2.03.01. Example 12. Magnetite Beds. Beds of magne- tite, often of lenticular shape, interfoliated with Archean gneisses and crystalline limestones. They are extensively developed in the Adirondacks, in the New York and New Jer- sey Highlands, and in western North Carolina. The presence of magnetite in Michigan (Example 9a), in Minnesota (Exam- ple 6b), on Shepherd Mountain in Missouri (Example 11), and in Virginia (Example 12) has already been referred to. Other magnetite bodies are known in Colorado, Utah, California and Wyoming, and will be mentioned subsequently. Titanium is often present, but the titaniferous ores are made a special exam- ple. The same is true of pyrite and pyrrhotite. Apatite is always found, although it may be in very small quantity. Chlorite, hornblende, augite, epidote, quartz, feldspar, and a little calcite are the common associated minerals. In New Jersey the beds occur in several parallel ranges or belts. 2.03.02. Example 12a. The Adirondacks. Deposits of magnetite are extensively developed in the crystalline area of the Adirondacks, and they show some interesting relationships between the character of the ore and the nature of the country rock. The titaniferous varieties to be later described favor the interior, mountainous core, but the nontitaniferous are especially found on the flanks and in the foothills. The region is in large part an eruptive area of plutonic rocks representing various members of the great gabbro family whose chief minerals are labradorite and some form of pyroxene. There are members which are little else than labradorite and which are called anorthosites ; there are others containing labradorite and hyper- sthene, the norites; still others are dark and basic, and consist MAGNETITE AND P TRITE. 161 of little else than labradorite, augite, hypersthene, ilmenite and garnets, the last-named having been formed by metamor- phism/ Augite syenites of massive character have recently been recognized by H. Po Gushing, and the discovery has thrown much light on many rocks only known before as gneisses. All these eruptives have suffered greatly from dyna- mic metamorphism, and are now as a rule decidedly gneissoid in structure. In addition to the eruptives there are white, crys- talline, graphitic marbles, usually charged with pyroxenes; black, hornblendic schists; quartzites; and quartzose gneisses that represent a series of sedimentary rocks of Algonkian age, but that are now much broken by the eruptives above mentioned. The Algonkian sediments are most satisfactorily exhibited on the western side of the mountains. ^ The general geology of the Adirondacks is described by E. Emmons in his "Report on the Second District of New York," N. Y. Natural History Survey, 1842. The later papers of importance are the following, and a general review of work that had been done up to 1892 is given by J. F. Kemp, " A Review of Work Hitherto Done on the Geology of the Adiron- dacks," Trans. N. Y. Acad, of Sciences, XII., 19, 1892. H. P. Gushing, "Re- port on the Geology of Clinton Co.," 13th Ann. Rep. State Geologist, 1893, 473; 16th Idem, 499. ' ' Report on the Boundary Between the Potsdam and Pre-Cambrian Rocks North of the Adirondacks," 16th Annual Report State Geologist, 1896. An additional report on 'Franklin Co. is in press (1899). "Augite- syenite Gneiss near Loon Lake, N. Y.," Bull. Geol. Soc. Amer., X., 177-192. J. F. Kemp, " Gabbros on the Western Shore of Lake Champlain," Jdem, V., 213, 1894. "Crystalline Limestones, Ophicalcites and Associated Schists of the Eastern Adirondacks, " Idem, VI. , 241. ' ' Pre- liminary Report on the Geology of Essex Co.," Rep. N. Y. State Geologist for 1893, 79, 1894; continued in the ISth Ann. Rep., Idem, 1895, 575. A report on Warren Co. is in press. ' ' The Geology of Moriah and Westport Townships, Essex Co.," Bull. N. Y. State Museurn, III., 325, 1895. "The Geology of the Magnetites near Port Henry, N. Y., Trans. Amer. Inst. Min. Eng. , XXVII. , 146, 1897. ' ' The Geology of the Lake Placid Region, " Bull. N. Y. State Museum, V., 51, 1898. C. H. Smyth, Jr., "A Geological Reconnoissance in the Vicinity of Gouverneur, N. Y. , Trans. N. Y. Acad. Sci., XII., 203, 1893. "Petrography of the Gneisses of the Town of Gouv- erneur, N. Y.," Idem, XII., 203, 1893. "Report on the Geology of Four Townships in St. Lawrence and Jefferson Counties," 13th Ann. Rep. N. Y. State Geologist, 491. "Crystalline Limestones and Associated Rocks of the Northwestern Adirondack Region," Bull. Geol. Soc. Amer., VI., 263, 189d. ' ' Report on the Crystalline Rocks of St. Lawrence Co. , " 15th Ann. Rep. N. Y. State Geologist, 1895, 477. Additional reports on the western Adirondacks are in press. 162 KEMP'S ORE DEPOSITS. 2.03.03. The magnetites are found in the fortn of lenticular masses that correspond perfectly to the foliation of the gneisses. They may extend long distances on the strike, as at Lyon Mountain, where the Chateaugay ore is said to be traceable four or five miles, but it is lean over most of the distance. Beits more or less continuous for a mile are opened up in several places. The ore may be in gneiss that is practically quartz and microperthite as at Hammond ville; or in pyroxenic gneisses as at Lj^on Mountain ; or on the contact of gneiss like that which forms the wall-rock at Hammondville just mentioned, and dark, basic, hornblendic gneiss, derived from intruded gabbro; or on the contact of gabbro like the last and gneisses which are involved with crystalline limestones, as at the Chee- ver mine; or finally, in the crystalline limestones near gabbro intrusions, as at the Weston niines, Keene Center. The ores at SOOFeet Fig. 47. — Gross-section of the Chee'cer iron mine, near Port Henry, N. Y., showing the occurrence of the ore in pyroxene gneiss, just over gabhro. Lake Champlain 'terminates the section at the right. After J. F. Kemp, Bull. N. T. State Museum, Vol. III., p. 346. Mineville have been regarded as contact deposits hy J. F. Kemp, and as having been developed by the neighboring gab- bro. As will appear from the accompanying map and sections, Figs. 48 and 49, there are two groups of mines. One on Bar- ton Hill is based on a long series of pods or lenses that occur between an underlying gabbro and gabbro-gneiss, and an over- lying gneiss, called the Orchard. The Orchard gneiss con- sists almost entirely of quartz and oligoclase. Above it is the Barton gneiss, containing some quartz with abundant micro- perthite, plagioclase, orthoclase, brown hornblende, augite and hypersthene. The lower group embracing the Miller pit, Old Bed and *'2.1,'* have the *'21'' gneiss, an aggregate of quartz and microperthite, exposed on the surface. Diamond drill cores have, however, revealed the gabbro-gneiss beneath the ore in depth. The map brings out the parallel pod-like shape of the Fig. 46. — View of open cut and underground work in Mine 21, Mineville, near Port Henry, N. Y. Photographed by J. F. Kemp, 1892. MAGNETITE AND PYRITE. 163 Fig. 48. — Heological map of the iron mines at Mineville, near Port Henry, N. Y. For details of formations see text. After J. F. Kemp, Trans. Amer. Inst. Min. hJng., XXVIL, 146. 164 KEMP'S ORE DEPOSITS. ores. In one instance, the New Bed mines, the workings have followed a pod over 2,000 ft. The magnetites have not yet been described in the same detail at other localities, but data are at hand which give ground for similar inferences regarding several additional ones. Gabbros are usually in the vicinity of the ore even when it does not occur on the contact. Never- theless some mines give no immediate evidence of the influence of any rock except that of the walls, as for instance the Palmer Hill workings near Ausable Forks; and the ore appears to be a great, basic segregation, drawn out into a band, parallel Fig. 49. — Cross-section of ore-bodies at Mineville, near Port Henry, N. Y., to accompany rnap, Fig. 48. After J. F. Kemp, Trans. Amer. Inst. Min. Eng., XXVII, 146. with the foliation. At Palmer Hill the walls are a siliceous gneiss, consisting of quartz, microperthite, microcline and augite. The ores follow all the foldings and flowing curves that are exhibited in the foliation of the gneisses, and because of this they exhibit manj- peculiar shapes. They swell and pinch, roll and fold and feather out. Still, at Mineville they show a marked parallelism in the long axes of the pods or lenses, and while these tongue out into the walls, they do so with a gen- eral parallel alignment. Faults are common and in instances have sharply cut off the ore. Dark, brecciated strips may mark I MAGNETITE AND PYBITE. 165 the fault line and may resemble trap dikes, as in No. 7 slope at Hammond ville. Small gulches are frequently over the places where the ore is lost, and serve to mark the fault line. Trap dikes are frequent in the mines, and hardly a solitary one fails to show them. They may fault the ore for a few feet.^ 2.03. 04. In their metallurgical relations the ores may be clas- sified, following the example of B. W. Putnam in his report for the Tenth Census, into (1) those high in phosphorus, but low in sulphur (Mine 21, Mineville); (2) Bessemer ores, low in both phosphorus and sulphur (Barton Hill mines, Hammond- ville mines); (3) pyritous ores (Buck Mountain, Ticonderoga). * The following papers relate especially to the ores as distinguished from the geology: L. C. Beck, Mineralogy of New York, Part I., 1-38, 1842. J. Birkinbine, " Crystalline Magnetite in the Port Henry (N. Y.) Mines," Trans. Amer. Inst. Min. Eng., XVIII., 747, 1890. Rec. "Note on the Magnetic Separation of Iron Ore at the Sanford Ore- bed, Moriah, Essex Co., N. Y., 1852, Idem, XXI., 378, 1892; see also p. 157. H. Credner, Zeitsch. d. d. g. Gesell, 1869, XXI., p. 516; B. und H. Zeit, 1871, 369. J. D. Dana "On the Theories of Origin," Amer. Jour. Sci., iii., XXII., 152, 402. E. Emmons, Geology of New York, Second District, pp. 87, 98, 231, 255, 291, 309, 350. Hist. C. E. Hall, "Laurentian Magnetite Ore Depos- its of Northern New York," 3M Ann. Rep. State Museum, 1884, p. 133. Rec. Hanns Hoefer, * ' Die Kohlen- und Eisenerzlagerstatten Nord Amer- ikas," 175, 1878. J. F. Kemp, "Notes on the Minerals Occurring near Port Henry, N. Y.," Amer. Jour. Sci., iii., XI., 62, and Zeitsch. f. Kryst., XIX., 183. "The Geology of the Magnetites near Port Henry, N. Y.," Trans. Amer. Inst. Min. Eng., XXVI., 146, 1897. G. W. Maynard, "The Iron Ores of Lake Champlain," Brit. Iron and Steel Inst., Vol. I., 1874. F. L. Nason, "Notes on Some Iron-bearing Rocks of the Adirondack Mountains," Amer. Geologist, XII., 25, 1893. B. T. Putnam "Notes on the Iron Mines of New York, " Tenth Census, XV. , 89, 1885. Rec. B. Silliman, "Remarks on the Magnetites of Clifton, St. Lawrence County, N. Y.," Trans. Amer. Inst. Min. Eng., I., 364. J. C. Smock, "Iron Mines of New York," Bull. VII. , N. Y. State Museum. Rec. J. Stewart, "Laurentian Low Grade Phosphate Ores," Trans. Amer. Inst. Min. Eng., XXI., 176, 1892. Wedding. Zeitschr. f B., H., und S. im. p. St., XXIV., 330, 1876. See also the general works on Iron Ores cited at begimiing of Part II. On Canadian magnetites the following papers may be mentioned: F. P Dewey, "Some Canadian Iron Ores," Trans. Amer. Inst. Min. Eng., XII. 192. B. J. Harrington, "On the Iron Ores of Canada," Can. Geol. Survey 1873^74. T. S. Hunt, Can. Geol. Survey, 1866-69, pp. 261, 262. T. D. Led yard, "Some Ontario Magnetites." Traris. Amer. Inst. Min. Eng., XIX. 28, and July, 1891. W. H. Merritt, "Occurrence of Magnetite Ore De posits in Victoria County, Ontario," Froc. Amer. Asso. Adv. Sci., XXXI. 413. 1882. 166 KEMP'S ORE DEPOSITS. On the western side of the mountains some extensive mining has also been done. The Benson mines at Little Eiver are based upon a broad, mineralized zone whose ore is inclined to be lean, and to be a subject for magnetic concentration. There are numerous deposits of magnetite in Canada, to the north of Lake Ontario, whose geological relations are similar to those above described. 2.03.05. Example 126. New York aud New Jersey High- lands, and the South Mountain of Pennsylvania, Lenticular or pod-like masses of magnetite in Archean gneiss and crystalline Fig. oO. Fig. 51. Figs. 50 and 51 . — Model of the TiUy Foster ore body. 50. Side mew, show- ing faulted shoulder. After F. 8. Ruttmann, Trans. Amer. Inst. Min. Eng., XV., 79. 51. View of bottom of same. Photo- graphed by J. F. Kemp from the model now at the School of Mines, Columbia College. limestone. From Putnam County, New York, a ridge of Archean rocks runs southwest across the Hudson River, trav- ersing Orange County, New York, and northern New Jersey, and running out in Pennsylvania. Lenses of magnetite occur throughout its entire extent. They are not as large as some in the Adirondacks, but they are more regularly distributed. East of the Hudson, in Putnam County, the Tilly Foster mine is the most important, and the descriptions and MA GNETITE A ND P YRl TE. 167 figures of it are the best illustrations of the shape of lenses published. West of the Hudson, in Oranpje Countj', the Forest of Dean mine affords considerable ore yearly. It is cut by an interesting trap dike. As the results of study of the Archean of this region, N. L. Britton has divided it into a Lower Massive group, a Middle Iron Bearing, and an Upper Schistose. {Oeol. of N. J., 1886, p. 77.) F. L. Nason has also sought to classify it on the basis of rock types, of which he naakes four, named, from their typical occur- rences. Mount Hope type, Oxford type, Franklin type, and Montville type. They are arranged in their order of probable age. They correspond in some respects to Britton's grouping, but differ materially in others. {Geol. of N. J., 1889, p. 30.) Four courses, or mine-belts, have been recognized in New Jer- sey — the Ramapo, the Passaic, the Musconetcong, and the Pequest — in order from east to west. The lenses strike north- east with the gneisses, and usually have, like them, high dips. In addition they have also a so-called "pitch" along the strike, so that they run diagonally down the dip. They have been observed to pitch northeast with an easterly dip and southwest with a westerly. Either by the overlapping of lenses or by an approximation to an elongated bed, they sometimes, as at Hibernia, extend a mile or more in unbroken series. Again, they may be almost circular in cross section (Hurd mine). At Franklin Furnace one is found in crystalline limestone.^ ' E. S. Breidenbaugh, "On the Minerals Found at the Tilly Foster Mine, New York," Amer. Jour Sci., iii., VI., 207. J. F. Kemp, " Diorite Dike at the Forest of Dean Mine," Idem, iii., XXXV., 331. F. H. McDowell, "The Reopening of the Tilly Foster Mine," Trans. Amer. Inst Min. Eng., XVII., 758; Engineering and Mining Journal, Sept. 7, 1889, 206. F. S.' Ruttman, " Notes on the Geology of the Tilly Foster Ore Body, Putnam County, New York," Trans. Ainer. Inst. Min. Eng., XV., 79. Rec. J. C. Smock, Bull. VIL, N. Y. State Museum. Rec. A. F. Wendt, 'The Iron Mines of Putnam County," Trans. Amer. Inst. Min. Eng., XIII., 478. "Iron Mines of New Jersey," School of Mines Quarterly, iv., III. N. L. Britton, Ann. Rep. N. J. Sm^ey, 1886, p. 77. Rec. G. H. Cook and J. C. Smock, Geol. of N. J., 1868. Rec. (See also subsequent annual reports, especially 1873, p. 12.) F. L. Nason, Ann. Rep. N. J. Survey, 1889. Rec. J. W. PuUmann, " The Production of the Hibernia Mme, New Jersey," Trans. Amer. Inst. Min. Eng., XIV., 904. J. C. Smock, "The Magnetite Iron Ores of New Jersey," Idem, II., 314; "A Review of the Iron Mining Industry of New Jersey," Idein, June, 1891. Rec. 168 KEMP'S ORE DEPOSITS. J. E. Wolff has contributed a very important and suggestive paper upon the large bed of magnetite at Hibernia. The ore extends for about one mile as developed, and forms a persist- ent band in a series of gneisses which under the microscope are found to contain quartz, orthoclase, plagioclase, microcline, microperthite, brown or green hornblende, a deep green or color- Fig. 52. — Sketch map illustrating the geological structure of the Hibernia mag- netite bed, Hibernia, N. J. The ore outcrops for one mile. After J. E. Wolff, Annual Report of the State Geologist of New Jersey for 1893. less augite, sometimes diallage, biotite, sometimes hypersthene, and as accessories, apatite, magnetite, and zircon. The dark silicates may form int;ermittent bands by their greater abund ance, but are of no stratigraphic value. All the large minerals are in elongated spindles, whose long axes correspond to the pitch of the gneiss. They are thought by Wolff t;o have as- MAGNETITE AND P TRITE. 169 sumed this shape in crystallizing, during metamorphism. About a half mile from the ore and parallel with it is a band of biotite-garnet-graphite gneiss that is persistent, and that is folded as shown in Fig. 52. This latter rock" is supposed to be a metamorphosed limestone, and the whole series is regarded as metamorphosed sediments by Wolff. ^ F. L. Nason has worked out the structural geology of the Ringwood mines, and has found that they are quite well interpreted as lying along a pitching series of folded gneisses.^ 2.03.06. South Mountain, Pa. Small lenses of magnetite occur in Berks, Bucks, and Lehigh Counties of southeastern Pennsylvania, in the metamorphic rocks of the South Moun- tain belt. They are very like those to the north in New Jer- sey, but are lower in both iron and phosphorus. Their product has reached 100,000 tons 5'early. The Cornwall magnetite is described under Example 13, for its geological structure is entirely different from the lenses.^ 2.03.07. Example 12c. Western North Carolina and Vir- ginia. Beds of magnetite, of the characters already described, in Archean gneisses and schists. The ore body at Cranberry, N. C, is the largest and best known. It occurs in Mitchell County, and has lately been connected by rail with the lines in east Tennessee. According to Kerr, the principal outcrop is 1,500 feet long and 200 to 800 feet broad ; but, of course, this is not all ore. The mines can afford very large quantities of excel- lent Bessemer grade. Pyroxene and epidote are associated with the ore. Kerr has referred the magnetite to the Upper Lauren- tian. In the southern central portions of North Carolina other magnetites occur in the mica and talcose schists, which have been referred to the Huronian. (See H. B. C. Nitze, Bull. I., N. C. Geol. Survey, toT detailed report) (Example 10.) Magnetite has also been lately reported from Franklin and ' J. E. Wolff, "Geological Structure in the Vicinity of Hibernia, N. J., and its Relation to the Ore Deposits," N. J. Geol. Survey, 1893, 859. ^ F. L. Nason, " The Geological Structure of the Ringwood Iron Mines, N. J.," Trans. Amer. Inst. Min. Eng., XXIV., 505, 1894. 3 E. V. d'Invilliers, Rep. D3, Penn. Survey, Vol. II. (South Mountain Belt of Berks County). Rec. F. Frime, Rep. DS, Vol I., Penn. Survey (Lehigh County). B. T. Putnam, Tenth Census, Vol. XV., p. 179. 170 KEMP'S ORE DEPOSITS. Heory Counties, Virginia, and Stokes County, North Carolina. Some doubt, however, is cast on its amount and quality/ 2.03.08. Example Vld. Colorado Magnetites. Beds of magnetite of a lenticular character in rocks described as sye- nite (Chaffee County) and diorite (Fremont County). With these a number of others are mentioned which vary from the example, but of which more information is needed before they can be well classified. The last are mere prospects. The mines in Chaffee County have been the only actual producers. There are three principal claims — the Calumet, Hecla and Smithfield. They extend continuously over 4,000 feet. The wall rock is called syenite. Chauvenet describes them as having resulted from the oxidation of pyrites, and as being in rocks of Silurian age. They average 57% Fe, with only 0.009 P, but are comparatively high in S, reaching 0.1 to 2.0%. These mines and those at the Hot Springs, mentioned under Ex- ample 2, have furnished the Pueblo furnaces with most of their stock. The deposit in Fremont County is at Iron Moun- tain, but is too titaniferous to be valuable. It is a lenticular mass in olivine-gabbro, and is again referred to under 2.03.11. A large ore body has been reported from Costillo County, in limestone (Census Report) or syenite (Rolker). In Gunnison County, at the Iron King and Cumberland mines, excellent ore occurs in quartzites and limestones, called Silurian. At Ashcroft, near Aspen, high up in the northern side of the Elk Mountains, is a great bed or vein of magnetite in limestones of Carboniferous age with abundant eruptive rocks near. It is thought by Devereux to be altered pyrite. Stiy, pyrite is a common thing with magnetite elsewhere. There are other smaller deposits in Bowlder County, and elsewhere in the State. ^ ^ H. S. Chase, "Southern Magnetites and Magnetic Separation," Trans. Amer. Inst. Min. Eng., XXV., 551-557, 1896. W. C. Kerr, Geology of North Carolina, 1875, 364. J. P. Kimball, "On the Magnetite Belt at Cranberry, N. C," etc., Amer. Geol., XX., 299-312, 1897. H. B. C. Nitze, "Notes on the Magnetites of Southwestern Virginia and the Contiguous Territory of North Carolina," Trans. Amer. Inst. Min. Eng., XX., 174, and discussion, 185. "The Magnetic Iron Ores of Ashe Co., N. C, Idem, XXL, 260. " Magnetic iron Ore in Granville Co., N. C," Eng. ajid Min. Jour., April 23, 1892, p. 447. B. Willis, Tenth Census, XV., 325; Eng. and Min. Jour., Jan. 7, 1888. Kerr and Hanna, " Ores of North Carolina," 1893. ^ R. Chauvenet, "Papers on Iron Prospects of Colorado," A7in. Reps. Colo. State School of Mines, 1885 and 1887; also Trans. Amer. Inst. Min. MAGNETITE AND PYRITE. 171 2.03.09. In Wyoming an immense mass of titaniferous mag- netite is known near Chugwater Creek. It is more fully described under Example 13, with which type of ore body it belongs. 2.03.10. Example 12e. California Magnetite. Beds of mag- netite of lenticular shape in metamorphic slates and limestones on the western slope of the Sierra Nevada. Others of different character are also known. In Sierra and Placer counties lenses of excellent ore are found, accompanying an extended stratum of limestone in chlorite slate. A great ore body of magnetite described as a vein has lately been reported from San Bernard- ino Count}^ It is said to be from 30 to 150 feet thick, and to lie between dolomitic limestone and syenite.^ A great bed of a kind not specified is reported from San Diego County. '^ 2.03.11. Example 13. Masses of titaniferous magnetite in igneous rocks which are most often gabbros or related types. General comments were made upon these in 1.06,14 and 1.06.16. In many cases such ore bodies seem undoubtedly to be exces- sively basic segregations of fused and cooling magmas. Whether the tendency of these early crystallizations to concentrate is due to Soret's principle, to magnetic currents or attractions, or to the high specific gravity of the mineral which might cause it to sink in the magma, is perhaps not always clear, for all these explanations have been suggested. The masses are not yet of practical value in North America, and hence are not, strictly speaking, ores; but no one familiar with their size and amount can resist the conviction that they will ultimately be utilized. The commonest rocks forming the walls are gabbros, norites, diorites or peridotites, all of which are close relatives. Later metamorphism, such as mountain-making processes and the Eiig., Denver meeting, 1889. Rec. W. B. Devereux, "Notes on Iron Prospects in Pitkin County, Colorado,' Trans. Amer. Inst. Min. Eng., XII., 608. B. T.Futnam, Tenth Census, Vol XV., i>. 4:72. Rec. C. M. Rolker, "Notes on Iron Ore Deposits in Colorado," Trans. Amer. Inst. Min. Eng., XIV., 266. Rec. ^ A7in. Rep. State Mineralogist, 1889, p. 235. • ' Ibid., 1889, p. 154. J. R. Browne, "Mineral Resources West of the Rocky Mountains," 1868. C. King and J. D. Hague, "Mineral Resources West of the Rocky Mountains," 1874, p. 44. H. G. Hanks and W. Irelan, Ann. Reps. State Mineralogist, California. (Very little on iron. ) F. von Richthofen, private reports quoted in Tenth Census, Vol. XV., p. 495. J. D Whitney, G-zol. Survey of Cal. , Vol. I. 172 KEMP'S ORE DEPOSITS. like, sometimes give the wall rock a gneissic structure and stretch out the ore into apparent beds. The ores have some characteristic peculiarities of chemical and mineralogical com- position. As a rule, although not invariably, they are low in sulphur and phosphorus. On analysis they almost always afford small percentages of vanadium, chromium, nickel and cobalt. They may be so rich in alumina and magnesia as to indicate the presence of spinel. In fact, one variety of these ores, that is found near Peekskill, N. Y., and at Routivara, in Sweden, is an aggregate of spinel and titaniferous magnetite. Ores of this variety show genetic relations with some deposits of emery and corundum. The pig iron afforded by the titanif- erous ores has certain excellencies peculiar to itself that may be due to one or more of the above ingredients.^ Many years ago T. S. Hunt recognized the fact that the titaniferous ores of Canada and the Adirondacks were limited to the labradorite rocks of the Norian or Upper Laurentian series. It is now known that they may occur both in anor- thosites and in basic gabbros. The ore-bodies are of enormous size on the lower St. Lawrence (Bay St. Paul), on the Sague- nay River, and near Lake Sandford, in the heart of the Adiron- dacks. Smaller, but still very large masses, are known in Que- bec, north of Montreal ; in Ontario, north of Kingston ; in West- port and Elizabethtown, N. Y., and in several other places not far from the national boundary.^ ^ The chemical characters are discussed by J. F. Kemp in a paper on "The Titaniferous Iron Ores of the Adirondacks," Nineteenth Ann. Rep. Dir. U. S. Geol. Survey, Part III. , p. 377. A detailed review of titanifer- ous ores the world over, by the same writer, will be found in the School of Mines Quarterly, July and November, 1899. All the analyses known to be published to date are compiled. ^ On the Canadian ores see: F. D. Adams, " Ueber das Norian oder Ober-Laurentian von Canada, Neues Jahrbueh, Beilage Band, VIII., 410; an English translation will be found in the Canadian Record of Science, 1894, 169; 1895, Jan., p. 1, July, p. 1. "On the Igneous Origin of Certain Ores," Proc. General Mining Association of the Province of Quebec, Jan. 12, 1894. E. 3r. Chapman, "On Some Iron Ores of Central Ontario," Trans. Royal Soc. of Can., 1885, 9. See also Idem, 1884, 159, R. W. Ells, Geol. Survey of Canada, 1888-89, 14K. B. J. Harrington, Idem, 1873-74, 227. T. S. Hunt, Idem, 1847, 59; 1867, 212. F. J. Pope, "Titaniferous Ores of Ontario," Trans. Amer. Inst. Min. Eng., May, 1899. On the ores in New York see: E. Emmons' Report on the Second District, N. Y., State Survey, 244, 1842. J. F. Kemp, "The Titaniferous Iron Ores of the Adi- MAGNETITE AND P TRITE. 173 The ores near Peekskill are low in titanic oxide, not ranging above four per cent., but they are extremely rich in alumina, and attention was first directed to them by J. P. Kimball, on account of this ingredient. They constitute excessively basic developments in the norites of the Cortlandt series of gabbroic rocks, that cover about twenty-five square miles on the Hudson River. They are also present as small, separate dikes. They consist of spinel, magnetite, corundum, garnet and occasional sillimanite, and are remarkably close parallels with some results of artificial experiments obtained by Josef Morozewicz. They have been utilized for emery and are near relatives in a geo- logical way to some deposits of corundum and emery. ^ A very curious and interesting knob, or boss, of peridotite is exposed at Iron Mine Hill, Cumberland, R. I., that is so en- riched with titaniferous magnetite as to receive attention as an ore. It protrudes through mica schists and is closely akin to the Swedish one at Taberg, as was recognized many years ago by M. E. Wadsworth.' A belt of titaniferous ores traverses New Jersey and affords magnetites of moderate percentages of TiO-2.^ Several belts rondacks," Nineteenth Ann. Rep. Director U. S. Geol. Survey, 377, 1899. Also Fifteenth Ann. Report of N. Y. State Geologist, 608, 1898. G. W. Maynard, "The Iron Ores of Lake Champlain," Jour. Brit. Iron and Steel Inst., 1874. A. J. Rossi, "Titaniferous Ores in the Blast Furnace," Trans. Amer. Inst. Min. Eng., XXI., 832, 1893. " The Smelting of Titan- iferous Ores," The Iron Age, Feb. 6 and 20, 1896. ^ J. D. Dana, Amer. Jour. Sci. Further notes by G. H. Williams, Idem, Feb., 1887, 194. J. P. Kimball, Amer. Chemist, IV., 1874, 321 ; Trans. Amer. List. Min. Eng., IX., 19, 1880. Their geological relations will be more fully described in a forthcoming paper bj^ J. F. Kemp and M. B. Yung. On the artificial production of these ore mixtures, see Josef Morozewicz, Tschei^maks Min. u. Petr. Mitth., "On the Related Swedish Ores." W. Petterson, Geol. Foren. iri Stockholm Forhandl., XV., 45, 1893. Hj. Sjogren, Idem, 55 and 140. » M. E. Wadsworth, " Lithological Studies," Bull. Mus. Comp. Zool. Harvard College, VII. , 1881, 183. A later note will be found in the Bulletin Amer. Iron and Steel Association, Nov. 20, 1889. See also, A. L. HoUey, Trans. Amer. Inst. Min. Eng., YI., 224, 1877. C. T. Jackson, Geological Survey of Rhode Island, 53, 1840. N. S. Shaler, Sixteenth Ann. Rep. U. S. Geol. Survey, II., 321. Bull. Mus. Comp. Zool, Harvard College, XVI., 185. B. Willis, Tenth Census, XV., 567. ^ On New Jersey, see the Annual Reports of the State Geologist as follows: 1873, 53, 55; 1875, 35; 1876, 54; 1877, 49; 1878, 99, 100; 1879,62, 67, 76; 1880, 125. R. W. Raymond, Trans. Amer. Inst. Min. Eng., XXI., 174 KEMP'S ORE DEPOSITS. occur in North Carolina.^ The wall rocks have not been as yet accurately determined in either State. In the extreme northeastern corner of Minnesota, on Mayhew Lake, and at other points within the huge area of gabbros in this State, the ores are known, and some small amount of work has been expended on them.^ Titaniferous ore has been described by Arnold Hague as forming great dikes in granite on Chug water Creek, Wyo. Olivine-gabbro and anorthosite are in the neighbor- hood, and have been determined as the wall rock of at least one mass of ore by B. F. Hill/ The rock was collected by W. G. Knight. The ores are also known in at least three plaaes in Colorado. One is in Fremont County, at the so-called Iron Mountain, which is situated about fifty miles west of Pueblo, in the Wet Mountain valley, on a tributary of Grape Creek. A sample of rock believed to have come from the walls has been determined by J. F. Kemp to be an olivine-gabbro.* An- other locality is Caribou Hill in Boulder County/ and a third 1892, 375. B. F. Fackenthal, lde7n, 279. Isidor Walz, Amer. Chemist, June, 1876, 453. The Church mine on Schooley's Mountain is the best known one. * On North Carolina, see North Carolina Geol. Survey, II., 1893, 181. J. P. Lesley, "Notes on the Titaniferous Iron-ore Belt near Greensboro, N. C," Proc. Amer. Phil. Soc, XII., 1871, 139. H. B. C. Nitze, Bulletin I., N. C. Geol. Survey. Bailey Willis, "On the Dannemora Mine," Tenth Census, XV., 310. ^ W. S. Bayley, "Peripheral Phases of the Great Gabbro Mass of North- eastern Minnesota," Jour. Geol., Vol. I., p. 818. See also, for notes on their petrography. Idem, Vol. III., p. 1. C. R. Van Hise, Bull. Geol. Soc. Amer., VII., 1895,488. N. H. Winchell. Tenth Ann. Rep. Minn. Geol. Survey, 1882, 85. N. H. and H. V. Winchell, Bulletin VI, Idem, 136. M. E. Wadsworth, Bulletin II, Idem, 63, 73. ^ Arnold Hague, U. S. Geol. Explor. Fortieth Parallel, II., 12, 1877. F. V. Hay den, U. S. Geol. and Geogr. Survey, Territories, 1870, 14. B. F. Hill, School of Mines Quarterly, July, 1899. W. G. Knight, Bull. XIV. Wyo. Agric. Experiment Station, 177, 1893. Howard Stansbury, Ex- ploration and Survey of the Valley of the Great Salt Lake, 1852, 266. F. Zirkel, U. S. Geol. Explor. Fortieth Parallel, VI., 107. * F. M. Endlich, U S. Geol. and Geogr. Survey of the Territories, 1873, 333. B. T. Putnam, Tenth Census, XV., 472. ® Regis Chauvenet, "Notes on Iron Prospects in Northern Colorado," Biennial Rept. of the Colo. State School of Mines, 1886, 16. B. T. Putnam, Tenth Census, XV., 476. MAGNETITE AND PYUITE. 175 is in the Cebolla district, Gunnison County/ where the amount is reported to be large. The ores in basic nepheline rocks in BraziP are the only others in the Western Hemisphere. The Swedish and Norwegian ores are similar in their geological rela- tions to the several American types, viz. : those at Ekersund and Soggendahl,^ to the ores of Quebec and the Adirondacks; those at Routivara* to the aluminous ores of the Cortlandt series; the Taberg^ ore is like that at Cumberland, R. I. ; and the Alno^ occurrence resembles the Brazilian type. The titan- iferous iron sands will be referred to under magnetite sands. 2.03.12. Example 14. Cornwall, Pa. Deposits of soft magnetite, resting against igneous dikes and associated with green, pyritous shales, Si luro- Cambrian limestone and Trias- sic sandstone. These ore bodies are to be classed among the largest ever mined. They form three hills extending in an east and west direction, and called respectively Big Hill, Middle Hill and Grassy Hill. As the accompanying contour map shows, Big Hill is the highest and narrowest, while Middle Hill contains the most ore. The hills lie just at the southeast- ern edge of the Great Valley, and are six miles from the flour- ^ Regis Chauvenet, "Iron Resources of Gunnison Co. ," ^mer. Rep. Col. State School of Mines, 1887, 18. "Iron Resources of Colorado," Trans. Amer. Inst. Min Eng., XVIII., 272. Arthur Lakes, "The Great Cebolla River Deposits," Colliery Engineer, XVI., 267, 1896. ^O. A. Derby, "Magnetite Ore Districts of Jacupiranga and Ipanema, Sao Paulo, Brazil," Amer. Jour. Sci., April, 1891, 311. * T. Dahl, F6rhandl. videnskabs Natm. i. Stockholm, 1863. D. Forbes, Chem. News, December 11, 1868, 275. S. Forbes, Jour. Brit. Iron and Steel Inst, 1874, 131. Th. Kjerulf, Nyt. Magazinfor Natv., XXVII., 1883. H. Rosenbusch, Idem. T. C. Thomassen, Idein, XXIV., 287. C. F. Kol- derup, Bergen's Museum's Aarbog. in Stockholm, 1896, 159. Rec. H. H. Reusch. Oeol. Foren in Stockholm, 1877, 197 ; Neues Jahrbuch. 1878. J. H. L. Vogt. Idem, XIII., 476, 683, XIV., 211; Geological Magazine, IX.. 82; Neues Jahrbuch, 1893, II., 69; Zeitschr. fur prakt. Geologic, January, 1893, 6; October, 1894, 384; Archiv. fur^Mathem. og Naturvidenskab, Kristiania, X. and XII., 1887. The papers of Kolderup and Vogt are of chief value for reference. * W. Petterson, Geol. Foren. i. Stockholm, XV., 45, 1893; (Neues Jahr- buch, 1894, I., 88) ; H. Sjogren, Idem, XV., 55, 140, 1893; (Neues Jahrbuch, 1894, I., 88). » A. Sjogren, Geol. Foren. i. Stockholm, III., 42, 1876; (Neiies Jahrbuch 1876, 434). A. E. Tornebohm, Idem, V., 610; Neues Jahrbuch, 1882, II., 66. J. H. L. Vogt, Zeitschrift fur prakt. Geologic, January, 1893, 8. « A. G. Hoegbom, Geol. Foren. i. Stockholm, XVII., 100, 214, 1895. 176 KEMP'S ORE DEPOSITS. ishing little city of Lebanon. The geological section (Fig. 53) illustrates the position of the strata. The Siluro-Cambrian series is cut by an immense diabase dike near its southeastern limit, and on the south side of the dike which forms the north- ern rampart of the three hills lies the ore. The ore is a soft, rather earthy magnetite, which occasionally shows octahedra. While richer and purer on the original weathered surface, it is now interlaminated and closely involved with layers of limey shales which contain pyrite, at times in beautiful crystals. Most of the ore is merchantable raw, but large quantities are so low from this admixture of shales that they are being saved for possible future magnetic concentration. The presence of the pyrite makes it necessary to roast all the raw ore before ■ 1 I .1 « III I 1 ? -I-... I I ^ I §'M ^cale of Miles. Fig. 53. — Section along Cornwall Railroad from Lebanon to Miner's Village. After E. V. d'Inmlliers, Amer. Inst. Min. Eng., XIV., 898, 1886. smelting, but the phosphorus is so low that Bessemer pig is the chief resulting product. Big Hill differs from the others in structure. The northern dike with a steep southerly dip has an offsetting and very heavy branch to the southwest which forms with it a great trough or basin so far as one can* see. The bottom of the ore has been reached by one rather shallow hole, but it seems quite certain that the dikes will come together at a point indicated by the several dips. The surface of the southerly branch is strongly corrugated. The ore of Middle HiH extends to a greater distance south from the dikes than that of Big Hill, and is cut by one small and linimportant offset of trap that is two or three feet across. At the western end of the workings, lime- 178 KEMP'S ORE DEPOSITS. stoDO is quite thick and in good exposure. It reaches well over to Grassy Hill. Grassy Hill is smaller, and is much less devel- oped than either of the others. E. V. d'Invilliers has empha- sized the important point that the dip of the ore in Big Hill is southwest at such an angle as to bring it below the Middle Hill bed, and that this latter also dips below the limestone and the Grassy Hill beds. Such being the case, enormous reserves must lie under the two western hills. The depths of the sev- eral bore holes given on the map and all in ore indicate its presence in very great amount, but it is important to show in this connection the absence of faults, for the map of Bailey Willis notes their presence, and observations of the writer cor- roborated their existence. The pyrite in the calcareous shales is occasionally replaced by chalcopyrite in irregular nodules or veinlets. The presence of copper was early noted, and some mining was done for it near the surface. Fine museum specimens of moss-copper, azurite, malachite, etc., were afforded. Even during the earlier iron- mining some copper ore was set aside as a small by-product. Copper is still present in the mine-water, for bright shovels left in it become coated, and the bones of dead animals thrown out on the ore banks, as well as chips of wood, etc., become tinted a bright green. Much difference of opinion has prevailed about the age and geological relations of these ores. Some have thought them Mesozoic and a part of the Triassic, while others, and notably J. P. Lesley, have regarded them as belonging to the Siluro- Cambrian series and analogous to the limonites of the Great Valley, but metamorphosed. The great trap dikes afford the most reasonable explanation or cause of the change, and to these may be referred the alteration. The apparent origin of many Siluro- Cambrian limonites from the hydration and oxidation of pyritous shales and schists gives much support to this view, and the association of limestone with the ore and the general stratigraphical relations are hard to explain in any other way.^ ^ E. V. d'Invilliers, "Cornwall Iron Ore Mines," Trans. Amer. Inst. Min. Eng., XIV., 873. Rec. Lesley and d'Invilliers, Ann. Rep. Second Penn. Geol. Survey, 1885, 491. Eec. J. P. Lesley, Final Rep., I, 351, 1892. T. S. Hunt, "The Cornwall Mines," etc., Trans. Amer. Inst. Min. Eng.. IV., 319. H. D. Rogers, First Penn. Geol. Survey, II., 718. B. Willis, Tenth Cenms, XV., 223. MAGNETITE AND P TRITE. 179 The total production to April, 1894, is stated by Mr. Boyd, the superintendent of the mines, to be upward of 12,000,- 000 tons, while an annual output of 800,000 can be easily main- tained. The ore varies from 40 to 55% Fe. It almost never con- tains as much as 0.02 P, but runs up to 4% S. It is also sil- iceous. 2.03.13. Several other mines of somewhat related character to the Cornwall deposits are known along the edges of this Triassic belt, and associated with its trap intrusions. The mining districts lie near its north and south boundaries, and not far from its contacts with the older rocks. On the north side from east to west there are the Boyertown (Berks County), the Fritz Island and the Wheatfield, near Reading, and finally the Dillsburg in York County, west of the Susquehanna. On the south side in the same order are the French Creek, St. Mary's and the Jones, all quite near together and nearly south of Reading. Of these the Boyertown mines have been most worked.^ The Cornwall mines are between the Wheatfield and the Dillsburg. At the Boyertown mines the ore lies both between a brecciated limestone and Mesozoic sandstone and wholly within the limestone, but trap dikes are not lacking. At Fritz Island the ore is entirely enclosed in limestone, and is penetrated by a trap dike. In the Wheatfield mines the same brecciated limestone appears, and has the ore intimately asso- ciated with it. On both occurs the Mesozoic sandstone, and the succession is five times repeated by faulting. The usual trap penetrates the ore. The French Creek and St. Mary's mines are unique in that they are contained in gneiss. They are famous sources of fine crystals of pyrite, chalcopyrite and other minerals. The Jones mine exhibits the ore between trap and limestone, the trap being over the ore in the North pit and * P. Fraser, "Study of the Specular and Hematite Ores of Iron of the New Red Sandstone in York County, Pa," Trans. Amer. Inat. Min. Eng., v., 132. Also Penn. Geol. Survey, Rep. CC. 205, 217. H. Hoefer, "Die Kohlen und Eisenerzlagerstatten Nord Amerika's," 241. Also Penn. Survey, Rev. C2. E. V. d'Invilliers, "Cornwall Iron Ore Mines," Trans. Amer. Inst. Min. Eng., XIV.. 873. Rec. Lesley and d'lnvilliers. Ann. Rep. Second Penn. Survey, 1885. J. P. Lesley, Final Report. Vol. L, p. 351, 1802 Fee. T. S. Hunt. "The Cornwall Mines," etc. Trans. Amer. Inst. Min Eng.. IV., 319 H. D. Rogers. First Penn. Geol. Survey, II., 718. B. Willis. Tenth Census, Vol. XV., p. 223. Rec. 180 KEMP'S ORE DEPOSITS. under it in the south. A green shale is also met here, as in- deed in most of the other localities, although not specially men- tioned. At Dillsburg th^ evidence against the Triassic age of the ores is less positive, and upon this occurrence Fraser has based a strong argument for the latter view. Triassic sand- stone at times forms both walls, although there are instances where limestone appears as the foot. In all these localities the presence of copper is notable. It and the magnetic or metamor- phosed condition of the ore are probably referable to the trap. 2.03.14. Example 14a. Iron County, Utah. Beds of mag- netite and hematite bearing evidence of being metamorphosed limonite, in limestones of questionable Silurian age, and asso- ciated with eruptive rocks described as trachyte. The lime- stones have been much upturned, metamorphosed, and pierced bj^ dikes and eruptive masses. The ore forms great projecting ridges and prominent outcrops, locally called "blow-outs.'' The usual lenticular shape is not lacking. Thej^ occur over an area of fifteen by five miles, and are in the southern end of* the Wasatch Mountains. The samples show rich ores, which at times exceed the Bessemer limit of phosphorus. In the Star district the ore apparently lies between the quartzite and gran- ite. Hematite occurs in large amount, as does quartz, while some streaks have large crystals of apatite. The importance of the deposits lies in the future. They are the largest in the West, and are interesting in their bearing on the general origin of the magnetite. Coal, not proved to be good for smelting, is near, but centers of iron consumption are XQxy far away.^ 2.03.15. Example 15. Magnetite sands. Beds of magnetite sands concentrated on beaches or bars by waves and streams. The magnetite has been derived from the weathering of igne- ous and metamorphic rocks through which it is everywhere distributed. When in the sand of a sea beach, it and other heavy minerals tend to become concentrated by the sorting action of the waves. They resist the retreating undertow better than lighter materials. Such deposits are very abundant at * W. P. Blake, "Iron Ore Deposits of Southern Utah/' Trans. Amer. Inst. Min. Erig., XIV,, 809. J. S. Newberry, "Genesis of Our Iron Ores," School of Mines Quarterly, March, 1880. Rec. Engineei'ing and Mining Journal, April 23, 1881, p. 286; Proe. National Academy, 1880. B. T. Putnam. Tenth Census, Vol. XV., 486. Rec. MAGNETITE AND PYRITE. 181 Moisie, on the St. Lawrence, below Quebec, and in the United States are known in smaller developments on Lake Cbamplain ; at Quogue, L. L; on Block Island; in Connecticut; along the Great Lakes, and on the Pacific coast. Grains of garnet, oli- vine, hornblende, etc., minerals of high specific gravity, are also in the sands. Many are too high in titanium to be of use, but there is no more difficulty in their concentration than in that of artificially crushed ore. In Brazil and New Zealand they have attracted attention.^ 2.03.16. On the Origin of Magnetite Deposits. It is im- portant to note that magnetite deposits are almost always in metamorphic rocks, which owe their character to r^ional metamorphism or to the neighborhood of igneous rocks (Penn- sylvania and Utah). Gneisses form the commonest walls, but so-called norites, or gabbros, and crystalline limestones also contain them* Where there is lamination or foliation the mag- netite conforms to it. As the history of the metamorphic rocks is so often uncertain, the magnetites share the same doubt. In igneous rocks magnetite is the most widely occurring of the rock-making minerals. In all explanations the prevailing lenticular shape, ihe general arrangement in linear order, and the existence of great beds must be considered. The shape is ver}' similar to that of deposits of specular hematite, with which magnetite is often associated. (Examples 9 and 10.) The following hypotheses have been advanced for the origin of magnetites: 1. Intruded (eruptive) masses. This supposes that the lenses have been intruded like a trap dike, and have then been squeezed and pinched apart. Though formerly much advocated, it is now generally rejected. 2. Excessively basic portions of igneous rocks. This supposes that large amounts of iron oxide have separated in the cooling and crystallizing of basic magmas. There are such occurrences, although seldom, if ever, pure enough or abundant enough for mining. The titaniferous magnetite of the Minnesota gabbros has been alluded to (2.02.25), and also the Brazilian ore and the Cum- ^ T. S. Hunt, Qeol Survey, Canada, 1866-69, 261, 262; quoted in Six teenthAnn. Rep. Dir. U. S. Geol. Survey, III., 50, 51; Can. Nat, VI., 79. A. A. Julien, "The Genesis of the Crystalline Iron Ores," Acad Nat. Sci., Phila. , 1882, 335 ; Engineering and Mining Journal February 2, 1884. On New Zealand sands, E. M. Smith. Proc. Brit. Iron and Steel Inst., May, 1896; Eng. and Min. Jour., June 13, 1896, p. 566. 182 KEMP'S ORE DEPOSITS. berland Hill (R. I.) peridotite. Should such igneous rocks be subjected to regional metamorphism and the stretching action characteristic of it, the ore masses might be drawn out into lenses. 3. Metamorphosed limonite beds. This idea has been most widelj^ accepted in the past It presupposes limonite beds formed as in Examples 1 and 2, which become buried and subjected to metamorphism, changing the ore to magnetite, and the walls to schists and gneisses. Igneous rocks have apparently changed limonites to magnetite at Cornwall, Pa., and in Utah, but such changes by regional metamor- phism are less easy to demonstrate. The limonite may have resulted from the oxidation of lenses of pyrite. 4. Replaced limestone beds, or siderite beds subsequently metamor- phosed. Such deposits may pass through a limonite stage. The general process is outlined under Example 9c, as devel- oped by Irving and Van Hise in the Gogebic district. The lenticular deposits of siderite at the Burden mines (Example 4) are very suggestive, and some such original mass might in instances be metamorphosed to magnetite. 5. Submarine chem- ical precipitates. This is outlined under Example 9d, as applied by the Winchells in Minnesota. 6. Beach sands. The lenses are regarded as having been formed as outlined under Exam- ple 15. The same heavy minerals sometimes occur with mag- netite lenses as are found on beaches.* 7. River bars. This regards the lenses as due to the concentration of magnetite sands in rivers or flowing currents. Hence the overlapping lenses, the arrangement in ranges or on lines of drainage, and the occasional swirling curves found on the feathering edges of lenses, as in the Dickerson mine, Ferromont, N. J.^ It is also reasonable to suppose that lakes or still bodies of water may have occurred along such rivers, and have occasioned the accumulation. 8. Segregated veins. By this method the iron oxide is conceived to concentrate from a state of dissemination in the walls by slow segregation in solution to form the ore bodies along favorable beds. The action is analogous to the formation of concretions, and is illustrated on a small scale by the well- ^ See also Dakyns and Teall, Qiiar. Jour. Geol. Sgc, LXVIII., p. 118. ''See B. J. Harrington, Can. Geol. Survey, 1873, 193; A. A. Julien, Phila. Acad. Sci., 1882, 335. ^ See H. S. Munroe, School of Mines Quarterly, Vol. III., p. 43 — an im- portant paper. MAGNETITE AND P TRITE. 183 known disks of pyrite, or of siderite, that form in clays and shales. It is a curious fact, however, that some magnetites are in wall rock that hardly shows a trace of a dark silicate. The lenses at Hammondville, in the Lake Champlain district, are in a white, or light- colored gneissoid rock, consisting of quartz, acidic plagioclase, and a few scattered garnets. In such surrovindings segregation could not be applied, but where the walls are supplied with hornblende and other ferruginous minerals, and are reasonably basic, it might be advocated. Several other hypotheses with small claims to credibility €Ould be cited. They are outlined at length in Bull. VI., Minn. Geol. Survey^ p. 224, but in this place there has been no desire to take up any but those deserving serious attention. It may be said that while one or the other of the above seven hypotheses may in instances be applied with reason, yet most candid observers with widened experience have grown less positive in asserting them as axiomatic. ANALYSES OF MAGNETITES. (Caution in interpreting analyses is again emphasized as under 2.01.26.) Fe. P. S. TiO,. SiO,. Al,03. Canada (Rideau Canal) 50.23 49.24 66.00 62.10 63.00 48.82 53.75 42 70 9.80 Chateaugay mines, N. Y., lump. . ' ' " concentrated 0.029 0.003 1.198 0.621 0.021 0.364 0.135 0.004 0.026 0.044 0.052 18.447 Mineville, N. Y. (Mine 21) Orange County, N. Y. (Forest of Dean) 0.148 0.080 Putnam County, N. Y 11.75 3.500 New Jersey (Hibernia) Cornwall, Pa 0.620 0.115 3.411 Cranberry, N. C 64.64 Colorado (Calumet) 49 23 3.85 ' ' (Iron King) 58.75 0.123 0.120 Utah (Iron County) 62.60 60.68 4.80 10.87 California (Gold Valley) . 2.03.16. Of importance in connection with iron ore deposits are the recent studies of the distribution of phosphorus along certain lines in the beds, by a knowledge of which it is possi- ble to keep more valuable Bessemer ore distinct from less valuable. Such lines have been found in Michigan, and have been called by D. H. Browne 'Msochemic lines." Though less 184 KEMP'S ORE DEPOSITS. marked at the Burden mines (Example 3), the phosphorus was characteristic of certain varieties of the ore. Much work has also been done on the same question at Iron Mountain, Mo/ PYRITE. 2.03. 17. Example 16. Pyrite Beds, Beds (veins) of pyrite, often of lenticular shape and of character frequently analogous to magnetite deposits, in slates and schists of the Cambro- Silurian or Huronian systems, and less often in gneiss of the Archean. Slates are most common, and gneiss least so. They extend from Canada down the Appalachians to Alabama, being found at Capelton, Quebec ; Milan, N. H. ; Vershire, Vt. ; Charlemont, Mass.; Louisa County, Virginia; Ducktown, Tenn., and at many points less well-known in Alabama. Anthony's Nose, N. Y., the Gap mine, Pennsylvania, and Sudbury, Ontario, being different geological relations, will be. mentioned under "Nickel" with other similar occurrences. 2.03.18. The ore bodies lie interfoliated in the slates or schists, and the different lenses often overlap and succeed each other in the footwall, and exhibit all the phenomena cited under magne- tites. Chalcopyrite is usually present in small amount, and where the copper reaches 3 to b% they are valuable as copper ores. (See under "Copper.") At present they are of increas- ing importance as a source of sulphuric acid fumes for the manufacture of vitriol. Small amounts of lead and zinc sulphide are often present, and rarely a little silver. Nickel and cobalt occur, especially in the pyrrhotitic varieties. They are worthless as a source of iron. The smaller deposits of auriferous pyrites in the Southern States will be mentioned under "Gold." 2.03. 19. Some pyrites lenses may have accumulated in a way analogous to the bog ore hypothesis, cited under "Magnetite" ; but instead of the iron being precipitated as oxide, it has proba- bly come down as sulphide from the influence of decaying or- ganic matter, and has subsequently shared in the metamorphism and solidification of the wall rock. At the same time it must be ' D. H. Browne, "On the Distribution of Phosphorus at the Luddington Mines," etc.. Trans. Amer. Inst. Min. Eng., XVII., p. 616. I. Olmsted, "The Distribution of Phosphorus in the Hudson River Carbonates," Trans. Amer. Inst. Min. Eng., XVIII., p. 252. W. B. Potter, "Analysis of Missouri Ore," published in Mineral Resources, 1890, p. 47. MAGNETITE AND PYRITE. 185 admitted to be an obscure point. Bj' many they are thought, with more reason, to have originated like a bedded fissure vein whose overlapping lenticular cavities have been formed by the buckling of folded schists.^ (Cf. '*Gold Quartz," as later de- scribed.) The Ducktown veins are on lines of dislocation be- yond question. Replacements of pinched beds of limestone are always to be considered, and the presence of intruded dikes, though disguised by metamorphism. is always to be kept in mind. 2.03.20. The excavations in some of the mines in the pyrite beds of Canada, just north of the Vermont line, have shown dikes of granite in close association with the ore. Thin sections of the granite indicate that it has suffered extremely severe dynamic metamorphism, for crushed and strained crystals make up nearly all of its substance. It is quite probable that the disturbance which causes the schistosity or slaty cleavage of the country rock likewise developed the strains in the granite which must thus have been intruded pre- vious to its operation. Before the shattering the dikes may have exerted a genetic influence in connection with the ore body, but now the ore is usually lean near them. The ore bodies are also cut by fine examples of the trap (camptonite) dikes which are abundant in the Lake Champlain Valley. Prof. J. H. L. Vogt, of Christiania, Norway, has written of late regarding the origin of similar great bodies of sulphides in Europe, and when they occur in connection with rocks, ' W. H. Adams, "The Pyrites Deposits of Louisa County, Virginia," Trans. Amer. Inst. Min. Eng., XII., p. 527. C. R. Boyd, "The Utiliza- tion of the Iron and Copper Sulphides of Virginia, North Carolina, and Tennessee," Trans. Amer. Inst. Min. Eng., XIV., p. 81; Resources of S. W, Virginia. H. Credner, "At St. Anthony's Nose, Hudson River," B. und H. Zeit., 1866, p. 17; "Pyrite in Virginia, Tennessee, and Georgia," B. und H. Zeit., 1871, p. 370. H. T„ Davis, Mineral Resources of the U. S., 1885, p. 501. William Martyn, Mineral Resources, 1883-84, p. 877. E. C. Mox- ham, "The Great Gossan Lead of Virginia" (altered pyrite in Carroll County), Trans. Amer. Inst. Min. Eng., XXI., p. 133. A. F. Wendt, "The Pyrites Deposits of the Alleghanies,' School of Mines Quar- terly, Vol., VII., and separate reprint; also Engineering and Mining Journal, June 5, 1886, p. 22, and elsewhere. Rec. H. A. Wheeler, "Copper Deposits of Vermont," School of Mines Quarterly, IV., 210. Arthur Winslow, "Pyrites Deposits of North Carolina," Ann. Rept. N. C. Experiment Station, 1886. 186 KEMP'S ORE DEPOSITS. which though now gneissoid, have been originally igneous, he regards them as basic segregations of an igneous magma. (See further 1.06.16.) Where they occur in schists he attributes their formation to ore-bearing solutions, penetrating along planes of weakness, and stimulated by neighboring igneous intrusions. In some of the instances cited the known igneous intrusions (as at Rammelsberg) are at some distance, and thus are not directly associated, so far as one can see, with the oreo The genetic connection is therefore somewhat hypothetical. 2.03.21. The relative importance of the different kinds of ore is shown by the following tables for 1880 and 1896. The increase in red hematite is due to the Lake Superior region, and to Alabama. In the immediate future the soft ores of the Mesabi district will help to greatly swell the total, but during 1893-94 there was great depression in the mining of iron ore throughout the country : Per cent. Per cent. 1880. of Total. 1896. of Total. Red hematite 2,512,713 31.51 12,576,288 78.58 Magnetite «... .2,390,389 29.98 1,211,526 7.57 Brown hematite 2,149,417 26.95 2,126,212 13.28 Carbonate 922,288 11.56 91,423 0.57 7,974,806 100.00 16,005,449 100.00 As indicating the relative importance of the different mining regions, the following figures are of interest. No individual State producing less than 100,000 tons is given. states. Total in \^m. States. TotalinlSdQ. Michigan 5,706,736 Tennessee 535,484 Minnesota 4,283,880 New York 385,477 Alabama 2,041,793 New Jersey 264,999 Virginia... 859,466 Colorado 215,819 Pennsylvania 747, 784 Georgia and N. Carolina 175, 331 Wisconsin „ 607.405 All the others 181,275 Grand total 16,005,449 2.03.22. NoTB. Large quantities of excellent Bessemer hematite are shipped to Baltimore and other Atlantic ports from the mines on the southeastern coast of Cuba, in the Jura- gua Hills. Santiago de Cuba is the largest town in this MAGNETITE AND PYRITE. 187 region, and is some twenty miles west of the mines. The coast range of hills consists mainly of syenite, according to J. P. Kimball, and the syenite is penetrated by many dikes and is mantled by sheets of diorite with which the ores are associated. Kimball refers the precipitation of much of the iron oxide which came from the diorite to coraline limestone, which had been accumulated as coral reefs on the syenite before the diorite was intruded, but he also mentions other deposits in the diorite not associated with limestone. From observations of another group of ores sixteen miles east of those studied by Kimball, F. F. Chisholm reached a different conclusion regard- ing their origin. Chisholm refers them to a source below and apparently regarded them as veins or replacements of dikes. The amount of ore along this coast, both in place and as float is very great, ^ and will be an important feeder, to American furnaces. Between three and four hundred thousand tons are now annually imported. Chisholm gives the following analyses : Fe. S. P. Juragua (Kimball) 64.65 .146 0.037 Sigua (Graham) 64.00 0.040 0.016 Berraco (Chisholm) 60.00 0.027 0.027 Although not a source of supply for American furnaces, it is interesting to note in this connection that in Mexico vast depos- its of hematite and martite occur in Cretaceous limestone asso- ciated with intrusions of diorite. The paper of R. T. Hill cited below gives a review and full bibliography of the various localities. The notable deposits so far as yet opened up are at the Cerro de Mercado, in Durango,^ the Sierra de Mercado, ' J. P. Kimball, ' ' Geological Relations and Genesis of the Specular Iron Ores of Santiago de Cuba," Amer. Jour. Sci., December, 1884, p. 416; also "The Iron Ore Range of the Santiago District of Cuba," Trans. Amer. Inst. Min. Eng., XIII., 613; Eng. and Min. Jour., December 20, 1884. p. 409. F. F. Chisholm, "Iron Ore Beds in the Province of Santiago, Cuba," Proe. Colo. Sci. Soc, III., 259, 1890. H. Wedding, "Die Eisenerze der Insel Cuba," Stahl und Eisen. 1892, No. 12. Prof. J. W. Spencer has been recently working on the geology of Cuba and presented some of jiis results at the meeting of the American Association in Brooklyn, August, 1894. ^ J. Birkinbine, " The Cerro de Mercado or Iron Mountain of Durango," Trans. Amer. Inst. Min. Eng.,XUI., 189, 1884. J. P. Carson, "Iron Manufacture in Mexico." Idem. VI., 399. R. T. Hill, "The Occurrence of 188 KEMP'S ORE DEPOSITS. near Monclova in Coahuila/ and others of minor importance in the States of Jalisco/ Guerrero^ and elsewhere. Several of these are now the basis of a small local smelting industry. Hematite and Martite Iron Ores in Mexico," Amer. Jour. Sci., February, 1893, 111. B. Silliman, "Martite of the Cerro de Mercado, or Iron Moun- tain of Durango, and Certain Iron Ores of Sinaloa," Amer. Jour. Sci., November, 1882, 375. See also on the Durango Iron Mountain, Annales del Ministerio de Fomento de la Rep. Mexicana Tomo, III. , 1877 ; Eng. and Min. Jour, on "Iron in Mexico, " November 10, 1888, p. 391. * P. Frazer, "Certain Silver and Iron Mines in the States of Nueva Leon and Coahuila, Mex.," Trans. Amer. Inst. Min. Eng., XII., 537. R. T. Hill, as cited in previous footnote. ' J. P. Carson, as cited in second footnote. ' N. S. Manross, "Notes on Coal and Iron Ores in State of Guerrero, Max., Amer. Jour. Sd., May, 1865, p. 309; Remarks by J. D. Dana, p. 358. CHAPTER IV. COPPER. 2.04.01. Copper Ores. TABLE OF ANALYSES. Native copper (generally with some silver) Chalcocite, CU2S Chalcopyrite, CuFeSj Bornite, CugFeSg Tetrahedrite, 4CuS2, Sb^S 3 (variable) 26.50 Sb. . Enargite, Cug ASS4 (As, 19. 1) Cuprite, CU2O Melaconite (tenorite) , CuO Azurite, SCuOCOg, H^O Chrysocolla, CuOSiOg, 2HgO. Cu. 100.00 79.80 34.60 61.79 36.40 48.40 88. 8G 79.86 40.28 46.31 22.06 20.2 34.9 25.8 26.7 32.5 Fe. 30.50 11.70 1.39 2.04.02. Example 16, Continued. Pyrite or pyrrhotite beds (veins), with intermingled chalcopyrite. Whether the deposits are true beds or veins parallel with the foliation, is as yet a matter of dispute. The resemblance to magnetite sug- gests a bed, and this view is generally taken by German writers. The California mines occur closely associated with the auriferous (pyritous) quartz bodies, which are always esteemed veins. But as detailed knowledge increases, it is more and more appreciated that the ore bodies are mostly if not entirely veins and have been deposited along lines of dig- location.^ Pyrites and pyrrhotite (called mundic by the miners) are the principal constituents of such bodies, but often the copper reaches 2.5 to 5%, and then they are valuable for copper. There * Compare in this connection J. H. L. Vogt. " Ueber die Kieslagerstat ten von Typus Roros Vigsnas, Sulitelma in Norwegen und Rammelsberg in Deutschland," Zeitschr. fur prakt. Geologie. February, April and May, 1894. 190 KEMP'S ORE DEPOSITS. is quite a characteristic group of minerals that is associated with the ores. Zinc blende is almost always present in small quantities, and is a great drawback to the ore when employed for acid. Galena is met in traces. Quartz, calcite, some form of amphibole, and often very beautiful garnets are associated. Ducktown is noted for its zoisite. All the secondary minerals of the oxidized zones of sulphides are met. The ores are often roasted for sulphurous fumeS in acid works, and afterward the residues are shipped to the copper smelters. The mines have been or are being worked for copper near Sherbrooke, and at a great number of other points in Quebec, just north of Vermont. There are also not a few localities in Maine, New Brunswick, Nova Scotia and Newfoundland, where operations of a more or less serious nature have been undertaken. Citations to the literature regarding these will be found at the close of the description of Ducktown. At Milan, N. H., there are several deposits in argillitic schists, and in the same region there are numerous other locations. At Vershire, Vt., there is a belt some twenty miles long, with three principal mining points. Of these the middle one, containing the Ely mine, is the largest. Two beds of ore occur, separated by from 10 to 20 feet of schists. The lower averages about four feet, but fluc- tuates; the upper is still more variable, and may reach 25 feet. They are both formed by a succession of thin lenses. The ore is chalcopyrite, mingled with pyrrhotite and quartz. 2.04.03. More complete observations are available upon the Ducktown, Tenn., deposits, than upon any others of the type in America. The excellent paper by Carl Henrich is here spe- cially drawn upon and has been supplemented b3' some few fur- ther notes by the writer. Ducktown is situated in the south- eastern township of Tennessee, and occupies a small plateau between bounding ranges of higher mountains. The plateau has been much dissected by the present drainage, but its stumps remain, and serve to indicate the peneplain of Tertiary date.^ The country rock is mica schist, with occasional heavier beds that tend toward quartzite or even gneiss. Some horn blend ic rocks are present with the ores, but whether they represent in- truded dikes as suggested by Henrich, or streaks of siliceous * C. W. Hayes, '' Geomorphology of the Southern Appalachians," Na- tional Geographic Magazine, VI., 68, 1894. ^ig. 2. yOutCTops of Scale li"- 1 Mile MAP Of THE DUCKTOW.N. MINES. FiQ.55.—Map of the mines and of the outcrop of gossan, showing the relations and extent of the veins at Ducktown, Tenn. After Carl Henrich, Trans. Amer. Inst. Min. Eng., XXV., 178, 1895. 192 KEMP'S ORE DEPOSITS. limestone, it is not possible to determine. The schists are metamorphosed shales, and the schistosity appears to be gener- ally parallel to the original bedding. The geological age is still in dispute, but is probably Pre-Cambrian. The schists strike N. 20-25 E., and have a prevailing dip of about 50 to 55 S. E. There are variations of the latter which are due to rolls and faults. The schists have been broken by dislocations along which the ores have been deposited. The strike of the ore is parallel to the strike of the schists, and the dip is, as a rule, the same as that of the schists, but cases have been observed where the ores cut the dip of the country rock, al- though with such soft and easily mashed materials it is diffi- cult to identify the unconformity. There are two principal belts of fracture as shown by the map, Fig. 55, and probably several minor ones, between. The Old Tennessee, Burra Burra, London and East Tennessee lie along the northwest belt; the Polk County, Mary, and Calloway form the southeast belt ; and the Culchote and Isabella lie in the interval. The ore bodies are huge lenticular masses of sulphides, which probably owe this shape, as far as it is at all discernible, to diagonal faulting since the veins were filled. The common ore is an aggregate of pyrrhotite, chalcopyrite, calcite, quartz, zoisite, and in some mines much actinolite. Zinc blende and galena are present, but are insignificant. Garnets are occasionally met in quantity. On some of the claims pyrites is abundant, as in the Burra Burra, and, as is reported to be the case at the Isa- bella, it taking the place of the pyrrhotite to a greater or less degree. The content of copper varies up to 3.5%, with occasional bunches that run higher. The old black copper ores that accumulated at the water-level are now exhausted. (See Fig. 56.) From observations on the succession and character of the minerals in the vein, J. F. Kemp has drawn the following conclusions regarding the geological history of the veins. By a process of regional metamorphism, a sedimentary series of shales and sandstones w^as altered to mica schists and quartz schists. Where the ore is now found, zoisite, tremolite, and garnet were also produced, but it is not known whether they are met outside of the mines or not. They indicate the former presence of magnesian and calcareous rocks, althougn, gener- ally speaking, lime is practically unknown in the metamorphic COPPER. 193 rocks of the district and the local waters are remarkably pure and soft. Whether a calcareous shale or an intruded dike yielded the lime silicates, or whether they are metamorphosed, calcareous, vein material from an older vein filling cannot be stated. After the general metamorphism, a series of disloca- tions was developed along the lines of the present veins, and Cross-Section A-A. (Fig. 8.) Shaft 3. Old Tennessee NIine^ Fig. 56. — Cross-section, Shaft 3, Old Tennessee Mine, Ducktovm, Tenn., show- ing the gossan, the black ore, the pyrrhotite and a fault. After Carl Henrich, Trans. Amer. Inst. Min. Kng., XXV., 198, 1895. pyrrhotite and sometimes pyrite were introduced. After the deposition of the pyrrhotite there was further movement which shattered the pyrrhotite and allowed the introduction of chal- copyrite in streaks and fine veinlets all through it. Still later, and apparently after another movement calcite came in and 194 KEMP'S ORE DEPOSITS. penetrated the shattered sulphides and older silicates. After the introduction of the calcite, by some movement fissures notably horizontal were produced, which became filled with glassy quartz, and which have yielded the so-called **fioors." More or less contemporaneously with the quartz, coarsely crystalline pyrrhotite, chalcopyrite and blende were produced, which are in marked contrast with the earlier sulphides. The oxidation of the veins above the ground water, the formation of the brown hematite outcrops and the development of the zone of enrichment (the black ores) bring the process down to the present.^ 2.04.03. Throughout the mountainous region of western North Carolina, eastern Tennessee and northern Alabama are many other copper deposits of rbore or less serious importance. One of the best known is the one formerly operated at Ore Knob. This is described by Kerr as a true fissure vein, extending 2,000 feet on the strike, which is parallel to that of the gneiss, but cutting the dip in descent. The width averaged about 10 feet. The gossan extended to a depth of 50 feet, and furnished the usual body of rich ore at the contact with the sulphides. The mine has not been operated for some years.^ ^ Trans. Amer. Inst. Min. Eng., 1899. " For a general account of the sulphides in the East, see A. Wendt, "The Pyrites Deposits of the Alleghanies," School of Mines Quarterly, VII., 1886. Canada, Geol. Survey of Canada, 1863, 709. James Richardson, Idem,, 1896, 34-44. R. W. Ells, "Copper in Quebec," Idem, 1890, Vol IV., 29K. Rec. "The Mining Industries of Eastern Quebec," Trans. Amer. Inst. Min. Eng., XVIII. , 316, 1889. John Blue, " Copper Pyrites Min- ing in Quebec in 1894," Journal Gen I Mining Assoc. Prov. Quebec, II., 147, 1894. S. L. Spofford, " Albert Mines and Capelton Chemical Works, " Idem, 214. C. T. Jackson, "The Great Copper-bearing Belt of Canada," Proc. Bost. SoG. Nat. Hist., IX., 202, 1862. Copper prospects have received attention in southwestern New Brunswick, on Adams, Campobello, and other islands. See Bailey and Matthew, Geol. of Canada, 1870-71, p. 13. " On Notre Dame Bay, Newfoundland, " M. E Wadsworth, Amer. Jour. Sci., in. , XXVIII. , 28, 102. Maine. — "Blue Hill District", E7ig. and Min. Jour., August 28, 1880, p. 140. F. L. Bartlett, "Mines of Maine," in Mines, Miners and Mining Interests of the United States, Philadelphia, 1882, 133. J. D. Whitney, Metallic Wealth of the United States, 312. New Hampshire.— C. H. Hitchcock, Geol. of N. H., III., Part III,, p 47. Vermont. — "Elizabeth Copper Mines," E7ig. and Min. Jour., November I COPPER. 195 2.04.04. Example 166. Spenceville, Cal. Copper ores are known and have been more or less worked in a number of places along the western Sierras, of which Spenceville, Nevada 6, 1886, p. 337; ''The Pyrrhotite of the Ely Mine," Idem, April, 10, 1886, 263. F. M. F. Cazin, Trans. Amer. Inst. Min. Eng., XXIII., 604, 1894. H. Koehnike, "Die Vermont Kupf er-Grube, " Berg- u. HiXtten. Zcit., 1892, 297. Richardson, "Copper Ore of Stafford, Vt.," Amer. Jour. Sci., i., XXI., 383. H. S. Wheeler, " Copper Deposits of Vermont," -Sc/iooZ o/ Mines Quarterly, IV., 219. Rec. Pennsylvania.— Maryland, and Virginia.— J. F. Bailey, "Copper Deposits of Adams County, Pa.," Eng. and Min. Jour., February 17, 1883, 88. J. F. Blandy, "Lake Superior Copper Rocks in Pennsylvania," frans. Amer. Inst. Min. Eng., VII., 331. P. Frazer, "Some Copper De- posits of Carroll County, Md.," Trans. Amer. Inst. Mm. Eng., IX., 23. 1881. "Hypothesis of the Structure of the Copper Belt of the South Mountain, Idem, XII. , 82, 1884. ' ' Geology and Copper Deposits of Adams County, Pa.," Eng. and Min. Jour., XXXV., 112, 1883. C. H. Hender- son, "Copper Deposits of the South Mountain, Pa.," Trans. Amer. List. Min. Eng., XII., 85, 1884. C. T. Jackson, "Copper Mine, Elk Run, Fauquier County, Va.," Proc. Bost. Soc. Nat. Hist, VI., 183, 1857. Arthur Keith , Harper's Ferry Folio, U. S. Geological Survey. North Carolina, Tennessee, and Alabama.—" The Stone Hill Cop- per Mine and Works, Cleburne, Ala,.," Eng. and Min. Jour., August 4, 11, 18, 1877, pp. 86 and following. W. P. Blake, " Notes and Recollections Concerning the Mineral Resources of Northern Georgia and Western North Carohna," Trans. Amer. Inst. Min. Eng., XXV., 796. W. B. Brewer "Ducktown Copper Mining District," £^ngr. and Min. Jour., March 23^ 1895, 271. "Copper Mining in Alabama," Proc. Ala. Ind. and Sci. Soc, VII., 13, 1897. Carl Henrich, "The Ducktown Deposits and the Treat ment of the Ducktown Copper Ores," Trans. Amer. hist. Min. Eng XXV., 173, 1895. Rec. J. F, Kemp, 'The Order of Formation of the Minerals in the Ducktown Veins," Idem, 1899. T. S. Hunt, "Ore Knob and Some Related Deposits," Trans. Amer. Inst. Min. Eng., II., 125. Kleinschmidt (on Virginia, Tennessee, and North Carolina), Gangstudien, Vol. III., p. 256. (A good, short, but old account.) E. E. Olcott, "Ore Knob Copper Mine and Reduction Works, ' Trans. Amer. Inst. Min. Eng., HI., 391. Rec. W. B. Phillips. "Copper Deposits of North Carolina," Eng. and Min. Jour., April 1, 1899, 382. Tripple and Credner, "Report on the Ducktown Region to the American Bureau of Mines," 1866. M. Tuomey, ' 'A Brief Note of Some Facts Connected with the Ducktown (Tenn.) Copper Mines," Amer. Jour. Sci.., II., 19, 181. A. F. Wendt, " The Pyrites Deposits of the Alleghanies, " School of Mines Quarterly, Vol. VII., 1886; Eng. and Min. Jour., July 10 and following, 1886. J. D. Whitney, "Remarks on the Changes that Take Place in the Structure and Composition of Mineral Veins," etc., with especial reference to Ducktown, Tenn., Amer. Jour. Sci., ii., XX., 53. 196 KEMP'S ORE DEPOSITS. County, Copperopolis and Campo Seco, Calaveras County, and Newton, Amador County, are the most important. There are some differences m the geological relations of these several deposits, but they are alike in being associated with igneous rocks. At Spenceville the ores occur in veins along the contact of diabase and grano-diorite.^ In Amador County two belts of ore have been developed in amphibole schists. There are mines at lone and Caledonia, and other openings extend in a southeasterly line to Copperopolis in Calaveras County. The amphibolite schist is a metamorphosed diabase or porphyrite. In some of the mines quartz porphyrite is associated with the veins.^ Other copper deposits have been discovered in the areas covered by the Sonora and Placerville folios.^ They occur in porphyrites, amphibole-schists, serpentine, and in contact zones next the intrusions of grano-diorite. Far to the north of all the deposits cited above a very extensive body of sulphides has been opened at Iron Mountain, and bids fair to afford high-grade ore for this type. The wall rock is described as a highly siliceous porphyry.* The California copper ores have been treated by wet methods to a large extent, and have contributed considerable amounts to the total output of the country. Note. For Example 16c, see under Nickel. Some of the California mines appear to be closely related to 16c. 2.04.05. Example 17. Butte, Mont. Veins in fissures in granite, which have involved but slight dislocation, and which have been enlarged by replacement of the walls with ore. The vein filling is siliceous, and the metallic ores in the deposits ' Lindgren and Turner, Smartsville Folio, U. S. Geological Survey. See also J. E. Ellis, "On the Spenceville Mines," Mineral Resources of the U. S.; U. S. Geol. Survey, 1884, 340. H. G. Hanks, Rept. of California State Mineralogist, 1884, 151. J. B. Hobson, Idem, for 1890, 392. ■^ H. W. Turner, Jackson Folio, U. S. Geol. Survey. H. G. Hanks, " On Calaveras County Mines," Fourth Ann. Rep. Cal. State Mineralogist, 48, 1890. Wm. Irelan, Idem, 1888, 150-153; "On the Newton Mines, Amador Co.," Idem., p. 106. ^ Turner and Ransome, Sonora Folio ; Lindgren and Turner, Placerville Folio, U. S. Geol. Survey. * H. Lang, "Iron Mountain Mine, Shasta Co.," Eng. and Min. Jour., April 15, 22, and May 13, 1899. The paper also mentions other copper mines in this region. COPPER. 197 productive of copper are chalcopyrite, pyrite, boroite, chalco- cite, enargite, aud rarely covellite and tennantite. The copper ores contain much silver and some gold, but there is a fairly distinct series of silver-bearing veins, which contain practically no copper, and which have manganese minerals that fail in the copper veins. And yet along the borders of the two areas there are veins which are somewhat transitional between the two varieties. The geological formations at Butte are illustrated on the accompanying map, Figs. 58 and 59, which are based upon the map of the areal geology in the Butte Special Folio of the U, S. Geological Survey. The colors of the original are reproduced in lines, and some small details have necessarily been omitted on account of the reduction in size, and the confusion of signs without colors. The only omissions, however, are a few small areas of the Bluebird granite, and of the rhyolite. In the orginal map the areal geology is by W. H. Weed, and the veins and mining geology have been mapped by S. F. Emmons and G. W. Tower. The work was difficult and complicated, but it has been admirably done. The Butte mining district lies on the southern and eastern slopes of a hillside or upland that rises from the vallej' of Sil- ver Bow Creek. The hillside is cut by several minor north and south gulches, and is bounded on the south and east by the valley of the creek, which makes a crescentic sweep around it. Just to the west of the town rises a sharp cone of rhj'-olite, which is shown in Fig. 60, and which gave the camp its name in the early days. In the distance, on all sides, high mountain- ous ridges rise like walls as is shown in Figs. 61 and 62. The oldest rock of the district, and the one which covers the greatest area, is a basic granite. Chemical analyses prepared by the U. S. Geological Survey have proved it to be exceptionally low in silica for a granite, and to be quite uniform. SiO^ 63.88-64.34, AI2O3, 15.38-15.84, FeO, Fe203, 4.5-4.7, CaO, 3.97-4.3, MgO, 2.08-2.23, K2O, 4.0-4.23, Na20, 2.74-2.81. This rock is called the Butte granite. It is the wall-rock of all the copper veins and of most of the silver ores. It lies east, north and south of the Big Butte. The intrusion of the Butte granite was followed, presumably after a short interval, by a white, acidic granite known as the Bluebird. An interesting contact of the two is 198 KEMP'S ORE DEPOSITS. BUTTE GRANITE BL UEBIRD GRAN ITE QU ARTZ PORPHY RY RHYOLITE ^^ Fig, 58. — Geological map of the Western half of Butte District, Montana, re- produced in line-work from the colored map of the Butte Special Folio, U. S. Geological Survey. COPPER. 19!) LAKE BEDS M^.UVIUM C npPEK VEIN S SILVER VEINS CoW^MZvek Fig. m.— Geological map, Kastern half, Butte District, Montana, See Fig. 58. 200 KEMP'S ORE DEPOSITS. shown ID Fig. 63. It is supposed to have separated from the same magma that afforded the Butte granite and to have pene- trated fissures in the latter while it was probably still hot, as it is now found in all manner of small veins and masses, which do not show any effects of quick chilling along the contacts. The Bluebird granite is most extensively developed in the western part of the district, but it appears on all sides of the Big Butte in small patches. The next rock in time is quartz-porphyry, which is found on the slopes west of Butte City, and between it and Meaderville. After the intrusion of the quartz-porphyry the fracturing occurred, which gave rise to the veins, for the latter cut the quartz-porphyry in a number of instances. After the deposition of the ore, the great intrusion and eruption of the rhyolite took place, which now appears as many dikes cutting the veins, as a great sheet, and as some masses of fragmental ejectments. While the rhyolite was in eruption a lake existed in the western part of the district, and in it were deposited great quantities of rhyolitic volcanic dust, which now chiefly constitutes the Lake Beds of the map. These beds have been traced to the south and west beyond the limits of the map, and have been found to contain Miocene fossils. Outside the area of the map the Butte granite is known to penetrate Carboniferous strata, and it is not certain that it may not have followed Laramie beds. It is, certainly post-Carboni- ferous, and it may be post-Laramie. The veins must, there- fore, have been filled in the interval between the close of the Carboiliferous and the Miocene, and perhaps are post-Cre- taceous. The recent gravels constitute the formation called alluvium. They are extensive in the valleys of the creeks and at times quite deep. Butte was first developed as a placer camp as early as 1864, when, according to Emmons and Tower, the gravels of Mis- soula Gulch were washed. As the quartz ledges constituting the veins still project in many instances, like great walls, it is not surprising that they were early noted and located. Figures illustrative of them and of the excessive weathering of the Butte granite will be found under silver in Montana, Chapter X. Small success attended the first efforts of the deep miners until rich silver ore was found in the Travona in 1876. The copper dis- coveries came three or four years later, because the copper had Fig. 60. — View of the Big Butte, Butte City, Mont., looking northwest across Missoula Gulch. From a photograph by J. F. Kemp, June, 1896. Fig. Ql.—View of the Anaconda Mine {with the nine stacks), Butte, Mont, From a photograph by Alexander Brown, E. M., 1896. ^ ■ii 10 e '^l '^ 1 g « ^ "♦»> g •K» 'S •fc. i so .^^ p« y V Q> «> ^ CO •1 c? 1-t !■ e 1 s s ^ CJ5 "♦0 f S •kT 1 ^ h '^ llii ?£ ■S S ^ Si^ 5s> ^ ?^ rO "iT 1^ fSi -^ §" f§ ■§ of g c 1 '2 ?- ?^ ?: -^ e » s ^ 6 ^ COPPER. 201 been leached out of the portion of the vein above the ground- water, leaving the silver behind. When, however, the huge masses of chalcolite and bornite were met in the zone of enrichment, the copper production became established. Study of the map will show that, although so numerous, the veins all run in an east and west direction, that they are closely parallel, and that at the most they vary not more than 45 degrees north or south of this line. They dip at high angles, being almost always over 60 degrees. The dip is to the south, except in the northern edge of the district, where the inclination is prevailingly to the north. Small offsetting veins often connect the larger ones and even run into the wall rock as blind veins. Veinlets of all sizes can be observed on the dumps. The ore varies from live or six feet to as much as 100 feet across in the extreme cases. The origi- nal fissures do not appear to have involved much empty space, however, and the deposition has been in the nature of a replace- ment of the walls, and the process may, indeed, have extended from fissure to fissure, removing the intervening, rarely brec- ciated country rock. The ore habitually fades out into the coun- try rock at least on one side, and as a rule all the companies have to concentrate the run of the mines. Since the completion of ore deposition, there has been extensive later dislocation, which is shown by brecciated faults, which maj^ follow along the veins, or may cross and fault them. They are now filled with material more or less fully kaolinized and are practically bar- ren, except where they have dragged vein matter into their substance during faulting, or have been impregnated during the alteration of the older veins. 2.04.06. The ground distinctively productive of copper is quite sharply marked off from that yielding silver alone (all the copper ores have silver) and a wavy line has been run around the former on the map. The copper area seems to have been the center of the mineralization, and in it the largest ore- bodies are found. Copper and silver solutions especially fav- ored this portion, and on its edges the copper gradually failed, while with the silver came more or less zinc and lead, and increasing manganese. The Gagnon mine that is on the border is transitional, as the ore yields copper, but is also very rich in silver, and contains considerable blende and galena. 202 KEMP'S ORE DEPOSITS. The miDeralogy of the silver series is more fully described under Silver, Chapter X. The copper ores contain a small but constant value in gold, and there is some reason for thinking that the gold occurs as a telluride. While tellurium is present in very small amounts, it can be saved by the refiners and sup- plied in quantities that are, for this rare element, enormous. The oxidizatiah or alteration of the veins above the ground- water presentsloints of interest. As the v^^all-rock is granite, carbonates and oxides of copper are poorly developed and the oxidized ores are in contrast with those in limestones and schists. Chalcocite, bornite and covellite are the principal secondary copper minerals that have resulted, and the last named lies chiefly along fractures. The chalcocite and bornite are not, however, limited to the present water-level, but have pene- trated far below it, and have enriched the veins, and a reasona- ble query may be raised as to whether they may not be in part original depositions. The gangue is quartz, in decomposed country rock. Barite in honey-yellow tabular crystals is oc- casionally met, but is only a curiosity. The outcrop of the silver veins is stained black by manganese oxide. To the east of the area of the map and on the slopes of the bounding range of granite mountains, the veins outcrop as ledges of quartz, and considerable prospecting has been done. Some copper ores have indeed been found, but the developments do not yet (1899) assure profitable mining. 2.04.07. The total production of Butte to the close of 1896 is estimated by Emmons and Tower to have been 1300,000,000, divided somewhat as follows: Gold, 500,000 ounces; silver, 100,000,000 ounces; copper, 1,000,000,000 pounds. In 1897, according to The Mineral Industry, the copper produced was 237,158,540 pounds, of which the Anaconda Company con- tributed 131,471,127. On the whole, the Butte copper district is the most productive of those as yet opened in the United States.^ ^ The best account of Butte will be found in the Butte Special Folio, of the U. S. Geol. Survey, in which the areal geology is by W. H. Weed, and the mining geology by S. F. Emmons and G. W. Tower. This reference has been especially drawn upon in the above description. ' ' Butte Copper Mines," Eng. and. Min. Jour., April 24, 1886, 299; June 19, 1886, 445. R. G. Brown, "The Ore Deposits of Butte City," Trans. Amer. Inst. Min. Eng., XXIV., 543. Rec. S. F. Emmons, "Notes on the Geology of Butte, Mont.," Trans. Amer. Inst. Min. Eng., XVI., 49. Ch. W. Goodale, 1 ^- — «^- 1 s«» 't , ■1 ^■'^,* ■ , 1m Vr 11^ ( If.; 1 \ ^ i n \. 1 w\ ■ i I «»^j^ ^^^^K, - ^kW '% l- v^^^^^^^H ll Its* ill « 5 ^ •■^ ^ ^ S -. o « i # = I >» '^ .0> V COPPER. 203 There are copper prospects in northwestern Montana within the limits of the Lewis and Clarke Timber Reserve, and amid the high peaks of the Rockies near the international boundary. The general geology ,^ the country involves Cambrian and Precambrian quartzites, in which are intrusions of igneous rocks, of the nature of andesites or diorites. Copper ores are found in association with the latter/ 2.04.08. Example 17a. Gilpin County, Colorado. Veins of pyrite and chalcopyrite, replacing gneiss (the rock may be granite), and dikes of quartz- porphyry, and felsite along the planes of joints, which cross the gneiss (or granite) perpendic- ularly to the laminations. The veins are highly auriferous, and are worked primarily for gold, the copper being produced as a by-product. The concentrates from the stamps are after- ward treated for copper. The veins occupy an area of only about a mile and a half in diameter, centering about Central City. They show little indication of having filled a fissure, as usually understood, but follow the cleavage joints of the gneiss, and replace the countr}" rock on each side of them. The joints also cross the porphyry dikes, and the veins are often in the latter rock. They are closely related in structure* and origin to the galena veins of the neighboring Clear Creek County, which are referred to under "Silver,*' but the contrast in min- eral contents between the two is very marked. They were the "The Concentration of Ores in the Butte District, Mont., Idem., XXVI., 599, 1108. Richard Pearce, "The Association of Minerals in the Gagnon Vein, Butte City, Mont. , Trans. Amer. Inst. Min. Eng., XVI., 63; "On the Occurrence of Goslarite in the Gagnon Mine, Butte City, '" Proc. Colo. Set. Soc, Vol. II., Part I., p. 12. E. D. Peters, Mineral Resources of the U. S., 1883-84, p. 374. A. Williams and E. D. Peters, "On Butte, Mont.," Eng. and Min. Jour., March 23, 1885, p. 208. G. vom Rath, "Ueber das Gangrevier von Butte, Mont.," Neues Jahrbuch, 1885, L, 158. Important annual reviews are also published in the Ann. Reps, of the Director of the U. S. Geol. Survey and in The Mineral Industry. The lat- ter is especially valuable in connection with the technology and mining. Geneml papers on copper production likewise touch on Butte, such as James Douglass, "The Copper Resources of the United States," Trans. Amer. Inst. Min. Eng., XIX., 678. Some additional literature is given under "Silver," 2.10.09. *^ R. C. Chapman, "The Geological Structure of the Rocky Mountains, within the Lewis and Clarke Timber Reserve," Trans. Amer. Inst. Min. Eng., February, 1899. 204 KEMP'S ORE DEPOSITS. basis of the first extensive deep mining in Colorado, and were located through the placer deposits in the neighboring gulches/ 2.04.09. Example 176. Llano County, Texas. Impregna- tions in granite, and veins with quartz gangue in granite, carry- ing carbonates above, but sulphurets and tetrahedrite with some gold and silver below. Contact depo^it^ between slates and granite are also known. It is not demonltrated as yet whether the ores are to be actually productive.^ 2.04.10. Example 18. Keweenaw Point, Michigan. Native copper, with some silver, in both sedimentary and interstrati- FlG. 64. — Cross section of the Boh-tail mines, Central City, Colo. F. M. Endlich, Hayden's Survey, 1873, 'p. 286. After fied igneous rocks of the Keweenawan system. The metal oc- curs as a cement binding together and replacing the pebbles of a conglomerate ; or filling the amygdules in the upper por- tions of the interbedded sheets of massive rocks; or as irregular masses, sometimes of enormous size, in veins, with a gangue of calcite, epidote, and various zeolites ; or in irregular masses along the contacts between the sedimentary and igneous rocks. (For the general geography see Fig. 24, p. 126.) 2.04.11. The rocks of the Keweenawan system are most ^ S. F. Emmons, Tenth Census, Vol. XIII. , p. 68. The veins are de- scribed as cited above. J. D. Hague, Fortieth Parallel Survey, III. , p. 493. The veins are called fissure veins by Mr. Hague. A. Lakes, Ann. Rep. Colo. State School of Mines, 1887, p. 103. A. W. Rogers, "The Mines and Mills of Gilpin County, Colorado," Trans. Amer. Inst. Min. Eng., II., 29. Further references will be found under "Silver and Gold in Colorado." ^ T. B. Comstock, First Ann. Rep. Texas Geol. Survey, 1889, p. 334. W. F. Cummins, Idem, 196. W. H. Streeruwitz, in Mineral Resources of the U. S., 1884, p. 342. COPPER. 205 strongly devreloped on the south shore of Lake Superior, espe- cially in Keweenaw Point, which juts out northeasterly, cut- ting the lake into two nearly equal portions. They extend some distance east and west, and are also known on the north shore. They consist of sandstone and thin beds of conglomerate, inter- stratified with sheets of diabase,- both compact and amygdaloi- dal, and of melaphyre. They are succeeded on the east by the Eastern Sandstone, which on the south shore is thought by Irving, Chamberlin and others in some places to abut uncon- formably against them, and in others to pass under them from an overthrust fault. Wadsworth, however, considers that the Eastern Sandstone passes conformably beneath the Keweena- wan, and that it is older. The Eastern Sandstone forms a comparatively low, flat bench some miles across, between the lake and the ridge of the Ke- weenawan, whose rocks rise quite abruptly in a marked escarp- ment. The several streams that fall over this scarp in cas- cades have served by their erosion to expose the contacts. The best known are the Hungarian and Douglas Houghton Rivers. On the west or northwest side the escarpment is much less pronounced and the contact is less well shown and has not been so sharply located. The sandstone is called the Western Sandstone. It is now pretty well shown that the Eastern Sandstone is a close equivalent to the Potsdam, for though itself lacking in fossils, it is known to pass conformably beneath fossiliferous Lower Silurian limestone near L'Anse. On Keweenaw Point the beds dip northwesterly and pass under Lake Superior to reappear with a southeasterly dip on Isle Royale and the Canadian shore. Western Lake Superior occupies this synclinal trough. In Keweenaw Point the dip is greatest on the southvest, being about 60° at Hancock. To the northeast it gradually flattens to 30° or less on the lake shore. (For the general geology of the neighboring region see under Example 9.) It is interesting to note that the early investigators of the geology of this country drew a parallel between the sandstones and traps of Lake Superior and the similar Triassic deposits of the Atlantic coast (see Example 21), even going so far as to regard the former as the western equivalent of the latter.* » C. T. Jackson, Amer. Jour. Set., i., XLIX., 1845, pp. 81-93. 306 KEMP'S ORE DEPOSITS. 1 ^ ^ 1 Ci5 ;a ^ g e IS ^ I- s COPPER. 207 There are three principal mining districts — the Keweenaw Point, on the end of the Point; the Portage Lake, in the middle; and the Ontonagon, at the western base. Mines have also been worked on Isle Royale, and copper is fonnd in small amounts on °^ / a m ■^ "^ 7 ^ MM K '/v r.' 10 ffl ^14 ^ ^' 18 \ Y 15 y S9-- s^/ 21 22 9 / 26 S'K 29 28 27 B ^' 'V 36 36 SlJ y ^34 ^ A sV 2 . 4 / 'is 7 f .mIu^A^, X fAT "^W to ■v, i iccot MINC u/-»n it' Mihi J u ^ K m r 22' m 29 28\ 27 26 ^ K 29°' teuM KHM Ti ^sj\26 28 27 9 K SI 82 33 La*^"*^ ^'. 1/ ~ffi T » sr; ^ » 34 1 w^ X « 6 ^i' /l \e 6 ¥ \ * l/iV ^ ^ u "^ 7 Aj w [^:/ ^ ^ n i 10 %jkj r^ » 10 K U u u // 17^16 16 1/14 £^ 13 s'V f 16 ^ m « % 22 2* ( 18 20 \ ^ 19 ^^ Si>C 22 20 81 V ao 29 \ ■?* ■^, 26 SO 29, f 1 so« oo^o .^^ 26 30X29 28 27 \ ae SI S2 A M A 81 ^ ^^ ^ 3 2 se 1 Sills: 33 V * . e 6 J, (^ \' S ^ sJB i 3 I ^ 5/^(ffl| 6 12 7 8 9 V V .y" 7 8 9 10 I- >- ,^ m 8 J 10 ^'; IS n . a 16 V 'l3 18 17 16 \'y ^ ^ 18 1i\ ^ 17 ^ 1 "\ » K Sn •y 'gv \« l» 20 n^ ^ ^ 24 X9 ^ 24 19 2>> ^ V i" i 28 V 26 SO ^ ^ ) 27 r 26 80 28 26v ^ <' 28 ^ y 4 \ Lg} "S T^ :s> ^" ) sT "sT 36 ^31 a s^KT/lll ?' \w "^ WmMm » e n ^ u \ 1 / 6 4 P V 1 1? Ik J^ / « > 4J fill u *7 •/ • ^ 4 IS '-, 8 ,v )ao t T ^ ff 12 7 »A HI u 18 A M k a 14 / •18 17 A s" 14 ^ 18 Aj !• i V ^11 [^ \A » 21 a V u 1» k n > /24 19 ^ te b Lj XXXV Fig. 66. — Map of the Portage Lake IHstHct, Keweenaw Point, Mwh. Adap- ted from a map in the catalogue of the Michigan College of Mines. the north shore. The Portage Lake district is now the princi- pal and almost the only producer. In the first-named district most of the mines are on original fissures, which have later ^08 KEMP'S ORE DEPOSITS. become much enlarged by the alteration of the walls. They are usually from one to three feet broad, but may reach 10, 20, and 30 feet, this last in the more loosely textured rocks. These expansions are also richer in copper. The veins stand nearlj^ vertical, and cross the beds at^ight angles. They were the earliest discovered, and the fir^fljo be extensively worked. The metallic masses, both large and small, occur distributed through the gangue. The best-known mines of the district are the Central, Cliff, Phoenix and Copper Falls. All have been recently closed except the Central, which, after temporary sus- pension in 1894, resumed operations in 1896. A conglomerate appeared to cut off the vein, although probably a fault and move- ment parallel with the dip occasioned the displacement. With favorable markets several other vein mines maj" be intermit- tently worked. The vein mines have been the great source of fine minerals in the past, the Phoenix being well known for its zeolites. 2.04.12. In the Portage Lake district the mines are either in conglomerate (Calumet and Hecla, Tamarack, Peninsula, etc.) or in amygdaloidal, strongly altered diabase, certain very sco- riaceous sheets of which are known as ash-beds (Quincy, Franklin, Atlantic, etc.). In the conglomerates the copper has replaced the finer fragments, so as to appear like a cement, and often the boulders themselves, or particular minerals in them, are permeated with copper. The rich portions are of limited extent along the strike as they give way to barren rock, after a stretch it may be of several thousands of feet, and they go down as great chutes somewhat diagonally on the dip to very great depths. The Tamarack workings, below the Calumet and Hecla, have been pushed on the bed nearly a mile below the outcrop, and show no diminution or essential change in the copper rock. Three copper- bearing conglomerates have been identified, the Calumet and Hecla, the Albany and Bos- ton (also called the Peninsula) and the Allouez. The first is much the richest, but has not been found productive at any other point on the strike than in the great mine which gives it its name. The amygdaloids have copper in their small cavi- ties, but in the open or shattered rock it fills all manner of irregular spaces, often in fragments of great size. It is asso- ciated with calcite, zeolites, datolite, epidote, and a chloritic COPPER. 209 mineralj or "green earth" containing Fe203. The distribution of the copper in the amygdaloidal sheets is much the same as in the conglomerates. It is limited along the strike, and goes down at a slight diagonal in great chutes whose ends have never yet been reached. This arrangement must have an important bearing on the method of origin. 2.04.13. In the Ontonagon district the copper follows planes approximately parallel to the bedding of the sandstones and igneous rocks, and in one case at least (the National mine) along the contact between the two. The copper is quite irregu- lar in its distribution, but has the same associates that are mentioned above. On the Origin of the Copper. — The original source of the cop- per was thought by the earlier investigators to be in the erup- tive rocks themselves, and that with them it had come in some form to the surface, and had been subsequently concentrated in the cavities. Pumpelly has referred it to copper sulphides dis- tributed .through the sedimentarj^ as well as the massive rocks from which the circulating waters have leached it out as car- bonate, silicate, and sulphate. Although the traps are said by Irving to be devoid of copper, except as a secoodary introduc- tion, it would be interesting to test their basic minerals for the metal in a large way, as has been so successfully done by Sand- berger on other rocks. It is probable that these may be its source. Irving states that the coarse basic gabbros of the system con- tain chalcopyrite, but they do not occur near the productive mines. The electro- chemical hypothesis of deposition was ear- liest advocated (Foster and Whitney), and on account of the electrolytic properties of the two metals copper and silver, at first thought, it seems to be a reasonable explanation. Still, the unsatisfactory character of all experiments made in other re- gions to detect such action militates against it. Pumpelly, however, has worked out an explanation much more likely to be the true one. He found, on studying the mineralogical changes which have taken place in the rocks, that the altera- tion had been very thorough, and that it had involved a most interesting series of minerals, which are now chiefly mani- fested in the cavity fillings. It is to be appreciated, as has been especially well shown by the recent detailed geologi3al 210 KEMP'S OME DEPOSITS. sections of L. L. Hubbard/ that, in the productive region, the Keweenawan rocks consist of a vast series of basic lava flows, with a few of more acidic types, and with occasional intercalated conglomerates. H. L. Smyth^ has also emphasized the fact that these successive lava sheets must have remained for pro- tracted periods after their outpourings, exposed to the atmos- pheric agents, and to weathering, befoWthey sank beneath the sea, and were buried under the conglonifrates. As a matter of observation the upper portions of the sheets are notably more cellular and decomposed than are the lower. Two kinds of amyg- daloids were indeed recognized by Pumpelly,^ brown ones, or true amygdaloids, in which the alteration was excessive, and which were probably derived from cellular lava sheets; and green ones, or pseudo-amygdaloids, which are hard and dense, and probably owe their apparent amygdules to the decom- position of pj'roxene, olivine or feldspar crystals. Pumpelly traces out the following series of minerals. The first to develop was chlorite. Either contemporaneously with the chlorite or next after it, laumontite, a hydrated basic silicate of calcium and aluminum, resulted. Laumontite, prehnite and epidote, all non-alkaline silicates, next segre- gated in the cavities, and were followed by quartz. They are thought to correspond to the deoay of the pyroxenic minerals in the lavas. The copper manifestly came in after this, and its deposition seems to have proceeded along with the formation of a green chloritic mineral, or green-earth, which has displaced the prehnite, quartz and calcite of the earlier stages. Calcite, it should be added, marks almost every stage of the paragenesis. Presumably the reducing action produced by the oxidation of FeO to Fe203 in the production of the chlo- ritic '* green -earth," caused the reduction and precipitation of the copper from some aqueous solution of sulphate, carbonate or silicate. After all this had occurred a quite different series of minerals (except that calcite continued to form) was intro- duced, which are characteristically alkaline silicates. Anal- ^ Geological Survey of Michigan, V., opp. p. 166. » Science, February 14, 1896, p. 251. ' Geological Survey of Michigan, I., Part II., 14. Amer. Jour. Sci., Sep tember, 1871. Proc. Amer. Acad. Arts and. Sciences, XIII., p. 268, 1878. Geol. Wisconsin, III., 31. COPPER. 211 cite, apophy llite, datolite, and last of all orthoclase, are the chief members. Pumpell}' regards them as produced by the altera- tion of the feldspars of the basalts, and in a continuous succes- sion of changes following those just cited, but H. L. Smyth advances the view that they and the copper came in after the tilting and faulting of the strata, and probably in uprising solutions along the fissures, which are illustrated in the vein mines. He remarks that apoph3^11ite contains fluorine and datolite, boron, and that the mineralization of the fissure veins is often extended in lateral enrichments, where the fissures cut porous beds. Pumpelly specially favored the overlying sand- stones and descending solutions as sources of the copper. Wadsworth gives a resume of all the views advanced up to 1880^ and himself favors a derivation by leaching of the neigh- boring and overlying trap. As stated in mentioning the ^reat ore-chutes above, the cir- culations must have followed the general lines indicated by them, so that it is evident that the rich currents were of lim- ited extent. The anomalous condition presents itself of native copper, a mineral that is usually characteristic of the oxidized zone of deposits of sulphides, extending to great depths below the ground-water level. It is natural to rai§e the query as to the possible passage of the native copper into sulphides in depth, but there is as yet no evidence of this change. Any minerals in the nature of sulphides are extraordinarily rare. A little whitneyite and domeykite (copper arsenides) and chalcocite occur in the amygdaloid, formerly worked at the Huron mine ; chalcocite has been found in the Bohemian Mountains and in the Copper Falls mine. Native copper changes to chalcocite 90 feet down in the Mamaisne mine, near the Sault (L. L. Hubbard). A pocket of melaconite, the black oxide, was opened in the early days at Copper Harbor. 2.04.15. The discovery of copper dates back to the explora- tions of the French, who, in the seventeenth century, left the * M. E. Wadsworth, "Notes on the Geology of the Iron and Copper Districts," Bull. Mus. of Comp. Zool, VII., 76, 123. Report of the State Geologist of Michigan, 1892, 167-170, and especially 169. Rec. Also in a pamphlet of the Duluth, South Shore & Atlantic R. R., 1890. "Origin and Mode of Occurrence of the Lake Sui^rior Copper Deposits, " Trans. Amer. Inst. Min. Eng., XXVII., 669. 212 KEMP'S ORE DEPOSITS. settlements on the lower St. Lawrenco and penetrated the Great Lakes. The country was the scene of a great mining excite- ment in the forties. After many vicissitudes and exploded schemes the district settled down to the largest production of any American region. WWithin the last few years, however, Butte, Mont., has exceeded it. Many interesting traces of pre- historic mining were found by the early explorers, for the copper was a much-prized commodity among the aborigines. 2.04.16. Some important mining for copper has been done on Isle Royale, along the Canadian shore, and in Minnesota, but although Keweenawan rocks are in great force, no large amount of the metal has been found. ^ * It would be impossible and undesirable to give in this place complete references to the literature. Such a bibliography will be found in Irving's monograph, and in Wadsworth's. The more important papers are given below, with some additions to the lists mentioned above. Bauerman, H., "On the Copper Mines of Michigan," Quar. Jour. Geol. Soc, XXII., 448, 1866. Good account of the minerals. Credner, H., On the geology, etc., Neues Jahrbuch, 1839, p. 1. Foster and Whitney, Report on the Lake Superior Copper Lands, 1850. Hall, C. W., "A Brief History of Copper Mining in Minnesota," Bull. Minn. Acad. Nat. Sci., Vol. III., No. 1, p. 105. "History of Copper Mining in the Lake Superior District," Engineer- ing and Mining Journal, March 18, 1882, p. 141. Hubbard, L. L., "Two New Geological Sections of Keweenaw Point," Proc. Lake Sup. Min. Inst. , II. Rec. Irving, R. D.. '.'The Copper-bearing Rocks of Lake Superior," Monograph v., U. S. Geol. Survey, especially p. 419. Rec. Bibliography, p. 14. " Keweenaw Point with Particular Reference to the Felsites and their Associated Rocks," Geol. Survey of Mich., VI., Part II., 1899. Lane, A. C, Geological Report on Isle Royale, Mich. Geol. Survey, Yl., Pt. I. Lawson, A. C, " Notes on the Occurrence of Native Copper in the Animi- kie Rocks of Thunder Bay," Amer. Geol., V., 174. Palache, Ch., "The Crystallization of Calcite from the Copper Mines of Lake Superior," Geol. Survey, Mich., VI., Part II., Appendix. Poole, H., " Michipicoten Island and its Copper Mines," Eng. and Min. Jour., August 6, 1892, p. 125; September 3, p. 220. Pumpelly, R., Geol. Survey of Mich., 1873, Vol. I. "On the Origin of the Copper." Amer. Jour. Sci., ii.. HI., 183-195, 243-253, 347-353. Rec. A later and fuller paper is in Proc. Amer. Acad., 1878, Vol. XIII., p. 233. Rominger, C, " Copper Regions of Michigan," Geol. Survey of Mich., V., 85, 1895. Wadsworth, M. E. , Notes on the Geology of the Iron and Copper DistHcts of Lake Superior. Cambridge, 1880. Bibliography, p. 133. See also footnote to page 211 above. COPPER. 213 2.04.17. Example 19. St. Genevieve, Missouri. Beds of chalcopyrite associated with chert m magDesian limestone of the Cambrian system. St. Genevieve is situated on the Missis- 2nd._M.agne3ian Limestone ^Roof Limestone J^> Chert seams Sulphuret ore ^Floor 2nd. Magnesian Ll'mestoaa Fig. 67. — Cross section in the St. Oenemeve copper mine, illustrating the rela- tions of the ore. After F. Nicholson, Trans. Amer. Inst. Min. Eng., X., 450. sippi, about forty miles south of St. Louis. The Second Magne- sian Limestone of the Cambrian outcrops, with the Carbonif- erous on the north, and more or less Quaternarj' in the vicin- Limestone vv: Chert and ore Fig. 68. — Section at the St. Genevieve mine, illustrating the intimate relations of ore and chert. After F. Nicholson, Ivans. Amer. Inst. Min. Eng., X., 451. ity. There are two nearly horizontal beds of ore, of widths varying between three inches and several feet. They lie be- Whitney, J. D. , " On the Black Oxide of Copper of Lake Superior, " Proc. Boston Soc. Nat. Hist., January, 1849, p. 102; Am,er. Jour. Sci. ii., VIII., 273. Metallic Wealth of the United States, p. 245. Rec. Whittlesley, C, "On Electrical Deposition," Am,er. Assoc. Adv. Sci., XXIV., 60. Wright, C. E., and Lawson, C. D., Mineral Statistics of Michigan. An- nual formerly issued. 214 KEMP'S ORE DEPOSITS. tween cbert seams, and are associated with ciay and sand. The ore is thought by Nicholson to have been deposited in cavi- ties formed by dolomitization, much as is advocated by Schmidt for the lead and zinc deposits of southwest Missouri, and as is described under Example 25. For ten years the mines have not been operated.^ Fig. 69. — Geological map of the Morenci or Clifton copper district of Arizona. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV 23. 2.04.18. Example 20. Arizona Copper. Bodies of oxi- dized copper ores in Carboniferous limestones, associated with eruptive rocks. In addition to these, which are the most important, there are veins in eruptive rocks, or in sandstones, or ore bodies of still different character as set forth under the several sub-examples. The copper districts are nearly all in ^ F. Nicholson, "Review of the St. Genevieve Copper District, " Trans. Amer. Inst. Min. Eng., X., 444. B. F. Shumard, "Observations on the Geology of the County of St. Genevieve, Missouri," Trans. St. Louis Acad. Sci., I., 40; abstract in ^mer. Jour. Sci., ii., XXVIII., 126. COPPBB. 215 the southeastern part of the territory, but the Black range is near the center. VONGFELUOW^<^HIUU Fig. 70. — Vertical section of Longfellow Hill, Clifton district, Arizona. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV., 52. Pig. 71.— Horizontal sections of Longfellow ore body. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV., 52. 2.04.19. Example 20a. Morenci. The Morenci district, known also as the Clifton or Copper Mountain, lies in a basin, 216 KEMP'S ORE DEPOSITS. six to ten miles across, whose high surrounding hills consist of limestone, probably Lower Carboniferous, which rests on sandstone, and this on granite. The principal mines are grouped about the town of Morenci. Clifton is seven miles distant at the point where the smelter of the Arizona Copper Company is located. In the basin is a mass of porphyry, con ■ taining frequent great inclusions of limestone^ Felsite or por- phyry dikes are also abundant in the surrounjEng sedimentary and granite rocks. Several miles to the east there is an out- flow of late trachyte and evidence of recent volcanic action. From this it appears that eruptive phenomena are abundant and widespread. Fig. 72. — Geological section of the Metcalf mine, Clifton district, Arizona. After A. F. Wendt, Trans. Amer. Inst. Min. Eng., XV., 36. 2.04.20. The ores are classified by Henrich as follows: 1. Contact deposits. These occur in a zone of decomposed and kaolinized porphyry, between a bluish, fine-grained lime- stone, and solid porphyry. Many ore bodies, and probably the largest, are directly on the limestone, while others are sur- rounded by the decomposed porphyry. As included masses of limestone, with associated ore, are found in the decomposed porphyry, it is probable that these ore bodies may have origi- nally replaced such. The ores are malachite, azurite, cuprite, with some metallic copper and melaconite, in a gangue princi- COPPER ^17 pally of limonite. Wad is also frequent. Much clay of a residual character occurs with the ores. 2. Deposits in limestone. These are closely associated with the first class, and have apparently formed as outlying bodies in the limestone, as they are connected by ore channels with the principal lines of circulation along the contact. They ap- pear to contain more wad and lime than the typical contact deposits. 3. Deposits in porphyry. These form sheets and pockets in porphyry, or impregnate the solid rock itself. They are oxi- dized at the surface, but pass in depth into chalcocite. The principal gangue is kaolinized porphyry. The impregnated porphyries are to-day the chief ore supply. According to Wendt the Coronado vein fills a longitudinal fissure in a quartz porphyry dike. It afforded chalcocite above, but passed into chalcopyrite below. Wendt also mentions a group of veins in granite that likewise afforded chalcocite.^ 2.04.21. Example 206. The Bisbee district, called also the Warren district, is situated in the Mule Pass Mountains in southern Arizona, near the Mexican line. The range runs east and west, and consists of beds of Lower Carboniferous lime- stone, dipping away from a central mass of porphyritic rock. The ores are found in the canons on the south side, which have been formed by erosion, along the contact of the limestone and porphyry. They are of the same oxidized character as at Morenci, and in the important mines occur in limestone. James Douglass describes them as being situated at a distance from the porphyry of perhaps a thousand feet or more, and as forming in their unaltered state huge masses of pyrites with copper often as low as two per cent. They have been pro- duced, as nearly as one can judge by replacement of the lime- stone, through the agency of solutions, which brought much siliceous and aluminous matter as well. It is natural to look to the porphyry as the source of the latter material. The sul- ^ J. Douglass, "Copper Eesources of the United States," Trans. Amer. Inst. Min. Eng., XIX. 678, 1890. Rec. "Arizona Copper and Copper Mines," Eng. and Min. Jour., August 13, 1881, p. 103. "Clifton Copper Mines of Arizona," i7)id, February 21, 1880, p. 133. C. Henrich, "The Copper Ore Deposits near Morenci, Ariz.," Ibid., March 26, 1887, pp. 202, 219. Rec. A. Wendt, "Copper Ores of the Southwest," Trans. Amcr Inst. Min. Eng., XV., p. 23. Rec. 218 KEMP'S ORE DEPOSITS. phides pass in alteration into bodies of oxidized ore, which re- main in the midst of ferruginous clay, called * 'ledge matter'' by Dr. Douglass. Thoroughly oxidized masses, as well as oth- ers whose outer shell is alone changed, are known. Ooe mass in the Czar shaft of the latter cH^i^ter is estimated at 1,000,- 000 tons of ore. The degree of altwation does not appear to be dependent on the vertical position, as bodies of sulphides are known to be higher up than thoroughly oxidized masses, but in this arid region the ground-water stands at a very consider- able depth, and appears not to have been yet actually reached, although much trouble is caused by floods during periods of rain. Above the bodies of ore empty caves are usually found, and so frequent is this association that when the prospecting drifts strike a cave the miners immediately sink in the expec- tation of striking an ore body in depth. Sink-holes on the sur- face have been successfully used as guides in the same way. In the accompanying picture of the mine. Fig. 73, the lime- stones dip into the hill, away from the shaft, and the ores are found in them, and beneath the valley below. The rock referred to as porphyry above has been microscopi- cally determined by A. A. Julien for Arthur Wendt to be a quartz-porphyry with a f elsitic ground mass (felsite- porphyry of Julien). Its contact with the limestones is marked by a zone of kaolinization, or alteration, and is not sharp. Positive evi- dence of contact metamorphism has not yet been recorded, but the effects of circulating waters are pronounced. The results of detailed geological study of the region will be awaited with interest.^ ^.04.22. Example 20c. Globe District. As in the other districts the most productive mines are in limestone near the contact with eruptive rocks. 1. Contact deposits in limestone. At the Globe mines the Carboniferous limestone abuts against a great dike of diorite, while trachyte and granite are near. Along the contact there is abundant evidence of thermal action in the kaolinized rock. * J. Douglass, "Copper Resources of the United States." Trans. Amer. Inst. Min. Eng., XIX., 678, 1890. Rec. "The Copper Queen Mine," New York meeting of the Amer. Inst. Min. Eng., February, 1899. See Eng. and Min. Jour., February 25, 1899, p. 230. A. Wendt, "Copper Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., p. 52. Rec. 3 h COPPER. 2J9 The great bodies of oxidized ores are found on this contact and extend out into the limestone. The one on the Globe claim is described by Wendt as resembling a great chimney. 2. A fissure vein in sandstone, containing arsenical and antimonial copper ores, and known as the Old Dominion, was formerly worked. 3. Fissure veins in talcose slate and gneiss, and filled by a quartz gangue with bunches of malachite and azurite (New York and Chicago mines), and now no longer worked. 4. Numerous small veinlets forming a stockwork, in gneiss near a dike of diorite, which is crossed by a dike of trachyte. These are known as the Black Copper Group. The ores are too low grade for profitable exploitation. Of greater interest are the bodies of chrysocolla, found in the wash down the hill from the outcrop of the veins, and evidently due to the super- ficial drainage of the stockworks. Similar bodies of ore, though not chrysocolla, were found at Rio Tinto, in Spain.* 2.04.23. Example 20d. Santa Rita District. Although in New Mexico, this district has much in common with those already mentioned. A great dike of felsite cuts limestones, and along the contact, as well as in the felsite itself, copper ores are found. 1. Contact deposits in limestone. These afforded the usual oxidized ores, but were not found to extend to any great depth, and while for a time productive, they were soon exhausted. 2. Deposits in felsite. These consisted of pellets and sheets of native copper in the dike itself, which were oxidized to cuprite near the surface. (Cf. Lake Superior amygdaloids, Example 18.) They were worked by the Mexicans in the early part of the present century.*^ * J. Douglass, " Copper Resources of the United States," Trans. Amer. Inst. Min. Eng., XIX. 678, 1890. Rec. "The Globe District," Eng. and Min. Jmir., April 9, 1881, p. 243. W. E. Newberry, "Notes on the Pro- duction of Copper in Arizona," School of Mines Quarterly, VI., 370. A. Trippel, "Occurrence of Gold and Silver in Oxidized Copper Ores in Arizona," Eng. and Min. Jour., June 16, 1883, p. 435. A. Wendt, "Cop- per Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., p. 60. ' A. F. Wendt, "Copper Ores of the Southwest," Trans. Amer. Inst. Min. Eng., XV., 27. Wislizenus, "On the Santa Rita Mines: Memoir of a Tour in Northern Mexico, 1846-47," p. 47; Amer. Jour. Sci., ii.. VI., 385, 1848 220 KEMP'S ORE DEPOSITS. 2.04.24. Example 20e. Black Range District. This is now the leading copper producer of Arizona, and has come intc great prominence within a few years. In its geological rela- tions it appears to be more like the California deposits than any others, but there are as yet but few recorded details. It appears that there is a great dike ofMnore or less porphyritic, dark green rock that has been extensively fractured along a broad line of dislocation for several miles. The fractured zone strikes north 10° west, and outcrops about 5,800 feet above tide. The writer has examined thin sections of the dike- rock, which is locally called diorite, but the specimens at hand were too thoroughly decomposed to admit of close identifica- tion. No dark silicates were visible, and chloritic products alone indicated their former presence. Broadly rectangular •feldspars were the chief minerals, but they w^ere too badly altered, even to indicate their character, although no positive, polysynthetic twinning could be detected. Quartz was com- mon. In depth sheared dike rock is met that resembles slate. The ore, which embraces both bornite and chalcopyrite, fills the cracks and larger fissures and impregnates the slaty rock. There is some galena present, and earthy lead sulphate has resulted from it in the gossan. The ore carries both gold and silver. The inaccessible situation of the mines long hindered their development, but now, with a mountain railway to give them an outlet, they are very productive. They are operated by the United Verde Company, and are about 20 miles west of Prescott. ^ 2.04.25. Example 20/. Copper Basin. Beds of closely tex- tured conglomerate and sandstone, resting on granite and gneiss, and having a cement of copper carbonates. Copper Basin lies about twenty miles southwest of Prescott, and is formed by a depression in greatlj^ decomposed granite, which is traversed by numerous small veinlets of copper ores. The granite is pierced by porphyry dikes, and covered by the sedi- * J. F. Blandy, "The Mining Region Around Prescott, Ariz.," Trans. Amer. Inst. Min. Eng., XI., 286. G. K. Gilbert, ''On the General Geology of the Black Mountain District," Wheeler's Survey, III., p. 35. A. R. Marvine, "Brief Details of the Verde Valley," Wheeler's Survey, III., p. 209. A. F. Wendt, " Copper Ores of the Southwest," Trans. Amer. Inst Min. Eng., XV., 63. Rec. COPPER. 231 mentary conglomerates and sandstones into which its copper is thought by Blake to have partially leached and precipitated as a cement. Reference, by way of comparison, may be made to the Lake Superior conglomerates, in which, in part, the native copper serves as a cement.^ 2.04.26. There are numerous other copper districts in Ari- zona of minor importance, or entirely undeveloped, but the ex- amples above cited probably illustrate the occurrences quite fully. Those not referred to are of sporadic development. Copper prospects are known in the Grand Canon of the Colo- rado, and have received some attention.^ Mention should also be made of the mines in Lower California, opposite Guaymas, a brief description of which will be found in Wendt's paper.^ The copper ores impregnate beds of submarine volcanic tuff, and are unique in their geological relations. Much copper is now met in depth at Leadville, Colo. The geology of the mines is set forth under Lead-Silver. 2.04.27. Example 20gr. Crismon-Mammoth, Utah. In the Tintic district, Juab County, are three great ore belts, in ver- ticallj' dipping dolomitic limestone, as more fully set forth under "Silver" (Example 35a). One of these, the Crismon- Mammoth, contains ores that bear silver, gold, and copper in proportions of about equal value. They have been a very diflS- oult mixture to treat successfully. Of late considerable copper has been produced, placing the ore deposits among those deserv- ing mention. The Crismon-Mammoth vein or belt covers a maximum width of 70 feet, and runs 500 feet on the strike, dipping 75° west. The ores seems to have been deposited along the bedding planes, though often cutting across them. The pro- ductive portions are found in richer chutes or chimneys, amid much low-grade material and gangue, and are of all shapes and sizes, from 25 feet in diameter, down. The Copperopolis * W. P. Blake, "The Copper Deposits of Copper Basin, Arizona, and their Origin," Trans. Amer. Inst. Min. Eng., XVII., 479. ' J. F. Blandy, "On Arizona Copper Deposits," Eng. and Min. Jour., 1897, Vol. LXIV.,p. 97. ^ See also M. E. Saladin, "Note sur les Mines de Cuivre du Boleo (Basse CaX\torin&)," Bull, de la Societe del Industrie Minerale, 3 Serie, VI., 5, 283. 222 KEMP'S ORE DEPOSITS. is thought to be od the same belt, and is a neighboring location of similar geological structure and ores/ A very important body of chalcocite was discovered in 1898 in Bingham Canon, whose geological relations are similar to those described for the lead-silver ir^s under 2.08.23. Its loca- tion was on the Highland Boy clarai. 2.04.28. Wyoming, Idaho, Washington. Oxidized ores have been exploited to some extent at the Sunrise mines, in the Laramie Kange, Wyoming. Iron ores are in the same region (see under Hematite). Other copper prospects have been opened in the Wood River region in northern Wyoming, and at other points, but the geological relations have not yet been described. 2.04.29. In the extreme western border of Idaho, near the Oregon line, the Seven Devils district has been located and developed to a considerable degree. Intrusions of diorite have pierced a white marble and upon the contacts and upon in- clusions have developed extensive aggregates of garnet, epidote and specular hematite, together with very considerable amounts of bornite. Green prophj^ritic dikes are also present. Lind- gren regards the ore as formed by pneumatolytic processes set up by the diorite. As also remarked by Lindgren the type of ore body is known in Mexico, and indeed a number of cases have come to the notice of the writer.^ Not a few copper prospects have been located in Washington, but they are as yet of somewhat undemonstrated value. North of Lake Chelan in the Stehekin district copper sulphides, pyrites and mispickel impregnate brecciated, andesitic dikes in marble.* A vein in King County* is described as occurring in syenite. 2.04.30. Example 21. Copper ores in Triassic or Permian sandstone. They occur as oxidized ores, with native silver, * O. J. Hollister, "Gold and Silver Mining in Utah," Trans. Amer. Inst. Min. Eng., XVI., p. 10. D. B. Huntley, Tenth Census, Vol. XIII., p. 456. A report on the Tintic District is in press with the U. S. Geol. Survey, but is not available at this writing. "^ R. L. Packard, "On an Occurrence of Copper in Western Idaho," Amer. Joun. Sci., October, 1895, 398. W. Lindgren, "Copper Deposits of the Seven Devils," Mining and Scientific Press, Feb. 4, 1899, 125. Rec. ^ As learned from the writer's friend, Charles Of, from whom material has been obtained and examined. * R. H. Norton, "A Washington Copper Deposit," Eng. and Min. Jour., February 11, 1899, 173. COPPER. 223 and chalcocite in contact deposits in Triassic and Permian sandstones at their junction with diabase or gneiss, or as dis- seminated masses replacing organic remains. • Copper ores are very common throughout the estuary Triassic rocks of the Atlantic coast, and although formerly much mined, they are 'now proved valueless, and of scientific interest only. 2.04.31. Example 21a. Contact deposits in sandstone at its junction with diabase. These include the New Jersey ores, vigorously worked before the Revolution. They consist of the carbonates, of cuprite and of native copper, disseminated through sandstone near the trap. The Schuyler mines, near Arlington, N. J., and several other openings near New Brunswick, N. J., are best known. These Triassic diabases often show chalcopy- FiG. 14:.— Gross section of the Schuyler Copper mine, New Jersey, a, trap; b. sandstone; e, shales; the black shading, copper ores. After N. H. Barton, U. S. Geol. Survey, Bull. 67, p. 57. rite, and it is probable that the copper came from this or from copper in the augite of the rock, in accordance with Sand- berger's investigations. The deposits are unreliable, and ex- cept at a very early period have never been an important source of ore. 2.04.32. Example 216. Contact deposits in sandstones at the junction with gneiss. A number of deposits were formerly worked of this character, especially at Bristol, Conn.', and at the Perkiomen mine, Pennsylvania. The mine at Bristol, Conn., is a well-marked contact deposit, on the line between the Triassic sandstone and the schistose rocks. The contact runs northeast and southwest, has suffered great decomposi- 224 KEMP'S ORE DEPOSITS. tion from mineral solutions, and has been largely kaolinized. A broad band of this decomposed material, 30 to 120 feet wide, lies next the sandstone, and contains disseminated ore. Then follow micaceous and hornbl^de slates, often with horses of gneiss. The slates are mucJTbroken by movements that have formed cavities for the ores. It is reasonable to connect the stimulation of the ore currents with the neighboring trap out- breaks. Unusually fine crystals of chalcocite and barite have made the mine famous the world over. While at one time a source of copper, for many years it has been unproductive.^ 2.04.33. Example 21c. Chalcocite and copper carbonates replacing vegetable remains, etc., in the Permian or Triassic sandstones of Texas, New Mexico, and Utah. In the Permian of northern central Texas are three separate copper- bearing zones, forming three lines of outcrop that extend in a general northeasterly direction over a range of about three counties. The ore is largely chalcocite in beds of shale, and often re- places fragments of wood. It may be available in time.^ At various places in Utah and New Mexico (Abiquiu, N. M., Silver Reef, Utah), the sandstones, as reported by Newberry and others, have copper ores disseminated through them and deposited on fossils, at times with associated silver (Utah). The copper, whether coming from the waters along the shore line or from subterranean currents, was precipitated by the organic matter. (See also under *' Silver," in Utah.) These deposits are not yet sources of copper.^ ^ L. C. Beck, "Notice of the Native Copper Ores, Copper, etc., near New Brunswick, N. J.," Anier. Jour. Sci., l, XXXVI., 107. G. H. Cook, Geol. of N. J., 1868, p. 675; also L. C. Beck, Ibid., 218-224. J. G. Perci- val, Rep. on Geol. of Conn., p. 77. C. A. Shaeffer, "Native Silver in New Jersey Copper Ore," Eiig. and Min. Jour., February, 1882, p. 90. C. U. Shepard, Geol. of Conn., 1837, p. 47. B. Silliman and J. D. Whitney, ' ' Notice of the Geological Position and Character of the Copper Mine at Bristol, Conn.," Amer. Jour. Sci., ii., XX., 361. J. D. Whitney, Metallic Wealth. Rec. ^ W. F. Cummins, "Report on the Permian of Texas and its Overlying Beds," First Ann. Rep. Texas Geol. Survey, p. 196. J. F. Furman, " Geology of the Copper Region of Northern Texas and Indian Territory," Trans. N. Y. Acad. Sci., 1881-83, p. 15. ' F. M. F. Cazin, " The Origin of the Copper and Silver Ores in Triassic Sand Rock," Eng. and Min. Jour., April 30, 1880; December 11, 1880, 331. "The Nacemiento Copper Deposits," Ibid., August 22, 1885, p. 124. A. COPPER. 225 2.04.34. Copper production in 1882, 1890 and 1897, in tons of 2,000 pounds each: 1882. 1890. 1897. Lake Superior 28, 578 50, 372 72, 920 Montana _.. 4,529 56,490 118,579 Arizona.......... 8,992 17,398 40,510 Colorado 747 441 4,719 New Mexico. .. ., oo. 434 ' 425 California..... .„.„...... 413 11 7,065 Utah 303 1 503 1,927 Elsewhere 1,412 3,906 2,874 Copper sulphate . 6,501 45,408 129,546 255,095 The figures indicate in general a vast increase in production, and, above all, the advance of Montana. For detailed statis- tics The Mineral Industry, issued annually by the Scientific Publishing Company, New York, and the Annual Reports of the Director of the U. S. Geological Survey are the chief books of reference. W. Jackson, Rep. Director of the Mint, 1880, p. 334. J. S. Newberry, " Copper in Utah, Triassic Sandstones," Eng. and Min. Jour., Vol. XXXI., p. 5. Also October 23, 1880, p. 269; January 1, 1881, p. 4. See also Tenth Census, Vol. XIII., Precious Metals, pp. 40, 478. C. M. Rolker, "The Sil- ver Sandstone District of Utah," Trans. Amer. Inst. Min. Eng., IX., 21. R. P. Roth well, quoted in Tenth Census, Vol. XIII., p. 478. B. Silliman, "The Mineral Regions of Southern New Mexico," Trans. Amer. Inst. Min. Eng., XVI., 427. CHAPTER V. LEAD ALONE. 2.05.01. The deposits of lead are treated in three different classes, according as they produce or have produced lead alone, lead and zinc, or lead and silver. Of late years the lead-silver ores have been the gjyftt source of the metal. Only the southeast Missouri region is of much importance among the others, although considerable lead is also obtained in associa- tion v^ith zinc. LEAD SERIES. Ph. S. Galena, PbS 86.6 13.4 Cerussite, PbCO., 77. 5 Anglesite, PbSO^ 68.3 .... Pyromorphite, Pb3P208+l/3PbCl2. 76.36 Earthy mixtures of these last three and limonite. 2.05.02. Example 22. Atlantic border. Veins of galena in the Archean rocks of the States along the Atlantic border ; also others in Paleozoic strata, as described in the sub- examples. 2.05.03. Example 22a. Veins in gneiss and crystalline lime- stone, sometimes with a bariteor calcite gangue. These depos- its were vigorously exploited forty years ago or more, but have since been of small importance other than scientific. They may be described best by districts, as they hardly deserve a greater prominence. 2.05.04. (1) St. Lawrence County, New York. Veins with galena in a gangue of calcite in Archean gneiss. Those near Rossie are perhaps best known, especially for their unusually interesting calcite crystals. There are numbers of veins in the district which are notable in that the galena is without zinc or iron associates. The lead carries a verv small amount of silver. LEAD ALONE. 227 not enough to separate. Hornblende and mica schists occur in the same region, and the Potsdam sandstone is not far removed. A few minor veins cut the Trenton limestone near Lowville, Lewis County, sometimes with fluorite for a gangue/ 2.05.05. (2) Massachusetts, Connecticut and eastern New York Veins of galena with more or less chalcopyrite and pyrite in a quartz gangue in gneiss, slates, limestones or mica schists. The mines near Northampton, Mass., w^ere formerly well known, although never productive of a great deal of metal; but as there is a large, prominent vein, it attracted attention. There are numerous others in the same region. Veins also occur at Middletown, Conn., where much silver is said to be found in the galena. More recently (circa 1873) at Newburyport, Mass., argentiferous galena attracted attention, but was not of any importance. Other veins are known at Lubeck, Me., and in various parts of New Hampshire and Vermont. For a time small lodes in the slates of Columbia County, New York, were unsuccessfully exploited, of which the Aocram mine is of historic interest. Although these galena veins are numerous, they are not to be taken too seriously.^ 2.05.06. (3) Southeastern Pennsylvania. Veins on the contact of Archean gneiss and Triassic sandstone and diabase. These were referred to under Example 216. As noted by Whit- ney, the copper is especially strong in the sandstone, and the lead in the gneiss. Trap dikes are abundant, and the eruptive phenomena in connection with them may have occasioned the activity of the circulations which filled the veins. The Wheat- ley mine is best known. It has afforded a great variety of lead ^ L. C. Beck, Mineralogy of New York, p. 45. E. Emmons, "Geology of the Second District," N Y. Geol Survey, 1842. G. Hadley, "Crystal- lized Carbonate of Lead at Rossie," Amer. Jour. Sei., ii., II., 117. F. L. Nason, " Calcite from Rossie," Bull. 4, N Y. State Museum, 1888. J. D, Whitney, Metallic Wealth. Rec. ^ B. K. Emerson, Geology of old Hampshire Co., Mass., comprising Franklin, Hampshire and Hampden counties. Monograph XXIX, U. S. Geol. Survey. See also Bulletin 1^6. — Idem. C. A. Lee, "Notice of the Ancram Lead Mine," Amer. Jour. Sci., i., VIII., 247. A. Nash, "Notice of the Lead Mines and Veins in Hampshire County, Massachusetts," Amer. Jour. Sci., i., XIL, 238. R. H. Richards, "The Newburyport Silver Mines," Trans. Amer. Inst. Min. Erig., HI., 443. B. Silliman, at South ampton, Mass Bruce' s Journal of Mineralogy, I., 65. J. D. Whitney, Metallic Wealth. 228 KEMP'S ORE DEPOSITS. minerals, especially pyromorphite. The mines have not been worked in years/ 2.05.07. (4) Davison County, North Carolina. Veins in talcose slate were formerly exploited, but are now little known, except as having furnished beautiful crystals of oxidized lead minerals.^ 2.05.08. Example 226. Sullivan and Ulster Counties, New York. Veins along a Lne of displacement on the contact between the Hudson River slates and the sandstones of the Me- dina stage (Shawangunk grit), carrying galena and chalcopy- rite in a quartz gangue; or else gash veins filled with the same in the grit. These mines formerly produced considerable lead and copper, but are now best known for the excellent quartz crystals which they have furnished to all the mineralogical col- lections of this and other lands.^ 2.05.09. Example 23. The Disseminated Lead Ores of Southeast Missouri. Gal*^na, accompanied by varying amounts of nickeliferous pyrite, disseminated through dolomitic lime- stone of Lower Silurian or Cambrian age, its determination be- ing in dispute. The dolomitic limestone is called the St. Jo- seph limestone by Arthur Winslow,* who considers it Lower Silurian. C. R. Keyes^ has designated it the Fredericktown, and classifies it with the Cambrian. As shown in the accom- panying map, which is based on one by Winslow, the mining districts ai^distributed along a line running west of north. At the nortj is Bonne Terre, the most productive of all up to the present. A few miles south is the Flat River district, in- cluding Desloge. The next is Doe Run, and then after a con- siderable interval Mine la Motte.. Recently prospects have been opened near Fredericktown. Much drilling has been done between these centers, but without notable results. The geo- logical relations are simple. On the south and southwest are ^ H. D. Rogers, Geol. of Penn., II., 701; also ^mer. Jour. Sci., ii., XVI., 422. J. D. Whitney, Metallic Wealth, p. 396. ^ J. C. Booth, "Analyses of Various Ores of Lead, etc., from King's Mine, Davison County, North Carolina," Amer. Jour. Sci., i., XLI., 348. W. C. Kerr, Geol. of North Carolina, p. 289. " J. D. Whitney, Metallic Wealth. W. W. Mather, N. Y. State Survey, Report on First District, 358. * Bull 133, U. S. Geol. Survey, p. 11. '' "Mine la Motte Sheet," in 3Io. Geol. Survey, Vol. IX., Report 4, p. 48. LEAD ALONE. 229 the Archean granites, porphyries and diabase dikes, earlier mentioned in connection with the specular hematites of Iron Mountain and Pilot Knob. Scattered knobs of them are also GEOLOGICAL MAP OF THE Frcdeh ViUageX SOITHEASTERN MISSOURI >i\DISSEJlINATED LEAD ORE SIB-DISTRICT From a Colored Map by Arthur Winslow 1895. In Bulletin 132 U.S. Geol. Survey Potosi Limestone „^^^' j^3 St.Joseph Silurian -|^^ Limestone ^Cambrian?)! Fig. 75. met to the eastward. On the granites and porphyries rests the La Motte sandstone, of variable thickness, but possibly reach- ing 400 feet, according to Winslow. Conformably on the sand- 230 KEMP'S ORE DEPOSITS. stone lies the St. Joseph dolomitic limestone, the ore-bearing formation. It varies from 200 feet at Mine la Motte to 600 feet at Bonne Terre. It varies from shaly to massive'struct- nres, and is often coarsely granular in texture. In rock of the latter character, and, in the southern districts, usually not far above the sandstone, is found tha ore. At Bonne Terre, however, the ore is a long distance above the base. The ore is galena, often mingled with more or less pyrites, and as a rule it is disseminated through the limestone so as to form an inte- gral part of the rock. It also forms sheets sometimes along joints and stratification planes, and seems to favor the darker or more bituminous varieties of the dolomite. At Mine la Motte certain *' diggings" or mines seem to have some connec- tion with a local fault, but others do not indicate such rela- tions, and elsewhere small fissures, or joints, often so tight as only to be revealed by the dropping of water, are the only cracks of an}^ kind apparent. The St. Joseph formation lies very flat, and is practically devoid of fossils. Above it comes a cherty limestone, called the Potosi by Winslow (Leseur by Keyes). It is widespread, but has no immediate connection with the ore. The ore bodies are in the nature of impregnations of the wall rock which extend fairly parallel with the stratification and are of varying thickness. They fade out gradually into low grade or barren rock. They may be cut at several horizons by the shafts or drill holes. One at Bonne Terre has been mined, according to Winslow, over an area nearly three-quarters by one half of a mile, and ore is known through almost 250 feet vertical thickness. The yield to date has been about a quarter of a million tons of lead. Throughout the districts the shafts are not deep, seldom reaching 400 feet. The ore as mined con- tains from 7 to 10 per cent, galena, although blocks of over a ton of the pure sulphide have been taken out. The formation of these ore bodies is a very obscure question. The writer in 1887 applied to them the views that had been early advanced by Whitney for the gash veins of the Upper Mississippi, namely, that decaying marine vegetation had pre- cipitated the sulphides from sea water. This is very doubtful, as traces of algae, or any other fossils, are extremely rare. W. P. Jenney in 1893 referred them to solutions uprising along LEAD ALONE. 231 faults, which were thought to cut the ore bodies, and from which the mineralizing waters had spread laterally through the porous beds. The fault at Mine la Motte along which the ore occurs has been earlier cited as giving some support to this view, although right at the fault the ore bodies tend to grow lean. Elsewhere faults are insignificant so far as known. Winslow favors the descent of solutions from above, and thinks that the sulphides have been supplied by the weathering of overlying strata, now in large part removed. These regions have been land since the early Carboniferous times, and the superficial decay has been enormous. Lead- bearing solutions, it is thought, have filtered downward through the joints, faults and small cracks, and have deposited their dissolved materials by replacement of the limestone. The conduits seem, how- ever, insignificant when compared with the ore bodies, and it is evident that all the explanations thus far suggested involve difficulties. In the Mississippi Valley in this portion of the country the Lower Carboniferous and earlier rocks contain lead over an area of more than 3,000 square miles. Aside from these dis- seminated ores, zinc is always associated with the lead ; but in southeastern Missouri it is practically unknown in the depos- its of the disseminated type. There are, however, in the neigh- boring districts several mines, such as the Valle, which are closely analogous to the gash veins later described, and which do contain zincblende. The history of Mine la Motte dates back to the early part of the eighteenth century, when this region figured largely in John Law's Mississippi bubble. The mine is said to have furnished lead for bullets during the war of the Revolution.^ ^ A bibliography of the lead and zinc regions of Missouri, by Arthur Winslow, will be found in the Reports of the Missouri Geol. Survey, VII. , Part II., p. 743. It conies down to 1894. A bibliography of Missouri geology in general was prepared by F. A. Sampson and issued as Bulletin 2 of the Mo. Geol. Survey, in 1890. A revised edition by C. R. Keyes appears in Vol. X., of the Survey, p. 221, and comes down to 1896. The more important or the more recent papers are given below: G. C. Broad- head, ' The Southeastern Missouri Lead District," Trans. Amer. Inst. Min. Eng., v., 100. Rec. J. R. Gage, " Occurrence of Lead Ores in Missouri," Idem, III., 116; also Geol. Survey of Missouri, 1873-74, pp. 30, 603. W. P. Jenney, "The Lead and Zinc Deposits of the Mississippi Valley," Irans. Amer. Inst. Min. Eng., XXII., 171, 621, 1893. J. F. Kemp, "Notes on the 232 KEMP'S ORE DEPOSITS. 2.05.10. The great increase in lead production in the United States came about 1880, with the opening of the Leadville ore bodies. From 1877 until 1881 Eureka, Nev., was an important source, but since then it has greatly declined. Utah has pre- served a fairly uniform production since the early seventies. Lead from all sources is here mentioned, although lead- silver ores are subsequently treated. The amounts are in tons of 2,000 pounds. For detailed statistics see the annual volume on The Mineral Industry (New York: Scientific Publishing Companj^ and the Annual Reports o^ the Director of the U. S. Geological Survey. The figures for 1896 are taken from the Eighteenth Annual Report, Part V., p. 240. Missouri, Kansas, Wisconsin, lUinois 27,690 55,000 51,887 Colorado 35,674 60,000 44,803 Nevada 16,659 2,500 1,173 Utah „ 15,000 24,000 85,578 Idaho, Montana 24,000 57,732 Elsewhere 2,802 15,994 6,323 97,825 181,494 197,496 From 80 to 85% of the tota l product is from lead-silver ores. Ore Deposits, etc., of Southeastern Missouri," aS'c/ioo? o/iUfmes Quarterly, October, 1887,74; April, 1888, 212. C. R. Keyes, " The Mine la Motte Sheet," Geol. Survey of Missouri, IX., Report 4, 1896. A. Litton, Second Ann. Rep. of the First Geol. Survey of Mo., 12-64, 1854. James E. Mills, Report on the Mine la Mo tie Estate, New York, 1877. H. S. Munroe, "The New Dressing Works of the St. Joseph Lead Co., at Bonne Terre, Mo.," Tran^. Amer. Inst. Min.Eng., XVII., 659, 1888. J. W. Neill, "Notes on the Treatment of Nickel-Cobalt Mattes at Mine la Motte, " Idem, XIII. , 634. F. Posepny, *'0n Mine la Motte," Genesis of Ore Deposits, p. 107; Trans. Amer. Inst. Min. Eng., XXIII., 303, 1893. H. A. Wheeler. "On Southeast Missouri Lead Mines, The Colliery Engineer, 1892. C. P. Williams, "Industrial Report on Lead, Zinc and Iron in Missouri," Jefferson City, 1877. Arthur Winslow, "Lead and Zinc Deposits of Missouri," 2 vols., Missouri Geol. Survey, VII., Parts I. and II., 1894. A very complete book on lead and zinc in general. Fairly complete bibli- ography. Part II. , p. 743. A fuller one by F. A. Sampson will be found in Bulletin 2 of the Mo. Geol. Survey, 1890. Arthur Winslow, "Lead and Zinc Deposits of Missouri," Trans. Amer. Inst. Min. Eng., XXIV., 634, 931, 1894. ' * Notes on the Lead and Zinc Deposits of the Mississippi Valley and the Origin of the Ores," Jour. Geol, L, 612, 1893. "Report on the Iron Mountain Sheet," Mo. Geol. Survey, IX., Report 3, p. 32, relates to Doe Run. " The Disseminated Lead Ores of Southeastern Missouri," Bid- letin 132, U. S. Geol. Survey, 1896. Rec. The best brief account, "His- torical Sketch of Lead and Zinc," Eng. and Min. Jour., November 17, 24, 1894; January 19, 1895. CHAPTER VI. LEAD AND ZINCo 2.06.01. Example 24. The Upper Mississippi Valley. Gash veins and horizontal cavities (flats), principally in the Galena and Trenton limestones of the Upper Mississippi Val- ley, and containing galena, zincblende, and pyrite (or marca- site), with calcite, barite, and residual clay. The deposits are found in southwest Wisconsin, eastern Iowa, and northwestern Illinois. The greater portion of the productive territory lies in Wisconsin, and covers an area which would be included in a circle of sixty miles radius, whose limits would pass a few miles into Illinois and Iowa. A low north and south geanti- cline runs through central Wisconsin, dating back to Arche- an times and called by Chamberlin *' Wisconsin Island." On its western slope the Cambrian and Lower Silurian rocks are laid down, and these in the western limit of the lead dis- trict pass in the adjoining States under the Upper Silurian. They are folded also in low east and west folds, but in the aggre- gate the whole series dips very gradually westward. The chief east and west fold forms the south bank of the Wisconsin River, and may have been the cause that deflected it from a southerly course. The easterly part of the lead region is 350 feet higher than the western, and the northern is 500 feet above the southern. The general slope is thus southwesterly. 2.06.02. The Galena limestone is a dolomite reaching 250 feet in thickness. On the hilltops left by erosion Maquekota (Hud- son River) shales are seen. The Galena has shaly streaks, which have largely furnished the residual clay of the cavities. There are also cherty layers and sandy spots. Under the Ga- lena lies the Trenton, from 40 to 100 feet thick, and made up of an upper blue portion, which is a pure carbonate of lime, 23i KEMP'S ORE DEPOSITS. and a lower bnff portion that is magnesian. The upper portion of the blue has a band of shale locally called the " Upper Pipe Clay," and the pure, cpyptocrystalline limestone under this is called *'Glass Rock." The blue contains much bituminous matter. The buff is locally called *' Quarry Rock," and is prolific in fossils. Under the Trenton lies the St. Peter's sand- stone, 150 feet below which is the Lower Magnesian (Oneota), 100 to 250 feet, and still lower the Potsdam, averaging 700 to 800 feet. The Potsdam rests on the quartzites and schists of the Archean. The ore bodies especially favor the shallow, syn- ^^SPSs^^^s '-^:!^ji^» :-^iii^ ■ Fig. 76. — Gash veins, fresh and disintegrated. The heavy black shading in- dicates galena. After T. C. Chainberlin, OeoL Wis., Vol. IV., 454. clinal depressions of the east and west folds. They occur in crevices, the great majority of which run east and west. The productive ground comes in spots, which are separated by stretches of barren ground. The lead ores are chiefly produced by the crevices in the Upper Galena. In the Lower Galena the zinc ores become relatively more abundant, and they are also in the Trenton. The ores do not extend in any apprecia- ble amounts either above or below these horizons. The upper deposits favor the vertical gash vein form ; the lower tend rather to horizontal openings, called flats, which at the ends 1 LEAD AND ZINC. 2;J5 dip down (pitches) and often connect with a second sheet (flat) lying lower. There are several minor varieties of those tw6 main types of cavity, which mainly depend for their differences on the grade of decomposition, which the walls have under- gone, and whether there was an original opening, or only a brecciated and crushed strip. Chamberliu cites twelve varie- ties in •^.11, some of which are based on rather fine distinctions. A. G. Leonard has described a sheet of galena, at the Lansing mine, in Iowa, that was three to four inches thick, 25 to 35 feet high, and over 1,000 feet long. Some of the Iowa crevices have proved remarkably persistent on the strike. H. F. Bain has called the writer's attention to the Lansing mine in Allamakee, Iowa, which has yielded lead ore without any zinc whatever, Fig. 77. — Idealized section of ''flats and pitches,'' forms of ore bodies in Wis- consin. After T. C. Chamherlin, Geol. Wis., Vol. IV., 458. and which is peculiar in that it occurs in the Oneota or Lower Magnesian limestone, and is therefore below the main product- ive horizon of the gash veins. The crevice also trends north and south as against the usual east and west strike of the gash veins. 2.06.03. The cavities were referred by J. D. Whitney to joints, formed either by the drying and consolidating of the rock, or by gentle oscillations of the inclosing beds. The later work has largely corroborated this, and they are generally thought to be chiefly caused by the cracks and partings formed by the gentle synclinal foldings. Such cavities have usually been enlarged by subsequent alteration of the walls. Whitney 236 KEMP'S ORE DEPOSITS. also esseotially outlined the explanation of origin, which ha» been more fully elaborated by Chamberlin. Both these writ- ers have urged that the ores could not have come from below, for the lower rocks are substantially barren of them. The con- clusion therefore follows that they were deposited in the lime- stones at the time of their formation. The source of the ores is placed in the early Silurian sea, from which it is thought they were precipitated by sulphuretted hydrogen, exhaled by decay- ing seaweeds, or similar dead organisms on the bottom. In carrying the idea further, Chamberlin has endeavored to re- produce the topography of the region in the Lower Silurian times and to indicate the probable oceanic currents. These are conceived to have made an eddy in the lead district, and to have collected there masses of seaweed, etc., resembling the Sargasso Sea. While interesting, this must be considered very hypothetical. When the sulphides became precipitated they were doubtless finely disseminated in the rock, and were gradually segregated in the crevices. The sulphurous exhala- tions from the bituminous limestones may have aided in their second precipitation. W. P. Jenney in 1893 referred the east and west fissures, mentioned above as crevices, to fiaults, which are as a rule not far from the vertical, but may dip 35^ to 40°. The smaller north and south series are considered to be likewise due to faulting, but to be earlier, as they are thrown by the east and west set. The displacement from the latter is horizontal rather than vertical. The intersections of the two sets are said to be especially favorable to ore bodies. The name **run" is applied to the ore body, it having been adopted from southwest Missouri. The ore is thought to have been deposited along the fault fissures by uprising solutions, which have spread laterally into those beds, that, from their chemical composition (being dolomitic) or their open structure, were fa- vorable to them. In the same year (1893), W. P. Blake discussed these ore bodies, paying a tribute to Percival's early views on faulting as a cause of the veins, and describing its obscurity and the difficulty of demonstrating its presence. Blake, however, cited the Helena mine near ShuUsburg as an instance in which the mineralization did occur near a pair of faults. Blake also lays stress upon the presence of thin seams of rich bituminous LEAD AND ZINC. 237 «hale, ID layers usually about as thick as cardboard, which occur in a richly fossiliferous limestone at the top of the Trenton, just beneath the ore- bearing '* Galena" dolomite, and which are regarded as very probable factors in the precipita- tion of the ore. The mining region, it should be emphasized, lies within the peculiar, unglaciated area, which is one of the notable geologi- cal features of this portion of the country. It has, therefore, long been exposed to the atmospheric agents, and has not been denuded of the residual products of decay as have the glaciated districts. The papers of Jenney and Blake led to a notable discussion of these ore bodies, and to wide divergence of views regarding them. Arthur Winslow, in connection with his more extended treatment of those in Missouri, has urged that the sulphides have been supplied from the overlying strata, during the exten- sive, subaerial decay to which these have been subjected. Pass- ing into solution they are thought to have percolated into the crevices and to have been precipitated. A. G. Leonard, in his study of the Iowa veins, reaches a similar conclusion, but on account of the impermeability of the Maquekota shales, restricts the source of the ore to the Galena dolomite. The frequent occurrence of the ores in stalactites projecting downward from the roof of a chamber gives support to these views. Leonard favors Chamberlin's view of the precipitation from a sup- posed Sargasso Sea of the Ordovican times. The paragenesis of the minerals shows the following suc- cession: (1) Pyrite, (2) Galena, (3) Pyrite; or (1) Pyrite, (2) Blende, (3) Galena, (4) Pyrite; or (4) Calcite. The ores, espe- cially of zinc, are often oxidized, and afford considerable cala- mine and smithsonite. Some oxidized copper ores are produced at Mineral Point, formed by the alteration of chalcopyrite. In the early mines lead alone was sought, but of late years the zinc has been produced in greater quantities, and is more valu- able than the lead.^ Smithsonite is found in commercial quan- tities as well as blende. ' Wisconsin.— J. A. Allen, "Description of Fossil Bones of Wolf and Deer from Lead Veins.", Amer. Jour. Sci., iii., II., 47. W. P. Blake, "The Mineral Deposits of Southwest Wisconsin," Trans. Amer. Inst. Min. Eng., XXII., 558, 1893. Rec. Amer. Geol, XII., 237, 1893. "The Ex- 238 KEMP'S ORE DEPOSITS, 2.06.04. Example 24a. WashiDgton County, Missouri, Gash veins in the Potosi cherty limestone of eastern Missouri in the same region as the disseminated ores of Example 23, and containing galena, barite (locally called "tiff"), calcite, and residual clay. The cavities are described by Whitney as re- sembling in all respects the gash veins further north, which, however, lie in rocks higher in the geological series. These mines were the earliest worked, but have been given up since the istence of Faults and Dislocations in the Lead and Zinc Regions of the Mississippi Valley, with Observations upon the Genesis of the Ores," Idem, 621. Rec. This last paper was written in discussion of one by W. P. Jenney, cited below. "Wisconsin Lead and Zinc Deposits, " Bull. Geol. Soc. Amer., V., 25, 1893. "Progress of Geological Surveys in the State of Wisconsin — a Review and a Bibliography,' Trans. Wis. Acad. Sci., IX., 325. T. C. Chamberlin, Wis. Geol. Survey, IV., 1882, p. 367. Rec. E. Daniels, " Geology of the Lead Mines of Wisconsin," Amer. Asso. Adv. Sci., VII., 290; Wis. Geol. Survey, 1854; Eng. and Min. Jour., July 6, 13, 20, 27, August 3, 10, 24, October 5, 1878, December 14, 1889, 522. James Hall, "Notes on the Geology of the Western States," Amer. Jour. Sci., i., XLII., 51. W. H. Hobbs, "A Contribution to the Mineralogy of Wiscon- sin," Bull. Univ. of Wis., Science Series I., 114; see sdso Zeitsch. fiir Kryst., XXV., 257, 1895. J. T. Hodge. "On the Wisconsin and Missouri Lead Region," Amer. Jour. Sci., i., XLIII., 35. R. D. Irving, "Mineral Re- sources of Wisconsin," Trans. Amer. Inst. Min. Eng., VIII., 478. E. James, "Remarks on the Limestones of the Mississippi Valley Lead Mines," Phila. Acad. Sci., V., Part I., p. 51. W. P. Jenney, "The Lead and Zinc Deposits of the Mississippi Valley," Trans. Amer. Inst. Min. Eng., XXII., 171, 621, 1893. Rec. J. Murrish, Report on the Lead Regions, 1871, as commissioner for their survey. D. D. Owen, "Report on the Lead Region," U. S. Senate Documents, 1844. J. G. Percival, Wis. Geol. Sur- vey, 1856. Squier and Davis, ''HistoricaX Account," Smithsonian Contri- butions, Vol. I., p. 208. M. Strong, Wis. Geol. Survey, 1877, I., 637; II., 645, 689. J. D. Whitney, Wis. Geol. Survey, 1861-62, I., 221. Rec. Me- tallic Wealth, p. 403, 1856. "On the Occurrence of Bones and Teeth in the Lead- bearing Crevices," Amer. Assoc. Adv. Sci., 1859. Arthur Wins- low, "Lead and Zinc Deposits of Missouri," Trans. Amer. Inst. 3Iin. Eng., XXIV., especially 677-690, 1894. See also Vol. VI. of Geol. Survey of Mo., 135-150, 1894. Illinois.— J. Shaw, Geol. Survey of Illinois, 1873, II., 340. J. D. Whitney, Idem, 1866, I., 153. Iowa. — A. G. Leonard, "Lead and Zinc Deposits of Iowa," Iowa Geol. Survey, VI., 1896. Rec. " Origin of the Iowa Lead and Zinc Deposits," Amer. Geol, XVI., 288, 1895; Eng. and Min. Jour., June 27, 1896, 614; Colliery Engineer, XVII., 121, 1896. C. A. White, Iowa Geol. Survey, 1870. II., p 339. J. D. Whitney, Idem, 1858, L, p. 422. LEAD AND ZING. 239 price of lead has been at present figures (1875 and subse- quently). The ore was obtained from pockets, caves, irregular cavities, and from the overlying residual clays. This whole region has been exposed and above water since the close of Carboniferous times, and has suffered enormous surface decay (seeR. Pumpelly, Tenth Census, Vol. XV., p. 12, and Geol. Soc. Amer., Vol. II., p. 20), which has left a mantle of residual clay spread widely over its extent. In this, more or less float mineral occurred. The mines were located in Washington, Franklin, Jefferson and St. Francois counties.^ Very similar deposits in rocks of about the same geological horizon also occur in the central part of the State, in the counties near the Osage River. The district has been called the Central by Winslow. 2.06.05. Example 246. Livingston County, Kentucky. Veins in limestone of the St. Louis stage of the Lower Carbon- iferous, containing galena in a gangue of fluorite, calcite and clay. The ore bodies have never been well described, and no very accurate account can be given. They are found in Liv ingston, Crittenden, and Caldwell counties, Kentucky, in that portion of the State lying south of the Ohio River and east of the Cumberland. While limestone always forms one wall, a sandstone of geological relations not well determined forms the other. The veins run frorn two to seven feet wide and in in- stances are richer in their upper portions than in the lower. As yet they are of greater scientific than practical importance. Some galena occurs also in irregular cracks in the limestone. As a possible indication of a stimulating cause for the forma- tion of the veins, the interesting dike of mica-peridotite may be cited, which has been described by J. S. Diller.^ The dike occurs in the same fissure with a vein of fluorspar.^ ^ Compare the older references under Example 23, and the following: A. Litton, Second Ann. Rep. Missouri Geol Survey, 1854. J. D. Whitney, Metallic Wealth, p. 419. Arthur Winslow, "Lead and Zinc Deposits of Missouri," Vols. VI. and VII. of Mo. Geol. Survey; Trans. Amer. Inst. Min. Eng., XXIV., 634. ^ "Mica-Peridotite from Kentucky," Amer. Jour. Sci., October, 1892. ^ S. F. Emmons, "Fluorspar Deposits of Southern Illinois," Tran^. Amer. Inst. Min. Eng., February, 1892. C. J. Norwood, "Report on the Lead Region of Livingston, Crittenden and Qaldwell Counties," Ken- tucky Geol. Survey, 1875, New Series, Vol. I., p 449. 240 KEMP'S ORE DEPOSITS. 2.06.06. Example 25. Southwest Missouri. Zincbleude and very subordinate galena with their oxidized products, asso- ciated with chert, residual clay, calcite, a little pyrite and bitu- men, in cavities of irregular shape and in shattered portions of Subcarboniferous limestone. Across Missouri, from a point south of St. Louis, and including the country as far to the northwest as Sedalia and Glasgow, a broad belt, called the Ozark uplift, extends southwesterly into Arkansas. It has formed a great plateau in central and southern Missouri, and consists largely of Silurian rocks. These have a fringe of Devonian on the edges and dip under the Lower Carboniferous. The plateau reaches 1,500 feet above the sea in Wright County, but on the limit is succeeded by lower country. To the southwest it drops somewhat, with Lower Carboniferous strata outcropping, which in Kansas are overlain by the coal measures. The surface then rises again in the prairies. At the edge of the plateau is a trough, in whose bottom the Lower Carbonifer- ous strata are cut by the Spring River, which flows southwest- erly from Missouri across the western State line into Kansas, and has a general direction parallel to the western limits of the uplift. It receives tributary streams on each bank, which cut the strata in strongly marked valleys, and afford good expo- sures. Those on the east bank, from south to north, are Shoal Creek, Short Creek, Turkey Creek and Center Creek, while from the west come the Brush, Shawnee, and Cow creeks, all in Kansas. Along the first mentioned creeks the principal mining towns are situated, but others are found on the minor streams. They extend through an area fifteen miles broad from east to west, and twenty-five miles from north to south. Newton and Jasper are the most productive counties in Mis- souri, while Cherokee County, in Kansas, also contains nota- ble mines. Undeveloped districts are recorded in Arkansas, but apparently at a lower geological horizon. The ore occurs in the Keokuk or Archimedes limestone of the Lower Carbonif- erous. A generalized section of the rocks, according to F. L. Clerc, is as follows : On the higher prairie, some 15 feet of clay or gravel; 10 feet of flint or chert beds; 40 feet of lime- stone with thin beds of chert; 60 feet of alternating layers of limestone and chert; 100 feet and more of chert, sometimes chalky with occasional beds of limestone; 225 feet in total. In LEAD AND ZINC. 241 basiDS and extensive pockets in these rooks, deposits of slates with small coal seams are found, of undetermined geological relations. The large bed of limestone of the section affords a datum of reference in relation to which the ores xm.y be de- P. % } •0 % : S i c a 1 § 3%Found Ore . f^ f 8% " " 75% Found 40 to 80 ft.LeaQ & No Ore No Pro CO"/$Found Ore No Ore 60deposit. •p^*^*' Flint rocK "^^^inc'blende ore-bodie» rf-i^ -it & Flint rock Worked out part of ore-deposit. -^ - f — ^te- Galenite ia fissures & bedding-planes injlmestone Fig. 79. — Vertical section of a typical zincUende ore body, near Webb City, Mo. After C. Henrich, Irans. Amer. Inst. Min. Eng., XX., p. 14. elusions have been controverted by others, on account of the difficulty in proving the existence of fauJts when evidence of displacement is so obscure. In Jenney's paper all the lead or lead and zinc regions of the Mississippi Valley are considered together. They are described as occurring along three lines of upheaval. The region of Wisconsin and Iowa is on the flanks of the Archean "Wisconsin Island" of Chamberlin, re- ferred to above under 2.00.01. The southeast and southwest 244 KEMP'S ORE DEPOSITS. Missouri regions are on the Ozark uplift, while a minor argen- tiferous galena district is on the line of the Ouachita uplift of Arkansas and Indian Territory. The formation of the ore bod- ies in the first three of these is regarded as having been in gen- eral the same. They are thought to have originated from up- rising solutions, which came through certain principal fissures, and spread laterally into strata favorable to precipitation. In southwest Missouri this was the Cherokee limestone of the Lower Carboniferous. In its unaltered state it is an extremely pure carbonate of lime. It has a maximum thickness, where not eroded, of 165 to 200 feet, and contains many interbedded layers of chert. Much organic matter, and more or less bitu- men, are also at times present. The limestone seems to have been raised above the ocean level at the close of the Lower Carboniferous, and to have remained for a long period exposed to the atmospheric agents. Much caving in of unsupported layers of chert and much attendant brecciation resulted. The general stratum became quite open and cellular in certain portions. At a later period, supposed from several indications to be at the close of the Cretaceous, dynamic disturbance oc- curred, which along certain lines produced fissures, sometimes parallel, sometimes intersecting. Solutions arose through these which dolomitized much of the remaining limestone and caused additional porosity. Zinc and lead ores were afforded, and where the conditions were favorable they spread laterally from the fissures and deposited the sulphides in the cellular rock or replaced the limestone itself. The intersection of crossing fis- sures is a frequent point of deposition, and at times parallel master fissures have given a wide area of impregnation. This form of ore deposit is called a run. The runs are from 5 to 50 feet in height, 100 to 300 feet long, and 10 to 50 feet across. At Webb City ih^y are even larger. As a general thing the ore is in the interstices of the brecciated chert, but it is also in limestone and dolomite, and associated with a silicified form of the insoluble residue left bj^ the solution of the limestone, which Jenney calls "cherokite." All the ores require con- centration. Galena usually occurs near the surface, while blende is more abundant in depth. Cadmium is at times pres- ent in the blende in notable amount. In 1894, the verj' thorough report of Arthur Winslow on lead LEAD AND ZING. 245 and zinc in Missouri, and incidentally elsewhere in the world, appeared, and likewise a briefer account before the American Institute of Mining Engineers. Winslow gives in the large volumes the most detailed work of reference yet issued, and reaches a quite different view regarding the derivation and for- mation of the ores. He emphasizes the fact that the region has long been a land area, in fact, ever since the close of the Lower Carboniferous times. The subaerial decay has therefore been excessive and a considerable thickness of overlying rock has gone. This has favored the formation of caves, sinks and un- derground waterways, which have often collapsed. Extremely careful analyses of fresh and large samples of the various lime- stones associated with or overlying the lead and zinc deposits of the State were made, as well as of a series of the Archean rocks, from which, in the course of long erosion, the others are supposed to have been derived. The Archean rocks yielded 0.00197 to 0.0068 per cent, lead (.04 to .136 pounds per ton), and 0.00139 to 0.0176 per cent, zinc (.028 to .352 pounds per ton); the Silurian Magnesian limestones, a trace to 0.00156 per cent, lead (up to .03 pounds per ton); and a trace to .0.01538 per cent, zinc (up to .307 pounds per ton); the Lower Carbon- iferous limestones, a trace to 0.00346 per cent, lead (up to .07 pounds per ton), and a trace to 0.00256 per cent, zinc (up to .05 pounds per ton). Winslow concludes from the above data and observations and from the difficulty, if not impossibility, of discovering actual evidence of fault fissures, that the ores have become concentrated in the shattered rock by the down- ward percolations of lead and zinc- bearing solutions, which have derived the metals from the overlying and largely decom- posed strata. 2.06.08. Some interesting alterations of the minerals have occurred, which have changed the blende to smithsonite and calamine. In one case a secondar}' precipitation of zinc sul- phide has yielded a white, amorphous powder, which is of very recent date. With the original precipitation of the blende, the asphaltic material may have had something to do. In the matter of production, W. P. Jenney fixes the ratios of the blende, galena, and pyrite at about 1,000 : 80 : O.5.* ^ Missouri. -t-G. C. Broadhead, "Geological History of the Ozark Up- lift," Amer. GeoL, III., 6. H. M. Chance, "The Rush Creek (Arkansas) 246 KEMRS ORE DEPOSITS. 2.06.09. Other zinc and lead deposits are known in central Missouri generally resembling the above quite strongly, but of less economic importance. Some, however, are described by Schmidt as conical stockworks. They sometimes are found in Lower Silurian strata. ENLARGED SECTION SHOWING RELATION OF ZINC-ORE TO THE -LIMESTONES AND CLAY. Fig. 80. — Oeological section of the Bertha zinc mines, Wythe County, Va. After W. H. Cas!\ Trans. Amer. Inst. Min. Eng., XXII. , p. 520. 2.06.10. Both the mines of Example 25 and those of Exam- ple 24 were originally worked for lead, and the zinc minerals Zinc District," !r?'a)is. Amer. Inst. Min. Eng., Yo\. XVIII., p. 505, 1890. F. L. Clerc, Geological description of the mines in a statistical pamphlet on the Lead and Zinc Ores of Southwest Missouri Mines, p. 4, published by J. M. Wilson, Carthage, Mo., 1887. Rec. See also Eng. and Min. Jour., June 4, 1887, p. 397; "Zinc in the United States," Mineral Resources, 1882, p. 368. G. T. Cooley, "Dressing Lead and Zinc Ores in Kansas," Eng. and Min. Jour., July 7, 1895, p. 9. Eng. and Min. Jour., November 8. 188'^, p. 380; March 8, 1890. p. 286. " Distribution of Lead and Zinc near Joplin, Mo.," Idem, March 18, 1891, 321. Rec. E. Haworth, " A Contribu- tion to the Geology of the Lead and Zinc Mining District of Cherokee County, Kansas, Oskaloosa. Iowa." 1884 C. Henrich, " Zincblende Mines and Mining near Webb City, Mo.," Trans. Amer. Inst. Min. Eng., XXI., p. 3, 1892; Eng. and Min. Jour., June 4, 1892. J. R. Hohbaugh, "The Lead and Zinc Mining Industry of Southwest Missouri and Southeast Kan sas." Eng. and Min. Jour.. LVIIL, 1894, 199, 394, 413. 437, 460, 485. 508 and 535. Also issued as a separate book by the Scientific Publishing Co . 50 cents. W. P. Jenney. "Lead and Zinc Deposits of the Mississippi Valley," Trans. Amer. Inst. Min. Eng., XXII., 171, 1893. Rec. C. Luedekingand LEAD AND ZING. 247 were regarded as a nuisance ; of late years the zinc has been much more of an object than the lead. The deposits in south- west Virginia (Example 26) also produce lead, but are best known for zinc. 2.06.11. Example 26. Wythe County, Va. Residual de- posits or crusts of calamine and smithsonite, resting upon Lower Silurian (Ordovician) limestone or dolomite, and prob- ably derived from disseminated blende, during the weathering of the country rock. Deposits of blende are also known in the limestone. The ore- bearing terrane is exposed over a considera- ble extent of country, running from near Roanoke, one hundred miles westward. The largest mines are in Wythe County, and of these the Bertha is best known. The Bertha ores are cala- H. A. Wheeler, "Notes on Missouri Barite,' Amer. Jour. Sci., December, 1891, p. 495. R. W. Raymond, "Note on the Zinc Deposits of Southern Missouri," Trans Airier, hist. Min. Eng., VIII., 165; Eng. and Min. Jour., October 4, 1879. J. D. Robertson, " A New Variety of Zinc Sulphide from Cherokee County, Kansas," Amer. Jour. Sci., iii., XL., p. 160. "Missouri Lead and Zinc Deposits," Amer. GeoL, April, 1895, 235. A. Schmidt and A. Leonhard, Missouri Geol. Survey, 1874. A. Schmidt, "Forms and Origin of the Lead and Zinc Deposits of Southwest Missouri," Trans. St. Louis Acad. Sci., III., 246; Amer. Jour. Sci., iii., X., p. 300. Die Bleiund Zink Erzlagerstdtten von SiXdwest Missouri, Heidelberg, Germany, 1876. E. J. Schmitz, "Notes of a Reconnaissance from Springfield, Mo., into Arkansas," Trans. Ainer. Inst. Min. Eng., February, 1898. W. H. Sea- mon, "Zinciferous Clays of Southwest Missouri," Amer. Jour. Sci., ill., XXXIX., p. 38. H. S. Wicks, "The Joplin District," Engineering Mag- azine, February, 1894. Arthur Winslow, " Notes on the Lead and Zinc Deposits of the Mississippi Valley and the Origin of the Ores," Jour, of Geol., I., 612, 1893. Rec. "Lead and Zinc Deposits of Missouri, " Trans. Amer. Inst. Min. Eng., XXIV., 634 and 931. Rec. "Report on Lead and Zinc," Missouri Geol. Survey, VI. and VII., 1894. Rec. See also pamphlet on "Missouri at the World's Fair," 1893. "Historical Sketch of Lead and Zinc," Eng. and Min. Jour., November 17, 24, 1894; January 19, 1895. Kansas. — G. P. Grimsley, "Kansas Mineral Products, " Eleventh Bien- nial Report Kansas Board of Agricidture, 1897-98, 502, E. Haworth, "A Contribution to the Geology of the Lead and Zinc Mining District of Cherokee County, Kan., Oskaloosa, la.," 1894, privately printed. R. Hay, ' ' Geological and Mineral Resources of Kansas, " Eighth Biennial Report State Board of Agriculture, 1891-92, 25. B. F. Mudge, Idem, 1878. O. St. John, Idem, 1881-82. See also J. D. Robertson, cited under Missouri. Arkansas. — E. J. Schmitz, "Notes of a Reconnaissance from Spring- field,- Mo., into Arkansas," Titans. Amer. Inst. Min. Eng., February, 1898. A Report on Lead and Zinc in Arkansas is now in press with the State Geol. Survey (1899). 248 KEMP S ORE DEPOSITS. mioe and smithsoDite, both crystallized and earthy or ochreous. They lie upon a limestone which is of very irregular surface, be- ing so deeply pitted by superficial decay that it projects in knobs and pil- lars, and sinks in interven- ing depressions. These are shown very graphically in Figs. 82 and 83, where they are left in relief by the stripping. They are mantled and rounded off by the overlying residual clay, which may be 50 to ?5 feet deep. The ore lies in crusts and chunks or as a powdery mass upon or near the limestone in the clay, and is won either by stripping this, or by shafts and drifts. (See Fig. 80.) According to Boyd, in one section there are 486 feet of strata impregnated with zinc and lead sulphides, with some pyrite. At the Wythe Company's mines both the oxidized ores and the unchanged sulphides of zinc and lead in the imderlying limestone are exploited, but at the Ber- tha mines there is practi- cally no lead, the product being a very pure spelter. More or less limonite is NiviNnownivd oNiavoH esNiMONiz vHxuaa •AM '0 'H 'M •« 'M V "M tl3AliiM3N AavtyAnawiM NlVJLNnOH uadvuo n«»M >> >::iss 7^< "i^-s S2 §^ il oo)OorN. W. P. Blake, Proc. Bost. Soc. Nat. Hist, 1859, Vol. VII., p 64. "Ge- ology of the Rocky Mountains in the Vicinity of Santa Fe," Amer. Asso. Adv. Sci., 1859. A. R. Conkling, "Report on Certain Foothills in North- ern New Mexico," Wheeler's Survey, Rep. of Chief of U. S. Engineers, 1877, II., 1298. E. D. Cope, " Report on the Geology of a Part of New Mexico," Wheeler's Survey, 1875; Appendix Gl. C. E. Button, "Mount Taylor and the Zuni Plateau," Sixth Ann. Rep. U. S. Geol. Survey, pp. 111-205. S. F. Emmons, Tenth Census, Vol. XIII., 100. O. Loew, "Re- port on the Geology and Mineralogy of Colorado and New Mexico. ' Wlieeler's Survey, 1875; Appendix G2, p. 37. J. Marcou, "The Mesozoic Series of New Mexico," Amer. Geol., IV., 155, 216. R. E. Owen and E. J. Cox, "Report on the Mines of New Mexico," Washington, 1865, 60 pp., Amer. Jour. Sci., ii., XL., 391. G. F. Runton, "On the Volcanic Rocks of New Mexico," Quar. Jour. Geol. Soc, Vol. VI., p. 251, 1850. B. Silli- man, Jr., "The Mineral Regions of Southern New Mexico," Trans. Amer. Inst. Min. Eng., X., 424. F. Springer, " Occurrence of the Lower Burling- ton Lime.stone in New Mexico," Amer. Jour. Sci., iii., XXVII. , 97. J. J. Stevenson, "Geological Examinations in Southern Colorado and North em New Mexico," Wlieeler's Survey, 1881. "Geology of Gahsteo Creek," Amer. Jotir. Sci., iii., XVIII., 471. "On the Laramie Group of Southern New Mexico," Amer. Jour. Sci., iii., XXII., 370. For the Bibliography of the Geology of the Territory in general, see Bulletin of the U. S. Geol. Survey, 127 (literature up through 1891); 130 (1892-1893); 135(1894); 146 (1895) ; 149 (1896) ; 156 (1897), and annual issues. 286 KEMP'S ORE DEPOSITS. mentioned (Example 29), and tbe copper in Permian sandstone under Example 21c. There are other silver- bearing lodes in the Socorro Mountains near tbe town of Socorro. Henrich has described (1. c.) a curious deposit of quartz carrying gold and silver (tbe Slayback Lode) on the contact between the older bedded eruptions and a later siliceous dike in the Mogollon range (Example 38). In Santa Fe County are important placer mines (Example 44) and thin veins of galena in rhyolite. In Bernalillo County are placers on the slopes of the Sandia Mountains. In Colfax County, in the Rocky Mountains, are other placers, and reported gold and silver mines. ^ COLORADO. 2.09.09. Geology, — The eastern portion contains plains and is a region lacking water. It consists of Quarternary and Cretaceous rocks. The plains rise in the foothills, which are chiefly upturned Jura-Triassic and Cretaceous strata. The Paleozoic is relatively limited, although known. It rests on the crystalline rocks of the Archean. There are some minor uplifts, running out at right angles to the Front range, that divide the foothill country into basins, and are especially important in connection with coal. Next come the easterly ranges of the Rocky Mountains, in linear north and south succession. They consist largely of dome-shaped peaks of granite, with great local developments of volcanic rocks. To the west follow the several parks, chiefly consisting of Meso- zoic strata. They are bounded by ranges again on the west, some of which, like the Mosquito range (see under Example 30), mark great lines of post- Cretaceous upheaval, and are accom- panied by immense igneous intrusions. On the east and west flanks of the Sawatch range (the granitic Continental Divide) are Paleozoic strata in considerable thickness, but to the west ' W. P. Blake, "Gold in New Mexico," Proe. Post. Soc. Nat. Hist., VII., p. 16, July, 1859. "Observations on the Geology, etc., near Santa Fe," Amer. Asso. Adv. of Sci., XIII., 314, 1860, S. F. Emmons, Tenth Census, XIII., p. 101. C. Henrich, "The Slayback Lode, New Mexico," Eng. and Min. Jour., July 13, 1889, p. 27. R. E. Owen and E. T. Cox, Rep. on the Mines of New Mexico, Washington, 1865. Rep. Director of the JIfmf, 1883, p. 339. B. Silliman, "Mineral Resources of Southern New Mexico," Trans. Amer. Inst. Min. Eng., X., 424. Eng. and Min. Jour., October 14 and 21, 1882, pp. 199, 212. SILVER AND GOLD. 287 they dip under the vastly greater development of Mesozoic ter- ranes, which shade out into the Colorado plateau. In northern, central and southwestern Colorado are vast developments of igneous rocks that have attended the geological disturbances/ 2.09.10. The San Juan region includes several counties in southwestern Colorado, in whole or in part, viz. : Ouray, Hins- dale, San Juan, Dolores, and La Plata. The chain of the San Juan Mountains consists of great successive outflows of erup- tive rocks, andesite, diabase, diorite, basalt, etc., which cover up the Archean and later sedimentary terranes, except in a few scattered exposures. Considerable masses of rocks formed of fragmental ejectamenta are also known. All these are crossed by immense vertical veins, largely with quartz gangue, and con-, taining argentiferous minerals of the usual species, galena, tetrahedrite, pyrargerite, and native silver, as well as bismuth compounds. Gold has been quite subordinate, although late developments near Ouray have shown some peculiar and inter- esting deposits. R. C. Hills, as quoted by S. F. Emmons, 1885, traced three systems of veins. (1) Silver bearing, narrow (six inches to three feet), nearly vertical veins, with base metal ores * G. L. Gannon, "Quaternary of the Denver Basin," Proc. Colo. Sci. Sac., III., 48. See also III., 200. "Geology of Denver and Vicinity," Idem, IV., 235. Rec. W. Cross, "The Denver Tertiary Formation," Amer. Jour. Sci., iii., XXXVII., 261." "Pike's Peak," Atlas Folio, U S. Geol . Survey, No. 7. Rec. ' ' On a Series of Peculiar Schists near Salida," Proc. Colo, Sci. Soc, IV., 286. Rec. "The Laccolitic Mtn. Groups of Colorado, Utah and Arizona," Ann. Rep. Dir. U. S. Geol. Sur- vey, XIV., 165. Rec. G. H. Eldredge, "On the Country about Denver, Colo.," Proc. Colo. Sci. Soc, III., 88. See also 140. S. F. Eminons, " Orographic Movements in the Rocky Mountains, " Geol. Soc. of America, I., 245-286. F. M. Endlich, "On the Eruptive Rocks of Colorado," Tenth Ann. Rep., Hayden's Survey. H. Gannett, "Report on the Arable and Pasture Lands of Colorado," Hayden's Survey, 1876, p. 313. H. C. Free- man, "The La Plata Mountains," Trans. Amer. Inst. Min. Eng., XIII, 681. G. K. Gilbert, "Colorado Plateau Province as a Field for Geological Study, " Amer. Jour. Sci. , iii. , XII. , 16, 85. J. D. Hague, Fortieth Paral- lel Survey, Vol. HI., p. 475. F. V. Hayden, Reps, of Hayden's Survey, 1873, 1874, p. 40; 1875, p. 33; 1876, pft 5, 70. R. C. Hills, "Preliminary Notes on the Eruptions of the Spanish Peaks," Proc. Colo. Sci. Soc. III., 34, 224. "The Recently Discovered Tertiary Beds of the Huerfano River Basin," Proc Colo. Sci. Soc, III., pp. 148, 217. "Jura Trias of South- eastern Colorado," Amer. Jour. Sci., iii., XXIII., p. 243. "Orographic and Structural Features of Rocky Mountain Geology," Proc. Colo. Sci 288 KEMP'S ORE DEPOSITS. and no selvage. (2) Large, strong, gold-bearing veins dipping 60° with selvages and intersecting (1). (3) Like (l), but larger and more persistent, and carrying occasional bismuth and anti- monial ores with gold and little or no silver. T. B. Comstock {Tr^ns, Amer. Inst. Min. Eng., XV., 218) has classified the veins in three radiating systems. (1) The northwest, with tetrahedrite (freibergite). (2) The east and west, with bismuth and less often nickel and molybdenum. (3) The northeast, with tellurides and antimon)^ and sulphur compounds of the precious metals. Quite recently a series of small caves near Ouray, in quartzite overlaid by bituminous shales have been found to contain native gold, and have excited great interest. It is thought by Endlich that they represent inclusions of shale, now dissolved away, and that the gold was precipitated on the walls. If this view is correct, they mark one of the very few illustrations of chamber deposits which are known. More extended mining work has proved them to be in all cases connected with a supply fissure from which small leaders guide the miners to the chambers. In the vicinity of Telluride there is a very interesting devel- opment of veins. One of the most remarkable and persistent Soc. , III., 363. Rec. ' ' Types of Past Eruptions in the Rocky Mountains," Idem, IV., 14. Rec. A. Lakes, " Extinct Volcanoes in Colorado," ^mer. Geol., January, 1890, p. 38. Oscar Loew, "Report on the Minerals of Colorado and New Mexico," Wheeler's Survey, 1875, p. 97. "Eruptive Rocks of Colorado," Wheeler's Survey, 1873. C. A. H. McCauley, "On the San Juan Region," Rep. Chief of U. S. Engineers, 1878, III., p. 1753. C. S^ Palmer, "On the Eruptive Rocks of Boulder County," etc., Proc. Colo. Sci. Soc, III., p. 230. A. C. Peale, "On the Age of the Rocky Mountains in Colorado," Amer. Jour. Sci., in., XIII., p. 172; Reply to the above by J. J. Stevenson, Amer. Jour. Sci., iii., XIII., 297. T. A. Rick- ard, "Gold Resources of Colorado," The Mineral Industry, II., 325; IV., 315. S. H. Scudder, "The Tertiary Lake Basin at Florissant," Hayden's Survey, 1878, p. 271 ; see also 1877. J. A. Smith, Catalogue of the Princi- pal Minerals of Colorado, Central City, 1870. J. J. Stevenson, " Notes on the Laramie Group of Southern Colorado," Amer. Jour. Sci., iii., XVIII. 129. "TheMesozoic Rocks of Southern Colorado," ^mer. Geol., III., p, 391. P. H. Van Diest, " Colorado Volcanic Cones," Proc. Colo. Sci. Soc. III., p. 19. C. A. White, "On Northwestern Colorado," Ninth Ann. Rep Director U. S. Geol. Survey, 683-710. For the complete geological bibli ography of the State, see Bulletins U. S. Geol. Survey, 127 (1732-1891) ; 130 (1892-93); 185 (1894); 146 (1895); 149 (1896); 156 (1897), and current annuals. SILVER AND GOLD. 289 is the Smuggler, recently described by J. A. Porter. It is known for a stretch of four miles and cuts the high divide that Not Classified ' Rhyolites and Andesites as to < Geologic Age. 2 "~[ S«n Juan Formation _J Andesitic Breccia Shales and SandstonM. Fig. 102. — Geological sketch-map of tlie Telluride district, Colorado. Ajter Arthur Winslow, Trans. Amer. Inst. Min. Eng., February, 1899, separates the Marshall basin near the town of Telluride, on the south, in the drainage area of the San Miguel River, from 290 KEMP'S ORE DEPOSITS. the valleys of Canon Creek, a tributary of the Uncompahgre River, that lies to the north. (See Fig. 102.) The summit of the 'divide is 13,200 feet above tide. Whitman Cross has been mapping an atlas sheet for the U. S. Geological Survey in the vicinity of Telluride, and has prepared in advance of its issue a sketch of the local geology. (** The San Miguel Formation, Igneous Rocks of the Telluride District,'^ Proc. Colo. Sci. Soc, September, 1896.) The formations of interest in connection with the vein, begin with the San Miguel conglomerate, which is probably of closiug Cretaceous or early Eocene age. On this is the San Juan formation, 2,000 feet thick, of bedded volcanic andesitic tuffs, the chief wall rocks. Above follow sheets of various andesites and rhyolites, which are cut by the highest parts of the vein. The fissure containing the ore body has cut this series and is known for 3,500 feet vertically, but what its character is in the San Miguel conglomerate is not yet demon- strated. The gangue is chiefly quartz, with some rhodochrosite, calcite, siderite and barite. The values in silver are highest at the north, and yield to gold values to the south. Two other notable veins cross and fault the Smuggler, one the Pandora, containing auriferous quartz, the other the Revenue, with con- siderable lead. So constant is the character of the Smuggler thatstoping ground has been broken for a mile without a break. (J. A. Porter, **The Smuggler-Union Mines, Telluride, Colo.,'» Trans. Amer. Inst, Min. Eng., XXVI., 449.) The region is indeed one of remarkably persistent and clear-cut fissures,^ which are shown on Fig. 102. Placer gold mines (Example 44) are quite extensively worked in San Miguel County. J. B. Farish has de- scribed the veins at Newman Hill, near Rico, in a valuable paper cited below. The lowest formation exposed is magnesian limestone, supposed to be Carboniferous. It contains large ore bodies of low grade, and is also, strangely enough, heavily charged with carbonic acid gas. Above this for 500 feet are alternating sandstones and shales, and then a narrow stratum of limestone 18 to 30 inches thick. This is followed by about * C. W. Purington, " Preliminary Report on the Mining Industries of the Telluride Quadrangle," Eighteenth Ann. Rep. Director U. S. Geol. Survey. Arthur Winslow, " The Liberty Bell Gold Mine, Telluride, Colo- rado," Trans. Amer. Inst. Min. Eng., Febiniary, 1899. SILVER AND GOLD. 291 292 KEMP'S ORE DEPOSITS. 500 feet additional of shales and sandstone, regarded as Car- boniferous. Fifty feet above the lowest limestone a laccolite of porpbyrite has been intruded. Two sets of fissures are pres- ent—one nearly vertical and striking northeast, the second dip- ping 30 to 45° northeast, and striking northwest. The former are the richest, are rudely banded and persistent, being worked in one case for 4,000 feet. The flatter fissures are less rich. The principal ore bodies, however, occur as horizontal enlarge- ments of both these sets of veins. Just over the thin bed of limestone mentioned above the ores have spread out into sheets from 20 to 40 feet wide, and from a few inches to three feet thick. They consist of solid masses of the common sulphides, galena, pyrite, gray copper, etc., and are very rich. Above Fig. 104. — Geological cross sections of strata and veins at Newman Hill, ne(Mf Rico, Colo. After J. B. Farish, Proc. Colo. Sci. Soc, April 4, 1892. See also Figures 5 and 6. them the fissures apparently cease, or at least are tight. Two hundred feet down from them the vein filling becomes nearly barren, glassy quartz. These are most remarkable ore bodies, and would appear to have been formed by uprising solutions, which met the tight place and spread sidewise, depositing their minerals; but as Mr. Farish advances no explanation, it is hardly justifiable for others, less familiar than himself with the phenomena, to do so. T. A. Kickard has also written of them, and has illustrated the details of vein structure in a verj^ significant series of plates, which show the banding to be ir- regular and not persistent. He has also introduced some cor- rected interpretations of the faults. The lead-silver ores of Red Mountain and Rico have al- SILVER AND GOLD. 293 ready been mentioned (2.08.17). Silverton and Ouray are the principal towns of the San Juan.^ 2.09.11. The new mining region of Creede, now decided to be in Saguache County, should be mentioned in this connec- tion. It is situated near the junction of Saguache, Ouray and Hinsdale counties, and some ten or twelve miles from Wagon Wheel Gap. There is a great development of igneous rocks as well as of Carboniferous limestone, but the veins as yet devel- oped are in the former. They appear to be fissure veins, and have quartz, in large part amethyst, with some manganese minerals as a gangue, and, with these, oxidized silver ores. The mines are on two mountains. Bachelor and Campbell, which are on opposite sides of Willow Creek Canon. ^ * T. B. Comstock, "The Geology and Vein Structure of Southwestern Colorado," Trans. Amer. Inst. Min. Eng., Vol. XV., 218; also XI., 165, and Eng. and Min. Jour., numerous papers in 1885. " Hot Spring Formation Iftin the Red Mountain District, Colorado," Trans. Amer. Inst. Min. Eng., XVII., 261. S. F. Emmons, "On the San Juan District," E7ig. and Min. Jour., June 9, 1883, p. 332. "Structural Relations of Ore Deposits," Trans. Amer. Inst. Min. Eng., XVI., 804. Rec. Tenth Census, Vol. XIII., p. 60. F. M. Endlich, "Origin of the Gold Deposits near Ouray," Eng. and Min. Jour. , October 19, 1889. ' ' San Juan District, " Hayden's Survey, 1874, p. 229. Ibid., 1875, Bull. Ill, Amer. Jour. Sci., iii., X., 58. J. B. Farish, "On the Ore Deposits of Newman Hill, near Rico, Colo.," Colo. Sci. Soc, April 4, 1892. Rec. W. H. Holmes, "La Plata District," Hayden's Survey, 1875; Amer. Jour. Sci., iii., XIV., 420. M. C. Ihlseng, "Review of the Mining Interests of the San Juan Region," Rep. Colo. State School of Mines, 1885, p. 27. G. E. Kedzie, "The Bedded Ore Deposits of Red Mountain Mining District, Ouray County, Colorado," Trans. Amer. Inst. Min. Eng., XV., 570. Rec. G. A. Koenig and M. Stocker, "Lustrous Coal and Native Silver in a Vein in Porphyry, Ouray County, Colorado," Trans. Amer. Inst. Min. Eng., IX., 650. T. A. Rickard, "Vein Structure in the Enterprise Mine." Proc. Colo. Sci. Soc, Adv. Sheets, Vol. V. T. E. Schwartz, "The Ore Deposits of Red Mountain, Ouray County, Colorado," Trans. Amer. Inst. Min. Eng., XVIII., 139, 1889. J. J. Stevenson, "On the San Juan," Wheeler's Survey, HI., p. 376. "The San Juan Region," Eng. and Min. Jour., August 27, 1881, p. 136; September 24, 1881, p. 201; July 17, 1880; December 20, 1879; and many other references in 1879 and 1880. P. H. Van Diest, "Notes on a Trip to Telluride, San Miguel Co., Colo.," Proc. Colo. Sci. Soc, II., 28, 1885; Idem, January, 1886. ' E. B. Kirby, "The Ore Deposits of Creede and their Possibilities," Eng. and. Min. Jour., March 19, 1892, p. 325. Rec. T. R. MacMechen, "7 he Ore Deposits of Creede," Eng. and Min. Jour., March 12, 1892, p 301. Rec. 394 KEMP'S ORE DEPOSITS. 2. 09. 12 . The Gunnison region lies on the western slope of the Continental Divide, and embraces both mountains and pla- teaus. West of the main and older range are the later Elk Mountains, in which several mining districts are located. Aspen ha^ already been mentioned, and the long series of ore bodies in the Carboniferous limestones. The other principal districts are Independence, Ruby, Gothic, Pitkin and Tin Cup. The ores at Independence are sulphides with silver, in the Archean granite rocks. In the Tin Cup district the Gold Cup mine is in a black limestone and contains argentiferous cerussite and copper oxide. In the Ruby district the ores are in the Cretaceous rocks, and in the Forest Queen they are ruby silver and arsenopyrite, partly replacing a porphyry dike. On Copper Creek, near Gothic, a series of nearly vertical fissures traverse eruptive diorite. They contain sulphide of silver and native silver. The Sylvanite is one of the principal mines. Arthur Lakes has described some very curious veins in Gunnison Co., the Yulcan and Mammoth, that contain opalineit silica and native sulphur together with pyrites.^ 2.09.13. Eagle County. The lead-silver mines of Red Cliff have already been mentioned (Example 30c), and also the underlying gold deposits. The Homestake mine, northwest of Leadville, over toward Red Cliff, is on a vein of galena in granite, and was one of the first openings made in the region.^ 2.09.14. Summit County. The Ten-Mile district, which is the principal one, has been mentioned under Example 30a. Lake County, containing Leadville, has been treated under Example 30. Mention should also be made of the placer depos- ^ F. Amelung, " Sheep Mountain Mines, Gunnison County, Colo.," Eng. andMin. Jour., August 28, 1886, p. 149. F. M. Chadwick, "The Tin Cup Mines, Gunnison County, Colorado," Eng. and Min. Jour., January 1, 1881, p. 4. See also Example 12d for iron mines. J. R. Holibaugh, "Gold Belt of Pitkin, Gunnison Co., Colo.,'' Eng. and Min. Jour., Decem- ber 12, 1896, p. 559. Arthur Lakes, "Sketch of a Portion of the Gunni- son Gold Belt," etc.. Trans. Amer. Inst. Min. Eng., XXVI., 440. « F. Guiterman, "On the Gold Deposits of Red Cliff," Proc. Colo. Set. Sac., 1890. "On the Battle Mountain Quartzite Mines," Mining hidustry, Denver, January 10, 1890, p. 28. E. E. Olcott, "Battle Mountain Mining District, Eagle County," Eng. and Min. Jour., June 11 and 18, 1887, pp. 417, 436; May 21, 1892. G. C. Tilden, "Mining Notes from Eagle County," Ann. Rep. Colo. State School of Mines, 1886, p. 129. SILVER AND GOLD. 295 its in California Gulch, which first attracted prospectors to the region in 1860. In its eastern part Summit County borders on Clear Creek County, and at Argentine are some veins related to those of the latter. They are high up on Mount McClellan, and are remarkable for the veins of ice that are found in them.^ 2.09.15. Park County, which lies east of Lake County and embraces the South Park, has some mines on the eastern slope of the Mosquito range, and in the Colorado range, to the north- west. The latter are similar in their contents to the George- town silver ores, mentioned under Clear Creek County, but the former are bodies of argentiferous galena and its alteration products in limestone and quartzite. Pyrite is also abundant, and at times a gangue of barite appears. The mines are in the sedimentary series, resting on the granite of the Mosquito range, and are pierced by porphyry intrusions, as at Leadville. The placer deposits at Fairplay deserve mention, as it was from these that the prospectors spread over the divide to the site of Leadville in I860.' 2.09.16. Chaffee County, on the south, contains the iron mines referred to under Example 12d. There are some other gold-bearing veins near Granite and Buena Vista. The lead- silver deposits of the Monarch district are mentioned under Example 306. In Huerfano County, in the Spanish Peaks, veins of galena, gray copper, etc., are worked to some ex- tent.' 2.09.17. Rio Grande County. In the Summit district are a number of rich gold mines, of which the Little Annie is the best known. The gold occurs in the native state, in quartz on the contact between a rhyolite and trachyte breccia and andesite. The deposits are thought by R. C. Hills to be due to a silicificationof the rhyolite along those lines, probably by the sulphuric acid, which brought the gold. Then the rocks were folded. Oxidation and impoverishment of the upper parts fol- _— _. I ^ E. L. Berthoud, ' ' On Rifts of Ice in the Rocks near the Summit of Mount McClellan," etc., Amer. Jour. Set., iii., II., 108. Ten-Mile Special Folio, U. S. Geol. Survey, by S. F. Emmons. Rec. " J. L. Jernegan, "Whale Lode of Park County," Trans. Amer. Inst. Min. Eng., III., 352. ' R. C. Hills, " On the Eruption of the Spanish Peaks," Proc. Colo. Sci. Soc, III., pp. 24, 224. 296 KEMP'S ORE DEPOSITS. lowed, forming bonanzas below. The paper has a very impor- tant bearing on the formation of manj^ replacements.^ 2.09.18. Conejos County. Some deposits of ruby silver ores have recently been developed in this county, near the town of Platoro. The county lies near the middle of the south- ern tier. 2.09.19. Custer County affords some of the most interesting deposits in the West. Rosita and Silver Cliff are the principal towns, and are situated in the Wet Mountain Valley, between the Colorado range on the north and the Sangre de Cristo on the south. In the northern portion of the area immediately concerned with the mines gneisses of undetermined but proba- bly very ancient age outcrop, which, to the south, are buried beneath an extensive development of igneous (mostly volcanic) rocks, and Pleistocene gravels, alluvium and lake beds. The igneous rocks embrace rhyolite, trachyte, dacite, three varie- ties of andesite, diorite, agglomerate and tuffs. The volcanic rocks were derived from outbreaks that took place during the Eocene, as nearly as can be determined by some fossil leaves which are buried in the tuffs. It is interesting to note that the Cripple Creek volcanic center lies about 40 miles north. The volcanic rocks are chiefly represented in the Rosita Hills near the town of the same name, and in the flow of rhyolite north of Silver Cliff. In addition to the volcanics there are syenite, granite and diabase in the gneisses. Several different forms of ore body have been developed, each of which possesses excep- tional claims to interest, and one of which forms a quite unique type, at least, so far as American experience has yet gone. 2.09.20. Example 39. The Bassick Mine. An explosive volcano seems to have broken out at the situation of the Bas- sick mine, and to have produced an elliptical pipe or conduit about 1,500x1,000 feet in the fundamental gneiss of the dis- trict, and to have subsided, leaving the tube filled with rounded boulders, which are chiefly andesite, but which em- brace also granite, gneiss and even carbonized wood. A small dike of basaltic rock (limburgite) is also known to be present. A portion of the agglomerate in the shape of one and perhaps more, nearly vertical pipes or chimneys, has been impregnated » R. C. Hills, Proe. Colo. Sci. Soc, March, 1883. Abstract by S. F. Emmons in the Eng. and Min. Jour., June 9. 1883, p. 332. SILVER AND GOLD. 297 with rich ores of gold and silver, which coat the rounded boul- ders in successive shells of metallic minerals. The first coat is a mixture of lead, antimony and zinc sulphides, and is alwaj^s present. A second, somewhat similar, but of lighter color and richer in lead and the precious metals, is sometimes seen. A third is chiefly zincblende, rich in silver and gold, and is the largest of all. A fourth, of chalcopyrite, sometimes occurs, and lastly, a fifth, of pyrite. Some lots of ore also yielded rich tellurides of the precious metals. On the Bassick chimney the workings have gone to 1,400 feet in depth, without losing the ore, which was roughly elliptical and 100x20 to 30 feet. From the seventh level downward cross-cuts opened up a second chimney lying 150 feet east. The Bassick has been considered by the earlier observers to be a geyser tube in which the bowl- ders were tossed about, rounded and coated with ore. Whit- man Cross has, however, satisfactorily demonstrated the exist- ence of the agglomerate, and S. F. Emmons has reached the conclusion that the ores have come in through fissures which can be detected in the mine. At the intersection of two which cross each other, the chief ore body has been found. The ores are of such a nature that Emmons regards their introduction in the form of vapors as possible, although at depths these vapors were probably confined in the liquid state. The ores would then befumarolic impregnations which have replaced the interstitial filling of the agglomerate. Example 39a. The Bull Domingo Mine. The Bull Do- mingo lies north of Silver Cliff and some miles northwest from the Bassick. The country rock is the ancient gneiss, but near the mine dikes of granite and syenite are known. The ore was found in an elliptical chimney, of variable size, but at the 150 foot level, 90x40 feet. It has been exploited down to the 550 level. The ore consists of rounded boulders of gneiss, syenite and granite, which are coated with successive shells of coarsely crystalline galena, somewhat fibrous zincblende, and specks of pyrite. Outside these are in order shells of white dolomite, ankerite or siderite, calcite, and chalcedony. There is abun- dant evidence of extensive fracturing of the rocks at the mine, and the evidence points, according to S. F. Emmons, rather to a shattered mass of country rock, whose brecciated fragments have been rounded, replaced and coated with ore b}' uprising 298 KEMP'S ORE DEPOSITS. solutions, than to an explosive volcanic outbreak or geyser, as had been previously thought. The general similarity in struct- ure of the ore to that of the Bassick suggested quite naturally a similar origin to the earlier observers. It is interesting to Hew Shaft Old Shaft Fig. 105. Fig. 106. Fig. 105. — Cross section of the Bassic Mine, near Rosita. After S. F. Emmons, XV IL Ann. Rep. U. 8. Oeol. Survey, Part 11. , p. 434. Fig. 106. — Cross section of the Bull- Domingo Mine, near Silver Cliff, Colo. After S. F. Emmons, X VIL Ann. Rep. U. S. Ceol. Survey, Part II. , p. 442. compare the two chimneys of the Bassick and Bull Domingo with that of the Annie Lee at Victor in the Cripi^le Creek district Specimens and notes given the writer by E. J. Chibas SILVER AND OOLD. 299 would indicate a similar deposit at the mines of the Darien Gold Mining Company, Cana, Columbia. (See also E. R. Woakes, Amer. Inst. Min. Eng., Atlantic Cit}' meeting, Feb- ruary, 1898.) 2.09.21. Humboldt-Pocahontas. This vein is one of sev- eral which have been discovered near Rosita. It is a fissure vein which cut in its upper portion a mass of andesite and andesite breccia, but which at the fourth level, as shown in Fig. 107, forked into several feeders. Above this point it was one of the most regular and clear-cut fissures ever mined in the West. The ore was tetrahedrite in a gangue of barite and ^Ml 1^!^ ROSITA AT^DESITE TRACHYTE -PORPHYRY GRANITE BROKEN ZONE OF PORPHYRY & ANDESITE Fig. 107. — Cross section of the Humboldt- Pocahontas vein, near Rosita, Colo. After 8. F. Emmons, XVIL Ann. Rep. U. S. Ueol. Survey, Part 11., V- 437 decomposed wall rock, with which were associated chalcopy- rite, pyrite, galena and antimonial sulphides of silver. In the lower levels the vein broke up into several small fissures and troubles, such that operations ceased. 2.09.22. Silver Cliff. At Silver Cliff there is a large flow of porous rhyolite just north of the town, which was early found to be impregnated along small fissures, with chloride of silver and black manganese minerals. For a time free-mill- ing ore was quarried. Later a deep shaft was sunk in the Gey- ser mine, which at 1,850 feet found the faulted contact with the 300 KEMP'S ORE DEPOSITS. Archean gneiss and 200 out into the rhyolitic tuff a cross-cut encountered a vein that proved productive of rich silver ore. This deep shaft afforded some interesting samples of deep and vados© waters, which have been analyzed by W. H. Hille- brand, as given in Emmons' paper (see above p. 31). The rhyolite also afforded in the surface workings some extraordi- narily large spherulites which have been described by Cross. Assays of fresh and unaltered samples of the country rocks, which were made for S. F. Emmons, indicated the presence of silver in five out of nine, viz. : trachyte, 0.007 oz. per ton; Fair- view diorite, 0.01 oz. per ton; rhyolite, 0.402 oz. per ton; red granite, 0.005 oz. per ton; black granite, 0.025 oz. per ton; bisilicates of the granite, 0.04 oz. silver per ton, and 0.045 per cent, lead.^ 2.09.24. Teller County. The region of Cripple Creek is the only one of serious importance in this county, but the remarka- ble developments of the last few years have placed it in a very important position. The productive mines are situated in the foothills of Pike's Peak, about ten miles west from the peak itself. The summit is clearly visible from many of them, as are also the peaks of the Sangre de Cristo range, many miles to the south. The town of Cripple Creek lies in the valley of the small strearri of the same name, which is a branch of Oil Creek, itself a tributary of the Arkansas River. The valley is an open and moderately broad upland, but the approaching depressions are narrow defiles, that have presented great diffi- culties to railways. The general country rock of the region is the red granite of Pike's Peak. This contains masses of still older mica schists, presumably caught up in its intrusion. The ^ R. N. Clark, " Humboldt- Pocahontas Vein," Trans. Amer. Inst. Mm. Eng., VII., 21, "Silver Cliff, Colorado," Eng. and Min. Jour., Novem- ber 3, 1878, p. 314. W. Cross, "Geology of the Rosita Hills," Proc. Colo. Sei. Soc, 1890, p. 269. Rec. Seventeenth Ann. Rep. U. S. Geol. Survey, Part II., 269. Rec. S. F. Emmons, "The Genesis of Certain Ore Depos- its," Trans. Amer. Inst. Min. Eng., XV., 146. Tenth Census, Vol. XIII., p. 80. "The Mines of Custer County, Colo. ," Seventeenth Ann. Rep. U. S. Geol. Survey, Part II., 411. Rec. L. C. Graybill, "On the Peculiar Features of the Bassick Mine," Trans. Amer. Inst. Min. Eng., XI., p. 110; Eng. and Min. Jour. , October 28, 1882, p. 226. Rec. O. Loew and A. R. Conkling, "Rosita and Vicinity," Wheeler's Survey, 1876, p. 48. See also Stevenson in the Report for 1873. 302 KEMP'S ORE DEPOSITS. schists are pre-CambriaD, as are the granites and certain dia- base dikes that occur in the streets of Cripple Creek and on Mineral Hill, but that are of no importance in connection with the ores. At the close of the Eocene or in the Miocene times a small volcanic center broke out in the granite hills now lying east of the town, and perhaps elsewhere. It was marked at first by explosive activity that besprinkled the neighboring region with a breccia made up of fragments of granite and andesite. Later came eruptions of phonolite of one or two varieties that form many dikes associated with the ore bodies. Some minor outcrops of nepheline-syenite and syenite-porphyry are possibly deep-seated and coarsely crystalline representatives of the phonolite magma. Explosive eruptions of this phase seem also to have contributed some phonolite to later breccias. Last of all, dikes of several kinds of basalt, including nepheline basalt, feldspar basalt, and limburgite, closed the eruptive phe- nomena. The breccias, after their formation, became in many cases silicified, so as to produce a very firm rock, and as a rule are so altered that their original rock is to be recognized more by its physical texture than its mineralogy. In areal distribu- tion the breccias are the most prominent rocks near the mines; next follows the granite, while through both are intruded the dikes of phonolite and basalt. The ores are almost entirely productive of gold, for although some little silver often occurs with it, and although lead, zinc and copper minerals are met in one or two mines, the former is of slight economic account and the latter are rareties. Iron pyrites is very widespread, but it is not a great carrier of gold. The real source is the telluride of gold, calaverite, froiu which more or less of the native metal has been derived in the uppor parts of the veins by oxidation. The gangue minerals are quartz, fiuorite and decomposed country rock. When the lat- ter is granite, it has lost its mica and often its quartz, leaving a cellular rock more or less impregnated with fresh or decom- posed telluride. The wash of these veins has yielded some placer diggings, especially on Mineral Hill. The ore deposits are true veins that have been formed along lines of displacement whose amount is, as a rule, slight. The fissures themselves are often insignificant in appearance, but the impreguations of the wall rock with ore to a width of from Fig. 109. — View of Cripple Creek, Colorado, from Mineral Hill; Gold Hill in the background. From a photograph by J. F. Kemp, July, 1895. Fig. no.— View of Battle Mountain, Victor, Colorado. From a window in Victor. The Portland group of mines is on the left in the background. The Independence mine is on the extreme right. From a photograph by J. F. Kemp, July, 1895. mr^^^^i^ 304 KEMP'S ORE DEPOSITS. one to several feet afford very rich and valuable ore bod- ies. The fissures frequently foUov^r the courses of dikes, but are clearly later than the latter because they cross them, leave them, return to them, and behave in a more or less independent way. Yet the presence of dikes is in a measure a favorable thing, because the dike itself has filled a fissure, and because it, being an offshoot from a larger body of heated rock, and with lines of weakness along the contacts with its walls, doubt- less has often exercised a directing influence on solutions. The [Fig. 113. — Stereogram of the Annie Lee ore-short, Victor, Colo. After R. A. F. Penrose, XVI. Ann. Rep. U. S. Oeol. Survey, Part II, p. 206. accompanying map, from the timely and valuable report of Cross and Penrose, which, with the Pike's Peak Atlas Sheet of the U. S. Geological Survey, should be consulted by all who are especially interested in the region, will give the main fea- tures of the geology. The veins are not large, but they have yielded in the aggregate great amounts of high grade ore. As elsewhere the ores follow shoots in the veins, and the shoots approximate the vertical. Small cross fractures have often exercised an influence upon them. The veins themselves are SILVER AND GOLD. 305 also often in a series of small parallel fissures, rather than in a single one, and impregnate the intervening walls. Ore has been found in blind veins, outside the main lines of deposition, so that frequent cross-cuts are desirable to make sure of the country. The most productive section is on Battle Mountain, just above Victor. The Portland group and the famous Inde- pendence, of which a cut is here reproduced from Penrose's report, are in this hill. Fig. 112 illustrates the Annie Lee ore- body, a very curious one that forms a chimney in a basaltic dike. Bull Mountain, with its spur. Bull Cliff, contains a considerable number around the town of Altman. The fissure on which the Buena Vista, Lee and Victor mines are located is one of the most extended in the district. Raven Hill, Gold Hill, Globe Hill and various minor spurs have also yielded important bodies of ore.^ It has been customary to send the ores up to $20 to the ton to the stamp mills, for which treatment, however, they are not well adapted, as the losses are heavy. Ores from $20 — $40 go to the cyanide mills, and above $40 to the smelters. 2.09.22. Gilpin County has already been mentioned under "Copper" (2.04.08). The general geology of the veins is much like that of Clear Creek, although the ores are quite different. ^ W. P. Blake, "The Gold of Cripple Creek," Eng. and Min. Jour., Jan- uary 13, 1894. Whitman Cross, Pike's Peak Atlas Folio of the U. S. Geol. Survey ; to be obtained by sending 25 cents to the Director of the Survey, Washington, D. C. Rec. Whitman Cross and R. A. F. Penrose, Jr., "Geology and Mining Industries of the Cripple Creek District. Colorado," Sixteenth Ann. Rep. of the Director of the U. S. Geol. Survey, 1894-95. Rec. W. F. Hillebrand, "Chemical Composition of Calaverite from Crip- ple Creek," in Cross and Penrose's Report, p. 133. W. H. Hobbs, "Gold- schmidtite, a New Mineral," Amer. Jour. Sci., May, 1899, 357. F. G. Knight, "On the Composition of the Cripple Creek Telluride," Proc. Colo. Sci. Joe, October 1, 1894. H. L. McCarn, "Notes on the Geology of the Gold Field of Cripple Creek, Colo.," Science, January 19, 1894, p. 31. R. Pearce, "The Mode of Occurrence of Gold in the Cripple Creek District," Proc. Colo. Sci. Soc, January 8, 1894; Eng. and Min. Jour., March 24, 1894. "Further Notes on Cripple Creek Ores," Proc. Colo. Sci. Soc, April Ti, 1894. S. L. Penfield, "On Calaverite Crystals from Cripple Creek," Cross and Penrose's Report, p. 135. E. Skewes and H. J. Eder, "The Vic- tor Mine, Cripple Creek, Colo," Eng. and Min. Jour., August 19, 1893, p. 198. E. Skewes, "The Ore Shoots of Cripple Creek," Trans. Amer. Inst. Min. Eng., September, 1896. G. H. Stone, "The Granitic Breccias of the Cripple Creek Region," Amer. Jour. Sci., January, 1898, 21. 306 KEMP'S ORE DEPOSITS. R. Pearce has shown the existence of bismuth in the ore, anct gives reasons for believing that the gold is in combination with it. Clear Creek County contains veins on a great series of jointing planes in gneiss (granite), and in large part replace- ments of the wall. Others are replacements of porphyry dikes or of pegmatite segregations. The ores are chiefly galena, tetrahedrite, zincblende, and pyrite,. and the gangue is the wall rock. The curious decrease of value in depth of a series of parallel veins in Mount Marshall was earlier referred to (1.05.05). Georgetown is the principal town and mining center. Others of importance are Idaho Springs and Silver Plume. ^ 2.09.23. Boulder County contains veins along joints or faulting planes in gneiss, or granite, or associated with por- phyry dikes, or pegmatite segregations, and carrying tellurides of the precious metals more or less as impregnations of the country rock. The prevalent country rock is called by Emmons a granite-gneiss. Van Diest distinguishes four successive ter- ranes of massive and schistose rocks along three principal axes and two side ones, and states that the mines are on the sides of the folds. The country is very generally pierced by porphyry dikes, with which the ore bodies are often associated. A large number of species of telluride minerals have been determined from the region, especially by the late Dr. Genth, of Philadel- phia. The mines afford very rich ores, somewhat irregularly distributed.^ ' S. F. Emmons, Tenth Census, Vol. XIII., p. 70. Rec. F. M. Endlich, Hayden's Survey, 1873, p. 293; 1876, p. 117. P. Fraser, Hayden's Survey, 1869, p. lot J. D. Hague, Fortieth Parallel Survey, Vol. III., p. 589. Rec. R. Pearce, Proc. Colo. Sci. Soc, Vol. III., pp. 71, 210. "The Asso- ciation of Gold with Other Metals in the West," Trans. Amer. Inst. Min. Eng., XVIII., 447, 1890. Forbes Rickard, "Notes on the Vein Formation and Mining of Gilpin County, Colo.," Trans. Amer. Inst. Min. Eng., Feb- ruary, 1898. J. J. Stevenson, Wheeler's Survey, Vol. III., p. 351. F. L. Vinton, "The Georgetown (Colo.) Mines," Eng. and Min. Jour., Septem- ber 13, 1879, p. 184. '^ Bergrath Burkart, "Ueber das Vorkommon Verschiedener Tellur- Minerale in den Vereinigten Staaten von Nordamerika, " Neues Jahrbuch^ 1873, 476; April, 492, 1874, 30. Whitman Cross, "A List of Specially Noteworthy Minerals of Colorado," Proc. Colo. Sci. Soc, I., 134, 1884; cites Tellurium, Melonite, Altaite, Hessite, Coloradoite, Sylvanite, Tellurite. A. Filers, "A New Occurrence of the Telluride of Gold and Silver," Trans. Amer. 'Inst Min. Eng., I., 316, 1872. Red Cloud Mine. S. F. Emmons,. SILVER AND OOLD. 307 2.09.25. The resources of the remaining counties of Colo- rado are chiefly in coal. "Sketch of Boulder County," Tenth Census, Vol. XIII., p. 64, 1885. F. M Endlich, " Tellurium Ores of Colorado," Eng. and Min. Jour., XVIII, 183, 1874. F. M. Endlich, " Minerals of Colorado Territory, " jEZat/den's ^'ttr?;ei|/, 1873, 353. J. B. Farish, " Interesting Vein Phenomena in Boulder County, Colo." (Golden Age Mine), Trans. Amer. Inst. Min. Eng., XIX., 541, 1890, "A Boulder County Mine " {The Golden Age and Sentinel), Proc. Colo. Sci. Soc., III., 316, 1890 (same as above). F. A. Genth, " On Tellurides from Red Cloud and Uncle Sam Lodes," Proc. Arner. Phil. Soc, XIV., 225, 1874. "Tellurides from Keystone, Mountain Lion, and John Jay Mines," Idem, XVIL, 115, 1877. J. K. Hallowell, "Boulder County as It Is," Denver, 1882. Worthless. N. P. Hill, "Announces Tellurides at Red Cloud Mine," Amer. Jour. Scl, V., 387, May, 1873. W. F. Hillebrand, "Melonite Forlorn Hope Mine, Boulder County," Proc. Colo. Sci. Soc, I., 123, 1884. E. P. Jennings, "Analyses of Some Tellurium Minerals " (Native Tellurium from John Jay Mine; Sylvanite, Smuggler Mine), Trans. Amer. Inst. Min. Eng., YI., 506, 1877. A. Lakes, " On Boulder County" Geology of Colorado Ore Deposits, c. 1888. A. R. Marvin, " Metamorphic Crystalline Rocks of the Front Range, " Hayden's Survey, 1873. ' ' On Boulder County, " pp. 144, 147-152, 685. Map. C. L. Palmer, "Eruptive Rocks of Boulder County, Colorado," Proc Colo. Sci. Soc, III., 230, 1889. C. L. Palmer and Henry Fulton, "The Quartz Porphyry of Flagstaff Hill, Boulder, Colorado," Idem, 351, 1890. R. Pearce, "Remarks on Gold Ores of Rocky Mountains," R. Pearce, In Discussion of Paper by P. H. Van Diest, Proc Colo. Sci. Soc, IV., 349, 1893. B. Silliman, "Mineral- ogical Notes; Tellurium Ores in Colorado," ^mer. Jour. Sci., July, 1874, 25-33. Reprinted in Hayden's Report, 1873, 686. J. Alden Smith, quoted by P. H. Van Diest as mentioning Boulder County Mines in his Biennial Report for 1880. P. H. Van Diest, " Notes on Boulder County Veins," Proc. Colo. Sci. Soc, II., 50, 1886. "The Mineral Resources of Boulder County, Colorado, " Biennial Rep. State School of Mines, 1886, 25. P. H. Van Diest, ' ' Evidence Bearing on the Formation of Ore Deposits by Lateral Secretion ; The John Jay Mine at Boulder County, Colorado," Proc Colo. Sei. Soc, IV., 340, 18. CHAPTER X. SILVER AND GOLD, CONTINUED.— ROCKY MOUNTAIN REGION, WYOMING, THE BLACK HILLS, MONTANA, AND IDAHO. WYOMING. 2.10.01. Geology, — The southeastern part of Wyoming is in the region of the Great Plains, the southwestern in the Colo- rado Plateau. The Rocky Mountains shade out more or less on leaving Colorado, but are again strongly developed in north- ern Wyoming. The northwestern portion contains the great volcanic district of the National Park, and the northeastern, a part of the Black Hills. The Cretaceous and Tertiary strata chiefly form the plains and plateaus. Granite and gneiss con- stitute the central portion of some of the greater ranges. Pale- ozoic rocks are very subordinate. The resources in precious metals so far as yet developed are small, consisting chiefly of gold in quartz veins in the gneisses, schists and granites of Sweetwater County. The great mineral wealth of the State is in coal. The iron mines have already been mentioned (2.03.09), and the copper (2.04.27).^ ^ H. M. Chance, " Resources of the Black Hills and Big Horn Country, Wyoming," Trans. Amer. Inst. Min. Eng., XIX., p. 49. T. B. Comstock, "On the Geology of Western Wyoming," Amer. Jour. Sci., iii., VI., 426. S. F. Emmons, Tenth Cenms, Vol. XIII., p. 86. F. M. Endlich, "The Sweetwater District," Hayden's Survey, 1877, p. 5; "Wind River Range Gold Washings," p. 64. A. Hague, "Geological History of the Yellow- stone National Park," Trans. Amer. Inst. Min. Eng., XVI., 783, and Yellowstone Park Folio, U. S. Geol. Surv. See also F. V. Hayden, Amer. Jour. Sci., iii., HI., 105, 151. F. V. Hayden. Rep. /or 1870-72. p. 13; also Amer. Jour. Sci., ii., XXXI., 229. A. C. Peale, "Report on the Geology of the Green River District." Hayden's Survey, 1877, p. 511. Raymond's Statistics West of the Rocky Mountains. W. C. Knight, Bull. U, Wyo. Exp't Station, October, 1893. SILVER AND GOLD, CONTINUED. 309 SOUTH DAKOTA.— THE BLACK HILLS. 2.10.02. Geology.— The Black Hills lie mostly m South Da- kota. They consist of a somewhat elliptical core of granite and metamorphic rocks, with a north and south axis, and on these are laid down successive strata of Cambrian, Carbonifer- ous, Jura- Trias, and Cretaceous rocks. There are some igne- ous intrusions. The principal product of the Black Hills is gold. The lead-silver deposits have already been described (2.08.18), and the tin, etc., will be mentioned later.^ Fig. 113. — Geological section of the Black Hills. After Henry Newton Report on the Black Hills, p. 206. 1. Schists. 2. Granite. 3. Potsdam sandstone. 4. Carboniferous. 5, 6, Jura-Trias. 7. Cretaceous. 2.10.03. The gold occurs in stream placers of Quarternary and recent age, and of no great importance; in supposed, old beach or channel placers in the Cambrian (so-called Potsdam), conglomerates, the **cement" deposits; in impregnations of the ^ F. R. Carpenter, "Ore Deposits in the Black Hills," Trans. Amer. Inst. Min. Eng., XVII., 570. Prelim. Rep. on the Geol. of the Black Hills, Rapid City, So. Dakota, 1888. W. O. Crosby, "Geology of the Black Hills," Bosf. Soc. Nat. Hist., XXIII., p. 89. P. Frazer, "Notes on the Northern Black Hills of South Dakota," Trans. Amer. Inst. Min. Eng., XXVII., 204, 1897. John D. Irving, "A Contribution to the Geology and Ore Deposits of the Northern Black Hills, South Dakota," Annals N. Y. Acad. Sciences, XII., Part II., 1899. Rec. Newton and Jenney, Report on the Black Hills, Washington, 1880. F. C. Smith, "The Occurrence and Behavior of Tellurium in Gold Ores, more particularly with Reference to the Potsdam Ores of the Black Hills," Trans. Amer. Inst. Min. Eng., XXVI., 485, 1103, 1896. " The Potsdam Gold Ores of the Black Hills of South Dakota," Idem, XXVII., 404, 428, 1897. Rec. C. R. Van Hise, "The Pre-Cambrian Rocks of the Black Hills," Bull. Geol. Soc. Amer., I., 203-244. N. H. Winchell, "Report on the Black Hills," i^ep. Chief, of U. S. Engineers, 1874, Part II., p. 630. The U. S. Geological Survey is preparing a report on the Black Hills, S. F. Emmons and T. A. Jaggar being in charge of the work. 310 KEMP'S ORE DEPOSITS. Cambrian lime-shales, with siliceous gold ores in the neigh- borhood of intruded dikes and sheets of phonolite; in crevices in the heavy Carboniferous limestone, now filled with siliceoup gold ores; and in broad zones or fahlbands of Algonkian slaty and mica schists, carrying auriferous pyrites. The above are CAMBMAN ' SHALOS ALGONKIAN SUTES. aUAimiTCS J tVU Fig. 114. — Geological section of the strata in the Northern Black Hills, S. D, After John D. Irving, Annals of the New York Academy of Sciences, XII, Part II, 1899. found in the northern Hills. In the central portion pegmatites have recently proved gold-bearing. The Quarternary and recent gravels were effective in attracting prospectors in the early days of settlement. They are scarcely worked to-day. The ancient beach gravels are still followed beneath the caps of por- phyry in some small mines in Deadwood Gulch. As described SILVER AND GOLD, CONTINUED. :ni l3y W. B. Devereux in 1882, the gravels were regarded as hav- ing derived their gold by the beating of the waves of the Cam- brian Ocean against the auriferous schists described below, but later work has made it probable that they are impregnations like the Potsdam siliceous ores. The pay gravel now runs as a shoot under the later lava sheets. The impregnations of the Cambrian, locally called Potsdam, lime-shales with tellu- Cambrian5hale and Sandrock. (Very Calcareous) Cambrian Qnartzite and Conglomerate ("Cement") Algonkian Plan of Ore Chute. The ore is broken awat TO show the verticals. Fig. 115. — Plan and cross-section of a Cambrian, siliceous gold-ore deposit in the Black Hills, 8. D. After John D. Irving, Annals N. Y. Atademy of Sciences, XTI, Part 11. , 1899. rides and pyrites, constitute a form of ore body that has been of rather recent development, but that is now the leading producer. The mines, as indeed nearly all the gold developments, are in the northern Hills, and are especially abundant around Terry Peak. The Cambrian lies flat, and is penetrated very abun- dantly by dikes and sheets of trachyte and phonolite. The ig- 312 KEMP'S ORE DEPOSITS. neous rocks have themselves sometimes been impregoated, when they lie near an ore body. Associated with the ore shoots and usually bisecting that portion of the floor that lies beneath them are found cracks, called "verticals," that run down to unknown depths, but that are not accompanied by any notable, if, in- deed, by any appreciable faulting. The verticals have di- rected, or ha\e served to introduce the solutions, which have then spread laterally into beds of lime-shales and have replaced ,4ttHt:nn:n+porphyryntttutuu:ru:i:-K ■+ + ++-)- + + +4-+-|. Fig. 116. — Plan and section. Mail and Express Mine, to illustrate the siliceous gold ores of the Black Hills, 8. D. After John D. Irmng, Annals N. T. Academy of Sciences, XIL, Part IL, 1899. the calcareous portion of them with ore and silica. Those beds of lime-shales have proved most favorable which rest upon a floor of hard quartzite, and this association is so constant that the miners, in regions of phonolite sheets, sink to the quartzite, and then explore for ore. The ore runs in long shoots on the strike of the verticals. The ores contain as gangue quartz, fluorite and the unre- placed residue of the lime -shales. The metallic minerals are Fig. 117.— Green Mountain, Black Hills, S.D ; a laccolite of phonolite, with the mines of siliceous ore on the so-called ' ' upper contact " around its foot Photographed by John D. Irving, 1898. Fig. 118. — Vieiv of tiie Union Mine, in siliceous ore, near Terry, in the Black Hills, S. D. Photographed by John D. Irving, 1898. Siliceous Gold Ore IN Limestone. Enlarged Boulder showing Siliciflcation \\';ill- ] of Brecciated Limestone and line of demarcation between the Oi-e and Wall-rock Type of Ragged Top Vertical IN Carboniferous Limestone on Dacy flat Lawrence Co, South Dakota. Fig. 120. — Pevfipect ire cross-section of siliceous gold ore in Carboniferous limestone, Dacy Flat, Black Hills. After John D. Irving, Annals N. Y. Academy of Sciences, XII., Part 11, 1899. Fig. 121. — View of the Golden Star open cut. Lead City, S. D. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD, CONTINUED. 313 pyrite and a supposed telluride of gold, whose presence is indi- cated by analysis, but which has not been actually seen. Tho- rium has also been detected by F. C. Smith. There are two varieties, red, or oxidized, ores, and blue, or unoxidized. They are collectively known as siliceous or Potsdam ores. The presence of tellurium, of fluorite, and of phonolite is highly suggestive of Cripple Creek, Colo., and of several newer dis- tricts in Montana. At times the vertical may lie alongside of an intruded dike as shown in Fig. 119, and then the ore fol- lows the dike and may impregnate it more or less. The intruded igneous rocks have seldom been able to pierce the heavy cap of Carboniferous limestone, but the laccolites YlOt. 119.— Cross-section of a siliceous gold-ore body lying next to a prophyry dike, Black Hills, 8. D. After John D. Irving, Annals N. T. Academy of Sbiences, XII., Part II., 1899. have served to dome it up, and to fissure it more or less. In the vicinity of the Ragged Top laccolite, on Dacy Flat, these fissures or crevices have been the seat of the deposition of rich, siliceous ores. The ores have replaced and cemented into a hard aggregate, the brecciated limestone that filled the fissure before their introduction. (See Fig. 120.) The older, and formerly the chief source of gold in the Black Hills, is in the great zone or fahlband of schists near Lead City, which carries little lenses and vein lets of quartz, with aurifer- ous pyrites. The pay is thought to lie in the schists. The ores are free-milling, and are controlled by the Homestake Com- pany. They are situated in and near Lead City, in hills which 314 KEMP'S ORE DEPOSITS. form steep divides between the narrow gulches. The schists strike about N. 20 W., and dip 60 E., and in the Golden Star are stoped out in a cross-section over 450 feet. Porphyry dikes cut the schists, and have spread laterally, so as in their present eroded condition to appear like surface caps of lava. They may have exercised an important influence in the enrichment of the schists, but it seems certain that gold was present in them in the Cambrian times, because the Cambrian sediments when carefully panned almost always afford some trace of the yellow metal. The special local enrichment of the schists may have been influenced by the porphyry. The ores are low grade, run- ning $3— $4 or less. The Old Abe, Golden Star, Dead wood- Terra and Father de Smet are the chief locations.^ In addition to the types of ore body described above, there are found throughout the schists of the Hills occasional quartz veins, of the old so-called "segregated" variety, that have yielded a little gold. Recently pegmatites near Harney Peak have proved productive, affording ores similar in their geology to those described by Hussak from Ouro Preto, Brazil,^ and to some in the Transvaal. MONTANA. 2.10.04. Geology. — The eastern part of the State belongs to the region of the Great Plains, which is, however, in portions greatly scarred by erosion, forming the so-called Bad Lands. The approaches to the Rocky Mountains are not abrupt and sudden as in Colorado, but are marked by numbers of outlying ranges of both eruptive and sedimentary rocks. The chain of the Rockies takes a northwesterly trend in Wyoming, and so continues across Montana. It is rather the prolongation of the Wasatch than of the Colorado Mountains, whose strike is for the Black Hills. The character of the ranges is also very dif- * A. J. Bowie, "Notes on Gold Mill Construction," Trans. Amer. Inst. Min. Eng., X., 87, 1881. W. B.' Devereux, "The Occurrence of Gold in the Potsdam Formation," Idem, X., 465: Eng. and Min. Jour., December 23, 1882, p. 334. H. O. Hoffman, "Gold Mining in the Black Hills," Trans. Amer. Inst. Min. Eng. , XVII. , 498 ; also in preliminary report cited under Carpenter, under Geology. See, in addition, references on pa^e 309. * E. Hussak. "Der goldfiihrende, kiesige Quarzlagergang von Passagem in Minas Geraes, Brasilien," Zeits. furprakt. Geologie, October, 1898, 345. 8ILVEB AND GOLD, CONTINUED. 315 ferent. They are less elevated, and have broad and well- watered valleys between, that admit of considerable agricul- ture. Geologically the country is in marked contrast with Col- orado. While in the latter the lower Paleozoic is feebly devel- oped, in Montana it is important. Special interest attaches to the Lower Cambrian or perhaps pre- Cambrian quartzites and associated sediments that are present in great thickness in the northwestern part of the State, and along the Idaho line. Fos- sils have recently been reported by C. D. Walcott from a very low horizon. On the east of the Continental Divide the gneisses and schists of the Archean are succeeded by metamor- phosed sediments of the Algonkian, involving 7,000 feet or more, and known as the Cherry Creek formation of the U. S. Geologists. Unconformablj' upon this lies the Belt formation, of 6,000 to 10,000 feet of sediments, which are doubtfully re- ferred to the Algonkian. Still above come the true Cambrian, 1,000 to 1,500 feet; Siluro-Devonian (of which the latter alone is identified by fossils), 200 to 600 feet; Carboniferous limestones, 800 to 1,000 feet, followed by a quartzite and shale series of 200 to 600 feet; Jura- Trias up to 500 feet; and then some thou- sands of feet of Cretaceous and Tertiary. Great batholites of granite, in part at least post-Carboniferous, have been intruded as set forth earlier under Butte, 2.04.05. They have basic phases on the margins, and locally, within the masses, as at Butte. The above grouping modifies somewhat the section given in earlier editions of this work, and has resulted from the more recent work of W. H. Weed and A. C. Peale of the U. S. Ge- ological Survey, whose folios should be consulted for local de- tails so far as available. East of the main chain of the Rock- ies there are peculiar isolated groups of, mountains of a lac- colite character, such as the High woods, the Judith, and the Little Rockies. They rise like huge blisters of sedimentaries, forced up by lenticular sheets of intrusives, and pierced by dikes in vast numbers. They are rocks prevailingly rich in soda, and present many rare and interesting types and some striking parallels with the Black Hills. ^ ^ S. Calvin, "Iron Butte: Some Preliminary Notes," Amer. Geol., IV., 95. G. E. Culver, "A Little Known Region of Northwestern Montana," Wis. Acad, of Scl, December 30, 1891. W. M. Davis, "The Relation of the Coal of Montana to the Older Rocks." Tenth Census, Vol. XV., p. 697. Rec. 316 KEMP'S ORE DEPOSITS. 2.10.05. MontaDa took the lead of all the States in 1887 in the production of silver, was second in gold, and first in the total production of the two. It is now second to Colorado in silver, and fourth on the list in gold, but in copper it is first. In its mineral wealth it yields to no other State in the Union. The mining districts are mostly in the western central and western portions. Developments have progressed so rapidly that all the desirable data are not available. 2.10.06. Madison County. The chief product is gold. Near Virginia City the gold-bearing quartz forms veins in schists; in the northeastern part of the county the veins occur in gran- J. Eccles, ' ' On the Mode of Occurrence of Some of the Volcanic Rocks of Montana," Quar. Jour. Geol. Sci., XXXVII., 399. G. H. Eldridge, "Mon tana Coal Fields,' Tenth Census, Vol. XV., p. 739. S. F. Emmons, Terith Census, Vol. XIII. , 97. Rec . Haydens Survey, Ann. Rep. , 1871-72. .J. F. Kemp, "On Tellurides in Montana," see The Mineral Industry, VI., 312, 1898. W. S. Keyes, in Brown's first report on mineral resources, etc., last part, Amer. Jour. Sci., II., 46, 431. Rec. W. Lindgren, "Eruptive Rocks." Tenth Census, Vol. XV., p. 719, forming Appendix B of Davis's first paper. See also Proc. Cal. Acad. Sci., Second Series, Vol. III., p. 39. J. S. Newberry, "Notes on the Surface Geology of the Country Bordering on the Northern Pacific Railroad," Annals N. Y. Acad. Sci., Vol. III., 242; Amer. Jour. Sci., iii., XXX., 337. "The Gnjat Falls Coal Fields," in Geol. Notes, School of Mines Quarterly, VIII., 327. A. C. Peale, Three Forks Folio, U. S. Geol. Survey, 1896. Rec. F. Rutley, "Microscopic Character of the Vitreous Rocks of Montana," Quar. Jour. Geol. Sci., XXX VII., 391. See Eccles, above. CD. Walcott, " Pre-Cambrian Fos- siliferous Formations," Bull. Geol. Soc. Amer., X., 199, 1899. Rec. W. H. Weed, "The Cinnabar and Bozeman Coal Fields of Montana," Idem, II., 349-364 Eng. and Min. Jour., May 14 and 21, 1892. "Montana Coal Fields," Bull. Geol. Soc. Amer., III., 301-330. Livingston Folio, U. S. Geol. Survey. Butte Special Folio, Idem; Little Belt Folio, Idem; Bull Folio (in preparation). Weed and Pirsson, "Highwood Mountains of Montana," Bull. Geol. Soc. Amer., VI., 389, 1895. "The Bearpaw Moun- tains of Montana, Amer. Jour. Sci., May, 1896, 283; June, p. 301; Septem- ber, p. 136; October, p. 188. "Geology of the Little Rocky Mountains. ' Jour. Geol, IV., 399. "The Castle Mountain Mining District," Bulletin 139, U. S. Geol. Survey, 1896. -"The Jadith Mountains," Anii. Rep. Dir. U. S. Geol. Survey, XVIII., 1899, Part III., 437. All these are Rec. R. P. Whitfield, "List of Fossils from Central Montana," Tenth Census, Vol. XV., p. 712; Appendix A to Davis's paper. J. E. Wolff, "Notes on the Petrography of the Crazy Mountains," etc.. Northern Trans. Sim.->ey. " Geology of the Crazy Mountains," Bull. Geol. Soc. Amer., III., 445. H. Wood, "Flathead Coal Basin," Eng. and Min. Jour., July 16, 1892, p. 57. H. R. Wood, "Mineral Zones in Montana.." Idem, September 24, 1892, p. 29C. SILVER AND QOLD, CONTINUED. 317 ite ; at Rochester the gold is associated with galena ; at Sheri- dan tetrahedrite and chalcopyrite are found in quartz veins and are rich in gold and silver.^ An interesting vein with tellur- ides has been discovered at the Mayflower mine in the Tobacco Root Mountains.^ It is a fault fissure nearly parallel to the bedding of upturned Cambrian limestones. The ore has re- placed the limestone and is largely oxidized. Placers were of extreme importance in this county in early days, and are still somewhat worked. Alder Gulch , near Virginia City, proved extraordinarily rich. 2.10.07. Beaverhead County. Near Bannack City quartz veins with auriferous pyrite on the contact between the lime stone and so-called granite. At Glendale, in the northern part of the count}', are the Hecla mines, referred to under *'Lead- silver" (Example 32). Auriferous quartz veins are reported farther north. ^ 2.10.08. Jefferson County. There are many varieties of ore bodies in this county, but the commonest type is similar to that at Butte, i.e., veins in granite along fissures of slight displace- ment. The ore is altered country rock, which is mineralized with quartz, pyrite, arsenopyrite and galena. Rich sulphides of silver have been met in the upper portions. The Alta mine near Wickes was located on a vein in andesite. The Ruby mine, on Lowland Creek, appears to be a chimney of boulders of rhyolite, which are coated with gold-bearing silver-sul- phides. It resembles the Bassick mine of Colorado (2.09.20) in geological relations. One of the largest mines yet opened in the county is the Elkhorn. The ore-deposits resemble the '^saddles" of the Bendigo Field, Victoria, Australia.* They ^ For these notes the writer is especially indebted to Mr. W. H. Weed, of the U. S. Geological Survey. See also S. F. Emmons, Tenth Census, XIII., 97. The northeastern portion of Madison County has been mapped by A. C. Peale— Three Forks Folio, U. S. Geol. Survey- -by whom are also given notes on the mines Rec. ^ R. Pearce, "Notes on the Occurrence of Tellurium in an Oxidized Form in Montana," Proc. Colo. Sci. Soc, November 2, 1896. ^ S. F. Emmons, Tenth Census, XIII., 97. R. W. Barrell, "The Min- eral Formation at the Golden Leaf Mines," Eng. and Min. Jour., July 17, 1897, 64. * E. J. Dunn, "Quarterly Report to the Mining Department of Victoria," December, 1888. T. A. Rickard, " The Bendigo Gold Field," Trans. Amer. Inst Min Eng., XX., 463, 1891. 318 KEMP'S ORE DEPOSITS. occur along the contact of Cambrian slate, and underlying lime- stone, and are replacements of the limestone at the crests of shattered anticlines. The ores are silver sulphides in a quartz gangue, but with occasional large bunches of galena, and very beautiful crystals of calamine.^ 2.10.09. Silver Bow County. The mines around Butte are the chief if not the only ones of the county. Their general ge- ology and distribution will be found described under *' Copper" — in connection with the copper veins, and a map is there given of the local geology. The silver veins surround the copper ones on the north, southwest and west. Their geological rela- •J \S) '^■<^' 4f %, \\\i\ a846 6 78'> Fig. 124. — Cross section af vein at tlie Alice mine, Butte, Mont. TJie width of vein is 4S) feet. After W. P. Blake, Trans. Amer. Inst. Min. Eng., XVI, p. 72. 1. Granite country. 2. Softened granite with small veins. 3. Clay wall with decomposed granite. 4. Quartz, broken and seamed. 5. Clay and decomposed granite. 6. Quartz and manganese spar — "■ curly ore." 7. Quartz and ore—" hard vein." 8. Soft granite with vein- ets. i\ Hard-colored, hard granite of the hanging-v all country. tions and character are much the same, but in mineralogy and distribution they are different. The silver veins occur both in the basic (Butte) granite, and in the acidic (Bluebird) granite. They contain as gangue in addition to quartz, manganese com- pounds, rhodonite and rhodochrosite. The outcrops of the veins appear as blackened ledges of quartz, the stain being due to manganese oxides. The ores are sulphides of silver, galena, blende and pyrite, with almost no copper minerals whatso- ^ The above notes were chiefly furnished by Mr. W. H. Weed. See also S. F. Emmons, Tenth Census, Vol. XIII., p. 97. J. S. Newberry, "On Red Mountain," Annals N. Y. Acad. Sci., III., p. 251. Fig. 122. — Outcrop of the Wabash silver lode, projecting above the granite^ Butte, Montana. From a photograph by A. C. Beatty, 1896. ^^- ^^M^^---' -» -^ -..» • "^ /^\ - ^v ' ^ "^ ' i -' ^^5*: " "•" 7^i^ ■£ ^,' ;^ -.1- ^S:: ^r:.-^^ }\. -■* "^ *-v / ,Jf - I**-*. -'" i:*'"^.A^-'*'-*'^»^-^ • '- - •^ ; -.i W* -^'<^ ^- ^ - > ^ ' > - 1 ^, /f;-" » ^ -. ' - .-' - '" -^' .■'^•- ^-.-q;.;-. ' V.M ►.t^-^^ Fig. 12d.— Weathered granite, Butte, Montana. The boulders are due to the rounding off of blocks, produced by joints. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD, CONTINUED, 319 ever, except along the border between the copper territory and the silver. The veins display recognizable banding of ore and gangne. One series of locations embracing the Moulton, the Alice and the Magna Charta, has been called the Rainbow lode by J. E. Clayton from its crescentic sweep. In other respects, as regards faults, relation to the walls and general origin, the remarks already recorded under "Cop- per" will hold good. Auriferous gravels were early washed in the valley of Silver Bow Creek, and led to the discovery of the deep veins. ^ 2.10.10. Broadwater County has recently been organized, and contains quartz veins in slates near Winston, and auriferous pyrites in shattered granite at the Diamond Hill mines. Granite County, formerly a part of Deer Lodge, has important mines near Phillipsburg. The Granite Mountain mine is located on a fissure vein in granite, and yielded rich silver ores, with considerable gold. The vein adjoins sedimentary rocks, which are much metamorphosed by the granite.^ 2.10.11. Deer Lodge County. Placers are numerous along the Deer Lodge River, and auriferous quartz veins are not * The Butte Special Folio of the U. S. Geological Survey is the best work of reference. It is by W. H. Weed, S. F. Emmons, and Geo. W. Tower. W. P. Blake, "Silver Mining and Milling at Butte, Mont.," Trans. Amer. Inst. Min. Eng., XVI., 38. "Rainbow Lode, Butte, Mont.," Idem, XVI., 65. Rec. R. G. Brown, "The Ore Deposits of Butte City," Idem, XXIV., 543,1894. Rec. S. F. Emmons, "Notes on the Geolo- gy of Butte, Mont.," Idem., XVI., 49. C. W. Goodale, "The Con- centration of Ores in the Butte District, Montana," Idem, XXVI., 599, 1896. Richard Pearce, "The Associations of Minerals in the Gagnon Vein, Butte City," Trans. Amer. Inst. Min. Eng., XVI., 63. E. D. Peters, Mineral Resources of U. S., 1883-84, p. 374. E. G. Spilsbury, "Placer Mining in Montana," Eng. and Min. Jour., September 3, 1887, p. 167. Rec. " Silver Mines of Butte, Mont.," Ibid., April 18, 1885, p. 261. Wil- liams and Peters, on Butte, Mont., Eng. and Min. Jour*., March 28, 1885, p. 208, See also references under Butte Copper. ^ H. M. Beadle, "The Condition of the Mining Industry in Montana in 1S92," Eng. and Min. Jour., February 11, 1893, p. 123. W. H. Dodds. "Granite Mountain Mine," Colliery Engineer, December, 1892. G. W. Goodale and W. A. Akers, "Concentration, etc., with Notes on the Geol- ogy of the Flint Creek Mining District," Trans. Amer. Inst. Min. Eng., XVIII., 242, 1890. Rec. "The Granite Mountain Mine, " ^/ig. and Min Jour., December 10, 1887; November 23. 1889. 320 KEMP'S ORE DEPOSITS. lackiDg. In the extreme eastern part are the veins of the Bald Butte group in slates and intrusive diorite/ 2.10.12. Lewis and Clarke County. The placer mines, near Helena (in Last Chance and Prickly Pear gulches), were the first in the county to attract attention. They were found by the prospectors who spread through the Rocky Mountains as the California gold diggings gave out. Since then many auriferous quartz veins in granite and slates have been devel- oped. Some twenty miles north of Helena, in the town of Marysville, is the Drumlummon group of veins, which carry refractory silver and gold ores, in a quartz gangue, on the con- tact between a diorite boss and the surrounding metamorphic schists. There are also other veins in the granite. Dikes of intrusive rocks occur associated with the ore bodies.^ 2. 10. 13. Meagher County contains the Castle Mountain min- ing district, once the heaviest producer of silver-lead ores in the State. The Castle Mountains embrace a geological section from and including the Algonkian to the present. Intrusions of granite, diorite, various porphyritic rocks and surface flows of considerable petrographical range are likewise present. In the closing years of the decade of the eighties discoveries were made of silver-lead ores in the Carboniferous limestones, in the neighborhood of intrusions of porphyry and sometimes in the contact zones. After several years of activity, which was maintained despite the remoteness from rail, the low price of silver caused their shutting down. The Cumberland mine, the largest opened, formed a chimney or tubular mass in the lime- stone, and was proved for over 500 feet in depth. Copper- bearing veins were also found in the Belt shales of the Algon- kian in the northern portion of the area.^ In the extreme northern portion of Meagher County, and near the line with Cascade County, the two mining districts of * R. G. Brown, ''Georgetown Mining District," Eng. and Min. Jour., October 13, 1894, 345. E. G. Spilsbury, "Placer Mining in Montana," Ibid., September 3, 1887, p. 167. ^ J. E. Clayton, "The Drumlummon Group of Veins," etc.; Eng. and Min. Jour., August 4 and 11, 1888, pp. 85, 106. S. F. Emmons, Tenth Ce7isus, Vol. XIII., p. 97. L. S. Griswold, "The Geology of Helena, Mont., and Vicinity," Jour, of the Assoc. Eng. Soc., XX., January 1898. ^ Weed and Pirsson, "The Castle Mountain District, Montana," Bull. 139, U. S. Geol. Survey, 1896. SILVER AND GOLD, CONTINUED. 321 Neihart and Barker are located in the Little Belt Mountains, but their outlets are to the north at Great Falls. At Neihart there is a series of fissure veins running north and south, in metamorphic gneisses and schists which are cut by diorite. The veins are narrow and barren in the dark colored gneisses and the diorite, but carry large bodies of galena, with zinc- blende and pyrite in the feldspathic gneiss. The vein filling is replaced and altered country rock with quartz seams in it. The quartz seams in some mines contain much polybasite, pyrargerite and chalcopyrite, carrying very high values in gold and silver. Dikes and larger intrusions of quartz-porphyry also occur, but are unfavorable to the veins, as in them the lat- ter split up and become barren, except within a hundred feet of the surface. At Barker the ores are chiefly silver- bearing galena and occur along the contact between granite-porphyry and limestone.^ 2.10.14. Cascade County contains important coal mines and the smelting center at Great Falls. In Missoula County at Quigley, southeast of Missoula, there is auriferous pyrite in slates of Lower Cambrian or Algonkian age (W. H. Weed). At Iron Mountain operations were formerly carried on, but are now suspended, and there are various minor camps throughout the country.^ The latter statement applies as well to Ravalli County in the south. Within the limits of the Lewis and Clarke Timber Re- serve there are occasional intrusions of porphyritic rocks in the Algonkian or Lower Cambrian shales and limestones, and in the neighborhood of the igneous rocks copper deposits are found. ^ The Reserve lies in several counties. Similar depos- its are found amid the high peaks of the Continental Divide <5n the so-called '*Roof of the Continent,'* along the line of Flat- head and Teton counties.* ^ The XX. Ann. Rep. of the Director of the U. S. Geol. Survey, which will probably be issued in 1901, will contain a paper by W. H. Weed, on the ' ' Mining Districts of the Little Belt Mountains. " The above notes have been kindly furnished by Mr. Weed, in advance of his longer paper. " F. D. Smith, "The Cedar Creek Placers," Eng. and Min. Jour., Feb- ruary 4, 1899, 143. ^ R. H. Chapman, "Geological Structure of the Rocky Mountains with- in the Lewis and Clarke Timber Reserve." Read at the New York meet- ing, Amer. Inst. Min. Eng., February, 1899. * G. E. Culver, " Notes on a little known Region in Northwestern Mon- tana," Trans. Wis. Acad, of Science, Arts and Letters, VIII., 187, 1891. 322 KEMP'S ORE DEPOSITS. 2.10.15. In Flathead County, in the extreme northwestern corner of the State, on Libbey Creek and the Yak River, there have been recently discovered large deposits of gold-bearing pyrrhotite in diorite similar in geological relations to the ores subsequently described at Rossland, B. C. Tellurides were re- ported some years ago at a little camp called Sylvanite. 2.10.16. Cboteau and Fergus Counties. Very great scien- tific interest and considerable economic importance are attached to several new districts, that have been opened up in the small outlying groups of mountains, which rise from the plains well to the east of the main chain of the Rocky Mountains. They are all characterized by intrusions of igneous rocks, rich in alkalies, such as syenite-porphyries, phonolites, and related types. These are the rocks which are present in the Black Hills, where, in the Potsdam sandstones, tellurides of gold occur, associated with fluorite; and at Cripple Creek, Colo., where the ore and gangue are the same. Weed and Pirsson have described the geology of the Little Rocky Mountains. In the central portion of a roughly elliptical area of upheaval, crystalline Archean schists are seamed by intrusions of granite- porphyry, syenite-porphyry, and, near Landusky, by phonolite, Cambrian, Siluro-Devonian, Carboniferous and Jurassic strata mantle the edges. The ore and gangue are found coating the fragments of decomposed porphyry, but do not seem to lie along well-defined veins. ^ The parallelism with Cripple Creek is close. The Little Rockies are situated in Choteau County, 180 miles east of the main Rockies. The Judith Mountains, in Fergus County, nearer the central part of the State, are larger, but of much the same geological structure. A core of syenite-por- phyry is surrounded by the sediments, which have been up- lifted by its intrusion as a laccolite. It is associated with phonolite. Where the igneous rocks cut the sedimentaries and especially along their contacts with a white Carboniferous limestone free gold and tellurides with associated fluorite are * W. H. Weed, "Ore Deposits of the Little Rocky Mountains," ^ngr. and Min. Jour., May 2, 1896, 423. Weed and Pirsson, "Geology of the Little Rocky Mountains," Jour, of Geol, IV., 399, 1896. See also E. S. Dana, in Col. Wm. Ludlow's "Report of a Reconnaissance from Carroll,. Montana, to the Yellowstone National Park," War Dept., Washington. 1876, 127. SILVER AND GOLD, CONTINUED. 323 found in the brecciated limestone/ Lewiston and Maiden are the chief settlements. The Sweet Grass Hills near the Canadian line in Chotean County are similar in geology and have been the scene of some placer mining. Other groups of mountain, such as the High wood and Bearpaw ranges, which are piles of volcanic lavas and tuffs, are known to contain richly alkaline, igneous rocks, but ore bodies have not yet been reported.^ IDAHO. 2.10.17. G^eo^ogf^. —The southern part of the State extends into the alkaline deserts of the Great Basin, and is dry and barren. North of this is the Snake River Valley, which is filled by a great flood of recent basalt, which stretches from the Wyoming line nearly across the State. North of the Snake River a large area of granite appears in the western portion, and contains many mines. Extensive deposits of gravel also occur. Metamorphic rocks and Paleozoic strata largelj^ consti- tute the northern portion of the State, and are penetrated by many igneous intrusions. The eastern part lies on the western slopes of the Bitter Root Mountains, whose general geology was outlined under Montana. The geology of Idaho has been but slightly studied, and the few reliable records have resulted from the scattered itineraries of Hay den's survey, iso- lated mining reports, and the collections of the Tenth Census,^ * W. M. Courtis, "Gold in Fossiliferous Limestone in the Judith Moun- tains," Eng. and Mm. Jour., June 28, 1884, 478. H. C. Freeman, "The Ammon Mines, Fergus Co., Mont.," Idem, May 4, 1895, 416. W. H. Weed, "Mineral Resources of the Judith Mines," Idem, May 23, 1896, 496. Weed and Pirsson, " Geology and Mineral Resources of the Judith Moun- tains," XVIII Ann. Rep. U. S. Geol. Survey, Part III., p. 437. ' Weed and Pirsson, ' ' High wood Mountains of Montana, " Bull. Geol. Soc. Amer., YL, 389. "Bearpaw Mountains, " ^mer. Jour. /Sci., May, 1896, 283 ;June, 351; August, 136; September, 188. "" G. F. Becker, Tenth Census, Vol. XIII., 52. F. H. Bradley, Hayden's Survey, 1S72, p. 208. G. H. Eldredge, "A Geological Reconnaissance across Idaho," XVI Ann. Rep. Dir. U. S. Geol. Survey, II., 217. F. V. Hay den, Ann. Rep., 1871, pp. 1,147; 1872, p. 20. W. Lindgren, "Mining Districts of the Idaho Basin and the Boise Ridge, Idaho," XVIII Rep. Dir. U. S. Geol. Survey, Part III., p. 617. Pec. Boise Folio, ?7. S. Geol. Survey. Rec. Other folios are in preparation. An extended paper by Lindgren is in press for the XX. Ann. Report of the U. S. Geol. Survey, which will 324 KEMP'S OliE DEPOSITS. but it is now receiving much attention from tiie U. S. Geologi- cal Survey. 2. 10. 18. The extreme northern portion of Idaho has assumed increasing interest in recent years on account of the notable mining developments in the neighboring parts of British Columbia, but discoveries are still largely in the nature of prospects. Kootenai County forms the so-called ''pan-handle," and in it some gold -quartz veins and placers are known. The great silver-lead mines of Coeur d'Alene in Shoshone Count}' have already been described (2.08.22). Some scattered mining camps occur in Talah, Nez Perces and Idaho counties to the south. In the extreme southern tongue of Idaho County is the Sheep Mountain district. The country rock is granite, with associated schists and slates in larger or smaller masses, often as inclusions. There are also dikes of quartz-porphyrites and diorite porphyrites. The ores are impregnations of zones of the schists or slates, with silver- bearing galena, and antimonial and arsenical sulphides.^ 2.10.19. In Lemhi County is the famous old gold diggings at Leesburg, which had a large population in 1859 --60, but which are now practically abandoned except for an extensive hydraulic workings at California Bar, further down Napias Creek. In the western side of Lemhi County is Yellow Jacket, with gold ores associated with a complex series of intruded Igneous rocks, in metamorphic schists.^ The^ ores lie along fractured zones and in the Columbia properties are chiefly gold- bearing chalcopyrite. H. H. Armstead, Jr., informs the writer that tellurides have also been detected. In the Yellow Jacket mines the ore is free-milling quartz. In northeastern Lemhi County is Gibbonsville, where auriferous pyrite occurs in quartz veins in slates.^ 2.10.20. Custer County lies south of Lemhi and contains several well-known mines. The Ramshorn is in metamorphic probably be issued in 1901. J. S. Newberry, '* Notes on the Geology and Botany along the Northern Pacific Railroad," Annals, N. Y. Acad. Sci., III. 252. Raymond's Reports on Mineral Resources West of the Rocky Mountains. O. St. John, Hayden's Survey, 1877, p. 323; 1878, p. 175. \ G. H. Eldredge, XVI. Ann. Rep. U. S. Geol. Survey. Part II., p. 258. ' G. H. Eldridge, "A Geological Reconnaissance Across Idaho," XVL Ann. Rep. U. S. Geol. Survey, II., 259. » B. MacDonald, Eng. and Min. Jour., October 3, 1896, 319. Fig. 125. — The old gold diggings on Napias Creek, Leeshurg, Idaho, illus trating an abandoned placer camp. From a photograph by J. F. Kemp, 1896. Fig. 136.— Ftew on Napias Creek, below California Bar, Idaho, after a freshet. From a photograph by J. F. Kemp, 1896. SILVER AND GOLD, CONTINUED. 325 slates on a fissure vein that has rich chutes of high-grade sil- ver ores in a siderite gangue. The Custer and the Charles Dickens are farther west, near Bonanza City, and afford both silver and gold in quartz gangue from veins in porphyry. Smelting ores occur in the region, and have been used in some operations based on this treatment. Boise and Elmore coun- ties, on the west and southwest of Custer, contain very impor- tant mining districts. Lindgren has shown the extensive de- velopment of a gray, rather basic granite, having close affini- ties with the quartz-mica-diorites. It is penetrated by numer- ous dikes of porphyries and minettes and is covered by Tertiary lake beds and effusive rocks. The granite has suffered consid- erable faulting, usually on a small scale, and in a number of districts the fissures thus formed have been the scene of ore de- position. Their general characters are shown by Fig. 127. They may occur as single and isolated fissures, as parallel series, or as lines of crushing with disjointed vein fillings. Quartz is the almost invariable gangue, calcite being very subordinate. The metallic minerals arepyrite, gold, arsenopy- rite. zincblende and galena. These sulphides likewise impreg- nate the wall rock, but they are then low in the precious metals. Silver is invariably present, and in the Banner district in Elmore County, it is the chief source of value. At Atlanta, likewise in Elmore County, the lode is of quite extraordinary size, being known for two and one-half miles, with an average width of sev- enty-five feet, and with many spurs. The pay ore occurs in four or five shoots in the main vein, which are of moderate widths. Silver predominates over gold. In the neighborhood of the gold- bearing veins in granite, placers have been and are extensively operated, and indeed, led to the settlement of the country. The principal deep- mining localities are the Idaho City belt, the Quartzburg-Grimes Pass belt, both within the depression known as the Idaho Basin ; and then in the mountains to the west, called the Boise ridge, there are the Neal, Black Hornet, Boise, Shaw Mountain, Willow Creek and Rock Creek districts.^ » J. E. Clayton, "Atlanta District," Trans. Amer. Inst Min. Eng., VI., 468. G. H. Eldridge, " A Geological Reconnaissance Across Idaho," XVL Ann. Rep. U. S. Geol. Survey, 217. W. Lindgren, " Mining Districts of the Idaho Basin and the Boise Ridge, Idaho," XVIII, Idem, Part III., p. 617. Rec. The Boise Folio, U. S. Oeol. Survey. Rec. An important paper may be expected in the XX Ann. Rep. of the Survey. KEMP'S ORE DEPOSITS. cz: '•///' / // W / A^J ' #' ' • J// // /^'^ •^ f; ^/''',^^^~ ^# '/J// ^^^^''^ ^ / 7//^^ ■ ■• / // -'/ ^p^\ MM. M mm 10 feet 6 El Fig. 137. — Sections to illustrate typical gold veins in the Boise granite region, Tdaho. After W. Lindgren, XVIII. Ann. Hep. U. S. Oeol. Survey, Part III., Plate XC. 1. Simple fissure vein on one fault plane, with quartz filling, which alone is ore. Wall-rock altered, but barren. 2. Complex fissure with four fault planes. Rich ore fills the long nar- row openings and impregnates adjacent, altered wall-rock. 3. Simple, narrow, fissure vein, filled with ore which also impregnates altered wall-rock. 4. Complex fissure vein, with two fault planes. Intermediate rock and outer walls altered, the former also sheeted. 5. Irregu- larly shattered zone between two fault planes. Intermediate rock excessively altered. Quartz fills seams and cracks. 6. Quartz vein of rich ore along under side of altered porphyry dike and with branches into hanging. Altered dike forms low-grade ore. SILVER AND GOLD, CONTINUED. 327 2.10.21. Alturas County contains one very important silver- lead district, the Wood River, which has been earlier referred to (under Example 32a). Owyhee County forms the southwest- ern corner of the State. Apparently the same granite that is so prominent in Boise and Elmore reappears from beneath the intervening Tertiary deposits, and comes up near Silver City. Still further southwest quartz- porphyry and metamorphic rocks are found with dikes of basalt. Gold-quartz and high-grade sil- ver ores are present. The Poorman Lode is famous for ruby silver ores. W. P. Blake mentions seeing a piece from this mine at the Paris Exposition which weighed about 200 pounds.* It was awarded a gold medal. The crystal from which it was broken weighed 500 pounds.^ In Cassia, Logan, Oneida and other counties in the southern part, placers are being or have been worked, and in Bear Lake County, in the southeast corner, salt and sulphur deposits are recorded.* The gold of the Snake River sands is extremely fine, and difficult to save. ^ Amer. Jour. Sci., ii., XLV., 97. ^ Raymonds Reports on Mineral Resources West of t?ie Rocky Mountains, 1868, p. 533. 3 G. F. Becker, Tenth Census, Vol. XIII., p. 59. T. Egleston, "The Treatment of Fine Gold in the Sands of the Snake River, Idaho," Trans. Amer. Inst. Min. Eng., XVIII., 597. Raymond's Reports on Mineral Re^ sources West of the Rocky Mountains. Rep. Dir. of the Mint, 1882, p. 227. * CHAPTER XL SILVER AND GOLD, CONTINUED. — THE REGION OF THE GREAT BASIN, IN UTAH, ARIZONA, AND NEVADA. UTAH. 2.11.01. Geology.— 'The eastern half of Utah, terminating with the western front of the Wasatch, is in the Colorado Plateau, but the western is within the limits of the Great Basin. The plateau portion consists largely of Mesozoic strata, quite horizontal and more or less carved by erosion. The east and west arch of the Uintah Mountains, in the northern part, has upheaved therii, so that where the Green River has cut a channel across, the Paleozoic is exposed in great strength. The Wasatch range rises with a gradual ascent from the east, and then terminates with a great fault line, having a steep westerly fro^. This line of weakness was developed in the Archean and has been a scene of movement even to recent times. It is a very important structural feature. West of the Wasatch, which is a fine example of block-tilting in mountain-making, the mountains belong to the Basin ranges, which are more typ- ically developed in Nevada. The Wasatch section was shown by the Fortieth Parallel Survey to involve 12,000 to 14,000 feet of the Upper Archean, and nearly 30,000 feet of the Pale- ozoic. In southern Utah the Triassic rocks are important and contain some rich mines. ^ » G. F. Becker, Tenth Census, XIII., 38. Whitman Cross, "The Lacco- litic Mountain Groups of Colorado, Utah and Arizona," XIV. Ann. Rep. U. S. Geol. Survey, Part II., 165. C. E. Dutton, Report on the High Pla- teaus of Utah, Washington, 1880. S. F. Emmons, "Origin of Green River," Science, VI., 19, 1897. Sir. A. Geikie," Archean Rocks of the Wa- satch Mountains," Amer. Jour. Set., iii., XIX., 363. G. K. Gilbert, "Lake Bonneville," Monograph I., U. S. Geol. Survey, and II. Ann. Rep., 169-300. SILVER AND GOLD, CONTINUED. dW 2. 11.02. The greater number of the Utah mines are for lead- silver ores, and have been mentioned under *' Lead- silver." The northwestern county, Box Elder, is in the alka- line desert region of the Great Basin. The mining districts occur in the central part of the State, in the Wasatch and Oquirrh mountains, and are also found in the extreme south- west. 2.11.03. Ontario Mine. Nearly east of Salt Lake City, in Summit County, is the Ontario mine, a vein from four to twenty-three feet wide (averaging eight feet), in quartzite, but extremely persistent, being opened continuously for 6,000 feet. In the lower working a porphyry dike has come in as one of the walls. It is extensively altered by f umarole action to clay. The best parts of the mine have quartzite walls. The ores consist of galena, gray copper, silver glance, blende, etc. The Ontario vein extends through a number of claims and at least one other important vein is known, the Daly West, which however, has one wall, limestone. Its product and the latter developments on the Ontario have changed the camp to a lead- silver producer.^ 2.11.04. The lead-silver veins of Bingham Canon, in Salt Lake County, have already been mentioned. Reference may "The Ancient Outlet of the Great Salt Lake," Amer. Jour. Sci., iii., XV., 256; XIX., 341; see also A. C. Peale, Ibid., XV., 439. "The Henry Mountains," Washington, 1877. R. C. Hills, " Types of Past Eruptions in the Rocky Mountains," Proc. Colo. Sci. Soc, IV., 14. International Geo- logical Congress, Washington meeting, 1891, Guide Book to the Rocky Mountains. J. D. Irving, " The Stratigraphical Relations of the Browns' Park Beds, Utah," Trans. N. Y. Acad. Sci., XV., 252. Hague, King, and Emmons, Fortieth Parallel Survey, Vols. I. and II. O. C. Marsh, " On the Geology of the Eastern Uintah Mountains," Amer. Jour. Sci., iii., I., 191. H. Montgomery, "Volcanic Dust in Utah and Colorado," Science, I., 656, 1895. B. Silliman, " Geological and Mineralogical Notes on Some of the Mining Districts of Utah Territory," ^mer. Jour. /Sci, iii.. III., 195. G. O. Smith, "Igneous Phenomena in the Tintic Mountains, Utah," Science, VII., 502, 1898. J. Walther, "The North American Deserts," Nat. Geog. Magazine, IV., 163. Wheeler, Gilbert, Lockwood and others, on Western Utah, Wheeler's Survey, Rep. Prog., 1869-71-72. Idem, Final Reports, III. * T. J. Almy, "History of the Ontario Mine, Park City, Utah," Trans. Amer. Inst. Min. Eng., XVI., S5. "The Ontario Mine," Eng. and Mm. Jour., May 28, 1881, p. 365. D. B. Huntley, Tenth Census, Vol. XIII., p. 438. H. L. J. Warren, "The Daly West Mine. Park City, Utah," Eng and Min. Jour., October, 14, 1899. 330 KEMP'S ORE DEFOSITS. again be made to the great bed-veins of gold quartz associated with them. Ophir Canon and Dry Canon, in Tooele County, and the Tintic district, in Juab County, have also been de- scribed. In addition to the smelting ores, others have been treated by milling. Quite recently interest has been directed to the mines of the Camp Floyd district, of which Mercur is the chief town. Rich deposits of gold ores, formerly refrac- tory, have yielded to the cyanide process, and have given a new and large lease of lite to a district that was abandoned years ago, after having had a short career as a silver producer. Mercur is situated in the southern end of the Oquirrh Moun- tains, in a valley known as Lewiston Canon. A thick series of Carboniferous limestones and very subordinate shales has S e-g; S> Gulch 8.66 30 W. i§ ll ~ B Tremont j^ ^ 14 Hin II Va. - "tdwef XTmestoi Great Blue Limestone lower inter- calated Series Lower SECTION E-E. Fig. 128. — Geological cross- sections at Mercur, Utah, reduced from colored ones by J. E. Spurr; XVI. Ann. Rep. Dir. U. S. Geol. Surmy, Plate XXVII. The sections cut each other at right angles. been folded into a low anticline, as shown in Fig. 128, whose axial crest is also folded , so that the beds constitute a Ioav dome or swell. One great stratum of limestone has been intruded by an interstratified sheet of quartz-porphyry, locally called the Eagle Hill porphyry, which at the most productive mines has split into three thin sheets, each 150 feet or less from its neighbor. At some time after the intrusion, ore-bearing circu- lations percolated along the lowest sheet and impregnated the limestone for a zone, usually 10 to 20 feet thick, but reaching even 50 feet or more, with silver-bearing minerals in a gangue of cherty quartz. Where mined the silver was present in thin films of the chloride coating fragments of the chert and lime- SILVER AND GOLD, CONTINUED. 331 stoDe. Associated metallic minerals are few. Stibnite is known, and pyrite has been detected with the microscope. Car- bonates of copper have been noted. As gangue minerals cal- QUAETZ-PORPUYRY ORE FRESH LIMESTONE (Altered) (Altered limestone} Fig. 129. — Diagram showing relations of ore to fault in Tunnel No. 3, Marion Mine, Mercur, Utah. Scale ^0 feet to the inch. After J. E. Spurr, XVI. Ann. Rep. U. S. Geol. Survey, 430. of Tunnel QUAKTZ-PORPHYRT (Altered ) ORE (Altered limestone, containing bowlders of decomposition.) FRESH LIMESTONB Fig. 130, — Section along the (leyser mine tunnel, Mercur, Utah. After J. E. Spurr, XVI Ann. Rep. V. S. Geol. Survey, 422, cite and barite are next to chert in abundance. Spurr favors heated waters as the vehicles of the ore. Long after the silver ores had been deposited the gold series were formed, probably as tellurides, along the contact of the next overlying sheet of 332 KEMP'S ORE DEPOSITS. porphyry. They are now found where this sheet is cut by a series of small northeast fissures in the limestone, which fis- sures are thought with great reason by Spurr to have been the conduits through which the ores were introduced. The gold in the oxidized ores is in some condition that is readily soluble in potassium cyanide, but it is uncertain what that state is. Re- algar and occasionally cinnabar are associated with it. In the unoxidized ores pyrites are abundant, but the gold is but slightly attacked by the cyanide. It is thought to have been deposited as a telluride. The ores average about ten dollars per ton. The region is poorly supplied with water, and all the springs are carefully utilized. R. C. Hills, ^ in the paper cited below, explained the ores as introduced through a series of fis- sures which, now filled with calcite, penetrate to the chutes. J. E. Spurr, ^however, regards the open fissures along which the chutes extend, as the conduits, and favors a vaporous or fuma- rolic method of introduction. A laccolite of igneous rock at some unknown point below is suggested as the source of the vapors.^ Considerable interest has been directed of late to the mines of the Deep Creek district, on the extreme western border of Utah, in the Ibapah range. Limestones regarded by Blake as Car- boniferous, and other sedimentary rocks, have been broken through by great outflows of granite, andesite, hypersthene-an- desite, etc. The ore bodies appear to be contact deposits in limestone near igneous rocks, and carry much free gold.* * R. C. Hills, "Ore Deposits of Camp Floyd District, Tooele Co., Utah,'* Proc. Colo. Set. Soc, August 6, 1894. Rec. ^ J. C. Spurr, "Economic Geology of the Mercur Mining District, Utah," with an Introduction by S. F. Emmons. XVI. Ann. Rep. Dir. U. S. Oeol. Survey, II., 349. Rec. 'Other papers on Mercur are the folio «^^ing: R. C. Gemmell, "The Camp Floyd Mining District and the Mercur Mine, Utah," Eng. and Min. Jour., LXIII., 403, 1897. A. Lakes, "The Oquirrh Mountains or the Mer- cur Mining District, Utah," Colliery Engineer, XVI., 243, 1896. W. H. Moeller, "The Mercur Gold Deposit in the Camp Floyd District, Utah," Eng. and Min. Jour., LVII., 51, 1894. D. Maguire, "Gold Mines of Mercur," Mines and Minerals, XIX., 81, 130, 1898. J. W. Neill, "Camp Floyd District, Utah," Eng. and Min. Jour., LXI., 85, 1896. * W. P. Blake, " Age of the Limestone Strata at Deep Creek, Utah, and the Occurrence of Gold," etc., Amer Geol. , January, 1892, p. 47. Eng. and Min. Jour., February 23, 1892, p. 253. S. F. Emmons, Fortieth Parallel ^mrl Fig. ISl.— Open cut, showing the pay-streaJc, at Mercur, Utah. From a photograph by P. K. Hudson, 1898. Fig. 132. — The Golden Gatecyanide mill, Mercur district, Utah. From a photograph by^L. E. Biter, Jr., 1898. SILVER AND GOLD, CONTINUED. In Beaver County the interesting deposits of the Horn Sil- ver, the Carbonate, and the Cave ore bodies have been men- tioned under Examples 30g, 33a, and 32&. The iron ore bodies of Iron County will be found under Example 14. In Piute County, near the town of Marysvale, around Mount Baldy, are a number of mines with lead-silver or milling ores in quartz porphyry (copper belt), or between limestone and quartzite (Deer Trail, Green-eyed Monster, etc.). Selenide of mercury is found in the Lucky Boy.^ 2.11.05. Example 41. Silver Reef, Utah. Native silver, cerargerite and argentite, impregnating Triassic sandstones, and often replacing organic remains. These deposits were earlier referred to under Example 21, p. 80. They were dis- covered in 1877. At Silver Reef there are two silver-bearing strata or reefs, with beds of shale between. Above the water- Ore Runs Into_ barren rock Fig. 133. — Two sections of the argentiferous sandstone of Silver lieef, Utah. After C. M. Rolker, Trans. Amer. Inst. Min. Eng., IX., p. 21. line the ore is horn silver; below it is argentite. At times it replaces plant remains; at other times no visible presence of ore can be noted, although the rock may afford $30 to the ton. The silver always occurs along certain ore channels, distributed through parts of the sandstone. The origin of the deposits has given occasion to a vigorous discussion. J. S. Newberry held that the silver was deposited in and with the sandstone from the Triassic sea, although it may have been concentrated since in the ore channels. F. M. F. Cazin holds that the or- ganic remains were deposited in and with the sandstone, and that these were the immediate precipitating agents of the ores. R. P. Rothwell explained them much as does Rolker, below. Survey, Vol. II., p. 475. J. F. Kemp, • ' Petrographical Notes on a Suite of Rocks Collected by E. E. Olcott," Trans. N. Y. Acad. Scl, XI., 127, 1892. * G. J. Brush, " On the Onofrite," etc, Amer. Jour. Sci., iii., XXI., 312. 334 KEMP' 8 ORE DEPOSITS. C. M. Rolker, who was for some years in charge of several of the mines has also written about them, and is probably nearest to the truth. Rolker argues that the impregnation was subsequent to the formation of the sandstone, and was caused by the igneous outbreaks in the neighborhood, and probably runs along old lines of partial weakening or crushing that afterward healed up. Eruptive rocks are known in the neighborhood of the ores both in Utah and in the Nacemiento copper district of New Mexico. From what we know of ore deposits in general this seems most probable.^ ARIZONA. 2.11.06. Geology. — Arizona lies partly in the plateau re- gion, and partly in the Great Basin. The Basin ranges con- verge with the Rocky Mountains, which, however, are chiefly in New Mexico. The uplands of the ranges are well watered and covered with timber, but the low-lying portion of the Great Basin is an arid desert, and in southwestern Arizona is the hottest part of the United States. Cretaceous and Jura- Trias largely form the plateau region. Running southeast to northwest is the great development of Carboniferous limestone so often referred to under ** Copper," and underlying this are found Archean granites, gneisses, etc. A great series of ore deposits is ranged along this contact. In the southwest are mountains of granites and metamorphic rocks. The Territory also contains vast flows of igneous rocks, and in the plateau country between the converging ranges some 20,000 or 25,000 square miles are covered by them. The Grand Canon of the Colorado has laid bare a magnificent geological section of many thousand feet, from the Archean to the Tertiary.^ * F. M. F. Cazin, ' ' The Origin of the Copper and Silver Ores in Triassic Sandrock," Eng. and Min. Jour., December 11, 1880, p. 381; April 30, 1881, p. 300. " The Silver Sandstone Formation of Silver Reef," Ibid., May 22, 1880, p. 351; January 10, 17, 24, 1880, pp 25, 48, 79 (Rothwell). A. W. Jackson, "Silver in Sedimentary Sandstone," i^ep. Dir. of Mint, 1882, p. 384, reprinted from Cal. Acad. Sci. J. S. Newberry, "Report on the Properties of the Stormont Silver Mining Company," etc., Eng. and Min. Jour., October 23, 1880, p. 269. "The Silver Reef Mines," Ibid. January 1, 1881, p. 4. C. M. Rolker, "The Silver Sandstone District of Utah." Trans. Amer. Inst. Min. Eng., IX., 21. ' " Central Arizona," Eng. and Min. Jour., April 23, 1881, p. 285. " Col orado River of the West," review of Ives Expedition, Amer. Jour. Sci., ii SILVER AND GOLD, CONTINUED. 335 2.11.07. Apache County is in the northeastern corner. In the southern part of the county gold and silver ores, in veins in limestone, associated with copper ores, are reported, and some small placers. 2.11.08. Yavapai County. Gold and silver ores, in quartz veins, in granite and metamorphic rocks. The Black range copper district has already been referred to under Example 20e. Mohave County. Silver sulphides, arsenides, etc., and alter- ation products in veins in granite, at times showing a gneissoid structure. Only the richest can now be worked. Yuma County. Quartz veins, with silver ores and lead min- erals in metamorphosed rocks (gneiss, slate, etc.), or in gran- ite. Maricopa County contains both Paleozoic and Archean ex- posures. The ore deposits lie mostly along the contact of the two, in granite or highly metamorphosed strata. They are usually quartz veins, with silver ores and copper, lead, and zinc minerals. The Globe district, extending into Pinal County, is the principal one. Mention has already been made of it under "Copper," Example 20c. Pinal County adjoins Maricopa on the south and contains a number of important mines. They produce mostly silver ores, with lead and copper associates, and some blende. The gangue minerals are quartz, calcite, etc., occasionally manganese com- pounds, and sometimes, in the granites, barite. Limestone, slate, sandstone, and quartzite, as well as granite, diabase and diorite, occur as wall rock. 2.11.09. Silver King Mine. A central mass or chimney of quartz, with innumerable radiating veinlets of the same, carry- ing rich silver ores and native silver, in a great dike of feld- XXXIII., 387. G. F. Becker, Tenth Census, Vol. XIII., p. 44. C. E. But- ton, " The Physical Geology of the Grand Canon District," abstract of Monograph II., Sec. Ann, Rep. Dir. U. S. Geol. Survey, 49-161 ; see also the Monograph. Patrick Hamilton, The Resources of Arizona, A. L. Bancroft & Co., San Francisco, 1884. B. Silliman, "Report on Mining Districts of Arizona, near the Rio Colorado," Eng. and Min. Joi^r., August 11, 1877, p. Ill ; taken from Amer. Jour. Sci., ii., XLI., 289. C. D. Wolcott, "Permian and Other Paleozoic Groups of the Kanab Valley, Arizona," Amer. Jour. Sci., iii., XX., 221. " Pre-Carboniferous Strata in the Grand Canon of the Colorado, Arizona, " Amer. Jour. Sci., December, 1883, 437. Wheeler's Survey, Vol. III. , and Supplement. 336 KEMP'S ORE DEPOSITS. spar porphyry, with associated graoite, syenite (Blake), por- phyry, gneiss, and slates, all of Archean age. The veinlets ramify through the strongly altered porphyry, and form a stockwork, which furnished the principal ores. In the region are also Paleozoic strata, w^hose upper limestone beds are re- ferred by Blake to the Carboniferous. The minerals at the mine were native silver, stromeyerite, argentite, sphalerite, galenite, tetrahedrite, bornite, chalcopyrite, pyrite, quartz, calcite, siderite, and, as an abundant gangue, barite. Graham County contains the Clifton copper district, referred to under Example 20a. Cochise County is the southeastern county, and contains the Tombstone district, once the most productive of the precious metals in the Territory. 2.11.10. Tombstone. A great porphyry dike up to 70 feet thick, faulted and altered, and carrying above the water line in numerous vertical joints, or partings, quartz with free gold, horn silver, and a little pyrite, galenite, and lead carbonate. Curiously enough, in the porphyry itself and far from the quartz veins, flakes and scales of free gold have been found, evidently introduced in solution. Ore also occurs along the side of the dike. There are also other fissures parallel with this principal dike, and still another series crossing these and the axis of the great anticline of the district. Connected with these fissure veins are bedded deposits in the limestone, along the bedding planes or dropping from one to another, appearing to have originated by replacement. Blake offers two explana- tions of the first- mentioned dike deposit — either that the dike itself held the precious metals, or that thej^ came from the pyrite of the adjoining strata. Several other mining districts of less note occur in the county. The important copper deposits of the Bisbee region have already been mentioned under Example 20/. The most productive mine of the territory for the last year or two has been the Pearce at the town of the same name, but operated by the Commonwealth Co. It is a quartz vein as 5^et productive of oxidized ores containing silver and gold. 2.11.11. Pima County is the central county of the southern tier, and has Tucson as its principal city. There are numbers of mines of the precious metals, and a few less important copper deposits. SILVER AND GOLD, CONTINUED. 337 Yuma County, in the southwestern corner, has some mines along the Colorado River, on quartz veins in metamorphosed rocks, containing silver and lead minerals/ The Fortuna mine is at present the chief producer. NEVADA. 2.11.12. Geology. — Nevada lies almost entirely in the Great Basin, only the western portion heing in the Sierras. The surface is thus largely formed by the dried basins of 'former great lakes, principally Lakes Lahontan and Bonne- ville. A large number of ranges extend north and south through the State, known collectively as the Basin ranges. They have been formed by block tilting on a grand scale, and present enormously disturbed strata. The geological sections exposed are of surpassing interest (cf. Example 36), and show Archean and Paleozoic in great thickness. In these mountains are found the mining districts, while between them lie the alka- line plains.^ ^ G. F. Becker, Tenth Census, Vol. XIII., p. 44. G. H. Birnie, 'Castle Dome District," Wheeler's Survey, 1876, p. 6. W. P. Blake, "The Geology of Tombstone, Arizona," Amer. Inst. Min. Eng., X., 334; Eng. and Min. Jour., June 24, 1882, p. 328; The Silver King Mine, a short monograph, New Haven, March, 1883. Rec. See also Eng. and Min. Jour. , April 28, 1883, p. 238. J. F. Blandy, "The Mining Region around Prescott, Ariz.," Trans. Amer. Inst. Min. Eng., XI., 286; Eng. and Min. Jour., July 21, 1883. "On Tombstone, Arizona," Ibid., May 7, 1881, p. 316; March 18, 1882, p. 145. " Silver in Arizona," General Review, Eng. and Min. Jour., September 21 and 25, 1880, pp. 172, 203. "Central Arizona, ' Ibid., April 23, 1881, p. 285. O. Loew, "Hualapais District," Wheeler-'s Survey, 1876, p. 55. B. Silliman, " Report on the Mining District of Arizona near the Rio Colorado," Amer. Jour. Sci., ii., XLI., 289; see also Eng. and Min. Jour., August 11, 1877, p. 111. Raymond's Reports and those of the Di- rector of the Mint contain notes on the Arizona mines. "" J. Blake, "The Great Basin," Proc. Cal. Acad. Sci., IV., 275; Amer. Jour. Sci., iii., VI., 59. W. P. Blake, " On the Geology and Mines of Ne- vada" (Washoe Silver Region), Quar. Jour. Geol. Sci., Vol. XX., p. 317. H. G. Clark, "Aurora, Nevada: A Little of its History, Past and Present," School of Mines Quarterly, III., 133. G. K. Gilbert, "A Theory of the Earthquakes of the Great Basin, with a Practical Application," Amer. Jour. Sci., iii., XXVII., 49. I. C. Russell, "Geology and History of Lake Lahontan, a Quaternary Lake of Northwestern Nevada," Monograph, XL, U. S. Oeol. Survey; also. Third Ann. Rep. Dir. U. S. Geol. Sut-vey, 195. C. D. Wolcott, " Paleontology of the Eureka District," -Monogrrop/j 338 KEMP'S ORE DEPOSITS. 2.11.13. Lincoln County is in the southeastorh corner, and contains a number of small mining districts. The ores are in general silver-lead ores in limestone, or veins with sulphiiret ores in quartzite and granite. Pioche is one of the principal towns, near which is found the once famous and now reopened Raymond & Ely mine. A strong fissure cuts Cambrian quartzite and overlying limestone, where the latter has not been eroded, and is occupied by a great porphyry dike. Along the contact between the porphyry and the wall rock the chutes of ore have been found. Mi. Ernest Wiltsee, at the Montreal meeting of the American Institute of Mining Engineers, February, 1893, described and figured the Half Moon mine, on this same great fissure, where the quartzite still retained a limestone cap. The ore-bearing solutions, on reaching a shaly streak containing a limestone layer, departed from the fissure and followed under the limestone, so as to form a lateral enlargement, much like those described and figured from Newman Hill, Colorado, under 2.09.10. The Pahranagat and Tern Pahute districts, still fur- ther south, have had some prominence, but the whole region is so far from the lines of transportation that the conditions are hard ones.^ 2.11.14. Ney County, next west, has an important mining center, in its northern portion, around the town of Belmont. Quartzites and slates rest on granites in the order named, and in them are veins with quartz gangue and silver chlorides, affording very rich ores. Southeast of Belmont is Tybo.^ 2.11.15. White Pine County lies to the northeast, and con- tains the White Pine district. The principal town is Hamilton, about 110 miles south of Elko, on the Central Pacific. The Humboldt range is prolonged southward in some broken hills, consisting chiefly of folded Devonian limestone. At Hamilton these are bent into a prominent anticline, and this has a strong fissure crossing the axis. The geological section is Devonian VIII., U. S. Geol. Survey. Gilbert, Wheeler, Lockwood, and others, ' ' Eastern Nevada : Notes on its Economic Geology, " Wheeler's Survey, Rep. Prog., 1869, 71, 72; also Vol. III. and Supplement. For further lit- erature, see under Example 36. » E. P. Howell, Wheeler's Survey, III., 257. G. M. Wheeler, Report, Wheeler's Survey, 1869, p. 14. ' S. F. Emmons, Survey of the Fortieth Parallel, Vol. III., p. 393. G. K. Gilbert, "On Belmont and Neighborhood," Wheeler's Survey, III., 36. SILVER AND OOLW, CONTINUED. 339 limestone, thin calcareous shale, thin siliceous limestone, ar- gillaceous shale, probably Carboniferous sandstone, and Carbon- iferous limestone. The ore bodies occur, according to Arnold Hague, in four forms, all in the Devonian limestone: (1) in fissures crossing the anticlinal axis ; (2) in contact deposits be- tween the limestones and shales; (3) in beds or chambers in the limestone parallel to the stratification; (4) in irregular vertical and oblique seams across the bedding. The ore is chiefly chloride of silver in quartz gangue. It is thought by Mr. Hague to have probably come up through the main cross fissure, and, meeting the impervious shale, to have spread through the limestone in this way.* Egan Canon is in the northern part of the county, and shows a geological section of granite, quartzite, and slate in the order named. In slates, and perhaps extending into the quart- zite, is a quartz vein five to eight feet wide, carrying gold and silver ores. Eureka County is the next county west of White Pine. The deposits at Eureka have already been described under "Lead- silver." (Example 36.) 2.11.16. Lander County lies next west to Eureka. The Toyabe range runs through it from north to south, and in its southern portion, in Nej^ County, contains the Belmont depos- its. (See above, 2.11.14.) At Austin, which is 80 or 90 miles south of the Central Pacific Railroad, now connected with- it by a branch, are the mines of the Reese River district, named from the principal stream near by. From Mount Prometheus, which consists of biotite granite or granitite, and which is pierced by a great dike of rhyolite, a western granite spur runs out, known as Lander Hill. The ore bodies are in this hill, and are narrow fissure veins with a general northwest and southeast trend, carrj^ing rich ruby silver ores, with gray cop- per, galena, and blende, in a quartz gangue with associated rhodochrosite and calcite. They are also often faulted. At times they show excellent banded structure. Antimony has recently been found in this region.^ (See under "Antimony.") * J. E. Clayton, "The geological structure and mode of occurrence of the silver ores in the White Pine district," Cal. Acad. Set., IV., 89. A: Hague, Fortieth Parallel Survey, Vol. III., p. 409. * S. F. Emmons. Fortieth Parallel Survey, Vol. III., p. 349. 340 KEMP'S ORE DEPOSITS. 2.11.17. Elko County lies north of White Pine and Eureka counties, and contains the Tuscarora mining district. The deposits are high-grade silver ores in veins, in a decomposed hornblende andesite.^ Humboldt County is the middle county of the northern tier, and contains a number of mining disrticts, which produce both silver and gold from quartz veins in the Mesozoic slate. Small amounts of the precious metals come also from Washoe County, in the northwest corner of the State. ^ Churchill County adjoins Lander on the west, and pos- sesses a few silver mines. Esmeralda County, in the southwest, has a considerable number of rich silver and gold mines, which produce high- grade ores from veins, with a quartz gangue in metamorphic rocks, slates, schists, etc. (See also under **Nickel.") 2.11.18. Storey and Lyon are two small counties in the western central portion of the State, but the former contains the most important and interesting ore deposit in Nevada, if indeed it is not the largest and richest single vein yet discov- ered. 2.11.19. Comstock Lode. A great fissure vein, four miles long, forked into two branches above, along a line of faulting in eruptive rocks of the Tertiary age, and chiefly andesites. In the central part of the vein the displacement has been about 3,000 feet, shading out, however, at the ends. The ores are high-grade silver and gold ores in quartz, and occur in great bodies, called *' bonanzas," along the east vein. Over $325,- 000,000 in gold and silver has been extracted, in the ratio of two of the former to three of the latter. The vein lies on the easterly slope of a northeasterly spur of the Sierras. West of it is Mount Davidson. Theoutcroppings lie on the flank of the latter, about 6,500 feet above the sea and 1,500 below the sum- mit. The general strike of the vein is east of south, and it dips east. Views regarding the geology of the Comstock have changed in the course of years, as they have been influenced by the successive writings of Von Richthofen, King, Church, Becker, and Hague and Iddings, the points in especial controversy being the determinations of the rock species. * G. F. Becker, Tenth Cormis, Vol. XIII., p. 34. « Ibid., p. 33. SILVER AND QuLD, CONTINUED. 3il 2.11.20. It may be remarked that the whole scheme of the classification of the volcanic (effusive) rocks rests largely on Von Richthofen's earlj^ studies, and that perhaps the most im- portant generalization of late years is due to the work of Hague and Iddings on the same. Von Richthofen (1865) de- scribed the ore body as filling a fissure on the contact of a so- called syenite, and an eruptive rock that he called "propylite." The ore and gangue are thought to have been brought up from below by solfataric action, in which fluorine, chlorine, and Flank of Mt.Davidson x^ ^\^ y X ^ X x^N. X X X >< X X ^^ < X XX X.X V ^\^ X X X X X x'^x ^ ^ ?^>. xxxxxxx xx x^^ft^. Vj. X X X X X X X j^ Q^m^^-^T^^^^^ CiTy xxxxxxxxxxx ^^^^jUg^ L_>^__^^ X XX X XX X XXX X ><'Vl^^SVV+-*^+ •^+ T>-— ^-^ xXXXXXXXXXX Xx XO^Ir;^r3v7iA'''j- 4- + 4- 4- + -L 4- + T xxxxxxxxxxx X :k y ypjf^QPwW + 4- + + -4- + + + +"*" XXX XXXXXXXXXXX xX^>^r5>^\+ . + , ■tL + 4."^a-"^-U + j.'^a+ ..-> .»-*^H^^^^^^^H Fig. 138. — View in the Malakoff Hydraulic placer mine, North BloomjieldL, California. From a photograph. Fig. 139. — View in the Malakoff Hydraulic placer mine, North Bloomfield, California. From a photograph. THE PACIFIC SLOPE. 351 2.12.07. Calico District. Deposits of silver chloride in fissure veins, and in small fractures and pockets in lipa- rites, tuft's and sandstones, probably of the Pliocene series. They occur in Southwestern California, in that portion of the State belonging rather to the Greatps^asin than to the Pacific slope. An immense outbreak of liparite has formed a seri^R of elevations, and the attendant tuffs are extensively devel- oped. The ore is thought by Lindgren to have come in heated solution from below and to have filled the fissures and overflowed, forming the surface de- posits in the tuffs. (Cf. Silver Cliff, Colorado.) 2.12.08. Likewise in the desert re- gion, a gold camp has sprung up at Kandsburg, in Kern County. Mica schists form the country rock of a series of hills that rise above an abandoned XXVI., 288. J. D. Whitney and others, reports of the CaUfornia Geological Survey, issued at Cambridge, Mass. L. G. Yates, "Notes on the Geology and Scenery of the Islands forming the Southern Line of the Santa Barbara Chan nel," Amer. Geol, V., 43. The United States Geological Survey has prepared a number of folios on the geology of the gold belt, which are invaluable to all who are interested in the region. Each embraces a geological descrip- tion and maps, which severally show the topo- graphy, geology, and mineral resources. The following have been issued and can be ob- tained at 25 cents each by addressing the Di- rector of the U. S. Geological Survey, Wash- ington, D.C. (the Nevada City Folio is 50 cents) : Placerville, Sacramento, Jackson, Lassen Peak, Marysville, Smartsville, Nevada City, Pyramid Peak, Downieville, Truckee, Sonora and Big Tree. Others are in preparation. I- ^ ;.v>': :::'.'<*::•'■ 352 KE^fP'S ORE DEPOSITS. lake basio. The schists are seamed by dikes of porphyritic ruck, which may have come from the volcaoic ceDter of Red MouDtain or from other volcanic emiDences not far away. The rock from the central and south peaks of Red Mountain, when examined in thin sections from specimens kindly sent the writer by H. A. Titcomb, E.M., proved to be hornblende- andesite, but the dikes from the vicinity of the mines were too decomposed for recognition. The gold ores occur iuagjuartz veins, which usually are in association with the porphyry dikes, the country rock being the mica schist. The region suffers for lack of water, but as it is now connected by rail with the Santa Fe system, a number of mines and mills are in successful operation. The accompanying photograph (Fig. 130) illustrates the country.^ The remoteness of other camps militates against their development. 2.1*2.09. On the eastern border of California and lying along the ea^ern slopes of the Sierras are Inyo and Mono counties, two that have been quite serious producers of silver (with sub- ordinate gold) in past years. Deserted or greatly dwindled mining camps are frequently met throughout the mountains. The region lies within the confines of the Great Basin, and is somewhat poorly supplied with water. In Inyo County, gran- ite, schists and crystalline limestone are very prominent in the general geolc^y, and the ores are prevailingly of the lead-silver variety, and in limestone walls. The Cerro Gordo and Pana- mint districts were heavy producers in their day." Mono * F. M. Endlich, "Mining in the Mohave Desert of California," Eng. and Min. Jour.. August 29. 1896. 147. H. G. Hanks. -On the CaHco Dis- trict." Fourth Rep. Cal State Mineralogist. 1884. 366. Wm. Irelan, - On the Calico District. • Eighth Rep. Cal. State Mineralogist. 1888. 490. W. Lind gren. "The Silver Mines of Calico District. California," Trans. Amer. Inst. Min. Eng., XT.. 717. F. K Nason. "The Goler Gold Diggings. ' Eng. and Min. Jour., March 9, 1895. 2*33. W. A. Skidmore. "On Calico District," Rep. Director of the Mint. 1884. 539. Rec. Other Reports of the Director of the Mint and Raj-mond's earlier reports may be advantageously con- sulted. In the Min. and Sei. Press. April 1. 1899. will be found a sketch of the Randsburg district and of the Yellow Aster Mine. The notes in the text on Randsburg were based on specimens and data kindly furnished by the v\-riter's friend. H. A. Titcomb. ' H. DeGroot. "Report on Inyo County." Tenth Rep. Cal. State Mineralo gist. 1890. 209. W. A. Goodyear. "Report on Inyo County/' Eighth Rep. Cal. State Mineralogist. 1888, 324-309. Rec. H. G. Hanks, "SUver in THE PACIFIC SLOPE. 353 County lies Dext north of Inyo, and is remarkable for the vast de- velopment of volcanic rocks that it contains. While there are not a few mining districts in the county of no inconsiderable moment, details of which will be found in the references cited below, yet the pre-eminent one is Bodie. At Bodie a quite complex series of veins cut hornblende-andesite, over which, on the surface, is volcanic breccia. Various other eruptives occur in the neighborhood. The faults in which the veins are found have been formed at several different periods, but the tracing of their exact relations will require very careful work. The gangue is chiefly quartz, through which are distribjited silver minerals with more or less gold.^ Nearly all the other deep mines for the precious metals in California yield little else than gold, and although a few, such as those at Ophir, afford con- siderable silver, they will be mentioned with the distinctively gold-quartz veins. 2.12.10. Example 44. Auriferous Gravels. (1) River gravels, or placers in the beds of running streams. These have been often referred to in other States, but the type is placed in California, as they are there best known. They were the first gravels washed in 1849, and although substantially exhausted by 1860, were very productive. Eastward from the great Sacramento Valley the surface rises with a quite gentle gradi- ent to the summit of the Sierras. The country consists chiefly of metamorphic rocks, which have yielded a very few well- determined fossils of both Carboniferous and Jurassic ages; but the identity of the strata in all the area is diflScult to make out, because where the fossils were originally present they are almost entirely destroyed by metamorphism. Down California," Fourth Rep. Cal. State Mineralogist, 1884, 361. W. A. Skid- more, "Gold and Silver Mining in California, Past, Present and Future," Rep. of Director of the Mint, 1884, 538. ^ H. DeGroot, " Report on Mono County," Tenth Rep. Cal. State Mineralo- gist, 1890, 336. H. W. Fairbanks, "Mineral Deposits of Eastern Califor- nia," Amer. Geol., March, 1896, 144. "Notes on the Geology of Eastern California," Idem, February, 1896, 63; describes Mono and Inyo Counties. C. D. Walcott, "Lower Cambrian Rocks in Eastern California," ^wer. Jour. *Scl, February, 1895, 141. "The Appalachian Type of Folding in the White Mountain Range of Inyo County, California," Idem, March, 1895, 169. H. A. Whiting, "Report on Mono County," Eighth Rep. Cal. State Mineralogist, '^^2-^02. "On Bodie," 382-402. Rec. 354 KEMP'S ORE DEPOSITS. the slopes of the range the modern streams have flowed and cut deep canons in which gravels have gathered. Out in the more open country the gravels have also accumulated and have furnished some productive bars. The gold has been derived principally from the quartz veins of the slates, which are later described, and has been mechanically concentrated in the streams. Befone coming to its final rest it may have lodged in the high or deep gravels, of which mention will next be made. It is accompanied by magnetite as a general thing, by zir- con, garnet, and rarely by other heavy metals, such as plati- num and iridosmine. The greatest amount is usually near the bedrock, and when this is at all porous the gold may work into it to a small distance from the top. The gold is usually in flattened pellets of all sizes, from the finest dust to nuggets of considerable weight, which show evidence of being water worn. The interesting phenomena connected with the possible circula- tion of the precious metal in solution through the gravels are discussed under the deep gravels. Important deposits of the same general character as these have also been dug over, near Santa Fe, N. M. ; in California Gulch, near Leadville, Colo. ; at Fairplay, Colo. ; in San Miguel County, Colorado ; in the Sweetwater district, Wyoming; near Butte, Mont.; in Last Chance and Prickly Pear gulches, near Helena, Mont. ; in the Black Hills; in southern Idaho, especially along the Snake River; and at various points in Washington and Oregon. Placers of this type have also been found on the slopes of the Green Mountains and in the Southern States, but they never have proved of serious importance. 2.12.11. (2) High or Deep Gravels. With the exhaustion of the river gravels the gold seekers of California were driven to prospect on the higher slopes, where auriferous gravels much less accessible had long been noted. Increasing observation and development have shown that these are the relics of former and very extensive drainage systems, which were more or less parallel with the present streams, but of greater volume. The beds lie in deep gulches in the slates, and are capped in most cases by basaltic lava flows or by consolidated volcanic tuffs, called cement. They extend some 250 miles along the Sierras and up to 7000 feet above the sea. They have at times great thickness, reaching 600 feet at Columbia Hill, but drop THE PACIFIC SLOPE. 355 elsewhere to 1 or 2 feet. Thej- vary from a maximum width in workable material of 1,000 feet to a minimum of 150. The inclosing slates on the sides of the old river valley are called "the rims," and on them are sometimes found other gravels. In some districts channels, belonging to two or three periods of flow, have been traced. They tend to follow the softer strata, breaking at times across the harder rocks. The channel filling consists of gravel, sand, and clays, volcanic tuffs, and firm basalt. With these are great quantities of silicified trees, and even standing trunks project through some beds. The gravel is oftenest formed of white quartz pebbles, but may contain all the metamorphic rocks of the neighborhood, and even boulders brought from a great distance. The gravel at times is cemented together by siliceous and calcareous matter, and it Fig, 140. — Oeneralized section of a deep graioel bed, with technical terms. After R. E. Browne, Rep. Cal. State Mineralogist, 1890, p. 437, then requires blasting; but loose gravel also occurs. The clays are locally called "pipe clays," and are often interbedded with sand layers. They are blue when unoxidized, giving rise to the term "blue lead," but red oxidized clays are not infre- quent. The clays contain many leaf impressions of species thought by Lesquereux to be late Tertiary. (See further under 2.12.13.) The gravels also contain bones of extinct vertebrates, and have afforded some authentic human remains and stone implements of good workmanship. The volcanic tuffs have been strong factors in modifying the original drainage lines. They have flowed into the ancient valleys in a state of mud and have then consolidated. 2.12.12. The richest gravels are those nearest the bed rock. 366 KEMP'S ORE DEPOSITS. In these the distribution of the gold is governed more or less by the character of the ancient channels. It favors the insides of bends and the tops of steeper runs. The gradients of the old channels were fairly high, often running 100 to 200 feet per mile. Gold has also been found by assay in pyrite that has been formed in the gravels since their deposition, and from this it is evident that the precious metal does circulate in solu- tion with sulphate of iron, but on this slender foundation some quite unwarranted chemical hypotheses for the origin of nug- gets have been based. Substantially all the gold has been de- rived by the mechanical degradation of the quartz veins in the slates on other wall-rock. 2.12.13. The depths to which the modern streams have cut I|^G. 141. — Section of Forest Hill Divide, Placer County, California, to illus- trate the relations of old and modern lines of drainage. After R. E. Browne, Rep. Cal. State Mineralogist, 1890, p. 4Ml. out their channels below the old drainage lines have received considerable attention. Whitney concluded that no disturb- ance had taken place since the old gravels were laid down, but Le Conte has inferred that there has been a tilting or elevation of the higher parts of the range, all moving as a block. Becker has recently described in the high portions a great series of small north and south faults with uniform downthrow on the western side or upthrow on the eastern. (See paper below, cited from Geological Society of America.) This is supposed to have been of varied intensity in different portions and to have been limited to the atrip just west of the summit. It is attributed to the Plio- cene and is thought to have increased the gradient of the streams where the present deep canons occur, but to have had no effect THE PACIFIC SLOPE. 357 near the plains, where the oJd and new channels are nearly on the same level. Later work has oast much doubt on these views. 2.12.14. After the formation of the deep gravels and after the volcanic flows, glaciation took place in great extent over the mountain sides, but it was doubtless later in time than the glacial period of the East. Eeferences to the similar great de- velopment of the ice in Washington have already been made. Many hypotheses were early advanced to explain the deep gravels. They have been referred to the ocean, to ocean cur- rents, and to glaciers; but it is now well established that they are river gravels, formed when the rainfall was probably in excess of what it is to-day, and when the attitude of the land toward the ocean probably was different.^ ' G. F. Becker, 'Notes on the Stratigraphy of Calif arnia," Bull. 19, U. S. Geol. Survey. "Structure of the Sierra Nevadas, " Geol. Soc. Amer., XL, 43. W. P. Blake, "The Various Forms in which Gold Occurs," Rep. Direc- tor of the Mint, 1884, p. 573. A. J. Bowie, Jr., "Hydraulic Mining in Cal- ifornia," Trans. Amer. Inst. Min. Eng., VI., 27. R. E. Browne, "The An- cient River Beds of the Forest Hill Divide," Rep. Cal. State Mineralogist, 1890, p. 435. Rec. "California Placer Gold," Eng. and Min. Jour., February 2, 1895, 101. T. Egleston, "Formation of Gold Nuggets and Placer De- posits," Trans. Amer. Inst. Min. Eng., IX., 63. "Working Placer Depos- its in the United States," School of Mines Quarterly, VII., p. 101. J. H. Hammond, "Auriferous Gravels of California," Rep. Director of the Mint, 1881, p. 616. Rec. Rep. Cal. State Mineralogist, 1889, p. 105. H. G. Hanks, "Placer Gold," Rep. Director of the Mint, 1882, p. 728. H. G. Hanks, William Irelan and J. J. Crawford, Rep. Cal. State Mineralogist, Annual. T. S. Hunt, 'On a Recent Formation of Quartz, and on Silici- fication in California," Eng. and Min. Jour., May 29, 1880, 369. J. Le- conte, "The Old River Beds of California," Amer. Jour. Sci., iii., XIX., 80, p. 176. J. J. McGillivray, ' ' The Old River Beds of the Sierra Nevada of California," Rep. Director of the Mint, 1881, p. 630. R. I. Murchison, ' ' Siluria," etc. ; contains a sketch of the distribution of gold over the t i th. F. L. Nason, "The Goler Gold Diggings," Eng. and Min. Jour., Mc .en 9, 1895, 223. J. S. Newberry, "On the Genesis and Distribution of Gold," School of Mines Quarterly, Vol. III. ; Eng. and Min. Jour., December 24 and 31, 1881. J. A. Phillips, "Notes on the Chemical Geology of the California Gold Fields," Philos. Mag., Vol. XXXVI., p. 321; Froc. Roy. Soc, XVI., 294; Amer. Jour. Sci., ii., XLVII., 134. F. L. Ransome, "The Great Valley of California: A Criticism of Isostasy," Bull. Dept. of Geol, Univ. of Cal, I., 370-428, 1896. B. Silliman, "On the Deep Placers of the South and Middle Yuba, Nevada County, CaUfornia," Arner. Jour. Sci., ii., XL., 1. J. D. Whitney, "Auriferous Gravels of the Sierras," Cambridge, 1880. "Climatic Changes in Later Geological Times," Cam- bridge. See also references on succeeding pages relating to California. 358 KEMP'S ORE DEPOSITS. 2.12.15. The U. S. Geological Survey has been directiog its attention in recent years to the geology of the gold belt in the Sierras in connection with the issue of atlas sheets, based on topographic and geologic surveys. Several of these are practically complete, and they and the auxiliary papers which have resulted from the work have served to throw a flood of light upon the obscure problems of the geology of the Sierras. At the same time, as cited under subsequent paragraphs, other local workers have been active. The geological relations of the gravels as well as the solid strata have been made clear in greater detail than ever befoi e. Waldemar Lindgren has dis- cussed the geological history of the American and Yuba rivers in his valuable paper entitled, '*Two Neocene Rivers of Cali- fornia" {Bull. Geol. Soc. of America, IV., 257, 1893.) The conclusion is that the old divide in general coincided with the present one, but that the slope of the Sierra has been consider- ably increased since the time when the Neocene {i.e., Miocene and Pliocene) ante- volcanic rivers flowed over its surface. "It finally appears probable . . . that the surface of the Sierra Nevada has been deformed during this uplift, and that the most noticeable deformation has been caused by a subsidence of the portion adjoining the great valley, relatively to the middle part of the range. ' ' A careful review of the age of the aurifer- ous gravels in general by Lindgren, and of the fossil plants from Independence Hill, by Knowlton, has led to the conclu- sion that the deep gravels, which themselves lack fossils, date, in instances, probably as far back as the Eocene, but not earlier. Some bench gravels certainly were strongly developed in the Miocene and gravels of one sort or another have been formed from that time to the present.^ Lindgren has even brought to light the existence of an aurif- erous conglomerate in the upturned Mariposa beds of Jurassic age, near Mine Hill, Calaveras County. The crushed con- glomerate gave good colors, bat no black sand, from which it was inferred with great reason that the gold came from veins already existing in pre- Jurassic time in the earlier strata and before the intrusion of the basic igneous rocks of the region.^ ^ W. Lindgren, " Age of the Auriferous Gravels of the Sierra Nevada," with a Report on the Flora of Independence Hill, by F. H. Knowlton, Jour. Oeql, IV., 881, 1896. ' W. Lindgren, " Auriferous Conglomerate of Jurassic Age in the Sierra Nevada," Amer. Jour. Sci., October, 1894, 275. THE PAClPiG SLOPE. 359 H. W. Fairbanks has cod tro verted the above interpretation and regards the presence of the gold as due to later mineraliza- tion.^ Fairbanks also takes issue with the interpretation by R. L. Dunn of an auriferous conglomerate in the Klamath Moun- tains, as a river gravel of pre-Chico age, regarding it rather as shore conglomerate in the Chico itself.^ J. S. Diller has discussed the early physiography but for a wider range of country than any of the papers hitherto <5ited.^ Mr. Diller shows that the western side of the present Sierras formed in the Eocene or Tejon times a gently -sloping base-level of erosion, with quiet streams and extensive super- ficial deposits of a residual character. The Sierras were from 4,000 to 7,000 feet below their present altitude. With the Miocene came a period of upheaval, of increased gradients and rapid denudation of the soft surface materials. The old aurif- erous gravels were thus formed in the stream channels while the lighter materials were transported out to sea. The course of development is graphically traced out by Diller in ac- cordance with our modern knowledge of stream -erosion and transportation. For southern California, A. C. Lawson has described a somewhat similar development in later geolog- ical time,* but as the region is not one of auriferous gravels, it is only cited here as of interesting correlative character. H. W. Turner has lately reviewed the whole stratigraphy of the region south of the fortieth parallel, has correlated the new formational names adopted in the survey atlas sheets, has added many valuable notes on the petrography of the igneous rocks, and has outlined the stratigraphical relations of the gravels.^ Mr. Turner distinguishes two series of Neocene river gravels (p. 241). (1) The older gravels composed ^ H. W. Fairbanks, "Auriferous Conglomerate in California," Eng. and Min. Jour., April 27, 1895, 389. ' R. L. Dunn, Twelfth Ann. Rep. Cal. State Mineralogist, 1894, 459. ^ J. S. Diller, ' ' Revolution in the Topography of the Pacific Coast since the Auriferous Gravel Period," Jour. Geol., II., 32, 1894. * A. C. Lawson, "The Post-Pliocene Diastrophism of the Coast of Southern California," Bull. Dept. of Geol., Univ. of Cal, I., 115, Decem- ber. 1893. ^ H. W. Turner, "Geological Notes on the SieiTa Nevada," Amer. OeoL, XIII.. pp. 228, 297, 1894. 360 KEMP'S CRE DEPOSITS. chiefly of white quartz pebbles and frequently capped by rhyo- litic flows. These may be characterized in a broad way as the gravels formed before the volcanic period. (2) A later series, containing volcanic pebbles chiefly of andesite and later in age than the rhyolitic flows. These may be called the gravels of the volcanic period. Such gravels are often capped by andesite- tuffs. Included fossil leaves indicate that the older gravels are Miocene or Eocene; the later, Pliocene. The Pliocene river gravels merge into shore gravels of the same age in Amador and Calaveras counties. The pebbles in the shore gravels are quartz- ite, mica-schist, quartz-porphyrite, granitoid rocks, andesite, and rhyolite, the last named being at times very abundant and characteristic. They appear to have been deposited along the shores of the great gulf which filled the central valley of Cali- fornia in these times. They now range as a general thing 500 to 700 feet above the sea. Later than the Pliocene gravels are the Pleistocene, both shore and river deposits. The former occur in the depressions between the Neocene and older hills and at a lower altitude, by one to several hundred feet. They seem to consist of the harder pebbles of the Pliocene gravels, the softer ones having been destroyed by abrasion. The Pleis- tocene river gravels lie usually less than 100 feet above the present streams, and also in remnants of the channels left be- hind by old changes of course. They and the shore deposits of this time are often highly auriferous. Several lake- bottoms of this period have been recognized where, for some reason, such as the damming of a stream by a volcanic flow, or a probable mountain upheaval, the waters were set back. These lakes have left benches which mark their old shore lines. Finally, we have the recent stream gravels and alluvium. These papers show that the geological relations are more complex than was earlier known, but in their practical bearings the gravels can perhaps hardly be better grouped than into the River gravels or placers, in the beds of running streams, and the High or Deep gravels, according to the old nomenclature. 2.12.16. In resume of the above review it should be first appreciated that stream gravels are the least favorable of all sediments to the preservation of organic remains. Not only are few animals with hard parts resident of swiftly flowing currents, but such shells or bones as might reach them would THE PACIFIC SLOPE. 361 be liable to destruction from the trituration of the boulders. The stratigraphical relations of the gravels must therefore be worked out in great part, by other forms of evidence. It should also be appreciated that the old channel-fillings remain to us to-day only as fragments of their former extent, and that they are largely buried under lava flows and tuffs. The gravels therefore appear in narrow outcrops and set up narrow valleys, which are cutoff from their neighbors, north and south by high divides. While they were being deposited, moreover, in past geological time, more extensive contemporaneous forma- tions were being laid down in the then submerged valley of California, and with the latter it is important to correlate them. The kinds of evidence that are available are the following : The lithological character of the pebbles ; the relations of the non- fossiliferous gravels to others in whose interbedded clays or tuffs, fossil plants occur; the physiographic conditions under which the gravels were laid down, and which must have been uniform over a great part of the State and have left correlative records, if they can be found ; and finally the relations of the gravels to the volcanic outbreaks, whose lithological succession may be worked out. In the following tabular statement the endeavor has been made to utilize the classification of the gravels into periods, which was prepared by Ross E. Browne (10th Ann. Rep. Calif: State Mineralogist, 437) and add thereto other determinations by the geologists of the U. S. Survey, or by California geologists. Jurassic. Auriferous gravel, now a con- glomerate.^ Cretaceous. Pre-Chico auriferous river gravel in the Klamath Valley, Siskiyou County.*' (They may be beach gravels of the Chico itself.)^ Eocene. Auriferous gravels doubtful. Miocene. Deep gravels with quartz pebbles of Browne's First Period,^ which was ' W. Lindgren, "An Auriferous Conglomerate of Jurassic Age from the Sierra Nevada, " Amer. Jour. Sci. , October, 1894, 275 ; see also H. W. Fair- banks, Eng. and Min. Jour., April 27, 1895, 389. ' R. L. Dunn, "Auriferous Conglomerate in California," Twelfth Arm. Rep. Cal. State Mineralogist, 1894, 459; see also H. W. Fairbanks as under preceding reference. ^ Ross E. Browne, "The Ancient River Beds of the Forest Hill Divide. '^ Tenth Ann. Rep. Cal. State Mineralogist, 1^90, 4:3 7-440. 36a KEMP'S ORE DEPOSITS. closed by Pliocene andesite erup- tions. The chief auriferous gravels belong in this period. Bench gravels. Some rhyolite eruptions occurred during it.^ (Turner's ** Intermedi- ate Period,"^ pebbles of pre-Creta- ' ^ ceous sedimentary and igneous rocks; presumably later than the first period, but of uncertain taxonomic relations with the second period.)^ Miocene Second Period of Browne* gravels Pliocene. formed in shifting channels during or between successive volcanic erup- tions and mud flows, both of andesitic nature. Pebbles mostly volcanic. Pliocene to Third Period of Browne,* dating Present. from last important lava and mud- flow; beginning and completion of present stream valleys. River gravels. 2.12.17. Example 45. Gold Quartz Veins. Veins of gold- bearing quartz, often described as segregated veins, in slates or metamorphosed igneous rocks, and more or less parallel with the schistosity. Less commonly the walls are massive, igneous rocks. The quartz contains auriferous pyrite, free gold, arsenopyrite, chalcopyrite, tetrahedrite, galena, and blende, but pyrites is far the most abundant. Tellurides have been occasionally detected in small amounts.* The veins approxi- mate at times a lenticular shape, which is less marked in Cal- ifornia than in some other regions, and which shows analogies of shape with pyrites lenses (Example 16) and magnetite lenses * H. W. Turner, "Auriferous Gravels of the Sierra Nevada," Amer. Geol, June, 1895, 372. ^ Lindgren and Knowlton, "Age of the Auriferous Gravels of the Sierra Nevada," Jour. Geol, IV., 881, 1896; see especially table, p. 906. ^ Ross E. Browne, "The Ancient lliver Beds of the Forest Hill Divide," Tenth Ann. Rep. Cal. State Mineralogist, 1890, 437-440. Each of the above papers has important complementary relations to the others. * For a review and bibliography of the Tellurides, see J. F. Kemp, The Mineral Industry, Vol. VI. , p. 295. THE PACIFIC SLOPE. 363 '(Example 12). In such cases the fissure-vein character is somewhat obscure. In California the veins occupy undoubted fissures in the slates. The largest and best known is the so- called Mother Lode, which is a lineal succession of innumerable larger and smaller quartz veins that run parallel with the strike, and rarely cut the steep dip of the slates at an angle of 10°. It was doubtless formed by faulting in steeply dipping strata. The wall rocks of the California veins embrace many types of igneous rocks, as well as sedimentary slates, for all these enter into the western' slopes of the Sierras. The frequent serpentine is prob- ably a metamorphosed igneous rock, while the diabase and diorite form great dikes. Considerable calcite, dolomite, and ankerite occur with the quartz, and very often it is penetrated by seams of a green, chloritic silicate, which was provisionally called mariposite, but which has been shown by Turner to be a potassium mica, colored green by chromium. The quartz veins vary somewhat in appearance, being at times milk white and massive (locally called "hungry," from its general barrenness), at times greasy and darker, and again manifesting other differences, which are difficult to describe, although more or less evident in speci- mens. The richer quartz in many mines is somewhat banded, and is called ribbon quartz. The quartz has been studied in thin sections, especially in rich specimens, by W. M. Courtis, who shows that fluid or gaseous inclusions of what is probably carbonic acid are abundant. In rich specimens the cavities tend to be more numerous than in poor, but more data are needed to form the basis of any reliable deductions. Some quartz shows evidence of dynamic disturbances. The walls of the veins are themselves at times impregnated with the precious metal and the attendant sulphides. The rich portions of the veins occur in chutes which run diagonally down on the dip. 2.12.18. The great Mother Lode is the largest group of veins in California. It extends 112 miles in a general north- west direction. Beginning in Mariposa County, in the south, it crosses Tuolumne, Calaveras, Amador, and El Dorado coun- ties in succession. It is not strictly continuous nor is it one single lode, but rather a succession of related ones, which branch, pinch out, run off in stringers, and are thus complex in their general grouping. Over 500 patented locations have 364 KEMP'S ORE DEPOSITS. been made od it. Whitney suggested that it may have origi- nated from the silicification of beds of dolomite, but others re- gard it, with greater reason, as a great series of veins along a Surface Surface 100 200 300 400 500 Ft. Figs. 143 and 144. — Ore shoots of Nevada City and Grass Valley mines, Col. After W. Lindgren, XVII. Aim. Rep. U. 8. Oeol. Sm^ey, Part II., Plate XVIII., slightly reduced. fissured strip. The veins are often left in strong relief by the erosion of the wall rock, and thus are called ledges, or reefs. Some discussion has arisen over the condition of the gold in THE PACIFIC SLOPE. 365 the pyrite, but in most cases it is the native metal mechanically mixed, and not an isomorphous sulphide. It has been detected in the metallic state, in a thin section of a pyrite crystal from Douglass Island, Alaska, as later set forth (2.13.13,) and the fact that it remains as the metal when the pyrite is dissolved in nitric acid makes this undoubtedly the general condition. The association of gold writh bismuth, v^^hich has been shown by R. Pearce to occur in the sulphurets of Gilpin County, Colorado (referred to on p. 30G), and the difficulty experi- -enced in amalgamating som^ ores, indicate the possibility of Pig. 145. — Section of the Pittsburg vein, ninth level, Nevada City district, Cal. XVIL Ann. Rep. U. S. Geol. Survey, Part IL, p. 304, reduced one half. other combinations. When crystallized, gold has shown, in one specimen and another, nearly all the holohedral forms of the isometric system, but the octahedron and rhombic dode- cahedron are commonest. 2.12.19. The veins are younger than the igneous rocks with which they are associated. Granite and grano-diorite are espe- cially frequent, but diorite, gabbro, diabase, porphyrite and serpentine, presumably derived from some basic intrusion, are also met. Although Von Richthofen stated that the veins sel- /^V|^5^^ Reproduced inline-work after a colored Map/ r? ^'"-' "^:- v^'-'il'-Qy^^^^^ by J.E. Spurr. XVIII Ann. Rep. /riIiri^.;J!:f:}^{y^}/j^^^^j^j:-^ U.S. Geological Sui-vey. Part III, PI. XXXVra-s^^\'>>;;-'i£^^|^^^J PLEISTOCENE MOSTLY LACUSTRINE SILTS N EOCEN E EOCENE MISSION CREEK KENAI SERIES TAHKANDIT SERIES RAMPART SERIES SECTION ON LINE A-A Fig. 150o— Western half of Geological map of the Yukon Gold Belt and adjacent regions. {See Ym. \^1.) JJATURAL SCALE Fig. 151.— Eastern Tudfof OedogicaZ map of the Yukon Gold Belt, and ad- jacent regions, reproduced in line work and slightly reduced from a colored map by J. E. Spurr, XVIIL Ann. Rep. V. S. Oeol. Survey, Part III., Plate XXXV III., p. 252. 388 KEMP'S ORE DEPOSITS. canics, some from vents still active, are the chief components of the coastal exposures. In the interior, in the Yukon basin, and especially in the area near the international boundary, the general stratigraphy has been more systematically studied, and may now be outlined, since the valuable paper of J. E. Spurr has become available. In order to make the geology of this important region clear, the colored reconnaissance map of Spurr is reproduced in Figs. loO and 151, in line work on a somewhat smaller scale than the original, and in it the results of his ex- plorations, as well as those of Dall, Hayes, Geo. Dawson, McConnell and others, are set forth. The oldest formation is granite, of massive or more rarely gneissoid structure. It consists chiefly of quartz, orthoclase, microcline, plagioclase and biotite, with accessory muscovite, calcite, epidote, garnet, hematite, kaolinite, pyrite and chlorite. It is most extensively exposed south of the Yukon basin, but outcrops to the north in sufficient amount to show that the later formations rest upon it. It is considered Archean, and is called the Basal Granite. Immediately above it is a series of quartz-schists, estimated at 25,000 feet in thickness, and called the Birch Creek series. Many quartz veins occur in it, chiefly parallel with the schistosity. The Birch Creek series passes into the Forty-Mile series, which consists of micaceous and hornblendic schists with interbedded crystalline limestones. The Forty-Mile series likewise contains many quartz veins, and both it and the Birch Creek series are penetrated by many dikes of granite and diorite. In geologic succession the Ram- part series follows, and exhibits a heavy cross-section and wide areal distribution of diabases, and associated tuffs, with some impure limestones and shales. The Rampart series is probably pre- Devonian, as is shown by the fossils in the next overlying series, and the Forty-Mile and Birch Creek series are still older, but all are uncertain in their taxonomic relations except for this approximate determination. Quartz veins are also present in the Rampart series. The Tahkandit series of white and gray limestones with alternations of carbonaceous shales and conglomerates follows next above. It is known from fossils to contain some Upper Carboniferous beds and probably also embraces others of Devonian iage. Upon it rests the Mission GOLD IN UNITED STATES AND CANADA, 389 Creek series of black, calcareous and feldspathic shales and thin beds of impure limestone, and gray sandstone. They are known to be Lower Cretaceous. The Kenai series succeeds with its fresh- water sediments and coal seams of Eocene age. Neocene deposits follow and embrace the Nulato sandstones, the Twelve-mile beds of gravels and lignites, the Porcupine beds of sands, clays and conglomerates, and the Palisades con- glomerates with the bones of huge, extinct vertebrates. The Yukon silts are Pleistocene and constitute a vast area of abandoned lake- bottoms along the middle Yukon. Eruptive basalt is also known, but in connection with the gold, the Basal granite, the Birch Creek, Forty-Mile and Eampart series and the recent gravels derived from them are of chief interest. In its topographic character the interior is largely a great, dissected plateau so far as known, with rugged and uneven topography on a minor scale. The ranges of mountains are chiefly developed near the coast. The surface of the interior plateau and the talus slopes are covered by a heavy mantle of moss, called a tundra, whose roots, at a depth of a foot or two, are frozen in perpetual ice. This hides the geol- ogy, and makes exploration difficult and fraught with great hardship. Along the streams dense thickets of alder and spruce, and in the glaciated regions, the drift, all hide the rocks. ^ ' "Alaska as a Mining Territory," Eng. and Min. Jour., June 27, 1885, p. 444. "Mineral and Agricultural Wealth of Alaska," Eng. and Min. Jour., August 24, 1887, p. 134. G. F. Becker, "Reconnaissance of the Gold Fields of Southern Alaska, with some Notes on General Geology," XVIII. Ann. Rep. U. S. Geol. Survey, Part III., p. 7. Rec. T. A. Blake, "Re- port on the Geology of Alaska," Ex. Doc, No. 177, Fortieth Congress, New Series, p. 314, Washington, 1868. W. P. Blake, "Geographical Notes upon Russian- America and the Stickeen River;" Report addressed to the Sec- retary of State, Washington, 1866. H. P. Gushing, "Notes on the A real Geology of Glacier Bay, Alaska," Trans. N. Y.Acad, of Sci., XV., 24. " Notes on the Muir Glacier Region and its Geology," Amer. Geol., Octo- ber, 1891, 207. W. H. Dall, "Explorations in Alaska," Amer. Jour. Sci., ii., XLV.. 96. Rec. "Notes on Alaska and the Vicinity of Bering Straits, " Ibid. , iii. , XXI. 104. " Notes on Alaska Tertiary Deposits, Geologi- cal Section of the Shumagin Islands," Ibid., iii., XXIV., 67. "Alaska and its Resources," Washington, 1870. Rec. " Glaciation in Alaska, ' Bull. Phil Soc, Vol. VI., p. 33, Washington, 1884. G. M. Dawson, "Report on the Yukon District in 1887," Geol. Survey of Canada, 1887-88, Vol. III., Part B, pp. 14B, 17B, 154B-ir)6B. H. W .Elliot, "Our Arctic Provinces," 390 KEMP'S ORE DEPOSITS. 2.13.13. Example 38. (See above, 2.09.01.) Douglass Island. A dike of shattered albite-diorite (sodium-syenite) impregnated with gold-bearing pyrite. The largest and most productive of the mines along the coast of Alaska is the Alaska- Tread well and its affiliated properties, on Douglass Island, about two miles southeast from the town of Jnneau. The ore body is peculiar and interesting, and while the grade of the ore is low, the conditions for treating it cheaply, and on a large scale, are very favorable. The geological relations have recently been described by G. F. Becker, upon whose paper the following outline is based. The country rock is a carbonaceous slate of uncertain but possible Triassic age. Its sedimentary bedding has been destroyed, but its cleavage strikes N. 50 E., and dips southeast. After the metamorphism to slate, it was penetrated by an irregu- lar dike, which is 450 feet and less wide, and is considerably split up by horses of country rock. The dike rock is a peculiar one, p. 163, New York, 1887, G. W. Garside, "Mineral Resources of Southeast Alaska," Trans. Amer. Inst. Min. Eng., XXL, 815. E. J. Glave, "Pioneer Pack-horses in Alaska, " The Century, September and October, 1892. C. W. Hayes, "An Expedition through the Yukon District," Nat. Geog. Mag., IV., 117-162, 1892. Angelo Heilprin, "Alaska and the Klon- dike, " New York, 1899. R. G. McConnell, "Glacial Features of Parts of the Yukon and Mackenzie Basins," Geol. Soc. of Amer., I., p. 540. H. F. Reid, "Glacier Bay and its Glaciers," XVI. Ann. Rep. Dir. U. S. Geol. Survey, 1896, I., 421. I. C. Russell, "The Surface Geology of Alaska," Geol. Soc. of Amer., I., p. 99. "An Expedition to Mt. St. Elias, Alaska," Nat. Geogr. Mag., III., 53, 204, 1891. "Mt. St. Elias and its Glaciers," Amer. Jour. Set., March, 1892, 169. "Origin of the Gravel Deposits be- neath the Muir Glacier, Alaska," Amer. Geol, March, 1892, 180. J. E. Spurr and H. B Goodrich, "Geology of the Yukon Gold District," XVIII. Ann. Rep. U. S. Geol. Survey, Part III., 87. Rec. E. R. Skidmore, "Alaska," Rep. Director of the Mint, 1883, p. 17, and 1884, p. 17. J. Stan- ley-Brown, "Auriferous Sands at Yakutat Bay, Alaska," Nat. Geogr. Mag., Vol. III., 196, 1891. J. J. Stevenson, "Some Notes on Southeastern Alaska and its People," Scottish Geogr. Mag., February, 1893. J. B. Tyrrell, "Glacial Phenomena in the Canadian Yukon District," Bull. Geol. Soc. Amer., X., 193, 1899. G. H. Willianis, "Notes on Some Eruptive Rocks from Alaska," Nat. Geogr. Mag., IV., 63, Note. — The Bulletin of the Boston Public Library for September, 1897, p. 153, has a complete bibliography of the Yukon region up to that date. In 1899, the U. S. Geological Survey issued a pamphlet entitled, "Maps and Descriptions of Routes of Exploration in Alaska," together with a valuable series of maps. GOLD IN UNITED STATES AND CANADA. 391 and is, as a rule, now much altered, but in tbe freshest material available, it is almost entirely albite. It contains small amounts of augite, born blende, biotite and a few plagioclases other than albite. Secondary quartz is abundant. After the intrusion of tbe diorite, a gabbro dike, with some tendencies toward diabase in its texture, penetrated along the northeast side of the diorite, being sometimes entirely in the slate. The gabbro is chiefly augite and plagioclase, and carries no value in gold that is practically serious. After the intrusion of the gabbro a narrow dike of analcite- basalt 4 to 6 feet wide cut all the other rocks. Before its intrusion, the others, and especially the albite-diorite, suffered severely from crushing, the latter being cracked by series of planes at right angles with each other, and inclined at 45° to the horizon. Along these cracks the mineralization has taken place, and quartz, calcite, gold-bearing pyrite, with rare chalcopyrite, mispickel, blende and galena entered. The analcite-basalt accompanied or closely followed the mineralization. During the latter the ferromagnesian sili- cates of the original albite-diorite were replaced by the pyrite.^ F. D. Adams has detected metallic gold in the midst of the pyrite in a thin section of the ore. South from the Tread well mine is an un worked claim, and then toe Mexican, which is operated by the same parties as the Tread well. In connection with the petrography of the Tread well ore, it is interesting to remark that numerous dikes of albitic rock occur in the Sierras of California, and are known to be gold- bearing in a number of instances.^ 2. 13. 14. The other mines that have been developed along the coastal region are not numerous as yet. Some three miles east of Juneau there is, in the midst of the mountains, a small abandoned lake basin called Silver Bow basin, whose sands are * F. D. Adams, ' ' On the Microscopical Character of the Ore of the Treadwell Mine, Alaska," Amer. Geol, August, 1889, p. 88. G. F. Becker, " Reconnaissance of the Gold Fields of Southern Alaska, with some Notes on the General Geology," XVIII Ann. Rep. Dir. U. S. Geol. Survey, Part III., p. 1. Rec. G. M. Dawson, " Notes on the Ore Deposits of the Tread- well Mine, Alaska," Amer. Geol., August, 1889, p. 84. Min. and Set. Press, San Francisco, September 27, October*4, 1884. ' SeeH. W. Turner, " Replacement Ore Deposits in the Sierras," Jour, of <3eol., May-June, 1899, 389. Compare also paragraph 2.12.20. 392 KEMP'S ORE DEPOSITS. gold-bearing to a degree that admits of profitable hydraulickiDg. In the surrounding mountains of schists there are a few veins that have received attention at the Bennet, the Lane and Hay- ward and the Taku mines. Over the divide to the south, in the drainage of Sheep Creek basin, are several other veins in schists. They carry silver-bearing sulphides, with minor gold values. The country rock is schist, carbonaceous and mica- ceous, with gabbro dikes. 2.13.15. At Sumdum Bay there are slates, which are pene- trated by granitic dikes. They also contain lenses of quartz Fig. 153. — Map of the Juneau mining district, southeast Alaska. After O. F. Becker, XVIII. Ann. Rep. Dir. U. S. Oeol. Survey, Part III., Plate XVI, reduced. with sulphides carrying gold and silver. Near Berner's Bay the diorite has quartz veins with sulphides, and at Funter's Bay, in the Admiralty Islands, schists derived from diabase hold veins in cross-fissures. Pyrite and pyrrhotite occur in a gangue of quartz. Near Sitka veins with low grade ores have been found in a pyroclastic diorite, and on Kadiak Island there are some prospects, as well as gold-bearing beach sands. Next, however, after the mines on Douglass Island, the largest on the Alaskan coast is the Apollo mine on Unga GOLD IN UNITED STATES AND CANADA, 39;i Island. The wall rock is andesite, probably post- Miocene. The ores are free gold, pyrite, galena, zincblende, chalcopyrite, and some native copper, in a large chute along a zone of frac- ture. 2.13.16. The Yukon Basin. The greatest interest, so far as the mineral resources of Alaska and the Northwest Territory of Canada are concerned, centers around the gold placers of the Yukon basin. So far as yet developed the richest lie in Cana- dian territory, and from these the chief production has thus far been obtained, but the older workings are on the American side, and some gold is annually obtained from them yet. The gold occurs in two different kinds of gravels. The ore lies on the bed-rock beneath the courses of the smaller streams and their tributary gulches, which latter are locally called ^'pups." Above the pay-streak lies a variable thickness of barren, frozen gravel, which is overlain by peaty muck. The pay-streak is exposed by thawing out a pit in the frozen gravel by means of fires and heated stones, so that it can be excavated and stacked up until the warm season affords water for panning, cradling, or more rarely, sluicing. Except that the ground is frozen the placers do not differ from those already fully outlined. 2.13.17. The second variety of gravels is the "bench" gravel, which occurs on the sides of the valleys above the pres- ent stream bottoms. They are regarded b}^ Tyrrell as the terminal moraines of small glaciers, which came but a compar- atively short distance down the hillsides and stopped. 2.13.18. ^he source of the gold appears to have been the quartz veins in the Birch Creek, Forty-Mile and Rampart series, as described under paragraph 2.13.12. The veins seem to have been individually small, for thus far no one has yet proved available for deep mining. A few have been proved to actually contain gold, and have thus given real as well as theoretical ground for the above inference. The veins chiefly run parallel with the foliation, although some fissure veins, that cross it, are known. Assays, so far as recorded, while they demonstrate the presence of gold, do not indicate great richness. (Citations of the literature will be found under 2.13.12.) 2.13.19. South of the headwaters of the Yukon, and after an interval of barren territory, so far as known, lies the Cassiar district, which is reached from the coast via Wrangell and 394 KEMP'S ORE DEPOSITS. the StickeeD River. From the coast inland schistose rocks, with a few limestones and extensive intrusions of granite form the oldest rocks, but there are many sheets of basalt of most interesting character, especially near the head of navigation on the Stickeen River. The chief gold discoveries have been made in the past in the drainage area of Dease Lake. The gold occurred in stream gravels, but the heavy glacial deposits have at times buried them under a great amount of later and barren debris. One of the routes to the Klondike passes through the region.^ 2.13.20. In the drainage area of the Columbia River just north of the international boundary, and lying between it and the line of the Canadian Pacific railway, important develop- ments in mining have been made in recent years. The region is mountainous and rugged. The Columbia and its tributary, the Kootenay, into v^rhich flow^s the Slocan, have their courses largely formed by long and relatively narrow lakes, which, being navigable, have greatly aided in the development of the mines. The Columbia passes through Upper and Lower Arrow Lake; the Slocan heads in Slocan Lake, lying to the east; and the Kootenay drains the waters of Kootenay Lake still further east. All these lie in long north and south valleys, and into them the smaller streams discharge from the mountains lying east and west. In the valleys, and on the mountain slopes along these creeks the veins have been located. The Slocan district extends from west of Lower Arrow Lake eastward be- yond Slocan Lake; the Ainsworth district surrounds Kootenay Lake; the Nelson lies along the Kootenay River between Kootenay Lake and the Columbia River; while Trail Creek embraces both banks of the Columbia as it leaves Canada and crosses the international boundary. Dr. Geo. M. Dawson^ recognizes on Kootenay Lake and on Adams Lake (which latter is 150 miles northward of the former) the following series, beginning with the oldest {Bull. Geol. Soc. Amer. IL, 1C8): ' G. M. Dawson, Oeol. Survey of Canada, III., 1888, Report B. E. D. Self, "TheCassiar District," Eng. and Min. Jour., February 18, 1899, 205. "^ G. M. Dawson, "Report on a Portion of the West Kootenay District, British Columbia," Rep. B. Can. Geol. Survey, IV., 1888-89. Rec. "Note on the Geological Structure of the Selkirk Range," Bull. Geol. Soc. Amer., II., 165, 1891. GOLD IN UNITED STATES AND CANADA. 395 1. The Shuswap series. Mica schists, gneisses and marbles. Archean. 2. The Nisconlith series. Black shaly or schistose argillite, with some limestone. Cambrian. 3. The Adams Lake series. Gray and greenish schists. Cambrian and Silurian. Above these are limestones, argillites and schists. W. A. Carlyle,^ in the report cited below, mentions above the Nisconlith series in the Kootenay region. 3. The Kaslo schists, comprising a series of greenish, proba- bly diabasic schistaj;^nterbedded with some slates or dark argil- lites, and limestones. 4. The Slocan slates, a series of dark shales and slates, with limestones and calcareous quartzites. {Bulletin Bureau of Mines, p. 45.) In addition to the stratified rocks there are vast intrusions of granite regarded as later, and also many, more basic rocks, such as porphyrite, diabase and gabbro, which are often intimately associated with the ore bodies. 2.13.21. In the Slocan district, W. A. Carlyle has recognized four kinds of veins, according to the variety of ores furnished, viz. : (1) Those with argentiferous galena, blende and some tetrahedrite in a gangue of quartz and siderite. They cut strati- fied rocks, dikes and granite in one place and another. Gold values are known but are not of great moment. These veins are the chief ones of the region. (2) Veins of argentiferous tetrahedrite, jamesonite and silver minerals in quartz gangue in granite and stratified rocks, but not numerous. (3) Veins in granite with quartz gangue, carrying argentite, native silver and gold. (4) Gold quartz veins in granite. {Bulletin III., yi^, 46-48.) In the Ainsworth district all the geological series are met, and any one may be the wall rock of a vein. The com- mon gangue-minerals are quartz and calcite, and the ores are silver-bearing galena, with some blende; or pyrites; or silver minerals with more or less of the other sulphides, or of tetrahe- drite with them. In the Nelson district the rocks and the ores ' Wm. A. Carlyle, "Report on Slocan, Nelson and Ainsworth Mining Districts in West Kootenay, British Columbia," Bull. J II., Bureau of Mines, Victoria, B. C, 1897. Annual reports, with maps, are issued by the Provincial Mineralogist, Victoria, B. C. 396 KEMP'S ORE DEPOSITS. are somewhat different from those previously described, and tend to resemble the ones mined at Trail Creek. The country rocks are porphy rites, gabbros, diabases and slates, cut by numerous dikes. The ores are silver-bearing sulphides of cop- per, especially chalcopyrite, and the common associate of the latter in rocks of this character, pyrrhotite. Gold is very sub- ordinate.^ In the Trail Creek district igneous rocks are the chief varieties present. There is an older series, according to R. G. McConnell,^ of porphyrites, diabases, gabbros, tuffs, and agglomerates, with occasional patches of limestone, which afford some fosSils of probable Carboniferous affinities, and with some inclusions in the igneous rocks of black slJfe. Later than this igneous series, is granite, and through both, dikes of both acidic and basic rocks have been intruded. The chief economic interest centers about a small area of gabbro, near the town of Rossland, and about four miles long by one mile wide. From a gabbroof granitoid texture in the central mass, it passes grad- ually into a rimof augite- and uralite- porphyrites and diabase, which are seldom over a mile across, and which are brecciated. At or near the contact of the gabbro and the porphy ri tic border, are met the ore bodies. The ores consist of auriferous and slightly argentiferous pjrrhotite and chalcopyrite. They are not of high grade as a rule, the gold ranging from a trace to several ounces, and the silver from a trace to four or five ounces. A little nickel and still less cobalt can also be de- tected. Other minerals are not prominent; molybdenite, high- ly auriferous, and rarely galena and blende have been recorded. The oxidized zone extends but a few feet below the surface. It is still somewhat of a mooted point among observers, as to whether they are direct crystallizations from the cooling magma; or secondary segregations from the enclosing basic walls; or replacements along lines of Assuring; or true fissure veins. One mine and another seem to give support to each of these views. The geological relations strongly suggest those of Sudbury, later described under nickel, and also those of many nickel ' The details of these districts are taken from the Bulletin of W. A. Carlyle, previously cited. "^ R. G. McConnell, '* Preliminary Abstract, " issued in Rossland Weekly Mining, March 18, 1897, a local paper. OOLD IN UNITED STATES AND CANADA. 397 Tegions in Norway and elsewhere in the world. The question of their direct origin from a fused and cooling magma, is an important and interesting one, and examination should be care- fully directed toward its solution. From observations made in connection with recent litigation over the War Eagle claim, W. Lindgren reached the conclusion that the ores had certainly been deposited by replacement. 2.13.22. Example 45c. Nova Scotia. The southeastern portion of Nova Scotia, exclusive of Cape Breton Island, is chiefly composed of a vast series of metamorphosed, fragmenfcal deposits, which in places contain gold-bearing quartz veins of very interesting geological relations. As a rule, the veins con- form to the bedding of the wall-rocks and therefore present structural problems, exactly like those of thin beds in a folded and, to some extent, faulted sedimentary series. The age of the sediments is thought by some. to be Cambrian, by others pre-Cambrian or Algonkian, the absence of assured fossils making the question an open one. The metamorphic rocks are penetrated by numerous, great intrusions of granite, which constitute no inconsiderable part of the 6,000 or 7,000 square miles that the area embraces. The strata have been divided by geologists into.two series. The upper, approximatelj' 3,000 feet thick, consists of dark, pyritous slates,' with some beds of quartzite, but with few veins. The lower series, roundly estimated at 8,000 feet, has a much larger proportion of coarse sediments and em braces slates, quartzites, sandstones, and even conglomerates. A Lower Carboniferous conglomerate is known to overlie the metamorphics, and to contain boulders of the gold- V)earing quartz veins, so that the mineralization certainly was of earlier date. The slates, and even the quartzites, are quite richly provided with pyrites, and are known to carry gold even at a distance from the veins. There is reason to think that this gold was deposited with them originally, and even the pyrite may be of metamorphic production, from materials laid down in the sediments. The presence of the gold and pyrites in the slates has an important bearing on the methods of enrichment of the veins and the direction taken by the gold- bearing solutions. Inasmuch as the larger veins lie parallel with the bedding -and conform to the folds of the sediments, it is evident that the GOLD IN UNITED STATES AND CANADA. 399 quartz was deposited in them before the folding took place. J. E. Woodman states that the original filling of the veins, pre- sumably by uprising solutions, was not accompanied by the in- troduction of much gold. This came later, during the meta- morphism, and probably was contributed by the pyritous wall- rock. The first and major folds w^ere developed with axes running approximately east and west. In time a second compression nearly at right angles to the first, threw these folds into a north and south series, and caused many faults, mostly reversed. The corrugations produced in the first series of folds by these later ones, gave rise to the so-called "barrel quartz," and as the latter has the reputation of carrying good values in gold, there may have been some additional enrichment of it during the later disturbances. Probably the intrusion of the granite followed the second folding, but it is not certain that it may not have preceded the first upheavals. The second period of disturbance produced some fissures, which were filled at Cow Bay with gold quartz. In the subsequent history of the series, a pronounced northeastern cleavage was developed, and some small faulting. Erosion has been severe, and has planed off the domes produced by the cross-folding, and has largely determined the location and extent of the mining dis- tricts. While the bedded character of the larger veins has been emphasized, it must be appreciated that they throw off stringers into the walls, called "angulars," and that parallel ones are connected by cross-veins. Still, except at Cow Bay, fissure veins of the ordinary type are not often met. The ore minerals of the veins are free gold, gold- bearing pyrite, mispickel, and rarely galena and blende. The gangue is chiefly quartz, but calcite occurs sporadically. The veins average less than a foot in width, but may be several feet as an exception. They favor horizons where a soft rock, usually slate, lies near a hard one, usually quartzite.^ ' In the following bibliography the citations given in the previous edi- tions are greatly expanded by the aid of Bulletin 127 of the U. S. Geo- logical Survey and the very complete list in the paper of J. E. Woodman. W. J. Anderson, " Gold Fields of Nova Scotia, " Trans. Lit. and Hist. Soc, of Quebec, Part II., pp. 35-56, 1864. L. W. Bailey, " Prehminary Report on Southwestern Nova Scotia," Oeol. Survey ('anada, 1892-93, Report Q. G. F. Becker, "Gold Fields of the Southern Appalachians," XVL Ann 400 KEMP'S ORE DEPOSITS, 2.13.23. Gold elsewhere in Canada. Auriferous gravels have been located at the headwaters of 'the Chaudiere River, in eastern Quebec, and some quartz veins are found in the meta- morphic rocks of the same region. They have been worked to Rep. U. S. Geol. Survey, III., 330. J. S. Campbell, "Report on the Gold Fields, Eastern Section," Halifax, 1862; "Report on the Gold Fields," Halifax, 1863. J. W. Dawson, "On Recent Discoveries of Gold in Nova Scotia," Can. Nat. and Geol, VI., 417, 1861. The various editions of "Acadian Geology," of which the third, London, is the latest, 1878. E. R. Faribault, "Report on the Lower Cambrian Rocks of Guysborough and Halifax Counties," Geol. Survey Canada, 1886, Report P, 129. H. Fletcher, " Report on Various Counties in Nova Scotia." Idem, 1886, Report P, 1-129. E. Gilpin, "The Gold Fields of Nova Scotia," Eng. and Min. Jour., XXXIV., 5,17,1882. " Results of Past Experience in Gold Mining in Nova Scotia," Brit. Assoc. Adv. Sci., LIII., 711, 1885. "Nova Scotia Gold Mines," Trans. Amer. Inst Min. Eng., XIV., 674, 1886. Rec. "Notes on Nova Scotia Gold Fields," Trans. Roy. Soc. Can., VII., 63, 1888. "The Evidence of a Nova Scotia Carboniferous Conglomerate," Idem, VIII., 117, 1890. "Ores of Nova Scotia," Halifax, 1898. W. Gossip, "The Rocks in the Vicinity of Halifax,' Proc. and Trans. Nova Scotian Inst. Nat. Sci., I., Part II., 44, 1864. "On the Barrel Quartz of Waverly," Idem, L, Part III., 141, 1865. P. S. Hamilton, "Auriferous Deposits of Nova Scotia," Idem, I., Part IV., 43, 1866. C. F. Hartt, "Pre Carboniferous Gold," Can. Nat., New Series, I., 459, 1864. A. Heathing ton, "Guide to the Gold Fields of Nova Scotia," 1868. H. Y. Hind, "Report on the Waverly Gold District," Halifax, 1869. "Gold Deposits of Nova Scotia," Can. Nat, New Series, IV., 229, 1869. "Notes on the Structure of the Nova Scotia Gold Districts, "Proc. and Trans. Nova Scotian Inst. Nat. Sci., II., Part III., 102. "Preliminary Report on a Gneissoid Series Underlying the Gold-bearing Rocks," etc., Halifax, 1870. See also Quar. Jour. Geol Soc, XXVI., 468, 1870, and Amer. Jour. Sci., XL., 347, 1870. "Report on the Sherbrook Gold District," etc., Halifax. 1870. "Report on the Mount Uniacke, Oldham, and Renfrew Gold Mining Dis tricts," Halifax, 1872. D. Honeyman. " On the Geology of the Gold Fields of Nova Scotia," Quar. Jour. Geol. Soc, XVIII., 342, 1862. "Geology of the Gay's River Gold Field, "Proc. and Trans. Nova Scotian Inst. Nat. Set.. II., 76, 1870. H. How, "Mineralogy of Nova Scotia," 1868, and again in official report, Halifax, 1869. J. Howe, "Report on the Gold Fields." Halifax, 1860. "Tangier Mines," report to the Provincial Secretary, Hali- fax, 1860. "Nova Scotia Gold Fields," Halifax, 1861. " Report on Gold Fields," 1871. T. S. Hunt, "Report on the Gold Regions of Nova Scotia," Geol. Survey Can., 1868; Can. Nat, February, 1868. W. E. Logan, Geol Survey of Can., 1863, and atlas, 1865. "Notes on the Gold of Eastern Canada,' Montreal, 1864. J. Marcou and C. T. Jackson, "Note on Gold Slates of Nova Scotia," Proc Post. Soc Nat Hist., IX., 47, 1862. O. C. Marsh, "The Gold of Nova Scotia," Amer. Jour. Sci., XXXII., 395, 1861. OOLD IN UNITED STATES AND CANADA. 40! a small extent.^ Auriferous mispickel has beeu developed in considerable quantity at Marmora (or Deloro), Hastings Count5% Ontario. It occurs with quartz in a vein of complex geological relations, and after proving refractory to older methods of treatment, has yielded to the cyanide process.^ Kegarding the mineral resources of the Hudson Bay terri- tory, some further notes have been recorded by Dr. Robert Bell.' 2.13.24. The following table gives an idea of the relative importance of the several States. Full details of the United States and other countries are given in the Annual Reports of the Director of the Mint, the Mineral Resources of the United States Geological Survey, and the Mineral Industry^ the annual statistical number of the Engineering and Mining Journal. A. Michel and T. S. Hunt, "Report on the Gold Region of Canada," Can. Oeol. Survey, 1866, 49-90. G. F. Monckton, " The Auriferous Series of Nova Scotia," Proc. Oeol. Assoc, XI., 454, 1891, London. H. F. Perley, "Gold in Nova Scotia," Can. Nat., II., 198, 1865. H. Poole, "Report on Gold Fields, Western Section," Halifax, 186^. "The Gold Leads of Nova Scotia," Quar. Jour. Geol. Soc, XXXVI., 307, 1880. W. H. Prest, "Deep Mining in Nova Scotia," Proc. and Trans. Nova Scotian Inst. Nat. Set., VIII., 420, 1895. A. R. C. Selwyn, "Gold Fields of Quebec and Nova Scotia," Can. Geol. Survey, 1870-71, pp. 252-289. B. Silliman, Jr., "On the so-called Barrel Quartz of Nova Scotia," Amer. Jour. Sci., XXXVIII., 104, 1864. 'Report on the Lake Loon Gold Mining Co.," 1864. "Report on the New York and Nova Scotia Gold Mining Co.," 1864. B. Symons, "The Gold Fields of Nova Scotia," Trans. Min. Assoc, and Inst. Cornwall, III., 80, 1892. J. E. Woodman, "Studies in the Gold-bearing Slates of Nova Scotia," Proc. Post. Soc. of Nat. Hist, XXVIII., 375, 1899. Rec. There are also several official reports to provincial officers of Nova Scotia's Department of Mines. * R. W. Ellis, " Report on the Mineral Resources of Quebec," Oeol. Sur- vey of Can., New Series, 1888-89, Report K. Trans. Amer. Inst. Min, Eng., XVIII, 316. A. Michel and T. S. Hunt, "Report on the Gold Re- gions of Canada," Oeol. Survey of Can., 1866, 49-90. "^ " The Marmora Gold Mine," Eng. and Min. Jour., October 23, 1880, p. 266. T. S. Hunt, " Report on the Gold Region of Hastings," Oeol. Survey of Can., Montreal, 1867. R. P. Rothwell, "The Gold bearing Mispickel Vein of Marmora, Ontario," Trans. Amer. Inst. Min. Eng., IX., p. 409. ' R. Bell, "Mineral Resources of the Hudson Bay Territories," Trans. Amer. Inst. Min Eng., XIV., 690, 1886. See also Trans. Roy. Soc. Can., II.. 241.1885. i02 KEMP'S ORE DEPOSITS. Alaska , Arizona California , Colorado Georgia Idaho , Michigan , Montana Nevada New Mexico North Carolina, Oregon South Carolina South Dakota. . Texas Utah Washington . . . Others Total Canada , 1890. Silver. 1, 1, 24, 4, 20, 5, 1, 10, §9,697 292,939 163,636 307,070 517 783,838 71,111 363,636 753,535 680,808 7,757 96,969 517 129,292 387,878 343,434 90,505 2,585 70,485,714 518,000 Gold. $762,500 1,000,000 12,500,000 4,150,000 100,000 1,850,000 90,000 3,300,000 2,800,000 850,000 118,500 1,100,000 100,000 3,200,000 6*80, 000 204,000 40,000 32,845,000 1,149,776 1898. Silver. $147,500 1,622,500 442,500 13,866,535 3, '707, 999 8,'743!6ii 826,000 383,500 "'*75",7i2 354,666 354,000 3,876,451 206,500 64,037 34,670,245 2,616,110 Gold. $2,820,000 2.800,000 14,900,000 23,534,531 2,050,666 5,247,913 3,000,000 480,000 1,216,669 5,'720',666 '2,372,442 600,000 340,875 65,082,430 13,790.000 The above figures for 1890 are from the Report of the Director of the Mint for that year. The figures for 1 898 are from the Mineral Industry, VII., 1899. The totals illustrate the great falling off in the value of silver, although the number of ounces was actually greater in 1898 than in 1890. The immense in- crease in the output of gold is also brought out. CHAPTER XIV. THE LESSER METALS: ALUMINUM, ANTIMONY, ARSENIC, HROMIUM, 3 ALUMINUM. 2.14.01. The importance of aluminum grows with improved and cheaper methods of production. Its sources are, or have been, alums, either natural or artificial, corundum, cryolite, kaolin and bauxite. The first of these is formed in nature by the decay of pyrite in shales and slates, and is little if at all used as an ore at present. The second is more valuable as an abrasive, and with the fall in the price of the metal has given way to other and cheaper ores. Still corundum (AI2O3) with 53.. 3 Al, is the richest natural mineral. Cryolite and bauxite are now the staple ores, but in the Grabau process kaolin is employed, although not as yet in any such amount as these other two. The fused cryolite plays the role of a bath in which the alumina is dissolved and reduced bj^ electrolysis, so that really bauxite has come to be the principal source. Cryolite occurs as an immense bedded deposit in gneiss at Evigtok, on the Arksut Fjord, Greenland. It is mined as an open cut, and being near the water's edge, on a steep cliff, after hand-pick- ing, it is loaded directly upon vessels, which moor to the cliff. The cryolite is associated with various related minerals, all rare and mostly limited to this locality, with sulphides of iron, copper and lead, and with siderite. The Pennsylvania Salt Co. of Natrona, Pa., receives by contract two-thirds of the output, the remaining third going to Denmark. The other localties of this mineral, at Miask, in the Urals, and near Pike's Peak, Colo., are small and commercially unimportant pockets. 404 KEMP'S ORE DEPOSITS. Cryolite when pure contains 13.02 Al, and of itself is thus a very low grade ore/ 2.14.02. Bauxite (AI2O3, 3H2O) is now the main source of the metal. In the pure condition and of the composition given above it contains AI2O3, 65.55, or Al, 34.94, but various im- purities are always with it, of which the commonest are silica, oxide of iron, oxide of manganese, carbonates of lime and magnesia, phosphoric acid, and, in the Southern States, sriiall but constant amounts of titanic acid. The merchantable ore ranges from about 40 to over 60%, or even over 70% AI2O3, but any analysis over 65.55% AI2O3 indicates a mineral of different composition from AI2O3, 3H2O. There is no doubt that such exist, and in an interesting paper entitled **The Bauxites : A Study of a New Mineralogical Family,'' M. Francis Laur^has advocated that there is a whole series of hydrated compounds of alumina which are as complex, perhaps, as the anhydrous compounds of this metal. Bauxite is now known to occur in economic quantities in Georgia and Alabama, and in Arkansas. It has been men- tioned, however, from numerous other points in States immedi- ately north of the two former. The deposits in Georgia and Alabama^ occur along a narrow belt in the Coosa Valley, ex- tending some sixty miles from Adairsville, Ga., to Jack- * On the geology of Greenland Cryolite see G. Hagermann, ' ' On some Minerals associated with the Cryolite in Greenland," Amer. Jour. Sci.. ii., XLII., 93. C. Hart, "On the Cryolite Deposit," Jour, of Analyt. and Applied Chem., October, 1893. G. Lunge, in the treatise entitled, "The Manufacture of Sulphuric Acid and Alkali." J. W. Taylor, "Cryolite of Evigtok," Quar. Jour. Geol. Soc, XII., 140. See also The Mineral Indus try, Vols. I. and II. , and a pamphlet published by the Pennsylvania Salt Manufacturing Co. 2 Trans. Amer. Inst. Min. Eng., XXIV., 234, 1894. ^ C. W. Hayes, "Geological Relations of the Southern Appalachian Bauxite Deposits," Trans. Amer. Inst. Min. Eng., XXIV., 243; also 855, 861, 1894. Rec. XVI Ann. Rep. Dir. U. S. Geol. Survey, 1894, III., 547. Rec. H. McCalley, "Alabama Bauxite," Proc. Ala. Indust. and Sci. Soc, 1893. Reprinted in Science, November 25, 1892, p. 303 ; a later paper in the issue January 19, 1894, p. 29. " Bauxite," in The Mineral Industry, II., 57, 1894. Idem, V., 51. Rec. "Coosa Valley Region," Ala. Geol. Survey, 1897. Many details as per index. E. Nichols. "An Aluminum Ore: Bauxite," Trans. Amer. Inst. ^Min. Eng., XVI., 905. R. L. Packard, "Aluminum," Mineral Resources, 1891, 147. J. W. Spencer, "Geology and Resources of Ten Counties in northwestern ^Georgia, " p. 210, 1893. Rec. THE LESSER METALS. 405 sonville, Ala. The mineral itself is pisolitic or oolitic in structure, as a general thing, and the individual masses are often in concentric layers, and are held together either by non-oolitic bauxite or by silica. Less often the ore is more massive, and may be in fairly hard lumps or soft and earthy. The surface ore is often pitted and cellular. The general geological relations will be best understood by referring to Fig. 4, p. 22. The region is largely formed by Cambrian strata, of which the Connasauga shales are the upper member, and the Rome sandstone, or Weissner quartzite, is the lower. Above the Cambrian is found the Lower Silurian, Knox dolo- mite, rich in chert. These strata are broken by folds and faults of several series and formed at different periods. The great overthrust shown in Fig. 4 is of post- Carboniferous time, long Fig. 3 'mui r?.?-:- v. ',2 , BAUXITE- ."^ .., ; . ->^?>Beoo5» 4^ ^^^^°25Btrk^=£^ • '• . — < .•'. • .* . ^. '^^ x:-vvX>^; • TALUS -N\\\ DEPTH N0T1 KNOWN " • • _ BOTTOM or PIT _' DRAINABE niTCH ^. -^ Bradley i Pbatet, Ennr'a, X T. Fig. 154. — Crosa-section of a Bauxite deposit in Georgia. After (J. Willard Hayes, Trans. Amer. List: Min. Eng., February, 1894. after the principal Appalachian upheaval. C. W. Hayes has shown that the ore bodies lie along certain of these fault lines, and the association gives us a possible clue to their method of deposition. They are very sharply limited to points lying be- tween the 900 and 950 feet contours, and seem to have been occasioned by the attitude of the land toward the sea during the formation of the Tertiary peneplain in the region. The ores are always found in the residual alteration products of the Knox dolomite, from which, however, they are quite sharply separable. The accompanying cross-section shpws the relations. While more or less irregular in shape they have proved quite persistent, and many 3^ears' supply is now in sight. Mr. Hayes suggests that the crushing attendant on the faulting, developed great heat, and that atmospheric waters 406 KEMP'S QBE DEPOSITS. penetrating along these zones became charged with sulphuric acid, derived from decomposing pyrite. The acid would dis- solve alumina from the Connasauga shales, possibly forming alums, with some alkali. Calcium carbonate would react on such solutions so as to precipitate hydrate of alumina, and this, rising as a flocculent precipitate in springs, gave rise to the ooli- tic and pisolitic deposits, which were afterward, in the decay of the Knox dolomite, involved in its residual products. The explanation is reasonable and has great claims to confidence. The same general hypothesis may be applied to the neighboring limonites. H. McCalley gives in Science^ January 29, 1894, p. 30, the following working analyses from the War- whoop Bank. The analyses are based on samples from car-load lots, and repre- sent 500 to 1,000 tons. The first column is the variety called **Hard White Ore"; the second, known as "War-whoop Ore," is the average of consumer's analyses. First. • Second. Alumina.. 57.-63. 56.-62. Ferric oxide under 1. 3.5-3.0 Silica, about 3.50 5.00 Titanic acid 3.0-4.0 3.0-4.0 Water, combined 39.0-30.0 about 30.0 Moisture, hygroscopic 3.0-4.0 3.0-4.0 A little over half (53.3%) of the alumina is the metal itself. 2.14.03. The bauxite deposits of Arkansas are found within a few miles of Little Rock, and further west in Saline County, near the town of Bryant. They favor the contact of the intruded syenites (regarded as Cretaceous) and Paleozoic sediments, but they are themselves involved in most cases in Tertiary sand- stones. The association with syenite is quite invariable. The bauxite is pisolitic and concretionary. The range in composition is considerable, some being high in iron, others in silica, while others are fairly pure. The variability even in the same open- ing is considerable, as indeed is always the case with deposits of this character. The deposits are individually somewhat irregular in shape and extent, but the quantity is large. J. C. Branner regards them as shore deposits, probably formed after the manner of oolitic concretions, which derived their hydrate of alumina from the syenite, through tho medium of hot springs. A submergence of the still heated syenite beneath THE LESSER METALS. A01 «ea water is suggested as a possible explanation of the solution and deposition. Dr. Branner gives, in the reference from the Journal of Geology, cited below, a complete bibliography and review of the literature on bauxite and of the views regarding its origin.^ 2. 14. 04. W. P. Blake has descri bed deposits of alunogen and bauxite, on the upper Gila Kiver, about 40 miles north of Sil- ver City, New Mexico. The bauxite has resulted from the action of sulphuric acid, produced in the decay of pyrites, upon basalts. Alunogen and sulphate of iron are removed while bauxite remains as a residual deposit. The geological relations, are therefore very like those of Glenariff, County Antrim, Ireland, and of the Vogelsberg, Germany.^ The Gila River deposits are too remote for utilization under present conditions. Bauxite is employed for many other purposes besides fur- nishing an ore of aluminum, as this is one of its later adapta- tions. Great quantities are used to produce alums, and as a refractory material it has long been appreciated. 2.14.05. In the earlier development of the aluminum indus- try corundum was somewhat sought as an ore. The varieties with vitreous luster and light colors are called sapphire, the duller and more smoky ones, corundum, while the impure kinds, which are mixed more or less with magnetite, hematite, spinel, etc. , pass under the name of emery. The last named is of no importance in this connection. Some sapphire and corundum have been obtained in Chester County, Penn., but practically the only source of any moment in the United States is in a belt of a curious rock called dunite, which consists of grains of olivine, and which traverses western North Carolina * J. C. Branner, "Bauxite in Arkansas," Amer. Geol, VII., 181, 1891. An extended report was announced for Vol. I., 1889, of Dr. Branner's Annual Reports as State Geologist of Arkansas, but it has not yet (1899) been issued. Preliminary reports appear in the Arkansas Gazette and Arkansas Democrat, Little Rock, January 8, 1891. Third Biennial Report, Bureau of Mines, Manufactures and Agriculture of the State of Arkansas, for 1893 and 1894, Little Rock, 1894, 119-125. Fourth Biennial Report, Little Rock. 1896, 105-110. "The Bauxite Deposits of Arkansas," Jour, of Geol, v., 263, 1897. J. Francis Williams, Ann. Rep. Geol. Survey Ark., 1880, II., 124. " W. P. Blake, "Alunogen and Bauxite of New Mexico," Travis. Amer. Inst Mm. Eng., XXIV., 571. i08 KEMP'S ORE DEPOSITS. and Georgia. The corundum occurs along the contacts of the dunite and a hornblende gneiss with which it is associated. It lies in scattered lumps distributed through decomposed micaceous material, which is at times so soft as to be washed out in the hydraulic way. In some instances the mineral ap- pears to have resulted from some reactionary effects of the two rocks, or of solutions emanating from them, on each other. The gneiss is aluminous, the dunite magnesian.^ Again it seems to have crystallized directly from fusion and to have become concentrated near the walls, either from the operation of Soret's law, or from convection currents as described under 1.06.13.^ J. H. Pratt has even been able to apply the results experimentally obtained by J. Morozewicz to the rocks which yield the corundum, and has made the following summary as the result of his observations and analyses, dealing in all cases with peridotites. 1. When the magma is a calcium -sodium-potassium silicate, no alumina held in solution will separate out as corundum, ex- cept when the ratio of the alumina to the other bases is more than 1 : 1, and the ratio of the silica is less than 6. (Molecular > T. M. Chatard, Mineral Resources, U. S. Qeol. Survey, 1883-84, 714. Rec. "The Gneiss-Dunite Contacts of Corundum Hill, N. C," etc., Bull. U. S. Geol. Survey, XLII., 45, 1881. Rec. Short abstract in the Eng. and Min. Jour., July 21, 1888, p. 46. J. P. Cooke, Froe. Amer. Acad., IX., 48, 1874. F. A. Genth, "Corundum: Its Alterations and Associated Min- erals," Amer. Phil. Soc, September 19, 1873; July 17, 1874; Amer. Jour. Sd., iii., VI., 461, 1873. T. S. Hunt, Trans. Roy. Soc. Can., II., 1884. C. W. Jenks, Quar. Jour. Geol. Soc, XXX., 303, 1874. A. A. Julien, Proc. Post. Soc. Nat. Hist, XXII., 131, 1893. W. C. Kerr, "Geology of North Carolina, Supplement," 64, 1875. F. P. King, "Preliminary Report on Corundum Deposits of Georgia," Geol. Survey Georgia, Bulletin 2, 1894. J. V. Lewis, "Corundum in the Appalachian Crystalline Belt," Trans. Am^r. Inst. Min. Eng., XXV., 832, 1895. Rec. R. W. Raymond. "Jenks' Corundum Mine, N. C," Trans. Amer. Inst. Min. Eng., VII., 83, 1878. C. U. Shepard, "On the Corundum Region of North Carolina and Geor- gia," Amer. Jour. Sci., iii., IV., 109, 175, 1872. Rec. C. D. Smith, "Geol ogy Noi-th Carolina, I., Appendix D.," 91, 1875; II., 43, 1881. J. L. Smith " Notes on the Corundum of North Carolina, Georgia," etc., Amer. Jour. Sci., iii., VI., 180, 1873. Rec. M. E. Wadsworth, Mem. Mus. Comp. Zool, XL, Part I., p. 118, 1884. 'J. H. Pratt, "On the Origin of the Corundum Associated with the Peridolites in North Carolina," Amer. Jour. Sci., July, 1898, p. 49. THE LE88ER METALS. 409 ratios are meaot, i.e., the quotients obtained by dividing the percentage by the molecular weight in each case.) 2. If magnesia and iron are present in the above magma, corundum will not form unless there is more than enough alumina to unite with the magnesia and iron (that is, spinels will form in preference to corundum where possible). 3. When the magma is composed of a magnesium silicate without excess of magnesia, all the alumina held by such a magma will separate out as corundum. 4. Where thare is an excess of magnesia in the magma just described, this will unite with a portion of the alumina to form spinel, and the rest of the alumina will separate out as corun- dum. 5. Where there is chromic oxide in a magma composed es- sentially of a magnesium silicate (as the peridotite rocks), and only a very little alumina and magnesia are present, these, uniting, separate out with chromic oxide to form the mineral chromite, and no corundum or spinel is formed. 6. When peridotite magmas contain, besides the alumina, oxides of the alkalies and alkali-earths, as soda, potash and lime, a portion of the alumma is used in uniting with these oxides and silica to form feldspar. 7. There is a strong tendency for the alumina to unite with the alkali and alkali-earth oxides, to produce double silicates like feldspars, whether such silicates form the chief minerals of the resulting rock, or are present only in relatively small amount. There is, however, but little tendency for the alumina to unite with magnesia, to form double silicates, when the magma is a magnesium silicate.^ 2.14.06. The most important recent discovery of corundum in commercial quantities is that of the deposits associated with the belt of nepheline syenite that covers a large area in eastern Ontario, north of Kingston. The syenite, which is at times very coarsely crystalline and pegmatitic, contains crystals of corundum, often of large size and of considerable regularity of form. Blue sodalite also occurs in the rock in large masses. Experiments in concentration have been carried on at the School of Mines in Kingston under Professor Miller, and actual ^ J. H. Pratt, "On the Separation of Alumina from Molten Magmas, and the Formation of Corundum," Amer. Jour. Set, September, 1892, 227. 4:10 KEMP'S ORE DEPOSITS. development is probable at an early date.^ Corundum of gem grade has been mined at Yogo Gulch, Mont., and beautiful sapphires are obtained.^ The commercial emery employed in America is largely imported from Smyrna, but it has no bear- ing on the production of aluminum. It is also mined at Ches- ter, Mass., and near Peekskill, N. Y.^ Corundum is reported in vast amount in India.* ANTIMONY. Senarmontite, SbgOs; Sb. 83.56; O. 16.44, Stibnite (Antimonite, Antimony Glance), Sb2S3; Sb. 71.8; S. 28.2. 2.14.07. Antimony occurs in composition with several silver ojes, but almost its sole commercial source is stibnite. The oxide, senarmontite, is rarely abundant enough to be an ore. Stibnite was one of the minerals formerly cited as having originated in veins bj' volatilization from lower sources. But it has probably, in all cases, been derived from solutions of alkaline sulphides. 2.14.08. Example 47. Veins containing stibnite, usually in quartz gangue. California, Kern County. At San Emigdio a vein of workable size has been found. It has a quartz gangue and is in granite. The vein varies from a few inches to several feet across, and has afforded some metal. Several others are'*^^^^"^ known in San Benito and Inyo counties. * F. D. Adams, ** Report on the Geology of a Portion of Central Ontario," Geol. Survey Can., 1892-3, Report J, 5. •' Occurrence of a Large Area of Nepheline Syenite in the Township of Dungannon, Ontario," Amer. Jour. Sci. , July, 1894, 10. (The corundum had not been discovered when these two papers were issued.) Archibald Blue, "Corundum in Ontario," Amer. Inst. Min. Eng., Buffalo meeting, 1898. A. P. Coleman, "Corun- diferous Nephehne-Syenite from Eastern Ontario," Jour. Geol, VII., July- August, 1899, 437. B. J. Harrington, "Nepheline, Sodalite and Orthoclase from the Nepheline Syenite of Dungannon, Ont.," Amer. Jour. Sci., July, 1894. 16. W. G. Miller, " Report of Ontario Bureau of Mines," VII., 207, 1898. * L. V. Pirsson, "Corundum-bearing Rock from Yogo Gulch, Mont.," Amer. Jour. Sd., December, 1897, 421. 3 J. D. Dana, Amer. Jour. Sci., September, 1880, 199. J. P. Kimball, Amer. Chemist, IV., 1874, 321. Trans. Amer. Inst. Min. Eng., IX., 19, 1881. G. H. Williams, Amer. Jour. Sci, March, 1887, 197. Rec. * T. H. Holland, "Corundum": in "A Manual of the Geology of India," Economic Geol, Part I., 1898, 1-69. THE LESSER METALS. 411 2.14.09. Nevada, Humboldt County, Stibnite has been known for some years in veins with quartz gangue. The Thies-Hutchens mines, about 15 miles from Lovelock station, were productive in 1891. Lander County. The most impor- tant of the American mines are the Beulah and Genesee, at Big Creek, near Austin. The vein is reported as showing three feet of nearly pure stibnite. It produced 700 tons of sulphide in 1891, and was operated in 1892. 2.14.10. Arkansas, Sevier County. Stibnite occurs in veins with quartz gangue in southwestern Arkansas. Some attempts have been made to develop them, but the ore is reported to be too remote for profitable working. The veins appear to be gen- erally interbedded in Trenton shales and to lie along anticlinal axes, which trend northeast. They are all controlled by the United States Antimony Company, of Philadelphia. 2.14.11. New Brunswick, York County. Veins of quartz or quartz and calcite, carrying stibnite, occur over several square miles. The wall rocks are clay slates and sandstones of Cambro-Silurian age. The mines have been commercially pro- ductive. The veins vary from a few inches to six feet. 2.14.12. Example 48. Utah, Iron County. Disseminations of stibnite in sandstone and conglomerate, following the strati- fication. In Iron County, southwestern Utah, masses of radiat- ing needles occur in sandstones and between the boulders of an associated conglomerate. Very large individual pieces have been obtained, but not enough for profitable mining. Blake thinks that the ore has crystallized from descending solutions. Eruptive rocks are present above the sandstones. 2.14.13. An interesting deposit of senarmontite was worked for a time in Sonora, just south of the Arizona line, but it was soon exhausted.^ ^ General References: W. P. Blake. "General Distribuoion of Ores of Antimony," Min. Resources of the U. S., 1883-84, p. 641. Arkansas: T, B. Comstock, Oeol. Survey of Kan., 1888, I., p. 136. F. P. Dunnington, "Minerals of a Deposit of Antimony Ores in Sevier County, Ark.," Amer. Assoc. Arts and Sci., 1877. Rec. J. W. Mallet, Chem. News, No. 533. C. E. Waite, "Antimony Deposits of Arkansas," Trans. Amer. Inst. Min. Eng., VII., 43. C. P. Williams, " Notes on the Occurrence of Antimony in Arkansas," Idem, III.. 150. California: W. P. Blake, "Kern County," U. S. Pac. R. R. Explor. and Survey, Vol V., p. 291. H. G. Hanks, -Rep. Cal. State Mineralogist, 1884. See also subsequent reports by William 412 KEMP'S ORE DEPOSITS. ARSENIC. 2.14.14. This metal occurs with many silver ores in the West and in arsenopyrite, or mispickel, a not uncommon arseno- sulphide in the gold quartz veins, east and west. At the Gat- ling mines, in the town of Marmora (more lately called Deloro), in Hastings County, Ontario, auriferous mispickel occurs in great quantity in granite, in veins with quartz gangue. Con- siderable oxide of arsenic has been obtained in the past from the roasters, but in recent years the cyanide process has been employed. For reference to the printed descriptions see under "Gold in Canada" (2.13.07). Considerable arsenic is also pro- duced as a by-product in treating the ores of the Monte Cristo mines of Washington State. BISMUTH. 2.14.15. Bismuth occurs with certain silver ores in the San Juan district, Colorado, and is referred to in the description of the country under ** Silver and Gold" (2.09.10). Lane's mine, at Monroe, Conn., has furnished museum specimens of native bismuth in quartz. Some neighboring parts of Connecticut have afforded bismuth minerals, and not a few other places in the country contain traces, but the San Juan is the only serious one as yet/ CHROMIUM. 2.14.16. Chromite, whose theoretical composition is FeO.CrgOs, with CrgOs 68%, often has MgO and FegOs re- placing its normal oxides. The percentage of CraOs is thus reduced. It is always found in association with serpentine, which has resulted from the alteration of basic rocks consisting of olivine, hornblende, and pyroxene. These minerals, or at Irelan, Jr. Mexico: E. T. Cox, "Discovery of Oxide of Antimony in So- nora," Amer. Jour. Set., XX., 431. J. Douglass, "The Antimony Deposit of Sonora," Eng. and Min. Jour., May 21, 1881, p. 350. Nevada: Idem, 1892, p. 6. New Brunswick: L. W. Bailey, "Discovery of Stibnite in New Brunswick," Amer. Jour. Sci., ii., XXXV., 150, and in Rep. on the Geol. of New Brunswick, 1865 ; also H. Y, Hind, in the same. Utah : D. B. Huntley, Tenth Census-, Vol. XIII., p. 463. * Min. Resources of the U. S., 1885, p. 399. B. Silliman, " Bismuthinite from the Granite District, Utah," Amer. Jour. Sci., iii., VI., 123. H. L. Wells, " Bismuthosphaerite from Williraantic and Portland, Conn.," Amer Jour. Sci., iii., XXXIV., 271 THE LESSER METALS. 413 least the pyroxenes, contain chromium as a hase, but in the unaltered rock there is no question that chromite itself has formed one of the component minerals, just as magnetite so commonly occurs in this relation. A chrome spinel, picotite is also not unusual. The basic rocks, peridotites and pyroxenites, almost alwaj^s yield on analysis some chromic oxide, and may in extreme cases afford several per cent. Vogt gives in the paper" cited below a series of percentages from 0.25 to 3.55 in twelve peridotites, from various localities. The invariable association of the metal with rocks rich in magnesium is strik- ing. Inasmuch as the chromite occurs, when mined, in ser- pentine, a secondary rock, it has usually been believed that it was a product set free in the change from the anhydrous original to the hydrated derivative.^ Meunier has referred it to the action of vapors or to a pneumatolj'tic process in the still molten peridotite magma. Vogt, however, includes the chromium ore bodies in the category of those formed by direct crystallization from a molten magma, and regards the chromite of the serpentines simply as the original crystallizations which have resisted alteration, while their associated minerals have undergone hydration and change. As chromite is a mineral that is extremely resistant to the action of the natural solvents and reagents, this view has much to commend it. Dynamic raetamorphism might afterward drag out the masses of chro- mite into a lineal alignment. Vogt also describes a fresh perid- otite from Hestmando under the polar circle in the extreme north of Norway,^ that is almost or quite rich enough in chromite to be worthj^ of exploitation. Hydrated nickel com- pounds are often associated with chromite. In recent investigations of the chromite deposits of North Carolina, J. H. Pratt ^ has reached the conclusion that the * See in this connection the following, which are cited by Vogt, Cossa and Arzruni, Zeitschr f. Krystal, VII., p. 1, 1883. A. v. Groddeck, Lehre von den Lagerstdtten der Erze, 146, 1879. A. Helland, Gesellsch. der Wissenschaften-Kristiania, 1873. L. de Launay, Formation Oites Metalliferes, 1893. ^ J. H. L. Vogt, Zeits. fur prakt. Oeol. , 1894, 385. L. de Launay sup- ports the same view, Annales des Mines, XII., 1897, 175. ^ J. H. Pratt, " On the Occurrence, Origin and Chemical Composition of Chromite," Trans. Amer. Inst. Min. Eng., New York meeting, Feb- ruary, 1899. Abstract in Eng. and Min. Jour., December 10, 1898. Re- fers especially to North Carolina. 414 KEMP'S ORE DEPOSITS. mineral has crystallized from fusion, and has become concen- trated near the walls by convection currents, as described un- der 1.06.13. 2.14.17. The chromite of commerce should contain at least 50% CrgOs. Values over this command a premium, while those below 50 suffer severe rebates. The less silica, the better. Wm. Glenn cites the following three analyses as typical of the run of the commercial product, the sources of the ore not being given. (XVll, Annual Report Director U. S. Geol Soc, Part III, 263.) SiOg 7.00 5.22 6.44 Cr^Og 39.15 51.03 53.07 FeO 27.12 13.06 15.27 MgO 16.11 16.32 16.08 CaO 3.41 2.61 1.20 AlgOg 7.00 12.16 8.01 99.79 100.40 100.07 Chromite in the arts is chiefly employed in the manufacture of potassium or sodium bichromate, so essential to dyeing, but of late years it is also proving of great value as an ingredient of refractory bricks, and as a lining for furnaces. 2.14.18. Example 49. Disseminations of chromite in ser- pentine. Pennsylvania and Maryland. Great areas of serpen- tine are found in southeastern Pennsylvania and in the adja- cent parts of Delaware and Maryland. Considerable mining has been done in the past. Where first obtained the chromite occurred in loose masses in the residual soil on the surface. It was identified and gathered in Harford County, Maryland, as early as 1827 by Isaac Tyson, Jr., and found a ready market abroad, to such an extent that from 1827 to 1860 the Baltimore re- gion was the chief source of the mineral for the world. In the ser- pentines of neighboring parts of Maryland and in southeastern Pennsylvania other deposits were found in the years following 1827, and a very important industry sprang up. The largest proved to be the Wood Pit or Mine in Lancaster County, Penn- sylvania, and it developed the most productive single deposit yet known. It has been worked to a depth of 700 feet or more — a striking thing for chromite, whose deposits, as a rule, are very limited in depth and extent, and very pockety. The so- THE LESSER METALS. 415 called Texas mine near or on the Maryland-Pennsylvania line also became well known. In addition to the surface boulders and included masses, chromite sand of commercial grade has been obtained from the beds of streams in this belt, and, as stated by Wm. Glenn, the supply is renewed after an interval of about fifteen years. The work of G. H. Williams and F. D, Chester has shown the great abundance of basic, plu tonic rocks, gabbros, pyroxenites, peridotites and the like in this region, and there is every reason to regard the serpentines as derivatives from such originals. During the process of alteration what- ever chromite there was present in the fresh igneous rock, was reinforced by the formation of secondary chromite from the alteration of chromiferous pyroxene, and other minerals, but only rarely were sufficient amounts produced to warrant min- ing. Dynamic metamorphism may have strung them out in linear alignment. 2.14.19. Chromite has also been met in several places in the south, but never, as yet, in minable amounts. The Baltimore region itself has not been active for some years. ^ 2.14.20. California. As already mentioned under the pre- cious metals, great areas of serpentine occur on the western flanks of the Sierras and in the Coast range. In Del Norte, San Luis Obispo, Placer, and Shasta counties, California, they furnish commercial amounts of chromite. In some places the ore is followed by underground mining, and in others it is ' F. D. Chester, in the Ann. Rep. Penn. Geol. Survey, 1887, describes the Serpentine along the State line with Delaware. D. T. Day, Mineral Resources, and since 1894, Ann. Reps. oftheDir. of U. S. Geol. Survey, 1882, p. 428; especially 1883-84, p. 567. J. Eyerman, "On Woods Mine, Pa.," Min- eralogy of Penn. , Easton, 1889. P. Eraser, ' ' The Northern Serpentine Belt in Chester County, Pa.," Trans. Amer. Inst. Min. Eng., XII., 349. Report C3, Lancaster Co., Penn., Geol. Survey. Rec. T. H. Garrett, "Chemical Examination of Minerals Associated with Serpentine," Amer. Jour. Sci., ii., XIII., 45, and XV., 332. F. A. Genth, Idem, ii., XLL, 120. Wm. Glenn, "Chrome in the Southern Appalachian Region," Trans. Jlmer. Inst. Min. Eng., XXV., 481. Rec. J. H. Pratt, "The Occurrence, Origin and Chemical Composition of Chromite," Trans. Amer. Inst. Min. Eng., February, 1899, New York meeting. G. H. Williams, "The Gabbros and Associated Hornblende Rocks near Baltimore," Bull. 23, U. S. Geol. Survey. " The Geology of the Crystalline Rocks near Baltimore," dis- tributed at the Baltimore meeting of the Amer. Inst. Min. Eng. , Feb- ruary, 1892. Rec. 4] 6 KEMP'S ORE DEPOSITS. gathered as float material. The irregular distribution, always characteristic of the mineralj renders underground work uncer- tain. Good ore should afford 50% Cr203, and in California no ore less than 47% is accepted. It brings in the East $22 to $35 per ton.^ 2.14.21. Quebec. In the serpentine belt that extends from northern Vermont to Gaspe, and which contains the well known asbestos mines near Black Lake, chromite has been known for many years. In 1894 some productive pockets were found that have since yielded about three thousand tons of high grade ore. The mines are two miles from Black Lake station, and are in a belt of serpentine south of the asbestos belt. In the best pocket the ore occurred next a dike of granulite,^ ac- cording to Donald, but elsewhere it lacks this associate. 2.14.22. Newfoundland. Chromite has verj' recently been discovered and developed at Port au Port Bay, on the west coast of Newfoundland. G. W. Maynard states that it occurs in bands of serpentine, which are themselves enclosed in diorite. The geological surroundings are thus those of the usual ser- pentinous and basic igneous rocks. The quantity exposed war ranted the erection of a concentrating plant. ^ COBALT (see under " NICKEL"). MANGANESE. 2.14.23. Ores: Pyrolusite MnOg, Mn. 63.2, braunite, Mn2 03, Mn 69.62. Some SiOa, which may be chemically com- bined, is usually present, and small amounts of MgO, CaO, etc. Psilomelane has no definite composition, but usually con- tains barium or other impurities. An Arkansas variety has afforded Brackett MnO, 77.85. * E. Goldsmith, " Chromite from Monterey County, Cal.," Proc. Phila. Acad. Set, 1873, 365. Wm. Irelan, Jr., Reports of Col. State Mineralo- gist, especially 1890, pp. 167, 189, 313, 582, 583, 638. J. J. Crawford be- came State Mineralogist in 1893 ; Chromite receives mention also in his reports. " J. T. Donald, "Chromic Iron in Quebec," Eng. aud Min. Jour., Sep- tember 8, 1894, 224. M. Penhale, Idem, December 8, 1894, 532. Wni. Glenn. 'Chromic Iron, with Reference to its Occurrence in Canada," XVII. Ann. Rep. Dir. U. S. Geol. Survey, Part III., 261. Rec. Contains a good bibliography. J. Obolski, Can. Min. Review, January, 1896. ^ Geo. W. Maynard, "The Chromite Deposits on Port au Port Bay, Newfoundland," Trans. Amer. Inst. Min. Eng., XXVII. 283, 1897. THE LESSER METALS. 417 There are various other oxides and hydroxides, which are rarely abundant enough to be ores. The carbonate, rhodochro- site and the silicate, rhodonite, are rather common gangue minerals with ores of the precious metals. Franklin ite is also an important source (2.07.04). Pyrolusite and psilomelane are the commonest ores the country over, but braunite is the one in the Batesville (Ark.) region. Manganese is widely dis- tributed, and yet is commercially important in but few locali- ties. It imitates limonite very closely in its occurrence, and is often associated with this ore of iron. To make a manganese ore valuable, at least 40% metallic manganese should be pres- ent, and this is a lower limit than was formerly admissible when the ores were chiefly used in chemical manufactures. Under present conditions, if iron is present, the ore may be suited to Spiegel, although even lower in manganese than 40%. Further, there should be low phosphorus; Penrose says not over 0.2 to 0.25% in Arkansas, and not over 12% SiOg. High-grade ores run 50 to 60% manganese. 2.14.24. The original home of manganese is in the ferro- magnesian silicates of the igneous rocks. In all of them it is known to enter as a minor base, acting much in the same way as iron. On being released from the ferro-magnesian minerals, its subsequent geological behavior is in some respects much like that of iron, but it diff!er& from iron in that its sulphides, though known, are very rare minerals. Aqueous circulations leach the manganese from the igneous rocks, whether deep-seated or superficial, and sea- water has a strong dissolving effect upon fragmental, volcanic ejectments that are thrown into the ocean. In the latter case the peroxide of manganese finally forms pellets and incrustations on the sea -bottom, especially at great depths;^ in the former rhodonite and rhodochrosite result as the familiar gangue minerals of many veins, and manganese oxide or carbonate enters into many f ragmen ta J sediments and limestones. Almost all the deposits of commercial importance have been produced by the subaerial alteration of these last ^ For a short review of Manganese in Nature see L. de Launay, Annales des Mines, XII., 1897, 185-191. The subject is discussed at length in Pen- rose's Report on Manganese for the Arkansas Geol. Survey. Chapter XXI. 2 John Murray, Proc. Boy. Soc, London, XXIV., 528. Sir C. Wyville Thomson, T7ie Atlantic, II., 14, 1873. 418 KEMP'S ORE DEPOSITS. named, so that nodules of manganese oxides remain embedded in residual clays, precisely like many brown hematite deposits. 2.14.25. Example 50. Manganese ores, chiefly psilomelane and pyrolusite, often in concretionary masses, disseminated through residual clay, which with the ores has resulted from the alteration of limestones and shales. The deposits are entirely analogous to Examples 2 and 2a, under "Iron.'' Along the Appalachians the favorite horizon is just over the Cambrian (Potsdam) quartzite. This is the case at Brandon and South Wallingford, Vt., where the ores occur in a great bed of clay between quartzite and limestone. They are referred to under Example 2a, where mention is made of the associated limonites SECTION NO. 2. SECTION NO. 4. Fig. 155. — Sections of the Crimora manganese mine, Virginia. T.Tie trough is formed by Potsdam sandstone a7id is filled with clay carrying nodules of ore. After 0. E. Hall, Trans. Amer. Inst. Min. Eng., XX., 48, June, 1891. and interesting lignite. They have never been important pro- ducers of manganese. Crimora, in Augusta County, Va., was formerly the largest mine in the country'. The containing cla}' bed is very thick, as a drill hole, 276 feet deep, failed to strike rock. The ores occur in pockets, which as a maximum are 5 to 6 feet thick and 20 to 30 feet long, and of lenticular shape. Other irregular stringers and smaller masses run through the clay, which preserves the structure of the original rock. Pots- dam quartzite underlies it. Other similar bodies occur at Lynd- hurst and elsewhere in the Great Valley of Virginia, but Crimora is now no longer a source of ore. Cartersville, Ga., THE LESSER METALS. 419 IDEAL Sections showing the/ormation of manganese-Bearing CLAY FROM THE DECAY OF THE ST. CLAIR LIMESTONE. ^m n— I Boone Chert ^^ Manganesc-BEaRinQ Clay L_1JIzaR0 LimestonC SACCMAROfDAL SANOSTONC St.Cuaib limestone ^--'=^-_ — ~ Z:^' r — --^'— _r-— -r=— ^IS" ^ — - _ - _^- - — < zr2 kr^F^S-^t^^^lSb^^-EbE^^^^&g H ' 1 ' 1 ' 1 1 1 1 1 1 1 1 1 1 1 j^ 1 ' 1 ' 1' 1 1 II II 1 III! •-r] — ' — T" r 1 1 1 1 1 1 1 I 1 1 T^ 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 ' 1 1 1 '■ 1 ' 1 ' 1 ' 1 xrl ' 1 1 1 1 1 1 1 ^Ufv II 1 1 1 1 1 II 1 1 1 II ^ -.'■'■<■} ■:y :['■'■:■■/: ■■\'':^//y:' :■'■'■■ :''-::'^^ ■■-. / Fig. 1.— Original Condition oe the Rocks. Fig. 2. —First Stage, of Decomposition. Fig. 3.— Second Stage of Deco:w position-. Fig. 4.— Third Stage of Decomposition. Fig. 156. — Geological sections illustrating the formation of the manganese ores in Arkansas. After R. A. F. Penrose, Geol. Survey of Ark.. 1890, Vol. L, p. 177. 420 KEMP'S ORE DEPOSITS. is secoDd to Crimora in production. As at Crimora, the ores occur in pockets in stiff clay, and are associated with quartzite which is not sharply identified as yet. It may be Cambrian (Potsdam), or Upper Silurian (Medina). West of Cartersville is the Cave Spring region, where the ores occur with Lower Silurian cherts. There are numerous other localities not yet of commercial importance along the Appalachians, in Ten- FlG. 157. — The Turner mine, BatesvUle region, Arkansas. After li. A. F. Penrose, Geol. Surveg of Ark., 1890, Vol. I., p. 272. nessee and elsewhere. Full descriptions will be found in Pen- rose's report, cited below. 2.14.26. Batesville, Ark. The ore is braunite, and is found in masses disseminated in a residual clay which was thought by Penrose to have been left by the alteration of a limestone locally called the St. Clair. The stratigraphy has been revised in some important particulars by H. S. Williams, as noted below. The St. Clair was regarded by Penrose as of geologic age be- TEE LESSEE METALS. 45^1 tween the Trenton and Niagara periods. It is underlain by another limestone called the Izard, which is later than the Cal- ciferous. On Penrose's St. Clair a series of cherts, called the Boone cherts, is found, which are of Subcarboniferous (Missis- sippian) age. The clays are sometimes in valleys, sometimes on hillsides, according to the unequal decay of the limestone. South of the Batesville district are th6 Boston Mountains, a range of low hills 500 feet high, and from these the manganifer- ous rocks form a low monocline to the north. The district is in northern central Arkansas. The ore was thought by Pen- rose to have been derived from the limestone, and to have separated in its decay. H. S. Williams has modified the above stratigraphy in important particulars by close paleontological determinations and the modifications bear on the origin of the ores in a very important way, changing them, as regards their original home from deep-water deposits to shallow-water ones. Williams observed that the limestone, called the St. Clair above, contained both a Lower Silurian fauna and an Upper Silurian one. In one good exposure on the Cason property they were separated by a thin band of shale, which shale contained the manganese ore, Williams therefore restricts the name St. Clair limestone to the Lower Silurian (or Ordovician) stratum, and calls the shale the Cason shale, and the overlying Upper Silurian (or Eo-Silurian) limestone the Cason limestone. Some of the clay, which was observed by Penrose to contain the nodules of ore has resulted from this shale, and it may be that the ore generally has come from the same source. The geolog- ical relations would then be closely parallel with Crimora, Va. (H. S. Williams, "Age of the Manganese Beds of the Batesville Region of Arkansas," Amer. Jour. Set., October, 1894, 325.) 2.14.27. Southwestern Arkansas contains a second district in which the ore occurs in a great stratum of novaculite of probable Lower Silurian age. The ores are of no practical im- portance, being too lean and too disseminated. Small amounts of manganese ore have been obtained in California, in San Joaquin County, and from Red Rock, in San Francisco harbor. The former, and perhaps others in the State, may prove impor- tant hereafter. Penrose has described an interesting deposit of manganese ore near Golconda, Nev. It is an interbedded, lenticular mass about 150 feet long and 10 feet thick as amaxi- 422 KEMP'S ORE DEPOSITS. mum in calcareous tufa, of Pleistocene age. It is remarkable fcr its content of 2.78% tungstic acid. Penrose interprets it as a superficial deposit from uprising springs, whose waters presumably formed a pool, allowing of the oxidation and precipitation of the dissolved manganese. The latter was derived from lower lying rocks, presumably igneous, although sediments are not an impossible source.^ Leadville, Colo., is now an important source of manganese ores, the shipments going as far as Chicago. The geological relations are the same as for the lead-silver ores, earlier described. 2.14.28. Considerable manganese occurs at times in some of the Lake Superior iron ores, especially those from the Gogebic range. Cuba has also afforded some shipments notably high in this metal. In the Santiago region the ore forms nodules in the soil from which it is obtained by stripping and washing. 2.14.29. Quite productive deposits are found in pockets at Markhamville, Kings County, N.B., in Lower Carboniferous limestone. Some thousands of tons have been shipped. Other mines are situated at Quaco Head. At Tenny Cape, in the Bay of Minas, Nova Scotia, is another deposit in Lower Car- boniferous limestone, which has furnished several thousand tons of ore. Others less important occur on Cape Breton.^ ^ R. A. F. Penrose, "A Pleistocene Manganese Deposit," Jour. ofGeol., I., 275, 1893. ^ "Manganese Mines near Santiago, Cuba," Eng. and Min. Jour., No- vember 24, 1888, p. 439. H. P. Brumell, "Notes on Manganese in Canada," Amer. Geol., August, 1892, p. 80. D. de Cortazar, "General Review of Occurrence and Manufacture," Reps, and Awards, Group L, Centen. Exposition, p. 196. D. T. Day, Mineral Resources, 1883, p. 424 ; 1883-84, p. 550. F. P. Dunnington, "On the Formation of the Deposits of Oxides of Manganese," Amer. Jour. Sci., iii., XXXVI., 175. Rec. W. M. Fon- taine, "Crimora Manganese Deposits," The Virginias, March, 1883, pp. 44-46. Rec. C. E. Hall, "Geological Notes on the Manganese Ore De- posits of Crimora, Va.," Trans. Amer. Inst. Min. Eng., June, 1891. E. Halse, " Notes on the Occurrence of Manganese Ore, near Mulege, Baja California, Mexico,' Trans. N. of Eng. Min. and Mech. Eng., XLI., 302, 1892. H. Hoy, "Ores of Manganese and their Uses," Proc. and Trans. N. S. Inst. Nat. Sci., Halifax. II., 1864-65, p. 139. " Manganese Mining in Merionethshire, England," Eng. and Min. Jour., December 18, 1886, p. 438. R. A. F. Penrose, Ann. Rep. Ark Geol. Survey, 1890, Vol. I. The best work published. Rec. " Origin of the Manganese Ores of Northern Arkansas,' etc., Amer. Assoc. Adv. Sci., XXXIX., 250. "The Chemical THE LESSER METALS. 423 2.14.30. Panama. Manganese ores have been shipped In large quantities from the mainland of South America, just east of the base of the Isthmus of Panama, although still in the province of that name. The ores occur about 5 to 6 miles from the coast and 8 miles from the dock, in the valley of the Rio Viento Frio. Great masses of the oxides of manganese (both braunite and pyrolusite) occur in residual clay. More or less quartz is associated with them. The original rock seems from the very decomposed pieces available to have been a clastic one, chiefly of feldspathic fragments. The ores are rich in man- ganese and low in phosphorus. There had been shipped to the close of 189G, 18,215 tons.' Relation of Iron and Manganese in Sedimentary Rocks," Jcmr. of Oeol., I., 356, 1893. J. D. Weeks, Mineral Resources of the U. S., 1885, p. 303 (Rec); 1886, p. 180; 1887, p. 144. D. A. Wells, " On the Distribution of Manganese," ^mer. Assoc. Adv. Sci., VI., 275. C. L. Whittle, "Genesis of the Manganese Deposits at Quaco, N. B,," Proc. Bost. Soc. Nat. Hist., XXV., p. 253. ^ E. J. Chibas, ' ' Manganese Deposits of the Department of Panama, Republic of Colombia," Trans. Amer. Inst. Min. Eng., XXVII., 63, 1897. "Railroad Building and Manganese Mining in Colombia." Eng. Mag., December, 1896, Vol. XII., 426. "Construction of a Light Mountain Railroad in the Republic of Colombia," Trans. Amer. Soc. Civ. Eng., XXXVI., 65, 1896. CHAPTER XV. THE LESSER METALS, CONTINUED — MERCURY, NICKEL ANI> COBALT, PLATINUM, TIN. MERCURY. 2.15.01. Ores: CinDabar, HgS. Hg. 86.2, S. 13.8. Meta- cinnabarite is a black sulphide of mercury. Native mercury also occurs. Tiemannifce the selenide HgSe, and onofrite the sulphoselenide, Hg(SeS) have been met at Marysvale, in south- ern Utah.^ Mercury, usually called quicksilver in commerce, has been dis- covered in vs^orkable quantities at a number of places along the Pacific coast of North America. Its chief localities are in the Coast ranges of California, where, though formerly more pro- ductive, it is still quite largely obtained. The deposits extend into Oregon, but are of no great importance. In small amount it has been mined in Nevada and Utah, and has recently been discovered in promising although not demonstrated quantity in w^estern Texas. Many localities are known in Mexico, but Guadalcazar, in the State of Guerrero, and Huitzuco, in San Luis Potosi, have proved most productive. In South America, the mines at Huancavelica, in Peru, have been in the past of vast productiveness. In Europe, Almaden in Spain, is much the most important of all the deposits known to-day, but Idria in Austria, and Avala in Servia are still of value. Several other well-known mining districts of former years have lapsed into inactivity. In Asia the great deposits of Kwei-Chau are described as being of great possibilities. ^ G. J. Brush and W. J. Comstock, "American Sulpho-selenides of Mer- cury, with Analyses of Onofrite from Utah," Amer. Jour. Sci., April, 1881, 312. G. F. Becker describes this as Tiemannite, Monograph XIII., p, 385, U. S. Geol. Survey, ISSS; Mineral Resources, 1892-5; Tenth Census. XIII., 463, 1880. THE LESSEE METALS, CONTINUED. 425 2.15.02. In their geological relations the ores of quicksilver are quite invariably associated with igneous rocks, although the walls are often sedimentary. 2.15.03. G. F. Becker^ has recently given an admirable re- view of quicksilver deposits, the world over, their mineralogi- cal associates and probable methods of origin, and the same subject has been treated by A. Schrauf.^ Becker has tabulated the minerals associated with cinnabar from twenty-eight world- wide localities, and has made it evident that silica, either as quartz or in the opaline state, and calcite are the common gangue associates. Pyrifce or marcasite is almost invariably present and bitumen is very widespread. Various other antimony, arsenic, silver, lead, copper and zinc minerals, as well as gold, are of somewhat irregular occurrence. Becker reaffirms his previously cited theory of origin, that the cinnabar has come up in solution as a double sulphide with the alkaline sulphides, but lays stress upon the precipitating properties of bituminous substances, which reactions were corroborated by experiment. He favors the view that the cinnabar has impregnated porous or decomposed rock, rather than that it has actually replaced it by metasomatic processes. The probable source of the ore in deep-seated and widely-distributed granitic rocks, and espe- cially in such portions as overlie the foci of volcanic activity is affirmed , 2.15.04. Example 50. New Almaden. Cinnabar with sub- ordinate native mercury, in a gangue of crystallized and chal- cedonic quartz, calcite, dolomite, and magnesite, forming a stockwork, or * 'chambered vein," in shattered metamorphic rocks (pseudo-diabase, pseudo-diorite, serpentine and sand- stone). There are two main fissures, making a sort of V, with a wedge of country rock between. The ore bodies are in the fissures and also in the intervening wedge. They are associated with much attrition clay. A great dike of rhyolite runs nearly parallel to the fissures, and to this Becker attributes the activity of circulations which filled the vein. The uprising solutions have often been influenced by the seams of clay and * G. F. Becker, "Quicksilver Ore Deposits, with Statistical Tables," Mineral Resources of the United States, 1892. 'A, Schrauf, " Aphorismen ueber Zinnoher, " Zeits. fiir prakt. GeoL, January, 1894, p. 10. 426 KEMP'S ORE DEPOSITS. appear to have especially deposited the ore along the lower sides of them. The ore has found a lodgment in the crevices of all sorts on the general line of disturbance, and has im- pregnated porous rocks, when they occurred in its course. It has been deposited simultaneously with the various gangue minerals. The wall rocks are of Neocomian (Early Cretaceous) age, but have suffered extreme metamorphism. Long after this ceased came the intrusion of the rhyolite, and probably the formation of the fissures now holding the ore. The intro- duction of the ore was in either Pliocene or post-Pliocene time, certainly not earlier. Several other mines, of which the Enri- quita and Guadalupe are most important, are near New Fig. 158. — Section of the Great Western cinnabar mine. After G. F. Becker, Monograph XIIL, U. 8. Ueol. Survey, p. 360. Almaden, but the New Almaden is much the largest of all the North American deposits yet developed. New Idria is farther south, high up toward the summit of the Coast range. The ore is deposited in shattered metamorphic rocks of Neocomian (Lower Cretaceous) age, and in overlying Chico beds. The ore is accompanied by bitumen. Basalt is abundant ten miles away. North of San Francisco other mines have been opened, among which are the Oat Hill, Great Eastern, and Great Western. The mines are in a region pierced by eruptions of basalt and andesite, which doubtless gave impetus to the ore- bearing solutions. The ores are deposited in both metamorphic and unaltered sedimentary rocks. I THE LESSER METALS, CONTINUED. 4>Z1 2.15.05. Example 50a. Sulphur Bank. This is in the same general region as the last, but from its peculiar character has been one of the best known of ore deposits. A great flow of basalt has come down to the shores of Clear Lake from the west, Waters charged with alkaline (including ammonia) carbonates, chlorides, berates, and sulphides, and with CO2, H2S, SO2, and marsh gas, have circulated through it. Sul- phur and sulphuric acid have formed at the surface, and the latter has dissolved the bases of the rock, leaving pure white silica behind. Lower down, cinnabar is found, both in the basalt and in the underlying sedimentary rocks, with other sul- phides and chalcedony. Le Conte attributed its precipitation to cold surface waters, charged with sulphuric acid, which trickled down and met the hot alkaline solutions. Becker refers the same to the ammonia set free toward the surface by diminished heat and pressure. The California cinnabar de- posits have been often, but wrongly, referred to vapors of the sulphide volatilized by internal heat and condensed above. 2.15.06. Example 506. Steamboat Springs, Nev. These springs are in Nevada, only six miles from the Comstock Lode. Granite is the principal rock, while on it lie metamor- phic varieties of the Jura-Trias, and much andesite and basalt. Issuing through small fissures, the hot springs deposit chal- cedony in some places, carbonates in others, and cinnabar as well as gold. The following minerals have been noted : "Sul- phides of arsenic and antimony; sulphides or sulphosalts of silver, lead, copper, and zinc; oxide and possibly sulphide of iron; manganese, nickel and cobalt compounds, and a variety of the earthy minerals'* (Becker). Becker thinks the source of the cinnabar is in all cases in the underlying granite, and that it has come up in solution with sodium sulphide, and has been precipitated toward the surface bj' the other compounds in the hot alkaline waters, with which it would remain in solution at greater depths, temperatures and pressures. The Steamboat Springs are often and properly cited as metallifer- ous veins in active process of formation.^ * W. P. Blake, " Quicksilver Mine at Almaden, Cal.," Amer. Jour. Sci., a.. XVII., 438. G. F. Becker, "Quicksilver Deposits of the Pacific Slope," Monograph XIIL, U. S. Geol. Survey, Chap. 17. Rec. "On New Alma den," Cal. Oeol. Survey, I., p. 68. S. D. Christy, "On the Genesis of Cin 428 KEMP'S ORE DEPOSITS. 2.15.07. Cinnabar has recently been reported by W. P. Blake from southwestern Texas, in a rough, broken and almost uninhabited district some 10 to 12 miles from the Rio Grande River. The cinnabar occurs "in massive limestone and in a sili- ceous shale, and a white earthy clay-like rock, and in part in a true breccia of grayish, white, siliceous shale, dense and com- pact, imbedded and cemented in a red and chocolate-colored fer- ruginous mass, also dense and hard.'* The age of the nearest determinable beds is Lower Cretaceous. The quicksilver ore seems to impregnate the beds, and also to lie along a shattered or brecciated belt. It is oftentimes in concentric layers with oxide of iron, with which it seems to have in general a common origin, but to have been laid down in intervals of changed con- ditions of deposition. In addition to the disseminated granules, there are bunches of soft, friable cinnabar in the shales, limestones and breccia. It is undemonstrated as yet, whether the deposits are workable or not. The conditions are some- what hard because water is lacking, and the location is remote.^ NICKEL AND COBALT. 2.15.08. These two metals almost always occur together.*^ nabar Deposits." Amer. Jour. Set., June, 1878, p. 453; Eng. and Min. Jour., August 2, 1879, p. 65. D. de Cortazar, "General Review of Occur- rence, etc., of Mercury," Reps, and Awards, Group I., Centennial Exposi- tion, p. 196. William Irelan, Ann. Reps. Cal. State Mineralogist. Laur, "On Steamboat Springs," Annates des Mines, 1863, 423. J. Le Conte and Rising, "Metalliferous Vein Formation at Sulphur Bank," J.mer. Jour. Sci., July, 1882; Eng. and Min. Jour., August 26, 1882, p. 109. J. Le Conte, "On Steamboat Springs," Amer. Jour. Sci., June, 1883, p. 424. "Genesis of Metalliferous Veins," Idem, July, 1883. J. A. Phillips, "On Sulphur Bank, California," Phil. Mag., 1871, p. 401; Quar. Jour. Geol. Sci., XXXV., 1879, p. 390. Rolland, Annates des Mines, XIV.. 384, 1878. B. Silliman, "Notes on the New Almaden Quicksilver Mines," Amer. Jour. Sci., ii., XXXVII., 190. Siveking, B. und H. Zeitung, 1876, p. 45. * W. P. Blake, "Cinnabar in Texps," Trans. Amer. Inst. Min. Eng.^ XXV., 68. ^ The following general papers on nickel and cobalt are important : F. D. Adams, "On the Igneous Origin of Certain Ore Deposits," Oen. Min. Assoc. Prov. Quebec, January 12, 1894. P. Argall, "Nickel: The Occur- rence, Geological Distribution and Genesis of its Ore Deposits," Proc. Col. Sci. Soc, December 4, 1893. W. L. Austin, "Nickel: Historical Sketch," Idem, same date. H. B. v. Foullon, " Ueber einige Nickelerzvorkommen,"" THE LESSER METALS, CONTINUED. 429 Their ores embrace the following general classes: (1) Com- pounds with arsenic and rarely with antimony, or with arsenic (or antimony) and sulphur; (2) Sulphur compounds, including nickeliferous pyrrhotite and pyrite; (3) Oxidized ores, mostly hydrated silicates related to serpentine.^ .Although the num- ber of minerals involving nickel and cobalt is quite large, the ores, properly speaking, are comparativelj^ few ; nickeliferous pyrrhotite is much the most important, especially as concerns this country, but the oxidized ores may yet prove serious. Only the ores {i.e., minerals commercially important) are men- tioned in the table below. Niccolite NiAs, Ni.44.06 As. 55. 94 Millerite ........ NiS, Ni. 64. 83 S. 35. 17 Linnaeite (00^)384 Co.21.34, Ni.30.53 Fe. 3.37 S. 41.54 Pentlandite . . . . (NiFe) S, Ni.34.23 Fe.30.25 S. 33.42 Genthite 2NiO,2MgO,Si02,6HgO. Ni.22.6. Garnierite H20(Ni,Mg)O.Si02+iH20 Ni.25.0. Zaratite NiC03,2Ni(OH) 2+4H80 Ni.46.8. To these nickeliferous pyrrhotite and pyrite should be added, i;he former being the most important of all. 2.1 5.09. Niccolite was reported years ago at Tilt Cove, New- foundland, in some quantity, but elsewhere has not been found in any serious amount in North America. It also occurs in some of the western openings of the Sudbury district. Millerite furnished a small portion of the nickel at the Gap Mine, Penn- sylvania, as noted below. Linnseite, variety siegeuite, occurs in a sandstone bed at Mine la Motte in disseminated octahedra, and although small attempts have been made to utilize it, the amounts are, so far as known, not large enough for success. Pentlandite must be mentioned together with nickeliferous pyrrhotite. It has been somewhat of a question among min- eralogists in just what relations the nickel ocqurs in pyrrhotite; Jahrbuchd. k. k. geol. Reichsanstalt, Vienna, XLIL, 223, 1892. D. Levat, Annalesdes Mines, 1892, Part II. J. H. L. Vpgt, " Nikkelforkoraster og Nikkelproduktion " (Occurrence and Production of Nickel), Norwegian Geol. Survey, Kristiania, 1892; a resume in German accompanies the paper. "Sulphidische Ausscheidungen von Nickelsulphiderzen," etc., Zeits. fur prakt. Geol, April, 1893, 125. ^ This is practically the same grouping that is given by J. H. L. Vogt, Zeits. filr prakt. Geol, April, 1893, 125. See also P. Argall, Proc. Colo. Sci. Soc, December 4, 1894. 430 KEMP'S CRE DEPOSITS. whether replacing the iron in FeTSg, or some other variety of FenSn+i, to the extent of a fraction of one per cent, up to five, or whether there is an isomorphous or distinct nickel or iron- nickel sulphide intermingled with the pyrrhotite. As far back as 1843 Scheerer identified pentlandite from southern Norway, and several other related minerals, such as polydymite, have been less definitely described. More recently it has been shown that the nickel-rich portions of the pyrrhotitic ores are quite feebly magnetic, and processes have even been suggested for con- centrating the nickel based on this principle.^ Pentlandite is non-magnetic, and possibly this mineral in very fine dissemina- tions may contribute of its richer percentage of nickel to raise the total of the pyrrhotites as mined. Some nickel, however, always remains in the strongly magnetic residues, so that we are not yet justified in abandoning the earlier view that this metal replaces some of the iron of the pyrrhotite. Pyrrhotite is the chief ore at Sudbury, and was the ore at the Gap Mine, Pennsylvania, until the workings were dismantled in 1894. In southeast Missouri, but more especially at Mine la Motte, nickeliferous pyrite accompanies the galena (see 2.05.09), and has furnished a considerable amount as a by-product in the metallurgy of lead. Of the oxidized ores it is not easy to speak as regards their individual importance. The hydrated silicates are of extremely variable composition, and while one or two illustrations of the type are selected for the table, no one of them is yet seriously mined in America. 2.15.10. Example 16c. (See 2.03.16 and 2.04.02.) Pyr- rhotite Beds or Veins. Lenticular masses of pyrrhotite inter bedded in gneisses and schists as described for pyrite They are known at various places in the East. Openings have been made at Lowell, Mass., Chatham and Torringtou, Conn., and on the mountain on the east bank of the Hudson, called Anthonj^'s Nose.^ The last is much the largest of those named, ^ See in this connection D. H. Browne, "On the Sudbury Ores, " Eng. and Min. Jour., December 2, 1893. Eec. S. H. Emmens, "The Consti- tution of Nickeliferous Pyrrhotite," Jour. Amer. Chem. Soc, XIV., No. 10. ' H. Credner, Berg, und Huett. Zeit., 1866, p 17. Dana's Treatise on Mineralogy, 6th Edition, under Pyrrhotite, gives several analyses from Putnam County, N. Y. J. F. Kemp, " The Nickel Mine at Lancaster Gap, Penn., and the Pyrrhotite Deposits at Anthony's Nose, on the Hudson," Trans. Amer. Inst. Min. Eng., XXIV., 620 and 883. THE LESSER METALS, CONTINUED. 431 and though never mined for the nickel which is known to be present, it was utilized as a material for sulphuric acid fumes during the ten years succeeding 1865. The geological relations give it especial interest. The ore body is entirely analogous to the magnetite lenses, which are not rare in the Highlands of the Hudson. It lies in a light-colored gneiss, conformably to the laminations, and must have attained 20 or 30 feet in thick- ness. It has been mined down 300 or 400 feet, and apparently for 50 feet or more on the strike. About 100 yards west is found a basic gneiss, consisting of green hornblende and plagioclase, with a little biotite. The wall rock contains quartz, plagioclase and very subordinate hornblende. In the thin section it appears fully as acidic as a quartz-diorite. Much hornblende is associated with the pyrrhotite, and occa- sional lumps of magnetite, with which are found titanite and apatite. The ore jnelded about 28% sulphur as used for years in the chemical works, and was especially prized because it contained no trace of arsenic. The geological relations give no reason for regarding the ore body as a basic segregation of a gab- broic magma, but quite the contrary. Several of the magne- tite mines in this region, it may be added, are troubled with pyrrhotite in the ore, but whether it is nickeliferous has not been determined.^ Similar pyrrhotites, low in nickel, occur in Ontario.*^ 2.15.11. Example 13a. Gap Mine, Penn. ; Sudbury, Ont. Bodies of nickeliferous pyrrhotite and chalcopyrite with verj' subordinate pyrite, in the outer portions of intrusions of basic igneous rocks, which may be metamorphosed to amphibolites. Cobalt is present in less amount than nickel and varies much in its relative proportions. Secondary millerite sometimes forms in cracks, as do quartz, siderite and one or two other minerals, but in variety of species ore bodies of this type are exceptionally barren. The type is of world-wide distribution, as noted by Vogt, and is well known in Norway, Sweden and one or two other European localities. The number of the Ex- ^ W. H. Hoffman, " The late Discovery of Large Quantities of Magnetic and Non-magnetic Pyrites in the Croton Magnetic Iron Mines, N. Y.," Trans. Amer. Inst. Min. Eng., June, 1892. J. C. Smock, Bulletin of New York State Museum, Dunderberg Mine, p. 18; Hobby Opening, p. 24. ^ F. D. Adams, Geol Survey Canada, Vol. VI., 1891-93, Part J. 432 KEMP'S ORE DEPOSITS. ample indicates its genetic parallelism with the titaniferous magnetites of 2.03.11. 2.15.12. The Gap Mine, in Lancaster County, southeast- ern Pennsylvania ,^ was originally opened for copper in the pre- ceding century. The copper enterprises were all failures, and not until in the fifties was the presence of nickel recognized. The mine then became the largest single producer of its day, and remained active until 1893, since which time it has been abandoned. As shown in the accompanying map and sections a lenticular outcrop or mass of greenish black rock, about 2,000 feet in length and 500 feet as a maximum width, is found in the midst of mica schist,, and apparently conformable to the laminations. It strikes nearly east and west, and is contracted along the section A A, where it was most productive. It seemed to pinch in somewhat in depth, so far as the workings extended (about 250 feet). The ore was chiefly found at the eastern end of the lense, and was much less abundant where followed to the westward on the south side with a drift, as far as is colored black. Prospect holes still further west proved the presence of the amphibolite, but failed to show ore. A dike of olivine-diabase of the familiar Triassic sort common in southeastern Pennsylvania outcrops about 1,500 feet southeast, but it is much later in time than the amphibolite, with which and with the ore it has no apparent connection. The ore is pyrrhotite in far the largest amount, but when cut in thin sec- tions along with the containing amphibolite, it is seen under the microscope that a light yellow- mineral, presumably pyrite, is mixed all through the bronze-colored pyrrhotite. The ore is richest near the contact and fades into lean disseminations as this is left. The lense consists in far the largest part of green hornblende of the common variety, quite pale in thin section, and with pleochroism from green to yellow. Many specimens are formed of this and nothing else, except scattered grains of ' P. Fraser, "Report CCC," SecoM Penn. Geol. Survey. A geological description and historical sketch are given, and also an outline map in the accompanying atlas, on which the figure here used is based. The descrip- tion, however, gives the impression that the ore is millerite, and hardly mentions pyrrhotite, whereas the millerite is a comparatively rare min- eral. Joseph Wharton, "Analysis of the(^Nickel Ore from the Gap Mine, Lancaster County, Penn.," Pi^oc. Phila. Acad. Sei., 1870, p. 6. 434 KEMP'S ORE DEPOSITS, pyrrhotite. Others show a little plagioclase, and a few flakes of biotite. Recognizable remains of orthorhombic pyroxene and olivine were detected despite the general and thorough meta- morphisni of the rock. No more accurate name can be given it than amphibolite, although there is little doubt that it origi- nally was a very basic gabbro or pyroxenite. The ore contains considerable secondary millerite, which forms crusts on the cracks of pyrrhotite, and often veins and stringers of quartz traverse it. In vuggs in these, beautiful crystals of vivianite are rarely met. The close parallel that the ore body affords in its geology to several Norwegian mines figured by Vogt in the Zeitschrift fiir prakt. Geologie, April, 1893, Plates V. and VI., is very striking. (See especially Meinkjar Grubenfeld, Fig. 3 of Plate VI.) The views of Vogt on the origin of such ore bodies by differentiation of a basic igneous magma in cool- ing, and by concentration of the early crystallizations at the contacts, according to Soret's principle, were outlined earlier in the discussion of the table of classification of ore deposits. In a metamorphosed rock, such as the Gap amphibolite, there is a reasonable ground for regarding the ore as a contact deposit due to deposition from solutions, but after seeing the larger, less metamorphosed but otherwise closely analogous ore bodies of the Sudbury district, the writer (J. F. Kemp) sees no escape from the conclusion that they and it are original crystalliza- tions from the igneous magma as much as any other component minerals of the intruded mass.^ 2.15.13. The Sudbury nickel mines are of quite recent de- velopment, as they were opened in 1886, although discovered earlier. They are situated forty miles north of Georgian Bay, an arm of Lake Huron, and on the eastern portion of the original Huronian belt. The Laurentian granites and gneisses, which to the east form a vast, monotonous stretch of low glaciated hil- locks and swamps, are covered near Sudbury, and for a hundred miles west, by a great area of later Huronian sediments (gray- * Literature on the Gap Mine, W. P. Blake, Mineral Resources, 1882, p. 399. J. Eyerman, " Mineralogy of Pennsylvania, " P. Fraser, Report CCC, Second Penn. Oeol. Survey, p. 163. J. F. Kemp, "The Nickel Mine at Lancaster Gap, Penn. , and the Pyrrhotite Deposits at Anthony's Nose, on the Hudson," Trans. Amer. Inst. Min. Eng., XXIV., 620, 883, 1884. J. Wharton, "Analysis of Nickel Ore from the Gap Mine,' Proc. Phila Acad. Sci., 1870, p. 6. THE LESSEE METALS, CONTINUED, 435 iv^ackee, quartzites, schists) and by immense intrusions and dikes of norites and more acid rocks, at times more or less metamor- phosed; emptive breccias and otiier interesting varieties too numerous to cite in detail are also present. The geology is veiry by swamps and however, sorite ran One on die 436 KEMP'S ORE DEPOSITS. has along its own southeastern side some rich deposits, includ- ing the Evans, Copper Cliff, Stobie and Blezard. The Evans is on a small outlier from the main mass, and the Stobie and Blezard are further in from the actual contact than is the Cop- per Cliff. Some miles west of the great diorite dike just referred to is the large Murray mine in another intrusion, with a stretch of supposed Laurentian granite between. Some twenty miles southwest, and in connection with a still differ- ent diorite dike are found the Worthington mine and several undeveloped openings in Drury and Denison townships. About the same distance northwest of Sudbury is a region around Wahnapitae Lake, well thought of, but not yet produc- tive. 2.15.14. In a recent valuable paper^ T. L. Walker has traced out the petrographical character of the basic intrusives that contain the ore. In crossing the dikes, the rock in its unmetamorphosed condition remote from the contacts is a norite. As the edge and therefore the ore body are approached, the hypersthene changes to bastite, and finally in the mines to hornblende, which has occasioned the use of the name diorite. Titan if erous magnetite accompanies the ore, and has been observed enclosed in it.' Walker concludes that the sulphides have crystallized directly from the fused magma, just as have the usual components of an igneous rock. It would seem that the change of hypersthene to hornblende at the borders would indicate some considerable metamorphism apparently dynamic in its nature. 2.15.15. The ore bodies betra}^ their presence by great out- crops of rusty gossan, consisting of limonit^ in layers and cellu- lar masses, which have resulted 'from the decay of the pyrrhotite and chaloopyrite. The outcrop of this gossan may run with local interruptions for long distances. ' When it was penetrated in the early prospecting the chalcopyrite lying below attracted attention, and the deposits were regarded as copper mines. Later the presence of the nickel in the pyrrhotite wsts recog- nized, and the nickel became the principal object. The two ores are inseparably intermingled and themselves form irregular masses often of great size in the. diorite. It is stated by Peters * T. L. Walker, " Geological and Petrographical Studies of the Sudbury Nickel District, Canada," Quar. Jour, of the Geol. Soc, 1897, 40. Fias. 161 AND 1Q2.—View of the Copper Cliff Mine, near Sudbury, Ontario. The mine is in diorite. The ridge at the background is granite. From photographs by T. G. White, 1894. THE LESSER METALS, CONTINUED. 437 that the early work at the Stobie showed ore over 100 feet across. The diorite is a dense black rock resembliog most closely black basalt in its appearance. Quite pure pieces of sulphides of large size are at times obtained, but practically all the ore contains rock up to 30% or more of its weight, and the sulphides form irregular masses in it. Great heaps of rock too lean to work, but showing bits of sulphides through the pieces, are thrown out on the dumps. The workings are in the form both of open cuts and of shafts, from which the drifts wander out somewhat irregularly in search of the ore-masses. While it is truly said the ores favor the contacts, this should not be too closely interpreted. The mines and the gossan do lie along the outer portions of the diorite masses, yet as now mined at all the large producers they are entirely in the diorite, and often very considerable distances from the actual contact, of which no evidence appears from the workings. Included masses of granite occur with the ore at Copper Cliff, and as a general thing have a rim of chalcopyrite. Some small, secondary and insignificant quartz veins ramify through the diorite, and con- tain chalcopyrite and some pyrrhotite, both of which are secondary, but they are trifling in amount. On the contrary, the masses of the sulphides are irregularly distributed, often as small isolated bits, throughout the fresh, dense diorite, and leave one no reasonable alternative but to conclude that they are as much an original crystallization from the igneous magma as any other of the minerals in the rock. Evidence of disturb- ance has been found in the region, and apparent fault lines are not lacking, but the great open cuts of the mines show no evidence of them. The method of igneous origin has been somewhat attacked. Posepny, for example, refers to it as something extraordinary when in his great essay on **The Genesis of Ore-Deposits," he cites Vogt's work, and controverts it strongly ; but it appears to the writer, after having seen the mines, that no process of solution and replacement can be con- ceived of as introducing these scattered masses of sulphides into dense, undecomposed and apparently unbroken igneous rock, which would not strain the faith of a conservative ob- server to a far greater degree.^ ^ D. H. Browne gives in the School of Mines Quarterly for July, 1895 p. 297, a very suggestive paper on " Segregation in Ores and Mattes." The 438 KEMP'S ORE DEPOSITS. 2.15.16. It is an interesting fact that sperrylite, the unique arsenide of platinum, occurs in the Sudbury region, but was not first discovered in a nickel mine. Traces are, however, said to occur in the nickel ores. Cobalt is in comparatively small amount, much less than in some other nickel regions. The ores vary in richness in different mines and in different parts of the same mine. They run from over 1% to over b% nickel, and have a copper percentage somewhat under the nickel. The Worthington has yielded a little gersdorffite (NiAsS), and niccolite (NiAs) in secondary quartz veins, and a vein is reported from Denison township containing both these. A galena vein is reported from the same region, and a little millerite is said to have been found in the Copper Cliff mine. Traces of zincblende have also been noted in some of the ores, but aside from these the mineralogy is limited to the two principal sulphides.^ 2.15.17. Example 49a. Riddle's, Douglass County, Ore- gon. Irregular deposits of hydrated silicates of nickel and magnesia, in serpentine formed by the alteration of peridotites or related rocks. Limonite, chalcedonic quartz and chromite are quite invariable associates, as are clays and other products results of a long experience with mattes show that in the matte pot the copper tends to collect at the top and sides, the nickel in the center. Parallels are drawn with the ore bodies, in the central parts of which the nickel is in excess of the copper, while at the edges the copper exceeds the nickel. 1 On Sudbury see F. D. Adams, "The Igneous Origin of certain Ore Deposits/' General Min. Assoc, Prov. Quebec, January 12, 1894, A, E, Barlow, "The Nickel and Copper Deposits of Sudbury, Ont.," Ottawa Naturalist, June. 1891. R. Bell, Geol. Survey of Can., 1890-91; F. 5, 91, Bull. Geol. Soc. Amer., II., p, 125. T. G. Bonney, "Notes on a part of the Huronian Series near Sudbury," Quar. Jour. Geol. Soc, XLIV,, 32, 1888. D. N, Browne, Eng. and Min. Jour., September 16 and December 2, 1893. E. R. Bush, "The Sudbury Nickel Region," Idem, March 17, 1894, p. 245. F. W, Clarke and C. Catlett, " Platiniferous Nickel Ore from Canada," A7ner. Jour. Sci., iii.,- XXXVII., 372. J. IJ. Collins, "Note on the Sud- bury Copper Deposits," Quar. Jour. Geol. Soc, XLIV., 834, J, Garnier, " Mines du Nickel, Cuivre et Platine, du District du Sudbury," ilfemozres de la Societie des Ingenieurs Civils., Paris, March, 1891. W. H, Merritt, Trans. Amer. Inst. Min. Eng., XVII., 295. E, D, Peters, "On Sudbury Ore Deposits," Idem, October, 1889; Eng. and Min. Jour., October 26,- 1889. Berg. u. Huett. Zeit., L., 149, 1891, Mineral Resources of the U. S.. 1888, 110. THE LESSER METALS, CONTINUED. 439 of alteration. The ore occurs in loose boulders on the surface, and as a coating on the walls of small cracks and vein lets that penetrate the more massive serpentine. The largest deposits of this character, so far as yet opened in this country, are in the Coast range, southwest of Riddle's Station, Douglass County, Oregon, on the Oregon and California Railroad. The mines occur on a steep hillside, in serpentine that has re- sulted from the alteration of the variety of peridotite, called harzburgite, i.e., bronzite and olivine. Open cuts, small drifts and test pits have served to show the nickel silicates, richest at the outcrop and fading out into small veinlets and reticulations in depth, until beyond the zone of superficial decay, they disap- pear. The openings are still in the condition of prospects, and productive mining is yet to be begun. The nickel has been shown by J. S. Diller to have been derived from the olivine of the rock, as chemical analysis of this mineral indicated 0.26% NiO By the familiar and ready alteration of the oliv- ine the nickel has separated as the silicate, and has finally been concentrated sufficiently to be noticeable.^ At Webster, in North Carolina, are surface deposits of nickel silicate which have attracted attention. They occur in the variety of perido- tite, which is chiefly olivine, and is called dunite. The geo- logical relations and origin are practically the same as those in Oregon, just cited. The mines are not yet producers.^ Green crusts of oxidized nickel compounds have been found with the chromite in the town of Texas, Penn., but are of no practical importance. Such superficial discolorations are very common in serpentinous districts, but it is a curious fact that they are notably lacking in the dioritic varieties of ExamplelSa. The greatest deposits in serpentines are found in New Cale- donia, in the South Pacific, where they have been mined for some years past, and have furnished in the last decade the largest part of the world's supply. The ores occur, as is the ^ F. W. Clarke and J. S. Diller, "Nickel Ores from Riddle's, Webster and New Caledonia," Amer. Jour. Set., iii., XXXV., 483. H. B. v. FouUon, "On Riddle's," Jahr. d. k. k. Geol. Reichsanstalt, 1893, 224. Rec. 2 Clarke and Diller, as cited in preceding reference. S. H. Emmens, •'The Nickel Deposits of North Carolina," Eng. and Min. Jour., April 30, 1892, p. 476. H. Wurtz, "On the Occurrence of Cobalt and Nickel in Gaston County, North CaroUna," Amer. Assoc. Adv. Set., XII., 221; Amer. Jour. Sci., ii., XXVII., 24. 440 KEMP'S ORE DEPOSITS. usual case, associated with serpeotine, and along the contact of the serpentine with overlying beds of red clay/ 2.15.18. Example 23a. Mine la Motte. Considerable pyrite occurs with the lead ores mentioned under Example 23, and is separated in the ore-dressing and treated by itself, as it contains nickel and cobalt. Such pyrite is most abundant at Mine la Motte, and considerable matte is made and shipped abroad. Siegenite, a variety of linnseite, is also found im- pregnating a bed of Cambrian sandstone that underlies the lead-bearing dolomite. It is not abundant enough to be of practical importance.^ 2.15.19. Nickel ores have also been reported from Salina County, Arkansas.^ Millerite occurs in a vein with quartz gangue in black shales. It is not practically productive. Nickel is also reported in a rather fine conglomerate from Logaji County, Kansas. It occurs with manganese and limonite in the cementing material of the rock.* Oxidized nickel ores have also been reported at the Lovelock mines, Cburchill Countj-, Nevada, which passed in depth into sul- phides.^ Although they were originally regarded as promising, they have not proved a productive source as yet. At the Gem mine, Colorado, sulphide ores have also been produced. Millerite occurs as an interesting mineral in many other places (St. Louis, Mo. ; with red hematite in Jefferson County, New York, etc.), but is only a rarity. Its interesting position at the former locality, in hair-like tufts in the midst of geodes indicates that * F. Benoit, " Etude sur les Mines de Nickel de la Nouvelle Caledonie," Bull, delas Societe de I'lnd. Minerals, VI., 753, 1892. J. Garnier, " Me- moire sur les Gisements de Cobalt, de Chrome et de Fer a la Nouvelle Caledonie," »Soc. des Ingenieurs Civils., 1887. S. Heard, Jr., "New Cale- donia Nickel and Cobalt," Eng. and Min. Jour., August 11, 1888, p. 103. D. Levat, Assoc. Frangaise pour VAdvanc. des Sci., Paris, 1887. L. Pelaton, "Carte Geologique de la Nouvelle Caledonie," Genie civile, 1891. ' J. M. Neill, "Notes on the Treatment of Nickel and Cobalt Mattes at Mine la Motte," Trans. Amer. Inst. Min. Eng., XIII , 634. For additional literature see under 2.05.09. 3 Ark. Geol. Survey, 1888, Vol. I., pp. 34, 35. * F. P. Dewey, " On the Nickel Ores of Russell Springs, Logan County, Kansas," Trans. Amer. Inst. Min. Eng., XVII., 636. * A. v. Hodges, " Notes on the Occurrence of Nickel and Cobalt Ores in Nevada," Trans. Amer. Inst. Min. Eng., X., 657. S. B. Newberry, " Nickel Ores from Nevada," Amer. Jour. Sci., iii., XXVIII., 123. THE LESSEE METALS, CONTINUED. 441 nickeliferous solutions must have circulated rather widely in these limestones. In Jefferson County it probably resulted from the decaying pyritous mineral to which Smyth refers the iron ore, as outlined earlier. PLATINUM. 2.15.'^0. Some hundreds of ounces of platinum are annually gathered from placer washings in northern California, and two or three times as much more from British Columbia. Much iridium and osmium are associated with it. In October, 1889, F. L. Sperry, the chemist of the Canadian Copper Company, of Sudbury, discovered a heavy crystalline powder in the con- centrates of a small gold-quartz mine in the district of Algoma. He detected the presence of platinum, and sent the material to Professors Wells and Pen field, of Yale, by whom it was ana- lyzed and crystallographically determined to be the arsenide of platinum, PtAs2, the first compound of platinum, other than an alloy, detected in nature. It has been appropriately named sperrylite by Wells, and although not at present a source of platinum, it may merit attention, as the price of the metal has sometimes approximated that of gold. The chief reliance of the world for platinum is Eussia, whose deposits are in the Urals. More or less comes also from Colombia, South America, and from placer washings elsewhere. Serpentine is very generally its mother-rock.^ TIN. 2.15.21. Ores: Cassiterite, SnO^, Sn. 78.67, O. 21.33. The sulphide stannite is a rather rare mineral. ' California: Eng. and Min. Jour., June 29, 1889, 587. B. Silliman, " Cherokee Gold Washings, California," Amer. Jour. Sci., iii., VI., 132. Canada: F. W. Clarke and Ch. Catlett, " Platiniferous Nickel Ore from Canada," Amer. Jour. Sci, iii., XXXVII., 372. H. L. Wells and S. L. Penfield, "Sperrylite, a New Mineral," Idem, iii., XXXVII., 67. Russia: A. Daubree, "On the Platiniferous Rocks of the Urals," Trans. French Acad. Sci., March, 1875; Amer. Jour. Sci., iii., IX., 470. General paper by C. Bullman, The Mineral Industry for 1882, p. 373. Rec. "^ An elaborate review of the tin mines of the world by C. M. Roelker will be found in the XVI. Ann. Rep. of the Director of the U. S. Geol. Survey, Part III., pp. 458-538, 1895. E. Reyer has given a general dis- cussion in "Zinn, einegeologisch-montanistisch-historische Monographic, " Berlin, 1881. A general, genetic discussion is given by J. H. L. Vogt, "Die Zinnstein gang-gruppe," Zeits. fiir prakt. Geol., 1895, 145. 442 KEMP'S ORE DEPOSITS. Cassiterite occurs in small stringers and veins on the borders of granite knobs or bosses, either in the granite itself or in the adjacent rocks, in such relations, that it is doubtless the result of fumarole action consequent on the intrusion of the granite. It appears that the tin oxide has probably been formed from the fluoride. A favorite rock for the ore is the so-called greisen, a mixture of quartz and muscovite or lithia mica, and probably an original granite altered by fumarole action. Topaz, tourmaline, and fluorite are found with the cassiterite, and indicate fluoric and boracic fumaroles. Wolframite, schee- lite, zinnwaldite and one or two other minerals are character- istic associates. Cassiterite seems also to crystallize out of a granite magma with the other component minerals. Cassite- FlG. 1^.— Horizontal section of the Etta granitic knob. Black HiUs, 8. D, After W. P. Blake. Mineral liesouvces, 1884, p. 603. rite, being a very heavy mineral, accumulates in stream gravels, like placer gold, affording thus the stream tin. When of concentric structure the ore is called wood tin. It is not yet demonstrated that the United States have workable tm mines. 2.15.22. Example 51. Black Hills. Cassiterite disseminated in masses of albite and mica and associated with immense crystals of spodumene, which are contained in knobs of granitic rock. Columbite, tantalite, and beryl are also found. There are two granite knobs which are best known, the Etta and the Ingersoll. The former is a conical hill, which pierces mica and garnetiferous slates and which is 250 feet high by 150 feet by 200 feet. Tunnels show it to have a concentric structure — first. THE LESSER METALS, CONTINUED. 443 a zone of mica; second, a zone of great spodumene crystals, with an albitic, so-called greisen which carries cassiterite in its interstices; lastly, a mixture of quartz and feldspar as a core. Other tin-bearing granites occur as dikes, or veins, as much as 80 feet wide, and bearing the so-called greisen and tin ore in quartz. They are called segregated veins by Carpenter, who doubts their true igneous character, probably on good ground. No tin is yet commercially produced. The tin deposits extend also into Wyoming.^ 2.15.23. Pebbles of stream tin have been found in gold washings in Montana and Idaho. Tin is also known in the Temescal Mountains, southern California. The area has re- cently been described by H. W. Fairbanks, who summarizes the geological relations as follows : "A semi-circular area of granite, over two miles in diameter, surrounded on the north- west and south by porphyries, and joined on the east to a great body of granitic rocks extending indefinitely in that direction. Around the border of this granite protuberance are many dikes of a fine-grained granite. Cutting through the granite in a northeast and southwest direction are black tourmaline veins, which form the gangue of the tin ore when it is present.*' While tourmaline is a common associate of tin ores, this great abundance of it is unusual. The ore occurs as a yellow, un- crystalline variety, in layers, and as a brown, granular, mas- sive form, or in brown crystals. The ore and veinstone seem to have replaced the usual minerals of the granite, doubtless by fumarole action along fissures. The mining proved unsuccess- ful after a serious attempt.^ -^ ^ W. P. Blake, Mineral Resources, 1883-84, p. 602, Rec. Amer. Jour. Set, September, 1883, p. 335; Eng. and Min. Jour., September 8, 1886. "Tin Ore Deposits of the Black Hills," Trans. Amer. Inst. Min. Eng., XIII., 691. F. R. Carpenter, Prelim. Rep. Dak. School of Mines," 1888; also Trans. Amer. Inst. Min. Eng., XVII., 570. " Tin in the Black Hills," Eng. and Min. Jour. , November 28, 1884, p. 353. Mineral Resources of the U. S., annually under "Tin." W. P. Headden, "Notes on the Dis- covery and Occurrence of Tin Ore in the Black Hills," Colo. Sci. Soc, III., 347. A. J. Morse, "Harney Peak Tin Mines," Eng. and Min. Jour., November 17, 1894, p. 463. "^ W. P. Blake, " Occurrence of Wood Tin in California, Idaho, and Mon- tana," Min. and Sci. Press, San Francisco, August 5, 1882. H. W. Fair- banks, "The Temescal Tin Distnct," Eleventh Rep. Cal. State Mineral- ogist, 1893, pp. 111-114. A fuller paper will be found in the Amer. Jour. -Sci., July, 1897, 39. H. G. Hanks, Rep. Cal. State Mineralogist, 1884, p. 121. 444 KEMP'S ORE DEPOSITS. 2.15.24. Narrow veins carrying cassiterite have been ex- ploited in the granite and schistose rocks of Rockbridge and Nelson counties, Virginia, in North Carolina, and in Alabama. Companies have been formed to work the two former, but as yet without a notable output.^ 2.15.25. Cassiterite has been discovered in narrow veins in mica schists with lepidolite and fluorite at Winslow, Me., and is known at other places in Maine and New , Hampshire. A salted tin prospect several years ago spread the impression that tin was to be found in Missouri.^ Narrow quartz veins have been recently discovered near El Paso, Tex., with cassiterite richly disseminated through them. 2.15.26. Mexico. Tin ores occur in a great number of places in Mexico, and small amounts of tin have been pro- duced during and since the time of the Aztecs. W. R. Ingalls has carefully described the deposits in the State of Durango, and has shown that those at Potrillos are in veinlets or small veins in rhyolitic tuffs, with associated topaz, chalcedony and hyalite. The cassiterite is in irregular bunches and nodules, but as in practically all the Mexican mines, the amount is too small to be the basis of extended mining. Alluvial gravels were earlier worked but have been long since exhausted. At Cacaria, likewise in Durango, the wall rock is described as quartz- porphyry, but near the city of Durango, and at Sain Alto, Zacatecas, the rhyolite tuffs are again the country rock.^ The tin of Durango runs high in antimony. ' H. D. Campbell, " Tin Ore, jpassiterlte, in the Blue Ridge in Virginia." The Virginias, October, 1883^. A. R. Ledoux, "Tin in North Carolina.' Eng. and Min. Jour., December 14, 1889, p. 521; see also February, 1887, p. 111. McCreath and Piatt, Bull. Iron and Steel Assoc, November 7, 1883, p. 209. W. Robertson, London Min. Jour., October 18, 1884. A. Winslow, "Tin Ore in Virginia," Eng. and Min. Jour., NovembDr, 1885. Rec. "" W. P. Blake, Mineral Resources, 1884, p. 538. C. H. Hitchcock, "Discovery of Tin Ore and Emery at Winslow, Me.," Eyiq. and Min. Jour., October 2, 1880, p. 218. T. S. Hunt, "Remarks on the Occurrence of Tin Ore at Winslow, Me.," Trans. Amer. Inst. Min. Eng., I.. 573. C. T. Jackson, "Tin Ore at Winslow, Me.," Proc. Bost. Soc. Nat. Hist., XII., 267. ' F. A. Genth, "On the Cacaria Ores," Proc. Amer. Philo. Soc, XXTV., 1887, p. 23. W. R. Ingalls, "The Tin Deposits of Durango," Trans. Amer. Inst. Min. Eng., XXV., 146. C. W. Kempton, "Note on Tin Ores at Sain Alto, Zacatecas," Idem, 997. CHAPTER XVL CONCLUDING REMAEKS. 2.16.01. In review of the western border of the country, we note the elevated plateau rising from the Mississippi to the Rocky Mountain system, which consists of various ranges of general north and south or northwest and southeast trend, with broad valleys between. To the west the Colorado Plateau is met, and then the Wasatch Mountains and the Great Basin, with its various, subordinate, north and south ranges. These are succeeded by the Sierra Nevada, and the great valley of Cali- fornia, the Coast range, and finally the Pacific Ocean. From the Archean to the close of the Carboniferous there were granitic islands around which active sedimentation pro- ceeded. At the close of the Carboniferous the elevation of the Wasatch and the region of eastern Nevada occurred. At the close of the Jurassic the elevation of the Sierra Nevada took place. The chief upheaval of the Rocky Mountain system came at the close of the Cretaceous and that of the Coast range at the close of the Miocene Tertiary. Smaller and less impor- tant oscillations have occurred before and since. Each eleva- tion was accompanied by foldings, faultings, and extensive outpourings of eruptive rocks. The resultant fractures and the circulation of hot and chemically active solutions, occasioned by the dying volcanic activity, constitute the primary cause of the formation of the ore deposits, which in some cases lie in ranges along the lines of faulting or of disturbances, and in others are irregularly scattered. We may recognize the Coast range belt with mercury and chromium; the California gold belt in the western Sierras; the silver belt of Utah on the west- ern flank of the Wasatch; a belt in Arizona from southeast to northwest, along the contact between Paleozoic limestone, 446 KEMP'S ORE DEPOSITS. mostly CarboDiferous, and the Archean ; and the great strt icb of lead-silver mines in the Carboniferous limestones of Colo- rado. The other areas are scattered, and apparently exhibit no such grand general relations to these geographical and geo- logical phenomena.^ 2.16.02. In the Mississippi Valley, W. P. Jenney has re- marked the connection of the antimony and silver deposits of Arkansas with the Ouachita uplift that traverses that State and Indian Territory; the location of the Missouri lead and zinc ores along the Ozark uplift; and he has referred the Wisconsin lead and zinc mines, as well as those in the neigh- boring parts of Iowa and Illinois, to an uplift south of the Archean area of Wisconsin. The limitation of the Lake Superior copper deposits to the Keweenawan system may be mentioned, and such parallelism as prevails among the Lake Superior iron ores. In the East the great belt of Clinton ores; the long succession of Siluro-Cambrian limonites in the Great Valley; the black-band ores and clay- ironstones of the Carbon- iferous; the closely similar geological relations of non-titan if er- ous, magnetite lenses in the Archean gneisses; and the general association of titaniferous magnetites with rocks of the gabbro family the country over — all are striking illustrations of broad, general geological features that may characterize extended series of ore deposits. To these may be appended the great series of pyritous veins in the slates and schists of the East, the gold belt of the Southeastern States, and the small copper de- posits associated with the Triassic traps and sandstones. Aside from the groups mentioned, while there are important mines not included in the list, the others do not exhibit the same wide- spread uniformities of structure or associations.^ Yet, from the » G. F. Becker, Amer. Jour. Sci., Third Series, Vol. XXIII., 1884, p. 209. W. P. Blake, Rep. Cal. State Board of Agriculture, 1866. S. F. Emmons, " The Structural Relations of Ore Deposits," Trans. Amer. Inst. Min. Eng., XVI., 804. R. W. Raymond, "Geographical Distribution of Mining Districts in the United States," Idem, I., 33. Fortieth Parallel Survey, Vol. III., Chapter I. " Precious Metals," Tenth Census, Vol. XII. ■^ It is only proper in this connection to refer to the paper by T. F. Van Wagenen, on "System in the Location of Mining Districts," School of Mines Quarterly, January, 1898, p. 189. The author regards the location of the veins and the mining districts as having been determined by the lines of terrestrial, magnetic currents, which converge at the magnetic CONCLUDING REMARKS. 447 list cited, it forcibly appears tbat similar conditions have brought about related ore bodies over great stretches of country ; and while in the opening schemes of classification points of difference were emphasized, in the closing pages points of re- semblance may be with equal right brought to the foreground. 2.16.03. A few general conclusions suggest themselves from the preceding pages. (1) The extreme irregularity in the shape of metalliferous deposits, and from this the unwisdom of the United States law in the West, which is based on well-defined fissure veins. The only practicable method is that a man should own all that is embraced in his property lines, whether the ore body out- crops outside or not. "A square location is the square thing" (Raymond). (2) The very general proximity of eruptive rocks in some form to the ore bodies. Except in the case of iron, there are only a few where these are not present, and apparently strong factors in the circulations which formed the ore. The lead and zinc deposits of eastern and western Missouri and the neighbor- ing States, and of New York and Virginia, are almost the only ones, and we are justified in concluding that eruptive rocks are of great importance. (3) We know from the investigations of Sandberger and others that the dark silicates of many rocks contain percentages of the common metals. The choice is open whether to refer the ore to original disseminations in these, and to derive it by gradual concentration, probably at great depths, or to some indefinite unknown source, which can only be described as *^ below." pole of the earth. They therefore are independent of the great lines of mountain making and igneous outbreaks. The latter are, however, re- garded by the present writer as of paramount importance. See above paragraph. APPENDIX I. In the following pages the principal schemes of classification of ore deposits are grouped according to certain relationships and similarities that run through them. It would be interest- ing to arrange them in chronological order, but points of like- ness and unlikeness would not thus be brought out, nor can the influence of one writer on another be so clearly emphasized. The underlying object, aside from showing in a bird's-eye view what has been done, is to lead up to the purely genetic class- ification which appears in Chapter VI, Part I., and which would properly come in after No. 16. In the earlier editions of the book it was so placed, and all the schemes formed part of Chapter VI, but so many have appeared in later years that it has seemed wiser not to overload the main text with matter that is largely a subject of reference, and that can be treated with greater freedom in an appendix. The importance of the genetic principle has been more and more appreciated in recent years, and it is a striking fact that the more weighty recent contributions on ore deposits have been dominated by it. In reading this appendix it should be further appreciated that the schemes were originally grouped so as to lead up to the one on page 56 as a climax, and that in it mere form is eliminated to the last degree, and well-recognized geological phenomena are brought to the foreground. It has indeed been said with force that the origin of ore deposits is a subject which is very largely a matter of hypothesis, and that it involves profound subter- ranean causes, of which we know but little. Still, it is held that an acquaintance with what has been accomplished in re- cent years by our best workers, and a rigid adherence to well- recognized principles in geology and mineralogy, especially as developed in rock study {i.e., in that department of geology that of late years we have grown to call petrology), will APPENDIX I. 449 establish much that cannot be questioned, and will aid in differentiating the cases which are still objects of reasonable doubt. It is, however, true that among the subjects on which human imagination, often superstitious, has run to wild ex- tremes, and on which cranky dreamers have exercised their wits, the origin of ore deposits stands out in particularly strong relief. A. Schemes Involving only the Classification of VeinSo (1) G. A. von Weissenbach.^ Gangstudien, 1850, p. 12. (a) Sedimentargange (Sedimentary Veins). (6) Kontritionsgange (Attrition Veins), (c) Stalactitische oder Infiltrationsgange (Stalactitic or Infiltration Veins). {d) Plutonische oder Gebirgsmassengange (Masses, dikes, knobs, bosses, etc., not necessarily with ores). (e) Ausscheidungsgange (Segregated Veins)c (f) Erzgange (True or Fissure Veins). (2) B. von Cotta, in comments on Von Weissenbach's Scheme. Gangstudien, 1850, p. 79. According to the vein filling. 1. Gesteinsgange (Dikes). {a) Not crystalline (Sandstone). (6) Crystalline (Granite). 2. Mineralgange (Veins). (a) Of one non-metallic mineral. ip) Of several non-metallic minerals. 3. Erzgange. Ore veins. (3) Bo von Cotta, Idem, p. 80. According to Shape and Position. I. Wahre, einfache Spalteogange (Fissures), (a) Querdurchsetzende (Cross fissures). {h) Lagergauge (Bed veins), (c) Kliifte (Cracks), Adern (VeinletB). » See also Whitney's Metallic Wealth of tlve U. S., 1854, p. 44. 450 KEMP'S ORE DEPOSITS. II. Gangziige (Linked Veins)/ III. Netzgange (Reticulated Veins). IV. Contaktgange (Contact Veins). V. Lenticulargange (Lenses). VI. Stockformige Gange (Stocks, Masses). (4) B. von Cotta, Idem, p. 80. According to the texture of the vein filling. I. Dichte Gauge {Compact Veins). II. Krystallinische Gauge. III. Krystallinisch, koruige (granular) Gauge. IV. Krystallinisch, massige (massive) Gauge. V. Gauge mit Lagentextur (Banded veins). (a) Ohue Symmetrie der Lagen (unsymmetrical). (b) Mit Symmetrie der Lagen (symmetrical). VI. Gauge mit Breccieu oder Couglomerattextur. (5) J. Le Conte, A7ner. Jour. Sci., July, 1883, p. 17. 1. Fissure Veins. 2. Incipient Fissures, or Irregular Veins. 3. Brecciated Veins. 4. Substitution Veins. 5. Contact Veins. 6. Irregular Ore Deposits. In von Weissenbach's table the sedimentary veins are much the same as the *' sandstones dikes" which J. S. Diller has recently described. (Bull. Geol. Soc. Amer., I., 411.) They and the stalactitic veins have small practical value, although of great scientific interest. Under (d), the stockworks with tin ores are the principal illustration of eco- nomic prominence. The attrition veins are an important class, and increasing study has widened the application of this or * Gangziige is happily translated "linked veins," by Dr. G. F. Becker (Quicksilver Deposits, p. 410). Any attempt to render the original by preserving the figure of a flock of birds or of a school of fish, etc., is, as Mr. Becker remarks, infelicitous, if not impossible. APPENDIX L 451 synoDymous terms. Segregated veins and true veins are well- known forms. In the comments of von Cotta, which follow von Weissenbach's paper, veins are grouped from every possi- ble standpoint, von Weissenbach's scheme being taken as the one based on origin. Nos. 2 and 4 have small claims to atten- tion. No. 3 foreshadows the drift of many subsequent writers. The meanings of the terms are self-evident, except perhaps Gaagzilge (linked veins). This refers to a group of parallel and more or less overlapping veins, deposited along a series of opening, evidently of common origin. It is a convenient term. The terms used by Le Conte may be passed without comment as being self-evident in their meaning, except (4) and (6). The scheme was devised, as a perusal of the citation will show, after the author had set forth some original views of the causes which lead to the precipitation of ores, and had forcibly stated others very generally accepted. In the explanatory text some quite curious associations are found, which are cited by way of illustration. Thus, under group (4), stalactites, caves, gash veins, and the Leadville ore bodies are considered examples, and under group (6) the grouping together of beds, igneous masses, and all other forms of so-called irregular deposit is decidedly open to criticism. This is the more emphatic be- cause the concluding sentences of the paper (of whose general value and excellence there can be no question) give the impres- sion that the author felt he had cleared up all the points in the origin of ore bodies which would be of interest or importance to a purely scientific investigator as contrasted with a practical miner. B. General Schemes Based on Form, (6) Von Cotta and Prime. Ore Deposits, New York, 1870. I. Regular Deposits. A. Beds. B. Veins. (a) True (Fissure) Veins. lb) Bedded Veins. (c) Contact Veins. (d) Lenticular Veins. 462 KEMP'S ORE DEPOSITS. II. Irregular Deposits. C. Segregations. (a) Recumbent. (6) Vertical. D. Impregnations (Disseminations)^ (V) Lottner-Serlo, Leitfaden zur Berghaukunde, 1869. I. Eingelagerte Lagerstatten (Inclosed Deposits). A. Plattenformige (Tabular). (a) Gange (Veins). (6) Flotze und Lager (Strata, beds, seams). B. Massige Lagerstatten (Massive Deposits.) (a) Stocke ) (6) Stockwerke ) C. Andere unregelmassige Lagerstatten (other ir- regular deposits), (a) Nester (Pockets). (6) Putzen. (c) Nieren (Kidneys). II. Aufgelagerte Lagerstatten (Superficial Deposits). D. Triimmerlagerstatten (Placers). E. Oberflacbliche Lager (Surface beds). (8) Koehler, Lehrbuch der Bergbaukunde, 1887. I. Plattenformige Lagerstatten (Tabular Deposits). (a) Gange (Veins). (b) Flotze und Lager (Strata, beds, seams). II. Lagerstatten von imregelmassige Form (Deposits of irregular Form). (a) Stocke und Stockwerke (Masses). (6) Butzen, Nester, und Nieren (Pockets, concre- tions, etc.). (^) Gallon, Lectures on Mining, 1886 (Foster and Galloway's translation). I. Veins. IL Beds. III. Masses (i.e., not relatively long, broad, and thin). APPENDIX I. 453 The scheme of von Cotta and Prime carries out the principle of form to its logical and somewhat trivial conclusion. Thus under irregular deposits it is a matter of extremely small classificatory moment whether an ore body is recumbent or vertical. Otherwise the scheme is excellent, and its influence can be traced through most of those that are of later date. The original draft came out in the German in 1859. All the others are from treatises on mining, in which this subject plays a minor role, and indicates the tendency, referred to above, of mining engineers, when writing theoretically, to imagine cer- tain fairly definite forms, which are to be exploited. As previ- ously remarked, however, considering the uncertainty of ore bodies and their variability in shape, it is here argued that the genetic principle might better take precedence. Several of the German terms are difficult to render into English mining idioms, as for example, Stock, Butzen (Putzen), Nester, and Nieren. C. Schemes, Partly Based on Form, Partly on Origin, (10) J. D. Whitney, Metallic Wealth of theUnited States^ 1854. I. Superficial. 11. Stratified. (a) Constituting the mass of a bed or stratified de- posit. (6) Disseminated through sedimentary beds, (c) Originally deposited from aqueous solution, but since metamorphosed. III. Unstratified. A. Irregular. {a) Masses of eruptive origin. {b) Disseminated in eruptive rocks, (c) Stockwork deposits. {d) Contact deposits. (e) Fahlbands. B. Regular. (/) Segregated veins. {g) Gash veins. {h) True or fissure veins. 454 KEMP'S ORE DEPOSITS. (11) J. S. Newberry, School of Mines Quarterly, March, 1880, May, 1880. L Superficial, II. Stratified. (a) Forming entire strata. (b) Disseminated through strata. (c) Segregated from strata. III. Unstratified. (a) Eruptive masses. (6) Disseminated through eruptive rock. (c) Contact deposits. (d) Stockworks. (e) Fahlbands. (/) Chambers. (g) Mineral veins. 1. Gash veins. 2. Segregated veins, 3. Bedded veins. 4. Fissure veins. (12) J. A. Phillips, Ore Deposits, 1884. I. Superficial. (a) By mechanical action of water. (6) By chemical action. II. Stratified. (a) Deposits constituting the bulk of metalliferous beds formed by precipitation from aqueous solution. (b) Beds originally deposited from solution but subsequently altered by metamorphism. (c) Ore disseminated through sedimentary beds, in which they have been chemically deposited. III. Unstratified. (a) True veins. (b) Segregated veins. (c) Gash veins. (d) Impregnations. (e) Stockworks. APPENDLS I 455 (/) Fahlbands. {g) CoDtact deposits. {h) Chambers or pockets. It is at once apparent that Whitney's scheme contains the essentials of the others, which are merely slight modi- fications. Newberry introduces impregnations, chambers, and bedded veins.. The first named is a useful term, although it is not always easy to distinguish impregnations from others earlier given. Thus, they may be very like the division, dis- seminated through strata, or disseminated through eruptive rock, or, if in metamorphic rock, fahlbands. The word is also used to indicate places along a vein where the ore has spread into the walls. The term "chambers," or "caves," has found application in the West, and is a useful addition. Bedded veins appear also in von Cotta above (No. 6). Phillips seeks to explain the methods of origin in his use of Whitney's scheme and clearly feels the importance of empha- sizing the genetic principle more strongly. Much of it is im- plied in the simpler phraseology, however, and the extended sentences lack the incisiveness of the earlier schemes. The arrangement as set forth hy Whitney is worthy of high praise, and the scheme is one of the manj' valuable things in a book that has played a large part in the economic history of the United States. • D. Schemes Largely Based on Origin, (13) [ J. Grimm, Lagerstdtten, 1869. I. Gemengtheile oder grossere Einschlusse in den Ge- birgsgesteinen. Einsprengung, Impragnation. (Essential component minerals and inclusions in country rock. Impregnations.) » (a) Ursprungliche Einsprengung. (Original with the inclosing rock.) (h) Von anderen Lagerstatten weggefiihrte Bruch- theile, etc. (Fragments brought from a dis- tance. Placers, ore- bearing boulders. Brec- cias. ) 456 KEMP'S ORE DEPOSITS. 11. Untergeordnete Gebirgsglieder oder besondere Lager-> statten. (Subordinate terranes or special forms of Deposits.) (a) PlatteDformige Massen. (Tabular masses.) 1. Lager oder Flotze. Bodensatzbildung. (Beds, strata.) 2. Gange, Kliifte, Gangtrummer, etc. (Veins of varying sizes.) 3. Plattenformige Erz-ausscheidungen und Anhaufungen. (Segregated veins.) if)) Stocke und regellos gestaltete Massen. (Stocks and irregular masses. ) 1. Lagerstocke Linsenstocke,Linsen. (Len- ticular deposits, etc.) 2. Stocke, Butzen, Nester, etc. (Masses, pockets, etc.) 3. Stockwerke. (Stockworks. ) (14) A. von Groddeck, Lehre von den Lagerstdtten der Erze.y 1879, p. 84. I. Urspriinglicbe Lagerstatten (Primary deposits). A. Gleicbzeitig mit dem Nebengestein gebildet. (Formed at tbe same time v^ith the walls. ) 1. Geschichtete. (Stratified.) (a) Derbe Erzflotze. (Entire beds in a stratified series. ) (6) Ausscheidungsflotze. (Disseminated in beds. ) (c) Erzlager. (Lenticular beds, mostly in schists.) 2. Massige. (Massive; the vrord is nearly synonymous vs'ith igneous.) B. Spater wie das Nebengestein gebildet. (Formed later than the walls.) 3. Hohlraumsfullungen. (Cavity fillings.) (a) Spaltenfiillungen oder Gange. (Fissure fill- ings or veins.) (1) In massigen Gesteinen. (In igneous rocks.) APPENDIX I. 457 (2) In geschicbteten GesteiDen. (In strati- fied rocks). (&) Hohlenfiillungen. (Chambers.) 4. Metamorpbiscbe Lagerstatten. (Altera- tions, replacements, etc. ) II. Triimmer-lagerstatten. (Secondary or detrital de- posits. ) (15) R Pumpelly, Johnson's Encyclopcedia, 1886, VI., 22 I. Disseminated concentra- tion. (a) Impregnations, Fabl- bands. II. Aggregated Concentration. (a) Lenticular aggrega- tions and beds. (b) Irregular masses. (c) Reticulated veins. (d) Contact deposits. III. Cave deposits. IV. Gash veins. V. Fissure veins. VI. Surface deposits. (a) Residuary deposits. (b) Stream deposits. (c) Lake or bog deposits. These three are all excellent, and give some interesting variations in the several points of view from which each writer regarded his subject. There are instances in the two German schemes where it is difficult to render the original into a corresponding English term and recourse has been had to the explanatory text. Grimm especially writes an obscure style. He divides accordingly as the ore forms an essential and integral part of the walls or a distinct body. Von Grod- deck has in view the relative time of formation as contrasted with the walls. Grimm afterward emphasizes geometrical shape, but this von Groddeck practically does away with, and continues more consistently genetic. His scheme might per- haps come more appropriately in the next section. Forms due to the text- ure of the inclosing rock, or to its mineral constitution, or to both causes. Forms chiefly due to pre-existing open cav- ities or fissures. 458 KEMP'S ORE DEPOSITS. Pumpelly's conception varies considerably from the others. He writes, as his full paper states, in the belief that the metals have all been derived primarily from the ocean, whence they have passed into sedimentary, and, by fusion of sediments, into igneous rocks. The group of residuary surface deposits, carrying out as it does a favorite idea of Professor Pumpelly, as set forth in his papers on the secular decay of rocks, is an important distinction. E. Schemes Entirely Based on Origin. (16) H. S. Munroe. Used in the Lectures on Mining in the School of Mines, Columbia University. I. Of surface origin, beds. {a) Mechanical (action of moving water). 1. Placers and beach deposits. (6) Chemical (deposited in still water). 1. By evaporation (salt, gypsum, etc.). 2. By precipitation (bog ores). 3. Residual deposits from solution of lime- stone, etc. (hematites), (c) Organic. 1. Vegetable (coal, etc.). 2. Animal (limestone, etc.). {d) Complex (cannel coal, bog ores, etc.). IL Of subterranean origin. (a) Filling fissures and cavities formed mechani- cally. 1. Fissure veins, lodes. 2. Cave deposits — lead, silver, iron ores. 3. Gash veins. The cavities of 2 and 3 are enlarged by solution of limestone. (6) Filling interstitial spaces and replacing the walls. 1. Impregnated beds. 2. Fahlbands. 3. Stockworks. 4. Bonanzas. 5. APPENDIX L 459 This scheme covers all forms of mineral deposits, whether metalliferous or not, while most of those previously given, as well as the one that follows, concern only metallifer- ous bodies. The scheme is consistently genetic and was elab- orated because such an one filled its place in lectures on min- ing better than one based on form. The general principle on which the main sub-division is made differs materially from any hitherto given. Deposits formed on the surface are kept distinct from those originating below, even though the first class may afterward be buried. It is immediately after this scheme that the one in paragraph 1.06.05 finds its place. In the report of the State Geologist of Michigan for 1891-92 (issued January, 1893), pp. 144, 145, Dr. M. E. Wadsworth has published a '* Preliminary Classification of Metalliferous or Ore Deposits." The main outline is as follows : I. Eruptive Deposits {a) Non-Fragmental. {h) Fragmental. II. Mechanical Deposits {a) Unconsolidated. (6) Consolidated. III. Chemical Deposits (a) Sublimations. (6) Water Deposits. (c) Impregnations or ^Replace- ments. {d) Segregations or Cavity De- posits. Each of the above, except III. (d), is then subdivided so that the table becomes practically a classification of rocks. Indeed, a moment's consideraton will show that the scheme in its main divisions is closely modeled after the prevailing classifi- cation of rocks. III. (d) Segregations or Cavity Deposits con- tains the following: 1. Pockets. 2. Chambers. 3. Contact Deposits. 4. Veins, including Gash Veins, Segregated Veins, Reticulated Veins or Stockworks, Contact Veins, Fissure or Fault Veins. The author states in some appended comments that the table is not limited to those deposits now practically worked (which we ordinarily understand the expression ore deposits to mean), but is intended to include all that have been or may be of value. But in this respect there is good ground for preferring to make 460 KEMP'S ORE UEF0SIT8. our classifications in ore deposits, as in mineralogy, zoology, etc., embrace only the authenticated varieties, expecting addi- tions to be incorporated as discovered and suitably described. The same general grouping as this scheme employs is inde- pendently adopted by R. S. Tarr, in the Economic Geology of the Lnited States, 1894. For the meeting of the American Institute of Mining Engineers, held in connection with the various congresses at the World's Fair in Chicago, July, 1893, Professor Franz Posepny, of Vienna, contributed a grand essay on the "Origin of Ore Deposits." The materials for it were specially as- sembled by Professor Posepny while giving a course of lectures at the Pribram Mining Academy in the ten years following 1879. The paper is a theoretical discussion of the origin of ores, with illustrations selected from all parts of the world, but especially from Europe and America. It forms one of the most important contributions to the literature that has yet been made. Posepny distinguishes at the outset between rocks and mineral deposits; i.e., between original materials, such as wall rock, and secondary- introductions, such as veins, etc. The former he calls ''idiogenites," the latter '^xenogenites," basing the names on the familar Greek terms that run through all our literature. The latter are especially characterized by "crustification," by which term is indicated what has been called "banded structure," on p. 47. The subject of cavities is then taken up, and, while minute pores are stated to be in all rocks, a distinction is made between the larger openings, which originate in a rock mass as a part of its own structure, such as contraction joints in igneous rocks, amygdaloids, and the like, and those induced by outside causes, such as fault fissures. The circulation of water through these is next treated : first, surface waters or "vadose" circulations, which descend; second, ascending waters from great depths, such as springs in deep mines, hot springs, etc. The common salts in solution in these latter are tabulated, being of course mostly alkaline carbonates, sulphates, chlorides, etc. The "exotic" metallic admixtures which would bear on the origin of ores are next discussed, so far as possible with analyses of actual cases. The alterations produced by mineral springs in rocks and the struc- APPENDIX I. 401 "tural relations of the deposits of mioeral springs, especially as expressed by "crustifieation," are then described. This pre- liminary material clears the way for the general discussion of the origin of ore bodies. The argument running all through the paper is that ore bodies, even when apparently inter bedded with sedimentary rocks, are of secondary introduction and, in general for veins, are from deep-seated sources. Precipitation from descending solutions and filling by lateral secretion are strongly controverted. The discussion of origin follows in its arrangement the fol- lowing classification of ore deposits: I. Filling of spaces of discission (fissures). II. Filling of spaces of dissolution in soluble rocks. III. Metamorphic deposits in soluble rocks; in simple sedi- ments; in crystalline and eruptive rocks. IV. Hysteromorphic (i.e., later or last formed) deposits. Secondary deposits due to surface action (i.e., placers, etc.). The treatment, both in the introductory pages and in the later discussions, is often strikingly similar to that of this book, and the underlying argument is much the same. The stand- point in both essays is essentially a genetic one, and the main difference lies in the fact that the one is an exposition of an in- dividual's views, fortified by examples from all parts of the world ; the other endeavors to be a judicial statement, with a fairly complete description of the ore bodies of the United States and Canada alone. The writer differs with Posepny however in the greater weight given to the ores of igneous origin. 1.06.28. An extended treatise on the useful minerals, earthy as well as metallic, by MM. E. Fuchs and L. De Launay, has recently appeared {Traite des Gttes Mineraux et Metalli- feres, Paris, 1893). The book is based on the lectures on economic geology delivered in the Ecole Superieure des Mines, at Paris, in the last fifteen years by the two authors. (Pro- fessor Fuchs died in 1889, and was succeeded by Professor De Launay.) A vast amount of valuable information is brought together and discussed from various points of view, useful applications and methods of treatment being set forth as well as geological occurrence. The work ife encyclopedic in scope 462 KEMP'S ORE DEPOSITS. and affords a reader descriptioDSof mineral resources and refer- ences to their literature in every quarter of the world. So far, however, as the United States are concerned the authors have suffered from the unavoidable limitations of those not native and conversant in a discriminating way with our literature. Nevertheless they have endeavored to give a large share of their space to this country, and where prominent monographs have appeared they have been read with care, but in many cases reference to later papers and descriptions would have im- proved the text. A later edition will doubtless correct these. The classification of ore deposits as well as other useful minerals on a genetic principle has evidently been in many minds in the last few years. Mr. Frederick Danvers Power, ^ of Melbourne, Victoria, reviewed the subject in 1892, and after giving the schemes of others and summing up the various characteristics of veins, has formulated a classification whose main divisions are as follows: I. Contemporaneous; Indigenous. II. Metasomatic or Chemical Alteration of the Original Constituents. III. Subsequently Introduced ; Exotic. Each of these has then a number of subdivisions too numerous to be repeated here. Prof. William O. Crosby,^ of Boston, has recently discussed the same subject in a very suggestive way. The main head- ings are: A. Deposits of Igneous Origin (Igneous rocks) ; B. Deposits of Aqueo-Igneous Origin; C. Deposits of Aqueous Origin. The first and last are then subdivided at considera- ble length, but the second is chiefly limited to the pegmatite (granitic) veins which attend many plutonic intrusions. Lack of space prevents the full reproduction of both these schemes, but sufficient has been mentioned, it is hoped, to indicate the line of attack and to place a reader desiring to look the sub- ject up in touch with the originals. * " The Classification of Valuable Mineral Deposits," Trans. Australas. Inst. Min. Eng., 1893. ^ "A Classification of Economic Geological Deposits based on Origin and Original Structure," Amer. Geol., April, 1894, p. 240. The paper also appears in the Technological Qimrterly, INDEX. Abiquiu, N. M., copper ores, 224. Acadian stage, 4, Adairsville, Ga., aluminum, 404. Adams, F. D., on ores of Treadwell Mine, 391. Adams Co., Penn,, limonites, 104. Adams Co., Ohio, Clinton ores, 114, 115. Adirondacks, N. Y., magnetites, 160. Admiralty Islands, Alaska, gold de- posits, 392. Agglomerates, 281. Ainsworth District, B. C. , gold mines, 394, 395. Alabama, aluminum, (bauxite), 404. Clinton ore, 114, 117. Copper, 194. Gold mines, 378. Limonites, 104. Tin ores, 444. Alaska, geology of, 885. Gold, 392. Treadwell mines, 390. Alder Gulch, Madison Co., Mont., 317. Aleutian Islands, Alaska, 385. Algonkian system, 4. Allamakee Co., Iowa, limonite, 98, 99. Almaden, Spain, mercury, 424. Alno, Sweden, 61, 175. Alta mine, Jefferson Co., Mont., 317. Alturas Co., Idaho, 327. Aluminum, in bauxite, 404. Origin, 404-410. Sources, 403. Amador Co., Cal., copper mines, 195. Animikie series, 4. Annie Lee mine, Colo. , 298, 305. Anthony's Nose, N. Y., nickel ores, 430. Pyrite ores, 184. Anticlines, arrested, 11. Defined, 11. With shattered bends, 17, 19. Antigonish Co., Nova Scotia, hema- tite, 120. Antimony, 410. Apache Co., Ariz., silver and gold ores, 335. Apollo mine, Unga Island, Alaska, 392. Appalachians, general description, 7. Geology of gold deposits, 376. Manganese ores, 418. Appendix, 447. Remarks on, 448. Appleton, Wis., fold at, 20. Archean Group, classification, 4. Argentine, Clear Creek Co. . Colo , 295. Arizona, copper mines, 214-220. Geology, 334. Gold deposits, 334. Lead -silver ores, 279. Silver deposits, 334. Arkansas, antimony, 411. Bauxite, 404-406. Iron ores, 96, 97. Manganese, 420. Nickel, 440. Silver mines, 283. Arksut Fjord, Greenland, 403. Arlington, N. J., copper mines, 223. Armstead H. H., Jr., gold ores, of Idaho, 324. Arrow Lakes, B. C, upper and lower, 394. Arsenic deposits, 412. (See Gold in Canada.) Ascension by infiltration, 40, 41-43. Ashcroft iron mines, Colo., 170. Ashland mine. Iron wood, Mich., 142. Aspen, Pitkin Co., Colo., 45. Iron mines, 170, Lead and silver, 268. Atlanta, Elmore Co., Idaho, 325. Atlantic Border gold, 283. Lead, 226. Silver, 283. Augusta Co., Va., manganese, 418. Auriferous beach sands. 348. Gravels, 353. h 464 INDEX. Austin, Nev., antimony, 411. Gold and silver ores, 339. Avala, Servia, mercury, 434. B. Bachelor Mt., Colo., 293. Baker Co., Ore., 347. Gold mines, 348. Bald Butte Group, Deer Lodge Co., Mont., 320. Baldy Mt., Utah, 333. Baltimore Region, chromite, 414. Banded structure of veins, 47. Bannack City, Mont. , 317. Banner district, Idaho, 325. Barker mining district, Meagher Co. , Mont., 320, 321. Barton Hill, N. Y., magnetite, 162. Barus, C, on electrical activity in veins, 52, 53. Experiments on the Comstock Lode, 343. Basal granite, 388. Bassick mine, Colo., 47, 49, 58, 296. Batesville, Ark., manganese, 420. Bath Co., Ky., Clinton ores, 115. Battle Mt., Teller Co., Colo., 305. Bauxite, 404-407. Bayley, W. S. , on Michigan iron ores, 127 129 Bear Lake Co., Idaho, 327. Bearpaw Mt., Mont., 323. Beaver Co. , Utah, gold and silver, 333. Beayerhead Co. , Mont. , gold and sil- ver, 317. Becker, G. F., on Alaska mines, 390. On cinnabar, 30, 44, 373. On Comstock Lode, origin, 340- 344. On gold ores, 35, 376, 378. On gold in Mad Ox mine, Cal., 368. On gravel beds, Cal., 356. On joints, 15. On quicksilver, 425. On silver ores, 35. On Soret's principle, 67. On Sulphur Bank mine, 427. . On Washoe rocks, 345. Beds defined, 6. Bell, Robert, on Hudson Bay gold ores, 338. Belmont, Nev., srold and silver ores, 338. Belt formation of Montana, 315. Bench gravels, Alaska., 393. Bennet mines, Alaska, 392. Benson mine, N. Y., iron ores, 166. Benton stage, 5. Bei'ks Co., Penn., iron ores, 169. Bernallilo Co., N. M., 286. Berner's Bay, Alaska, gold, 392. Bertha mines, Va., zinc, 247. Bessemer limit of Lake Superior ores, 85. Beulah antimony mine, Nev., 411. Big Cottonwood Canon, Utah, 274. Big Creek, Nev., 411. Big Hill, Penn., 175. Bingham Caiion, Utah, 329. Bingham Co., Utah, 274. Birch Creek series, 388. Birmingham district, Ala., iron ores, 118. Bisbee, Ariz., copper, 217. Region^ gold and silver, 336. Bischoff , on silicate of gold, 372. Bismuth, 412. Bitter Root Mts., Idaho, 323. Black-band iron ore, 107. Black Hills, S. D., 57. Geology, 309. Gold in Potsdam, 309. Placers, 309. Tin, 442. Black Hornet district, Idaho, 325. Black Lake asbestos mine, 416. Black range copper mines, Ariz. , 220. Blake, W. P., aluminum deposits, N. M., 407. Antimony ores, Utah, 411. Copper Basin ores, Ariz., 221. Deep Creek ores, Utah, 332. Gold and silver. Tombstone. 336. Lead and zinc ores, 236. Mercury, Texas, 428. Silver King mine, Ariz., 336. Zinc ores, N. M., 259. Blanco stage, 5. Blende in the Rocky Mts., 258. Blezard mine, Ontario, 436. Block iron ore, 107. Block Island, R. I., magnetite sands, 181. Blow, A. A., cited on faults. 21, 22. Origin Leadville ores, 265. Blue lead in Cal. , gravels, 355. Blue Mts., Oregon, 347. Bodie, Cal. , gold and silver, 353. Bog iron ore, 87-93. Boise district, Idaho, 325. Bonanza City, Idaho, 325. Bonanza, defined, 49. Bonne Terre, Mo. , lead mines, 228. Bonneville, Lake, Nev., 337. Bonsacks, Va. , illustration of gossan, 51. Zinc mines, 249. Boss of igneous rock defined, 12. Boston Mt., Ark., 421. INDEX. 465 Boulder Co., Colo., 306. Iron ores. 109. 170. Box Elder Co.. Utah, 329. Boyd. C. R., Bertha mine zinc ores, 248. On production of Big Hill mine, Penn., 179. Boye, Dr., iron ores, 102. Boyertown, Penn., iron mines, 179. Bradley, F. P. . on limonites, 104. Brandon, Vt., iron ores, 100. Manganese ores, 418. Branner. J. C. origin of, Ark., alu- minum, 406. Brazil, iron ores, 175. Brewer mine, S. C. 380. Bridal chamber mine, N. M., 361. Bridger stage, 5. Bristol, Conn., copper deposits, 223. British Columbia gold gravels, 324. Platinum, 441. Britton, N. L., on Staten Island bog ores, 91. Magnetite ores, N. Y. , 167. Broadwater Co., Mont., 319. Brooks, T. B., on Marquette district, 135. Browne, D. H., on isochemic lines, 183. Browne, R. E. , on California gravels- 361. Bryant, Ark., aluminum, 406. Bucks Co., Penn., iron ore, 169. Buckwheat zinc mine, N. J., 253. Buena Vista mine. Cripple Creek, Colo., 305. Bull Domingo mine, Colo., 49, 297. BullMt., Colo., 305. Burden spathic ore mines, Hudson. N. Y., 110. Burra Burra mine, Tenn. , 192. Pm-ro Mt.. New Mexico, 285. Putte, Mont., 36, 44, 51, 58, 315. Copper ores, 196, 199, 200, 202. Development of, 200. Placers near, 354. Jalaveras Co. , Cal., 195. Caldwell Co., Ky., lead and zinc mines, 239. Caledonia, iron mines, Mo., 125. Calico, silver district, Cal., 351. California Bar, Idaho, 324. California, antimonv, 410; chromite, 415. Copper mines, 195. Geology, 349. Gold gravels, 353, 360, 361. Gulch, near Leadville, Colo., 295. California, Lead-silver ores, 279. Magnetite, 171. Mercury, 424. Platinum, 441. Tin, 325. ^ Gallon, on scheme of classification of ore deposits, 452. Calloway Co., Tenn., 192. Calumet and Hecla copper mines, Mich., 208. Calvin, S. , on limonites, 99. Cambrian system, 4. Campbell Mt., Colo., 293. Campbell, J. L. , on limonites, 94. Camp Floyd district, Utah, 330. Campo Seco, Cal. , copper mine, 196. Canada, gold, 400, 412. Magnetite ore mines, 166, 172. Canadian Northwest, geology, 385. Series, 4. Caiion City, Colo. , zinc works, 258. Diablo, Ariz., 19. Cape Ann granite, 13, 14. Cape Breton, Nova Scotia, gold ores, 397. Manganese ores, 422. Capelton, Quebec, pyrite mine, 184. Carbonate iron ores, 107. Lead-silver, S. D., 272. Lead-silver, Utah, 276. Carboniferous series, 5. System, 5. Carbonic acid in subterranean waters. 28. Caribou Hill, Colo., magnetite, 174. Carlyle, W. A , on Slocan veins, 895. Carolinian gold belt, 378. Carpenter, F. R., on Black Hills tin, 443. Carroll Co., Md., iron ore, 102. Va., iron ore, 103. Cartersville, Ga., manganese, 418. Cascade Co., Mont., 321. Mts., Cal, 349. Cascaria, Durango, Mex., tin ores, 444. Cason property, Ark., 421. Cassia Co., Idaho, 327. Cassiar district. Alaska, 393. Cassiterite, 441. Castillo Co., Colo., magnetite, 170. Castle Mts. district, Mont., 320. Cave mine, Utah, lead silver ore, 58, 276. Cave Spring manganese mines, Ga., 420. Cavities, secondary modifications, 26. Cayuga Co., N. Y., Clinton iron ores, 115. 486 INDEX. Cazin, F. M. F., on Silver Reef, Utah, ores, 333. Cebolla district, Colo,, magnetite, 175. Cedar Mt., Mo., 157. Ceilozoic Group, 5. Central California, 349. Central district, Mich. , copper, 208. Cerro de Mercado, Mex., iron ores, 187. Cerro Gordo district, Cal., 353. Chaffee Co., Colo., 395. Magnetite, 170. Chalcopyrite, of igneous origin, 61- 65. With pyrite, 189. Chamber deposits, 58. Chamberlin, T. C, 68. On Lead ores, 335, 236. Champlain series, 5. Chandler and Pioneer mines, Minn., 148. Chapin mine, Mich. , 138. Charlemont, Mass. , pyrite mines, 184, Charles Dickens mine, 335. Chateaugay iron mines. N. Y. , 85. Chatham, Conn., nickel ore, 430. Chattahoochee stage, 5. Chattanooga, Tenn., iron ores, 117. Chaudiere River, Can., gold gravels, 400. Chauvenet, R., on Colorado magne- tite, 170. Iron ores, 98. Chazy stage, 4. Cheever mine, N. Y., 163. Chemung series, 5. Cherokee Co. , Kansas, 340. Cherry Creek, Mo., 315. Cherry Valley, Mo., 133. Chester, A. H., on yield of standard iron ores, 85. Co., Penn., aluminum ores, 407. F. D., on chromite, 415. Mass., alumium deposits, 410. Chibas, E. J. gold mining, Columbia, 399. Chico stage, 5. Chipola stage, 5. Chisholm, F. F., on Cuban iron ore, 187. Choteau Co., Mont., 333. Chromite, analysis, 414. Dissemination in serpentine, 414. Of igneous origin, 61, 63. Uses, 414. Chromium, 413. Chugwater Creek, Wyo., iron ores, 171. Churchill Co. , Nev. , silver ores, 340. Church, J. A., on Comstock Lode, 340. On faults, 34. Chutes, 49. Cincinnati stage, 4. Uplift, 9. Cinnabar, 434. Claiborne stage, 5. Clarke Co., Mont., 330. Clarke, E., on lead-silver ores, Lake Valley, N. M., 361 Clarke, F. W., on earth's crust, 447. Clarke Timber Reserve, Mont. , 331. Classification of ore deposits, 447. Clay, attrition, in a vein, 49. Ironstone, 106. Seam, selvage, 49. Clayton, J. E., cited, 49, 319. Clear Creek Co., Colo., 306. Clear Lake, Cal., 437. Clerc, F. L., on Missouri ores, 340, 343. Cliff copper mine, Mich. . 308. Clifton copper district, Ariz,, 336. Clinton Co., Ohio, 114. Ores. 57. 114, 131, 446. Stage, 4. Coal measures, classification of, in Penn., 107. Coastal Plain, 7, 376. Coast Range, Cal., 349, 445. Mercury, 434. Cobalt, in Sudbury Region, 438. (/Sfee nickel, 416.) Cochise Co., Ariz., lead-silver, 379. Coeur d' Alene, Idaho, lead-silver ores, 374, 334. Colfax Co., N. M., silver and gold, 386. Colombia, South America, 441. Colorado, Creede, gold ores, 393. Geology, 386. Iron ores, 98, 170, 174. Lead-silver mines, 363-372. Magnetite, 170. Plateau, 445. Stage, 5, Silver and gold, 386-307. Columbia Co., N. Y., lead ores, 227 Limonites, 101. Columbia Hill, Cal., gold gravels, 354. Mines, Idaho, 324. River district, B. C, 394. Comanche stage, 5. Commonwealth mines, Mich. , 138. Comstock Lode, 20, 35. Geology of, 340-345. Comstock, T. B., on Colorado gold ores, 388. On Colorado lead-silver ores, 732. INDEX 467 Conejos Co. , Colo. , 296. Connecticut bismuth, 413. Copper contact deposits, 323. Lead mines, 237, Limonite, 101. Nickel ores, 430. Contact deposits, 58, 69. Continental divide, 331. Montana, 315. Coosa Valley, Ga. , aluminum, 404. Copper Basin, Ariz. , 330. Copper Cliff mine, Ont., 436. Copper Creek, Colo., 394. Copper districts in Arizona, 331. Copper Falls district, Mich. , 308. Copper Mt., Ariz., 315. Copperopolis, Cal., 196. Copperopolis mine, Utah, 331. Copper ores, analysis, 189. Discovery of, in Michigan, 211. In mine waters, 52. In sandstone, 223, 333. Origin of, 309. Copper, tables of production, 83, 90, 97, 335. Corniferous stage, 5. Cornwall, Penn., iron mines, 85, 175. Cortland series, 61. Corundum of igneous origin, 56, 61, 63. Cotta, B. von, cited, 451. On method of vein filling, 39. On schemes of classification of deposits, 449. Courtis, W. M., on gold quartz 363. Cow Bay, Nova Scotia, 399. Cramer, F. , on faults, 20. Cranberry, N. C, magnetite, 169. Crawford Co., Mo., hematites, 69, 133. Credner, H., on origin of Marquette ores, 135. Creede, Colo., 393. Crescent mine, Utah, lead-silver, 375. Cretaceous system, 5. Crimora, Va., manganese, 418. Cripple Creek, Colo., 300. Cripple Creek, Va. , iron ores, 102. Crismon Mammoth copper mine, Utah, 221. Lead-silver, 275. Crittenden Co., Ky., lead and zinc ores, 239. Crosby, W. O , on joints, 15. Cross, W., Bassick mine, 297. Map of Telluride, Colo., 290. Pike's Peak deposits, 304. Crustification, 47. Cuba, iron mines, 1 86. Cumberland mine, Mont. , 320. Cumberland iron mine, R. I. , 173. Cumberland, R. I., peridotite, 56, 61. Curry Co. , Ore. , gold gravels, 348. Curtis, J. S., 44, 46. Eureka, Nev., 277. Metasomatic interchange, 32. Silver in porphyry, 35. Gushing, H. P., discovery of augite syenites, 161. Custer Co., Colo., 296. Idaho, 324. Custer mines, Idaho, 325. Dacy Flat, S. D., 313. Dade Co., Mo., 69. Dahlonega, Ga., gold deposits, 377. Dakota stage, 5. Dall, W. H., on Alaska, 388. Daly West mine, Utah, 329. Dana, J. D., on limonites of N. Y., 105. Daubree, on joints, 15. Tin ores, 70. Water in rocks, 27, 28. Davidson, Mt., Nev., 340. Davis Creek, Va., 108. Davison Co. , N. C. , lead deposits, 238. Dawson, G. M., 388. Kootenay Lake, rock series, 394. Origin of gold, Alaska, 375. Day, John, stage, 5. Deadwood Gulch, S. D., 310. Dean iron mines, N. Y., 167. Dease Lake, gold mines, Alaska, 394. Deep Creek, Utah, lead-silver mines, 275. Silver and gold mines, 332. Deep gravels, California, 354. Deep River, N. C. , iron ores, 109. Deep River stage, 5. Deer Lodge Co., Mont., 319. Deer Trail mine, Utah, 333. De la Beche, on formation of veins, 53. De Launay, L. , on vein fillings, 38. Delaware, chromite, 414. Del Norte Co. , Cal. , chromite, 415. Deloro, Can., arsenic mine, 412. Dent Co., Mo., iron ores, 123. Devereux, W. B., gold gravels of Black Hills, 311. Magnetites of Colo. , 70. Devonian system, 4. Diadem Lode, Cal., 368. Diamond Hill mines, Mont., 319 Dike, defined, 12. Diller, J. S., on Cascade Range, Cal., 349. Geology of Sierras, Cal., 359. Gold; Minersville, Cal , 369. Lead and zinc, Ky., 239. 4G8 INDEX. Diller, J. S., on Nickel ores, origin of, 439. Sandstone dikes, 450. Dillsburg mines, Penn., 179. d'Invilliers, E. V., on Big Hill mine, Penn., 178. Disseminated ores, 57. Dodge Co., Wis., iron ores. 114. Doe Run Mo., lead mines, 328. Dolomitization, 33. Dolores Co. , Colo. , gold and silver, 287. Dona Ana, Co., N. M., 260. Don, J. R. , on Australian gold Depo- sits, 383. Occurrence of gold in sea water, 373. Donald, J. T. on chromite, 416. Douglass Island, Alaska, 365, 390. Douglass, James, on Bisbee Copper ores, 317. Drinker, H. S., zinc ores of Penn., 351. Drumlummon mines, Mont., 330. Dry Canon mines, Utah, 375, 330. Ducktown, Tenn., 51, 103. Chalcopyrite mines, 190. Pyrite mines, 184. Dutchess Co., N. Y., limonites, 101. Dutton, Capt. C. E. , on geology of N. M., 284. Dyestone iron ore, 114. Eagle Co., Colo., 294. Eagle Hill, porphyry, Utah, 330. Eagle River, Colo., 268. Eakins, L. G. , on eruptive rocks, 35. East Tenn., mine, 192. East Tintic district, Utah, limonite, 100. Eastern sandstone, Keweenaw Point, Mich., 205. Egan Canon, Nev., 339. Egleston, T., on solubility of gold, 372. El Dorado Co., Cal., 363. Electrical activity of veins, 52. Elizabethtown, N. Y., 172. Elk Mt., Colo., iron ores, 170. Elkhorn mine, Mont., 58, 317. Elko Co. , Nev. , silver ores, 340. Elmore Co., Idaho, 325. El Paso, Texas, tin ores, 444. Ely copper mine, Vt. , 190. Ely, Minn., iron ores, 144, 150. Emma mine, Utah, 375. Emmons, S. F., on Bassick mine ores, 297. On Butte copper ores, 197. On contact deposits, 67. On hematite ores, 134. Emmons, S. F. , on Lead-silver ores of Colo., 370, 373. On Leadville ores, 363. 365. On metasomatic interchange, 33. On replacements, 44. On silver ores, 35. Endlich, F. M., on gold mines of Colo., 388. Enriquita mercury mine, Cal. , 436. Enterprise, Miss. , iron ores, 109. Eocene series, 5. Esmeralda Co. , Nev. , 340. Eureka, Nev., 35, 51. Aragonite, 46. Lead-silver ores, 377. Silver and gold, 339. Europe, mercury of, 434. Eutaw stage, 5. Evans nickel mine, Ont., 436. Evigtok, Greenland, aluminum, 403. "Ewige Teufe", 36. Fahlbands, defined, 73. Related to zones, 17. Fairbanks, H. W., on Cal., gold depo- sits, 359, 367. Tin deposits, 443. Parish, J. B., on veins at Newman Hill, Colo., 390. Faults. 17-35. Fayette Co., Penn., 108. Felch Mt., district Mich., 139. Fergus Co., Mont., 333. Finlay, J. R. , on iron ores of Penokee- Gogebic, 144-150. Flagstaff mine, Utah, 375. Flathead Co., Mont., 321. Flat River district. Mo., 228. Floetze, defined, 55. Florence mines, Mich., 138. Floridian stage, 5. Flucan, defined, 49. Foerste. A. F., on Clinton ores, 120. Folds, defined, 11, 12. Forest Queen mine, Colo., 294. Formation, defined, 6. Fortuna mine, Ariz., 337. Forty mile series, 388. Foster, on iron ores of Mich. , 135. Foumet's series, 66. Fox Hill stage, 5. Franklin copper mines, Mich. , 208. Franklin Co., Mo., lead and zinc mines, 239. Franklin, Co., Va., magnetite, 169. Franklin Furnace, N. J., iron ores, 167. Franklin Furnace, N. J., Zinc 251-257. Frazer, P., on Penn. limonites, 104. Frederick Co. , Md. , limonites, 102. Fremont Co. , Colo. , magnetite, 170. INDEX. 469 French Creek mines, Penn. , 179, Friedensville zinc mines, Penn. , 250. Frisco, Utah, 276. Fritz Island mine, Penn., 179. Frost Drift, N. C, 377. Fuchs, E., on useful minerals, 461. Fttnter's Bay Alaska, gold, 392. C. Gagnon mine, Butte, Mont., 201. Galena (town), S. D., lead-silver mines, 272. Galvanic action in veins, 52. Gangue, defined, 55. Minerals, 33. Gap mine, Penn. , 62, 65. Nickel ore, 429. Pyrite ore, 184. Gasconade sandstone. Mo., 122. Gatling arsenic mine, Ont. , 412. Gay Head, Mass., 109. Genesee antimony mine, Nev., 411. Genesee stage, 5. Genth, F.A., on Boulder Co., Colo., 306. Geological classification, 4. Geology, general principles, 3. Georgetown, Colo., 306. Georgia, bauxite, 404, 408. Clinton ore, 114, 117. Gold ore, 379. Limonite, 103. Manganese, 418, 420. Georgian stage, 4. Geyser mine, Colo. , 30. Giants Range, Minn. , 151. Gibbonsville, Idaho, 324. Gila River, N. M., Aluminum depo- sits, 407. Gilbert. G. K., on faults, 18. Gilpin Co., Colo., 47, 305, 306. Copper ores, 203. Glacial series, 5. Glenariff, Ireland, aluminum ores, 407. Glendale, Mont., lead-silver deposits, 273, 317. Glenn, Wm., analyses chromite, 414. Globe district, Ariz., copper ores, 218, 219. Gold and silver ores, 335. Gogebic Range, Mich. , 69. Manganese ores, 422. Golconda, Nev., manganese ores, 421. Gold, Alaska, 392. Analysis of minerals containing, 281. Chemical reactions in precipita- tion. 371. Classification of gravels, 361. Deposits, general examples, 280. Gravels, 353, 354, 393. Gold, introductory, 280. Quartz veins, 362. Statistics, 401. Gold Hill, Colo., 305. Good Night stage, 5. Gossan, defined, 51. Gothic district, Colo., 294. Gouge defined, 49. Graham Co. , Ariz. , 336 Grampian Mt. , Utah, 276. Grand Canon of Ariz. , 334. Granite Co. , Mont. , 319. Granite Mt. mine, Moxit. , 319. Grant Co., N. M., silver and gold ores, 285, Grant Co., Ore., gold mines, 348. Grant, U. S. , on Rainy Lake district, 384. Grassy Hill, Penn., 175. Great Basin, 445. Arizona, 334. California, 349. Nevada, 337. Oregon. 347. Utah, 328. Great Eastern mercury mine, Cal. , 426. Great Falls, Mont. , iron ores, 90, 109. Gold and silver, 321. Great Valley, 101, 102. California, 445. Great Western mercury mine, CaL, 426. Greenbrier Co., W. Va., hematites, 121. Green-eyed Monster mine, Utah, 333. Greenland, aluminum, 403. Gregory Company, Mont. , 273. Greisen, defined, 70. Gresley, W. S. , on Mich, iron ore, 138. Griffin, P. H., on Canada bog ore. 90. Grimm, J., on scheme of classifica- tion, 455. Groddeck, A. von, 73. On scheme of classification of ore deposits, 456. Groundwater, 27. Guadaleazar, Mex., mercury, 424. Guadalupe mercury mine, Mex., 436. Guanaco, ChiK, gold, 34. Guaymas copper mines, Lower Cal., 221. Guerrero, Mex., hematite, 188. Gunnison Co., Colo., magnetite, 170. Gunnison Region, Colo., silver and gold, 294. H. Hade of a fault, 21. Hague, A., Comstock Lode, 340-344. Formation of magnetites, 174. Hamilton, Nev., gold-silver ores, 470 INDEX. Haile gold mine, S. C, 380. Harzburgite, 439. Hall, J., cited, 124. Hall's Valley, Colo., bog ore, 90. Hamburg zinc mine, N. J. , 252. Hamilton, Nev., 338. Hamilton series and stage, 5. Hammondville, N. Y., iron mines, 162-165. Handcart Gulch, Colo. , bog ore, 90. Hanging Rock iron region, Ky. , 95. Hanna, on North Carolina gold belt, 380. Hanover, N. M., zinc ores, 259. Harford Co., Md., chromite, 414. Harney Peak, S. D., 314. Hartman zinc mine, Penn. , 250. Hartwell iron district, Wyo., 154. Hastings Co., Ontario, 412. Haworth, E., on lead and zinc of Missouri, 242. Hayden's Survey, 323. Hayes, C. W., 388. On aluminum deposits, 405. Head Center mine, Ariz., 43. Hecla lead-silver mines, Mont. , 273. Hecla mines, Mont., 317. Heim, cited, 23. Helena Company, Mont. , 273. Helena, Mont., 320. Hematite, brown, 87-106. Red and specular, 114-159. Henrich, C, on copper ores, Clifton district 216. Copper pyrite, Tennessee, 190. Gold of New Mexico., 286. Henry Co., Va., magnetite, 169, Henwood, cited, 55. Herder, von, on vein fillings, 39. Hesse, Germany, bog ore, 92. Hestmandjo, Norway, chromite, 413. Highland Co., Ohio, Clinton ores, 114. High or deep gravels, Cal. , 354. Highwood Mt., Mont., 315. Hillebrand, W., on Geyser mine waters, 300. Gold deposits of Cal. , 369. Vanadium, 36. Hill, R. C, Colo., gold, 287. Concentration of gold in veins, 51. Iron ores of Wyo., 174. Mercur mines, 332. Replacements, 45. Hill, R. T., Mex., iron ores, 187. Hinsdale Co. , Colo. , gold and silver, 287. Hitchcock, E., on limonites, 100. Hoefer, H., on faults, 23. HoUister, cited, 275. Homestake mine, Colo. , 294. Homestake mines, S. D., 313. Honorine mine, Utah, 275. Horizon, defined, 6. Horn Silver mine, Utah, 276. Horses, formation of, 48. Huancavelica, Peru, mercury mine, 424. Hubbard, L. L., on Mich., copper ores, 210. Hudson Bay, gold deposits, 4Q. HudsoQ River, stage, 4. Huitzuco, Mex., mercury mines, 424 Humboldt Co., Nev., antimony, 411. Gold and silver deposits, 340. Humboldt-Pocahontas mine, Colo., 299. Hunt,T. S., on Canada magnetites, 172. Huronian ores, 127. System, 4. Hurst, limonite bank, Va. , 93. Hussak, cited, 314. Ibapah range, Utah, 332. Idaho Basin, 325. Idaho City mining belt, 325. Idaho Co., Idaho, 324. Idaho, geology, 323. Copper, 222. Gold, 323. Tin, 443. Idaho Springs, Colo., 306. Iddings, J. P., cited, 59. Comstock Lode, 340-344. Idria, Austria, mercury, 424. Igneous rocks, defined, 6. As sources of metallic ores, 34, . 59-62. Illinois lead zinc mines, 233. Impregnations, 57. Independence, Colo., 294, 305. India, aluminum ores, 410. International Geological Congress, 3. Inyo Co. , Cal. , antimony deposits, 410. Lead-silver deposits, 279. Iowa, iron ores, 98, Lead and zinc mines, 233. Ireland, aluminum ores, 407. Bog ores, 92. Iron Co., Utah, antimony deposits (411.) Hematites and magnetites, 180, Irons, defined, 66. Iron hat, defined, 51. Iron in nature, 86, 87. IronMt., Colo., 170. IronMt., Mont., 321. IronMt., Mo., 59, 71, 157. Iron ores, analyses, 85. Composition, 84, 186. INDEX. 471 Iron ores, Discussion of, 85-87. Impurities, 85-86. Iron ores, magnetite, 160-184. Iron ore localities: Adirondack Mountains, 160. Alabama, 104. Brazil, 175. Colorado, 98, 170-174. Connecticut, 101. Cuba. 186. Georgia. 103, 117.. Hesse, Germany, 92. Ireland, 92. Kentucky, 95, 107. Clinton ore, 114. Maryland, 116. Massachusetts, 101. Mexico, 187. Michigan, 125-150. Minnesota, 96, 150, 174. Missouri, 96, 122. Mississippi, 109. New Jersey, 101, 160, 173. New York, 114, 167. North Carohna, 104-109, 160. Nova Scotia, 120. Ohio, 96-115. Oregon, 92. Pennsylvania, 93, 104, 113. Tennessee, 103, 114. Vermont, 100, 184. Virginia, 114, 169. West Virginia, 107, 114, 131. Wisconsin, 114. Wyoming, 171. Iron ore, pyrite, 184. Red and specular hematite, 140- 159. Iron ores : Siluro-Cambrian limonites, 100- 106. Spathic, 112. Statistics, 186. Irving, R. D., cited, 205. Copper ores, origin, 209. " Fimdamental complex," 128. Michigan, ores, 127. Penokee district ores, 139. Replacements, 44. Isle Royale mines, Mich. , 207. Isochemic lines, 183. Jackson, C. T., on Penn. limonites, 104. Jackson stage, 5. Jacksonville, Ala. , 404. Jacupiranga, Brazil, iron ore, 56, 61. Jalisco State, Mexico, hematite, 188. James River, Va., hematites, 154. Jasper Co., Mo., lead and zinc mines, 241. Jefferson Co., N. Y., nickel ores, 123, 440. Jefferson Co., Mo., lead and zinc mines, 239. Jefferson Co., Mont., 317. Jenney, W. P., cited, 43. Gold deposits, 283. Lead and zinc mines of the Miss. Valley, 237, 243, 446. Lead and zinc mines of Mo. , 230, 245. Joachimsthal, Bohemia, cited on water, 31. John Day stage, 5. Johnson, L. C. , on limonites, 97. Joints, compression, 13, 14. Jones copper mine, Cal. , 196. Joplin, Mo., zinc and lead mines, 240. Josephine Co. , Ore. . gold mines, 348. Juab Co., Utah, 330. Judith Mt., Mont., 315. Julien, A. A., on origin of magnetite, 218. Juniata district, Penn., Clinton ore, 116. Jurassic system, 5. Jura-Trias system, 5. Kadiak Island, Alaska, gold ores, 392. Kansas, lead and zinc mines, 240. Kearney mines, N. Y. , iron ores, 125. Kelley lode, N. M., lead-silver ores, 260. Kemp, J. F., on Iron Mt., Colo., ores, 174. On N. J. zinc deposits, 257. On Tenn. copper deposits, 193. Kennedy, W., on nodular ores, 97. Kentucky, Clinton ore, 114. Lead and zinc ores, 239. Limonites, 95, 107. Kern Co., Cal., antimony, 41Q. Kerr, W. C, cited, 377. On N. C. magnetite ore, 169. On copper ores, 194. Keweenawan svstem. 4, 166. Keweenaw Point, Mich., 57, 204, Keyes, C. R., on Mo. lead ores, 228. Kimball, J. P., on chemistry of limonites, 112. On Cuban iron ores, 187. On formation of iron ores, 111, 112. On hematite, 124. On magnetite, 173. King, C. , on Comstock Lode, 340, 343. 472 INDEX. Kingston, Canada, corundum de- posits, north of, 490. Kittitas Co., Wash., gold placers, 347. Klamath Mt., Cal., 359. Klausen, Austria, cited, 42, 43. Knight, W. C, cited, 174. On Hartwell iron ores, 154. Knob of igneous rock defined, 13. Knowlton, cited on Cal. deep gravels, 358. Koehler, G. , on scheme of classifica- tion of ore deposits, 452. Kongsberg, Norway, cited, 73. Kootenai Co. , Idaho, 324. Kootenay Lake, B. C, 394, Kwei-Chau, mercury deposits, Asia, 424. Laccolite defined, 12. Lager defined, .55. Lagorio, cited on ore deposits, 59. Lahontan Lake, Nev. , 337. Lake Champlain iron region, 160. Lake Co.. Colo., 294. Lake of the Woods, gold district, 384. Lake Superior, copper deposits, 446. Gold and silver, 283. Iron deposits, 125, 446. Manganese ores, 422. Lake Valley, N. M., 285. Lancaster Co., Penn., chromite, 414. Lander Co., Nev., antimony mines, mines, 411. Gold and silver mines, 339. Lane and Hayward mines, Alaska, 392. Lane's bismuth mine. Conn. , 412. Lansing, Iowa, lead and zinc mines, 235. La Plata Co.. Colo., 287. Laramie Co., Wyo., 154. Laramie stage, 5. Lassens Peak, Cal. , 349. Lateral enrichments of a vein, 49. Lateral secretion, 40. 41, 42. Launay, L. de, cited, 461. Laurentian system, 4. Laur, M. F., on occurrence of alu- minum, 404. Lawson, A. C, on geology of Cal., 359. On California granite, 375. On Rainy Lake gold region, 384. Lead alone, 226. Lead and zinc, 233. Lead City. S. D., 313. Lead, production of, 232. Lead series, 226. Lead-silver ores, 260-263. Lead veins in gneiss, 226. Leadville, Colo., cited, 17, 21, 35, 51. Copper mines, 221. Lead-silver mines, 262. Silver ores, 265. Le Conte, J., on Cal. gravels, 356. On mercury deposits, Cal. , 427. On scheme of classification of ore deposits, 450. Lee Hill mines, Minn., 146. Leesburg, Idaho, 324. Lehigh Co., Penn., iron mines, 101, 169. Lemhi Co., Idaho, 324. Leonard, A. G., on Lansing mine, Iowa, 235. On origin lead-zinc of Miss. Val ley, 237. Lesley, J. P., cited, 120. On Marcellus stage, 94. On Penn. iron mines, 178. Lesquereux, on Cal. gravels, 355. Lewis Co., Mont, 320. Lewiston, Mont., 323. Libbey Creek, Mont., 322. Lignitic stage, 5. Limonites, analysis, 106. Iron ore, 87-106. Lincoln Co., Nev., 338. Lindgren, W., on Boise Co., gold veins, 325. On Cal. gold veins, 365. On Cal. gold, occurrence, 369. On Calico district, 351. On War Eagle claim, 397. Little Annie mine, Colo. , 295. Little BeltMts., Mont., 321. Little Cottonwood Canon, Utah, 274. Little Rock, Ark., aluminum, 406. Livingston Co., Ky., 239. Llano Co., Texas, copper mines, 204. Logan Co., Kansas, nickel ores, 440. London mines, Tenn., 192. Lottner-Serlo, on schemes of classifi- cation of ore deposits. 451. Louisa. Co. , Va. , pyrite mines, 184. Loup Fork stage, 5. Lovelock mines, Nev. , nickel, 440. Lovers Pit, Mineville, N. Y. , 85. Low, A. P., on Hudson Bay iron ores, 154. Lowell, Mass., nickel ores, 430. Lower Helderberg series, 4. Lower Claiborne stage, 5. Low Moor, Va. , zinc ores, 95, 256. Lubeck, Me., lead mine, 227. Lucky Boy mine, Utah, 333. Lyman, B. S., on limonite, 94 Lyndhurst, Va., manganese, 418. Lyon Co., Nev., 340. INDEX. 473 Lyon Co., Ky., 95. Lyon Mt. , N. Y. , iron ores, 162. M Madison Co., Mont., 316. MagdalenaMt., N. M., 260. Magna Charta mine, Butte, Mont., 319. Magnetite iron ore, 56, 60-63, 160-181. Analyses, 183. Beds. 160. Origin of deposits, 181. Sands. 180. Maiden, Mont., 323. Maine, copper pyrite, 190. Gold, 383. Tin, 444. Manganese ores, 416, 418. Mansfield ores, Penn., 121. Marcellus stage, 5. Margerie and Heim, cited on faults, 23. Maricopa Co., Ariz., 335. Mariposa Co., Cal., 363. Markhamville, N. B., manganese, 422. Marmora. Can. , arsenic mines, 412. Gold mines, 401. Marquette district, 129-136. Marquette range, 69. Marshall Mt., Colo., 306. Marshall tunnel, Georgetown, Colo., 50. Maryland, chromite, 414. Clinton ore, 116. Gold mines, 381. Limonite, 102. Mary Co., Tenn., 192. Marysville, Mont., 320. Marysville, Utah, 424. Massachusetts, lead mines, 227. Limonite, 101. Mayflower mine, Mont., 317. Maynard, G. W., on chromite, 416. Mazon Creek, 111., 107. McCalley, H., aluminum, 406. McConnell, R. G., cited, 388. On Trail Creek rock series, 396. McCreath, A. S., cited, 107. On slates, 93. Meagher Co., Mont., 320. Means, E. C. , referred to, 256. Medina stage, 4 Menominee district, Lake Superior, 135-139. Meramec hematite mines. Mo., 123. Mercur gold mines, Utah, 330. Mercury, occurrence of, 424. Merrill, G. P., cited, 35. Merritt, W. H., on Lake of the Woods district, 385. Mesabi district, Minn. , 134. Mesabi range, Minn., 144. Mesozoic group, 5. Metamorphic rocks, defined, 6. Metasomatic defined, 32. Methods of vein filling, 39. Meunier, on origin of chromium, 413. Mexico, iron ore, 187. Mercury, 424. Tin, 444. Mexican mine, Alaska, 391. Miask, Urals, aluminum, 403. Michigan, copper, 204. Gold, 383. Iron, 125-150. Michigamme jasper, 137. - Middle Hill, Penn , 175. Middletown, Conn., lead^lpaine, 227. Midway stage, 5. Milan, N. H. , pyrite mine, 184. Miller, Prof., on Kingston, Ont.j aluminum, 409. Mine Hill, Cal., 358. Mine Hill. N. Y. , zinc mine, 252. Mine la Motte, Mo., cited, 58, 69. Lead, 228. Nickel, 429, 440. Mineral Hill, Colo., 302. Mineville, N. Y.. 72, 85. Mine waters, 52. Mining laws, 447. Minnesota copper mines, 212. Iron ore, Mesabi range, 150. Limonite, 96. Magnetite, 174. Miocene series, 5. Mississippi Valley, 19, 446. Iron ores, 109. Lead and zinc, 231, 233. Mississippian series, 5. Missoula Co., Mont., 321. Missouri, Cambrian red hematite, 122. Copper, 213. Lead ores of southeastern Mo., 228. Limonite, 96. Red hematites, 122. Tin, 445. Zinc and lead in the southwest, 240. Moericke, cited, 34. Mohave Co., Ariz., 335. Moisie, Can., magnetite sands, 181. Monarch district, Colo., 268. Monheim, V., on zinc ores of Stol berg, 257. Monocline defined, 11, 19. Mono Co., Cal., 352. Monroe, Conn., bismuth, 412. 474 INDEX. Montalban series, 4. Montana, geology of, 314 Copper, 203. Lead-silver, 273. Silver and gold, 314 Tin, 443. Montana stage, 5. Monte Cristo mine, Wash., arsenic, 412. Moore, P. N., on iron ores, 109. Morenci, Ariz. , copper district, 215. Morozewicz, J., cited 173. On laws of separation of ores, 62, 63. Mosquito range, Colo. , 262. Mother Lo(^ of California, 363. Mount Baldk^, Utah, 333. Mount DavMson, Nev. , 340. Mount HopI, N. J., 167. Mount Marshall, Colo. , 306. Mount McClellan, Colo., 295. Mount Prometheus, Nev., 339 Mount Shasta, Cal, 349. Mule Pass, Mt., Ariz., 217. Mullica Hill, N. J., 89. Munroe, H. S., cited 71. On limonites, 41. On scheme of classification of ore deposits, 457. Murphee's Valley, Ala., 120. Murray nickel mine, Ont. , 436. Nacemiento copper mines, N. M., 334. Nason, F. L., on geology of Ring- wood mines, 169. On N. J. zinc deposits, 252, 257. On Mo. iron ores, 158. Neal district, Idaho, 323. Neck of igneous rock defined, 12. Neihart mining district, Mont., 320. Nelson Co., Va., tin ore, 444. Nelson, B. C, gold, 394. Neocene system, 5. Nevada, antimony mines, 411. Geology of, 337. Gold and silver deposits, 338. Mercury, 424. Nickel, 440. New Almaden, Cal. , mercury, 425. Newberry, J. S., on copper deposits of N. M., and Utah, 224 On iron ore, 120. On lead- silver deposits, Utah, 276. On Silver Reef, Utah, 333. On schemes of classification of ore deposits, 453. Newberry, W. E. , on Colorado mines, 271. New Brunswick, N. J., copper mines, 190. New Caledonia nickel, 439. Newfoundland, chromite, 416. Copper, 190. New Hampshire, lead mines, 227. Tin, 444. New Idria mines, Cal., 426. New Jersey, copper ores, 223. Gold ores, 383. Iron mines, 173. Limonite, 101. Magnetite, 160. Zinc mines, 253. New Jersey, Greensand stage, 5. New Jersey Zinc and Iron Co.'s mines, 252, 254. Newman Hill. Col., 24, 47, 50. Mines of, 338. New Mexico, aluminum deposits, 407. Copper, 224, 334. Geology of, 284. Lead-silver, 260. Silver and gold, 285. Zinc ores, 259. New River, Va. , limonite. 103. Newton, Cal., copper ore, 196. Newton Co. , Mo. , zinc mines, 240. New York copper mine, Ariz. , 219. New York, CUnton ore, 114, 120. Gold deposits, 383. Iron mines of the Highlands, 167. Iron ore of Adirondacks, 166. Lead mines, 227. Limonite, 101, 105. NeyCo., Nev., 338. Nez Perces Co. , Idaho, 324. Niagara series and stage, 4. Nicholas, W., on precipitation of gold, 373. Nicholson, F., on Missouri copper mines, 214. Nickel, Arkansas, 440. Nevada, 440. Norway, 431. Ores, table and general remarks, 428, 429. ^ Ores of igneous origin, 61, 64. Pennsylvania, 439. Niobrara stage, 5. Northampton, Mass. , lead mines, 227, North Carolina, aluminum, 407. Copper, 194. Gold, 376, 380. Limonite, 104-109. Magnetite, 160, 174. Nickel, 439. Specular ores, 155. Tin, 444. Northern States, gold deposits, 381. INDEX. 475 Northwest Territory, gold deposits, 393. Norway, chromite, 413. Nova Scotia, Clinton ore, 120. Copper pyrite, 190. Gold, 397. Oat Hill, Cal. , mercury mine, 426. Ocean as a source of ores, 33. Ogdensburg, N. J., 250. Ohio, Chnton ore, 114, 115. Limonite, 96, 107. Okanogan Co., Wash., 347. Old Dominion copper mine, Ariz., 219. Old Sterling mine, Mo., 125. Old Tenn. mine, 192. Oligocene series, 5. Oliver mine, Va., 152. Olmstead, I., on Burden mines, 111. Oneida Co.. Idaho, 327. Ontario, arsenic mine at Deloro, 412. Nickel mine, 436. Ontario mine, Utah, 329. Ontonagon copper district, Mich., 207, 209. Ophir Canon. Utah, 275, 330. Ophir silver mine, Cal. , 353. Oppel, von on strata beds, 55. Oquirrh Mt. mines, Utah, 274. Orange Co. , N. Y. , zinc mines, 256. Orchard gneiss, 162. Ore deposits, classification, 54. Literature on, 74-79. Ore -minerals, 33. Oregon, geology of, 347. Gold mines, 348. Mercury, 424. Organic matter as a precipitating agent, 68. Oriskany series, 4. Orton, E., on black band ore, 108. On dolomitization, 32. Ouachita uplift, 446. Ouray Co., Colo., 287. Owyhee Co., Idaho, 35, 327. Ozark uplift, 122, 155. Pacific Ocean, 445. Pahranagat district, Nev., 338. Paleozoic group, 4. Palo Duro stage, 5. Panama manganese, 423. Panamint district, Cal., 352. Park Co., Colo., 295. Parting in a vein, defined, 49. Passaic iron belt, N. J. , 167. Patton mines, Ore. , bog ore, 90. Peale, A. C, on Montana gold de- posits, 315. Pearce mine, Ariz., silver and gold, 336. Pearce, R., Colo., gold, 306, 365. On gold with pyrite, 372. Pechin, E. C, cited, 95. Peekskill, N. Y., aluminum ores, 410. Magnetite, 172, 173. Penfield, S. L., cited, 441. Pennsylvania, brown hematites, 93, 94, 101. Chromite, 414. Clinton ore, 116. Gold, 383. Lead mines, 227. Limonite, 101, 104. Mansfield ore, 121. Spathic ore, 112. Penokee-Gogebic district, Mich. , 139. Penrose, R. A. F., on Arkansas iron ores, 96. On Arkansas manganese ores, 420. On Colorado gold deposits, 304. Pentlandite, 429. Percival, on Connecticut limonite, 104. Permian series, 5. Perry Co., Penn., 108. Peru, S. A., mercury, 424. Peters, cited, 437. Phelps Co. , Mo. , iron ores, 123. Phillips, J. A., on scheme of classifi- cation of ore deposits, 454. PhiUipsburg, Mont., 319. Phoenix copper district, Mich. , 208. Phosphorus in iron ore, 85, 183. Pictou Co., Nova Scotia, iron ore, 120. Pierre stage, 5. Pike's Peak, Colo., 403. Pilot Knob, Mo. , iron ores, 155. Pima Co., Ariz., lead-silver, 279. Silver and gold, 336. Pinal Co., Ariz., gold and silver, 335. Pinches in a vein, 49. Pioche, Nev., 338. Pirsson, on geology of Little Rocky Mts., 322. Pitch of a fold defined, 12. Pitkin district, Colo, 294. Pittsburg iron ore group, 108. Pittsburg seam, 108. Piute Co., Utah, 333. Placer Co., Cal., chromite, 415. Magnetite, 171. Placers, 59, 70. Plateau region of Rockies, 445. Platinum, 441. 476 INDEX. Platoro, Colo., 296. Pleistocene system, 5. Pliocene series, 5. Point Orford. Ore., 348. Poorinan lode, Idaho, 327. Portage Lake copper mines, Mich., 207. Portage stage, 5. Port an Port Bay, Newfoundland, chromite, 416. Porter, J. B., on Clinton ore, 120. Porter, J. A., on Colo, gold, 288. Portland mines. Cripple Creek, Colo. , 305. Posepny, F., cited, 47, 376. On contact deposits, 67. On ore origin, 459. On replacement, 44. Potrillos, Mex., tin ores, 444, Potomac formation, 5. Potsdam stage, 4. Power, F. D., on classification of ore deposits, 56, 461. Pratt, J. H., on chromite, 61. On North Carolina chromite, 413. On origin corundum, 408. Prescott, Ariz., 220. Prime, F. , on Siluro-Cambrian limon- ites, 94, 104. On classification of ore deposits, 451. Prometheus Mt., Nev., 339. Prosser mines, Ore., bog ore, 91. Psilomelane, 416. Puei'co stage, 5. Puget Sound, 90. Puget Sound Basin, Wash., 346. Pumpelly, R. , on classification of ore deposits, 456. On copper rock of Michigan, 309. On hematite, 122. On replacements, 44. Putnam, B. W., cited, 72. On magnetite ore, 165. Putnam Co., N. Y., iron mines, 166. Pyrite beds, 184. With copper, 189. Pyrrhotite, of igneous origin, 61, 64, 65. With nickel, 430. Pyrolusite, 416. Quaco Head, N. B., manganese, 422. Quaquaversal, defined, 12. Quartzburg Grimes Pass belt, 325. Quaternary system, 5. Queen of the West mine, Colo., 266. Quicksilver, 424. Quigley, Mont., 321. Quincy mines, Mich., 2( Quinnesec mines, Mich. Quebec, chromite, 416. Copper mines, 190. 138. Raibl, Austria, lead-silver deposits, 44. Rainbow lode, Mont., 319. Rainier Mt., 346. Rainy River gold district, Minn. , 383. Rampart Series in Alaska, 388. Ramshorn mine, Idaho, 324. Randsburg gold mines, Cal., 351. Raritan stage, 5. Rathgeb mine, Cal. , 370. RavaUiCo., Mont., 321. Raven Hill, Colo., 305. Raymond & Fly mine, Nev., 838. Recent series, 5. Red Cliff, Colo., 294. Red Mt , Ala., 117. Red Mt., Kern Co., Cal.. 352. Red Mt., Ouray Co,, Colo., 272. Red Rock, San Francisco, manganese, 421. Reese River district, Nev., banded veins, 47. Gold and silver, 339. Reich, on electrical action in veins, 52. Replacement, 32, 44, 58. Republic mine, Mich. , 85. Residual clay in a vein, 49. Residual deposits, 59, 71. Rhode Island, gold deposits, 383. Richmond, Mass., limonites, 101. Richthofen, von, on California gold veins, 365. On origin Comstock lode, 340-341. Rickard.T. A., on California gold, 370. On Newman Hill, Colo., 292, Rico, Colo., lead-silver, 271. Riddle's, Oregon, nickel, 438. Rifting in granite, 13, 15. Rio Grande Co., Colo., 295. Rio Tinto, Spain, old timbers, 52. Rio Viento Frio, S. A., manganese 423. Ripley stage, 5. River gravels with gold, 353. Roanoke, Va., zinc ores, 249. Roaring Fork Creek, Colo. , 268. Robert E. Lee mine, Colo., 263. Robinson mine, Colo., 266. Rochester, Mont., 317. Rockbridge Co. , Va. , tin ores, 444. Rock Creek district, Idaho, 325. Rocks, classified, 6. Eruptive, 447. Magmas, 60-67. INDEX. 471 Eocky Mts., faults of, 20. Lead and zinc deposits, 249. Silver and gold deposits, 308. Eogers, H. D., cited, 120. On New Jersey zinc deposits, 251. Rolker, C. M., on Silver Reef ores, 334. Ropes gold mine, Mich. , 383. Rosenbusch, H., cited, 59. Rosita. Colo., 296. Rossland. B. C, 62, 396. Roth, J., on analyses igneous rocks, 87. Rothwell, R. P. , on Silver Reef ores, 333. Rotten limestone stage. 5. Roubidoux sandstone. Mo., 122. Routirara, Sweden, magnetite, 6, 172, 175. Roxbury, Conn., limonite, 112. Ruby mine, Colo., 317. Russell, I. C. , on Clinton ore, 120. Russia, platinum, 441. Rye, N. Y., bog ore, 91. S Sacramento Valley, Cal. , 349. Safford, J. S., on siliceous group, 96. On Tennessee limonites, 103. Saguache Co. , Colo. , 293. Sain Alto, Mex. , tin. 444. Salina Co. , Ark. , nickel ore, 440. Salina series, 4. Salisbury, Conn., limonites, 101. Salt Co.. Utah, 329. San Benito Co. , Cal. , antimony, 410. San Bernardino Co., Cal., iron ore. 171. Sandberger, F., on derivation of ores, 34, 41. On dark silicates, 447. San Diego Co., Cal., iron ores, 171. San Emigdio, Cal. , antimony, 410. Sangre de Cristo Range, Colo., 260- 300. San Joaquin Co., Cal., manganese, 421. San Juan Mt. , 287» San Juan Co., Colo., bismuth, 412. Gold and silver, 287. San Luis Obispo Co., Cal, chromite, 415. San Miguel Co.. Colo., 290. Sante Fe Co.. N. M., 286. Santa Rita copper district, N. M., 219. Santa Rita Mt., N. M., 285. Santiago, Cuba, iron ores, 186, 187. Saucon Valley, Penn. , zinc mines, 58, 250. Sawatch Mt., Colo., 262. Schapbach, cited, 42. Schemes of classification of deposits. 448-457. Schmidt, A., on Missouri iron ores, 122, 158. On Missouri lead and zinc ores, 242, 246. On replacement, 44. Schrauf, A., on mercury deposits, 425. Schoharie stage, 5. Schuyler copper mines, N. J. , 233. Secondary alteration in veins, 50. Sedimentary rocks defined, 6. Segregation, 59, 72. Selvage in a vein defined, 49. Servia, mercury, 424. Seven Devils' district, Idaho, 222. Sevier Co., Ark., antimony, 411. Shaler, N. S., on origin of Clinton ore, 120. Shasta Co., Cal., chromite, 415. Shasta Mt., Cal., 349. Shasta stage, 5. Shaw mine, Cal., 369. Shaw Mt. district, Idaho, 325. Shear zones defined, 17, 58. Sheep Creek Basin, Alaska, 393. Sheep Mt. district, Idaho, 324. Sheerer, cited, 430. Sheet defined, 12. Shepherd Mt., Mo., 157. Sherbrooke, Quebec, 190. Siderite, genetic relations, 112. Spathic ore, 106-113. Sierra Co., Cal., iron ore, 171. Sierra de Mercado, Mex., hematite, 188. Sierra Nevada Range, Cal., geology of, 349, 358. Siluro-Cambrian limonites, 100-105. Silver and gold ores, analyses, 281. Deposits. 280. Statistics, 401. Silver Bow Basin, Alaska, 391. Silver Bow Co., Mont., 318. Silver Bow Creek, Mont., 197, 319. Silver, Cahfornia, 351. Silver City, N. M., 407. Silver Cliff, Colo., 57, 296. Silver Islet, 42, 283. Silver King mine, Ariz., 335. Silver minerals, 281. Silver Plume, Colo.. 306. Silver Reef, Utah. 333. Silverton, Colo., 293. Silver, Washington, 347. Simmon's iron mines. Mo., 123. Simundi. H. . on gold ores, 35. Sitka, Alaska, 392. Slickensides or slips defined, 23. 478 INDEX. Slocan gold district, B. C, 394. Smithfield iron mine, Colo., 170. Smith, F. C, on Black Hills gold de- posits, 313. Smith, J. P., on auriferous strata, 374. Smuggler mine, Colo. . 289. Smuggler Mt., Colo., 270. Smyrna, alumimmi, 410. Smyth, C. H., Jr., on hematite, 121, 124, 125. On limonites, 113, Smyth, H. L., 139. On Menominee district mines, 136. 138. On Michigan copper; 210. On Michigan iron ores, 127, 144. Snake River, Idaho, 273, 323. Snohomish Co., Wash., silver de- posits, 347. Socorro Co, , N. M. , gold and silver, 285. Sonora, Mex., antimony, 411. Soret's principle, 64, 171. Sources of the metals, 33, 34. .South Carolina, gold deposits, 380. South Dakota, gold and silver ores, 309. Lead-silver, 272. Tin, 442. Southern States, gold, 446. Pyrite under gold, 184. South Mt., Penn., iron ores, 166, 169. Gold belt, 378. South Park, Colo., 295. Spanish Peaks, Colo. , 295. Spathic iron ore, 112. Spenceville, Cal., copper mine, 195. Sperry, F. L., on Algoma district, 441. Spenylite, 438. Spurr, J. E., on Aspen, Colo., 269. On iron ores, 152. On Mercur gold deposits, 331. On Mesabi ores, 152. On Yukon Basin, 388. St. Frangois Co. , Mo. , lead and zinc, 239. St. Genevieve, Mo., copper mines, 213. St. Lawrence Co., N. Y., lead mines, 226. St. Louis, Mo. , nickel ores, 440. St. Mary's mine, Penn. , 179. Stannite, 445. Star district, Utah, iron mines, 180. Staten Island bog ore, 91. Steamboat Springs, Nov., 30, 35, 44, 57. Mercury mines, 427. Stehekin copper district, Wash., 222. Stein Mt., Ore., 347. Stelzner, A. W., cited, 34. Step- faults defined, 24. Sterling Hill zinc mine, N. J,, 251- 257. Sterling mines, Cayuga Co., N. Y., 115. Stevens Co., Wash., gold, 347. Stevenson, J. J., cited, 50. Stibnite, 410. Stickeen river, Alaska, 394. Stobie nickel mine, Ont. , 436. Stokes Co., N. C, iron ore, 170. Storey Co. , Nev. , silver and gold, 340. Storms, W. H., on Alvord mine, Cal.^ 370. Stratum defined, 6. Stratigraphy of auriferous strata, 374. Stream tin, 443. Strike-faults, 21, 25. Sub-carboniferous series, 5. Succession of minerals in an igneous rock, 33, 34. Sudbury, Ont., Can., 62. Cobalt, 438. Iron, 184. Nickel, 429, 431. Sullivan Co., N. Y., lead deposits, 228. Sulphur Bank, Cal. , mercury, 44, 427. Sulphur in iron ores, 85, 86. Sulphur in rocks, 37. Sumdum Bay, Alaska, gold deposits, 392 Summit Co., Colo., 294. Lead-silver, 266. Summit Co., Utah, lead-silver, 275. Summit district, Colo., 45, 52. Sunrise copper mines, Wyo. , 222. Sweden, lake ores, 92. Sweden, magnetites, 175. Sweet Grass Hills, Mont., 323. Sweetwater Co., Wyo., 308. Swells in a vein, 49. Syncline defined, 11, 17. Taberg, Sweden, iron ore, 60, 175. Taku mines, Alaska, 392. TalahCo.. Idaho, 324. Tamarack copper mine, Mich. , 208. Tarr, R. S., on Cape Ann granite, 13, 14. On classification of ore deposits, 459. Telegraph lead-silver mine, Utah, 275. Teller Co., Colo., 300. Telluride, Colo., 288. Tellurides in gold quartz, 362. Temescal tin mine, Cal. , 443. INDEX. 479 Tern Pahute district, Nev., 338. Ten-mile district, Colo.*, 266, 294. Tennessee, Clinton ore, 114, 116. Copper, 194. Lead zinc, 249. Limonite, 96, 103. Manganese, 420. Tennessee mine, Polk Co., Tenn., 192. Tenny Cape, Nova Scotia, 422. Terrace series, 5. Terrane defined, 6. Terry Peak, S. D., 311. Tertiary system, 5. Teton Co., Mont., 321. Texas, copper ores, 204, 224. Limonite, 97, 98. Mercury, 424, 428. Tin, 444. Texas mine, chromite, 415. Texas, Penn., nickel ore, 439. Thies-Hutchins antimony mines, Nev., 411. Three Rivers, Que., bog ore, 90. Thunder Bay, Can., 284. Tilly Foster iron mine, N. Y., 166.. Tilt Cove, N. F., nickel ore, 429. Tin, concluding remarks, 445. Deposits, 69, 70. Veins. 72. Tin Cup, Colo., 294. Tintic district, Utah, copper mines, 221. Lead-silver mines, 275. Tioga Co., Penn., 121. Titaniferous magnetite, 160, 165. In the Adirondacks, 171. In Canada, 172. Colorado, 174. Minnesota, 174. New Jersey, 173. North Carolina, 174. * Norway, 173. Sweden, 172. Virginia, 171. Wyoming, 171. Titanium in iron ores, 85, 86. Titcomb, H. A., cited, 352. Tombstone, Ariz., 43, 336. Torrington, Conn., nickel ores, 430. Tower, G. W. , on Butte copper ores, 197. Tower, Mich., 85. Toyabe Range, Nev., 339. Trail Creek district, B. C, 394. Trail of a fault, 23. Treadwell mine, Alaska, 390. Trenton series and stage, 4. Triassic system, 5. Trigg Co., Ky., 95. Trotter zinc mine, N. J., 252. Tucson, Ariz., 336. Tuolumne Co., Cal., 363. Turner, H. W., California gold gravels, 359. Tuscaloosa stage, 5. Tuscarora district, Nev. , 340. Tybo, Nev., 338. Tyrrell, on Alaska gold gravels, 393. Tyson, I., Jr., on chromite market. 414. U Ueberroth zinc mine, Penn., 250. Uintah Mt., Utah, 325. Uinta stage, 5. Ulster Co., N. Y., lead deposits, 229. Limonites, 111. United States Antimony Co., Phila.. 411. United States, geological review of the, 8-10. Topography of the, 7, 8. Magnetite sands, 181. United Verde copper mine, Ariz., 220. Utah, antimony, 411. Copper, 224. Geology, ,328. Gold and silver, 329. Limonite, 100. Mercury, 424. Silver-bearing sandstone, 68. Utica stage, 4. Vadose circulation, 27. Vanadium distribution, 36. Van Diest, P. H., on Boulder Co., Colo., 306. Van Dyck, F. C, analysis by, 254. Van Hise, C. R., cited, 44. On classification of Michigan ores, 133. On joints, 14. On Marquette district, 129. On Penokee district, 139. On zones of fracture, 25. Van Wagenen, T. F., cited, 53. Veins, changes in filling, 50. Methods of filling, 39. Swells, 49. Vermilion district, Minn., 134. Lake, iron mines, 144-146. Vermont chromite, 416. Gold, 383. Iron, 184. Lead, 227. Limonite, 100. Manganese, 418. Vershire, Vt., copper ore, 184, 190 480 INDEX. Verticals in gold mines, Black Hills, 312. Vicksburg stage, 5. Victor mines, Colo. , 385. Virginia, Clinton ore, 114, 116. Gold deposits, 381. Lead and zinc, 347. Liraonite or brown hematite, 87- 114. Magnetite, 169. Manganese, 418. Virginia City, Mont., 316. Vivianite in bog ore, 89. Vogelsberg, Germany, aluminum, 407. Vogt. J. H. L. , on chromite, 413. On ore deposits, 61-65. On nickel ores, 434. On sulphides of iron, 185. Vuggs of a vein, 48. W Wabner, R., cited, 55. Wadsworth, M. E., on iron ores, 127, 135. On classification of ores, 458 On copper ores, Keweenaw, 205. On Marquette district, 128. On origin of copper ores, 211. Wahnapitae Lake nickel mines. Can., 436. Walcott, C. D., on fossils of Montana, 315. Walker, T. L. , on nickel ore, 437. Wallingford, Vt. , manganese ore, 418. Wardner. Idaho, lead -silver mines, 274. War Eagle mine, B. C, 397. Wasatch Mt., Mont., 314. Utah, 180, 274. Wasatch stage, 5. Washington Co., Mo., lead and zinc mines, 239. Washington copper deposits, 322. Geology, 346. Silver, 347. Washoe Co., Nev., gold and silver mines, 340. Water, underground, 26-33. Waukon, Iowa, limonite, 98. Wawa Lake gold deposits, 385. Wayne Co., N. Y., Clinton ore, 115. Waynesburg coal seam, 107. Webster, N. C, nickel, 439. Weed, W. H., on copper deposits, 197. On gold deposits, Montana, 315. On sinters, 68. On vein formation, 38. Weissenbach, von, cited, 47, Weissenbach, von, on scheme of classification of ore, 448. Wells, Professor, cited, 441. Wendt, A., mineral veins, 51. Werner, cited on his epoch, 55. Westport, N. Y., magnetite, 172. Weston mine, N. Y., 162. West Stockbridge, Mass., limonite, 101. West Virginia, Clinton ore, 114. Limonite, 107. Red hematite, 121. Wet Mt. Valley, Colo., 296. Wheatfield mine, Penn., 179. Wheatley lead mine, Penn., 227, White Oak gold district, N. M., 385. White Pine Co., Nev., 338. White River stage, 5. White Quail mine, Colo., 267. Whitney, J. D., on California grav- els, 356. On origin Michigan iron ore, 135. On Missouri ores, 158. On lead ores, 236-42. On Mother lode, CaUfornia, 364. On scheme of classification of ores, 453. On Seaweed, 68. Wickes, Mont. , lead-silver mines, 373. Williams. G. H., cited, 138. On chromite, 415. On manganese, 430. WilKs, B., cited, 178. Willow Creek, Idaho, 325. Wiltsee, E. , on Half Moon mine, Nev. 338. Winchell, H. V., on Rainy Lake dis- trict, 384. Winchell, N. H., and H. V, on Pen- okee iron ore, 150. Wind River stage. 5. Winslow, A., Missouri lead and zino mines, 230-244. On Tin, 444. Winston, Mont., 319. Wisconsin, Clinton ore, 114. Lead and zinc mines, 68, 233. Wisconsin Island, 9. Wolff, J. E., on Hibernia magnetite, 168. On New Jersey zinc deposits, 252. Woodman, J. E., Nova Scotia gold, 399. Wood River mines, Idaho, lead-silver, 273, 327. Woods mine, chromite, 414. Woodworth, J. B., on joints, 15. Worthington nickel mine, 436. Wyoming, copper mines, 223. Geology of, 308. INDEX. 481 Wyoming iron mines, 171. Tin ores, 443. Wythe Co., Va., zinc, 247, 248. Yak River, Mont., 323. Yakima Co., Wash., placer mines, 347. /akutat Bay, Alaska, gold sands, 349. Yavapai Co., Ariz., gold, silver ores, 335. Yellow Jacket mines, Idaho, 324. Yogo Gulch, Mont., aluminmn, 410. York Co., N. B., antimony, 411. York Co., Penn., iron ores, 101, 179. Yukon Basin, Alaska, 393. Yukon silts, 389. Yuma Co., Ariz., 335-337, Z Zinc minerals, 250. Analyses, 254. Statistics, 259. Zone of fracture in the earth, 25. Of oxidized ores, 50-52. I I OF INTEREST TO ••»BOOK=BUYERS*«* OUR NEW I TECHNICAL CATALOGUE WILL RENDER YOU MATERIAL i* ASSISTANCE IN THE FORMATION J OF AN INDUSTRIAL AKD MIS- ^ CELLANEOUS LIBRARY, AS IT J GIVES ONLY THE BEST BOOKS IN ^ EVERY DIVISION OF SCIENCE AND ^ INDUSTRY. WE CAN KEEP YOU IN ■^ TOUCH WITH THE TIMES. 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