OP THK EAR7W "f- C C v-/ , receipt of this volume.) GEOLOGICAL SURVEY OF MISSOURI ri RAPHAEL PUMPELLY, DIRECTOR PRELIMINARY REPORT ON THE IRON ORES AND COAL FIELDS FROM THE FIELD WORK OF 1872 With 190 Illustrations in the Text and an Atlas PRINTED BY AUTHORITY OF THE LEGISLATURE OF MISSOURI UNDER THE DIRECTION OF THE BUREAU OF GEOLOGY AND MINES. NEW YORK JULIUS BIEN 1873- EARTH SCIENCES LIBRARY TABLE OF ERRATA. I., p. 40, 41, for Mr. Otto Worth, read Mr. Otto Wuth. I., p. 122, for Big Bogg Mountain, read Big Bogy Mountain. I., p. 125, 154, 157, 160, 165, 167, 174, 183, for Chapter V., read Chapter VI. I., p. 179, for Chapter IV., read Chapter VI. I., p. 160, for Chapter IV., read Chapter V. OFFICE OF THE GEOLOGICAL SURVEY, ST. Louis, April, 1873. To the President and Members of the Bureau of Geology and Mines. GENTLEMEN : I have the honor to transmit to you herewith reports of the work of the Geological Survey during the season of 1872. Entering upon the duties of Chief Geologist in the Spring of that year, the larger portion of my time had necessarily to be devoted to the organization of field and office corps, to the pre- paration of the plans of the survey and its administrative work. But little opportunity was left me, during the brief tenure of my office, to engage in scientific investigations, and the ill-health which compelled me to tender to you my resignation, has also prevented me from making those final observations in the field, requisite to a report on the general Geology, and more especially on the Iron Deposits, of the Porphyry region of the State. I have, therefore, been obliged to limit my remarks on that District to a somewhat fragmentary discussion of the questions involved, leaving untouched many important points for want of a few connecting facts. I have the honor to be, Gentlemen, Your obedient servant, RAPHAEL PUMPELLY, Director Geological Survey. GEOLOGICAL SURVEY OF MISSOURI. IN 1849, a Memorial was presented to the i5th General Assembly, signed by Falkland H. Martin, Sol, D. Caruthers, Saml. T. Glover, W. G. Minor and De Witt C. Ballou, setting forth the advantages to be derived from a geological survey of the State, and urging liberal appropriations therefor. In their Memorial they stated in detail, what should be required in connection with such a survey, making it incumbent to show, by descriptions and maps, all the various features of surface-configuration ; to investigate the causes affecting health ; the agricultural capacity of the various soils ; to describe the water-courses and water-powers ; to analyze the waters of the springs and to -give full descriptions of the rock-formations and analyses of minerals. But it was not until the session of 1852-53 that a " Geological Survey " was really inaugurated. On April 12, 1853, Prof. G. C. Swallow was appointed "State Geologist," and began work in May. The First Annual Report of Progress (4 pages) and the Second Annual Report (in two parts, respectively 207 pages and 239 pages) were published together in one volume in 1854. The Third Annual Report of Progress (6 pages) was printed in 1857; the Fourth (14 pages) in 1859; and the Fifth (19 pages) in 1861. The Second Annual Report contains a preliminary discussion of the general geology of the State ; reports on five counties St. Louis, Franklin, Moniteau, Cooper and Marion ; and a report on the then more important mineral resources. The other annual re- ports are statements of progress. During the period which intervened between the publication of viii PREFACE. the Second Report and the stopping of the Survey in 1861, a large portion of the State had been visited by members of the corps, and full reports were written on the following counties : Cape Girar- deau, Perry, St. Genevieve, Jefferson, Crawford, Phelps, Pulaski, Laclede, Wright, Ozark (including Douglas), Clark, Morgan, Miller, Saline, Chariton, Macon, Randolph, Shelby, Osage and Maries. The gentlemen connected with the Survey under Prof. Swallow, from its beginning to the suspension in 1861, were, Dr. A. Litton, 1853-1861 ; Dr. J. G. Norwood, 1858-1861; F. B. Meek, 1855; Dr. B. F. Shumard, 1853-1858; G. C. Broadhead, 1857-1861; Henry Engelman, 1857; Edwin Harrison, 1858; Dr. John Locke, 1860; C. G. Wheeler, 1860; P. C. Swallow, 1857-1861 ; F. Hawn, 1854; W. Hough, 1857; R. B. Price, draftsman, 1853-1858; H. A. Ulffers, draftsman, 1854 and 1860. After the Survey had been discontinued, the Legislature author- ized L. D. Morse and G. C. Swallow to publish all the results of the work of the previous seven years ; but the project was aban- doned on account of the expense. In 1870 the Legislature passed an act organizing a Mining Bureau, to be composed of the Governor and nine members, one from each congressional district. Upon this Board was conferred the power of appointing the geologist. Under that law Albert D. Hagerwas appointed State Geologist, and held the position until the end of August, 1871. Mr. Hager published one Report of Progress. The law was amended March 18, 1871, and the Board made to consist of four members besides the Governor. Dr. Norwood re- mained temporarily in charge of Survey from September I, 1871, until my appointment in November, 1871. Under Dr. Norwood, G. C. Broadhead was appointed assistant, and C. M. Litton sub- assistant. I was appointed State Geologist on the 25th November, 1871. The law concerning the Survey at that time was as follows : AN ACT to provide for a " Bureau of Geology and Mines," to complete the Geological Survey of the State of Missouri. Be it enacted by the General Assembly of the State of Missouri, as follows : SECTION i . There is hereby created and established a Bureau of Geology and Mines for the State of Missouri, which shall be under the direction and in charge of a board of managers, which shall consist of the Governor, who shall be presi- PREFACE. ix dent of the board, and four citizens from the State at large, who shall be ap- pointed by the Governor, shall hold their office for the term of two years, and until their successors are appointed and qualified. SEC. 2. As soon as the board of managers is organized, as provided in the preceding section, the present State Geologist may appoint, subject to the ap- proval of the board of managers, one assistant paleontologist and geologist and one assistant chemist, to assist him in the discharge of his duties ; and said State Geologist may employ such subordinates and laborers as may be deemed neces- sary by the board; provided, the whole expenditure of the board shall not exceed the sum hereinafter appropriated. SEC. 3. It shall be the duty of the State Geologist and his assistants, under the instructions and directions of the board of managers, to carry on and com- plete the geological survey of the State already begun, with a view to determine the order, succession, arrangement, relation, position, dip or inclination and comparative magnitude of the several strata or geological formations within this State, and to discover and examine all beds or deposits of ore, coal, marls, and such other mineral substances and mineral waters as may be useful or valuable, make full and complete examinations, assays and analyses of such rocks, clays, marls, ores, and other substances as may indicate useful results, and to perform such other duties as may be necessary to make a full and complete geological and mineralogical survey of the State. SEC. 4. It shall be the duty of the State Geologist to make, or cause to be made, a detailed report of -each county, as soon as the survey thereof shall be completed ; each county report shall be accompanied by an accurate map and section of the county, on which shall be represented, by colors and other appro- priate means, the various areas occupied by the prairie, timber, and bottom lands, and by the different geological formations in the State, and to mark thereon the localities of the respective beds or deposits of the various mineral substances discovered ; and on the completion of the survey of the State he shall make a complete report of the geology and mineralogy of each county, compris- ing a full account of the discoveries made ; and each of such reports shall be delivered to the board of managers as soon as completed. SEC. 5. It shall be the duty of the State Geologist to collect, in triplicate, all rocks, ores, coals, fossils, and such other mineral substances discovered as may be necessary to form a complete cabinet collection of the geology and mineralogy of the State. SEC. 6. It shall be the duty of the board of managers to report to the General Assembly, on the first week of each session, the progress and condition of the survey, a detailed account of all moneys spent, and all such reports of the State Geologist and his assistants as have been completed, together with all such information as may be deemed necessary and useful. SEC. 7. It shall be the duty of said board to collect and take possession of all materials accumulated by the previous surveys, whether reports, maps, sections, collections, instruments or other property belonging to the State ; and all per- x PREFACE. sons now in possession of the same shall deliver them up to the order of the president of the board of managers. SEC. 8. It shall be the duty of the board to determine, as far as may be, what work has been done by each one employed in previous surveys, the character of the work done by each, the condition of such work, how much of the State has been actually surveyed, and how much of said work may be made available in completing the survey of the State, and embody the same in their first report to the General Assembly. SEC. 9. The board may make such by-laws and regulations for the govern- ment and control of its own meetings, and the labors of the State Geologist and his assistants, as may be deemed necessary ; it may appoint officers and com- mittees to audit and allow accounts and look after particular departments of the work, and discharge such other duties as may be necessary to carry on the objects of this bureau. SEC. 10. As a full compensation for the members of the board of managers, they shall be allowed their necessary expenses while attending to the duties assigned them by this act. The board shall fix the salaries of the State Geolo- gist, not to exceed three thousand dollars, and his assistants, which shall not exceed two thousand dollars per annum of actual service, and of all others em- ployed in the work of the survey. SEC. 1 1. All accounts for salaries and expenses shall be made under oath, and certified by the board and filed with the Auditor of the State, and the pay of the State Geologist and his assistants shall be made out of the appropriation made for civil officers of the State. SEC. 12. The sum of five thousand dollars is hereby annually appropriated out of any money in the treasury not otherwise appropriated, to defray the inci- dental expenses of the bureau created by this act, and the geological survey, and no more than this amount shall be thus expended in any one year. SEC. 13. The board of managers shall have the general management of the survey, and have full power to remove the State Geologist or any of his assist- ants and appoint their successors when deemed necessary for the good of the work entrusted to them. SEC. 14. It shall be the duty of the board to cause the geological collections made previous to the year 1870, to be distributed in accordance with the laws under which those collections were made, except the one collected for the State Capitol, which shall be given to the School of Mines and Metallurgy ; and all subsequent collections made in triplicate shall be given, one suit to the State University, one to the State School of Mines and Metallurgy, and one to the city of St. Louis, which shall be deposited by the authorities of that city in some institution for the advancement of science or general education. SEC. 1 5. The president of the board shall, from time to time, certify to the State Auditor the sums of money required to pay the salaries of the State Geolo- gist and his assistants, and for the incidental expenses of the bureau ; and on receiving such certificates, the Auditor of State shall draw his warrant on the Treasurer of the State for the requisite amounts in favor of the parties and per- PREFACE. xi sons entitled to receive the same, and shall charge the several sums so paid to the account of the proper appropriation. SEC. 1 6. The entire expenses of carrying out the provisions of this act shall not exceed, in any year, the sum often thousand ($10,000) dollars. SEC. 17. The State Geologist and his assistant, before entering upon the dis- charge of their duties, shall each take an oath before some officer of this State qualified to administer oaths, that they will honestly, faithfully, and fairly per- form all the duties required of them by this act, to the best of their ability, and that they will not permit any person to have access to any of their books or papers, or communicate their contents to any person or persons, and that they will not disclose or make public any mine or valuable deposit, other than in their official reports (except to the owner or owners of the land surveyed), and that they will abstain from all speculations in their own behalf, or in the behalf of others, during the progress of such survey and in relation thereto. SEC. 1 8. An act entitled an act to establish a Mining, Metallurgical, and Geological Bureau for the State of Missouri, and to provide for its support and management, and to authorize a geological survey, approved March 24, 1870, and all other acts and parts of acts inconsistent with this act, are hereby repealed. SEC. 19. This act shall take effect and be in force from and after its passage. Approved March 18, 1871. At the end of March, 1872, this act was amended in the follow- ing manner : AN ACT to amend Sees. 2, 11, and 12 of an act entitled An Act to provide for a Bureau of Geology and Mines, to complete the Geological Survey of the State of Missouri, and to repeal Sec. 16 of said Act. SECTION r. Sec. 2 of said act is hereby amended so as to read as follows : Sec. 2. The board of managers are authorized to appoint one State Geologist, and, upon the nomination by the State Geologist (which nomination shall be made within sixty days after his appointment), one assistant palaeontologist and geologist, one analytic chemist and one assistant chemist : and said geologist may employ such additional subordinates and laborers as may be deemed ne- cessary by the board. SEC. 2. Sec. ii is hereby amended so as to read as follows : Sec. n. All accounts for salaries and expenses shall be made under oath, and certified by the board and filed with the Auditor of State. SEC. 3. Sec. 12 is hereby amended so as to read as follows : Sec 12. The sum of 20,000 dollars is hereby appropriated annually out of any money in the treasury not otherwise appropriated, to pay the salaries and incidental ex- penses of the bureau created by this act, and of the Geological Survey ; and the expenditure in connection with the same shall not in any event exceed the appropriation herein designated and set apart for that purpose. SEC. 4. Sec. 16 is hereby repealed. xii PREFACE. SEC. 5. This act shall take effect and be in force from and after its passage. The organization of the Survey was as follows : Board of Managers, Governor B. GRATZ BROWN, ex-officio President, 1872. Governor SlLAS WOODSON, ex-officio President, 1873. MR. EDWIN HARRISON, MR. FORREST SHEPHERD, PROF. SYLVESTER WATERHOUSE, GEN. J. H. HAMMOND. The two last-named gentlemen resigned during the summer, and their places were filled by HON. A. W. MEYERS, HON. L. A. BROWN. Mr. A. A. BLAIR was appointed as Secretary of the Board. State Geologist, RAPHAEL PUMPELLY. Assistants, MR. G. C. BROADHEAD, DR. ADOLF SCHMIDT. MR. REGIS CHAUVENET, Chemist. MR. W. E. GUY, PROF. W. B. POTTER, MR. C. J. NORWOOD, MR. J. R. GAGE, MR. ALEXANDER LEONHARD. At different times during the year the following gentlemen were employed : J. Pumpelly, in charge of the triangulation in Iron Coun- ty ; P. N. Moore, in magnetic observations; F. Tunica, topographer; C. Gayler and B. Vitzthum v. Eckstadt, draftsmen. W. Bartlett, T. J. Caldwell, T. A. Minor, A. J. Pills, A. Hoeber, M. F. Healy. Considering the fact, that Missouri presents both considerable diversity in regard to its rock-formations, and a wide range of ex- tensively developed mineral resources, it appeared desirable to organize the new Survey in such a manner, that, while the general and stratigraphical geology of the State should be studied by com- petent geologists, the study of the distribution and manner of occurrence of the various important mineral resources should be entrusted to two or three departments, in charge, respectively, of men whose previous experience should prove them to be specially adapted to this difficult work. ' PREFACE. xiii Conformably with this plan, the survey of the general and strati- graphical geology was divided into five departments, viz. : Survey of the North-west. South-west. " North-east. South-east. Porphyry region of the South-east. That portion of the survey relating to Economic Geology was divided into three departments, viz.: Department of Iron-Ores and Iron-Metallurgy. " Ores other than Iron. " Fuels and Construction Materials other than Iron and Wood. During the past year Mr. Broadhead, assisted by Mr. Norwood, has studied the general geology of the north-west. In the north-east, Prof. Potter, assisted by Mr. Leonhard, sur- veyed Lincoln County. In the porphyry region of the south-east, I began work in May, assisted by Mr. Gage and Mr. Guy. In July, the Pilot Knob Iron Company requested the Geological Survey to make, at the expense of the company, an examination and a topographical map of their lands, which occupy a large part of four townships. As these townships contain the key to the geology of the porphyry district, the offer of the company was accepted. At the end of the season, a considerable portion of the district had been surveyed, and a map of Pilot Knob and vicinity (Plate I. of the Atlas), embracing about twenty-four square miles, had been drawn. In the department of Economic Geology, Dr. Schmidt was en- gaged in studying the distribution and mode of occurrence of the iron-ores, and the condition and experience of the iron-metallurgy of the State. Dr. Schmidt was appointed to this important position because of his extensive experience, obtained first as director of iron-works in Europe, and afterward when in charge, during several years, of the scientific department of an extensive Bessemer steel establishment. In the department of Economic Geology, important work has also been accomplished in the analyses of coals by Mr. Chauvenet, and of iron-ores by Mr. A. A. Blair, and by Dr. Wendel, of Troy. xiv PREFACE. During 1873, in the department of Economic Geology, especial attention will be given to the study of the distribution and modes of occurrence of lead, zinc, nickel and other ores, while the study of the iron-ore deposits will be extended beyond the fields of last season's work. It is intended to begin a systematic study of the building ma- terials of the State, as soon as a sufficiently large amount of material shall have accumulated to justify the employment of a specially qualified assistant, and the establishment of a laboratory for the experimental tests. In this connection, the report of Prof. Smith (Appendix A), on the methods and results of the extended series of tests made by the St. Louis Bridge Company, will be of interest. It was considered desirable to publish the results of the work of the Survey of 1872, and the hitherto unpublished results of the former Surveys, in separate volumes. After hearing an able speech by General Rozier favoring the bill, the Legislature passed an act appropriating $3,000 for printing the reports of B. F. Shumard, F. B. Meek, and G. C. Broadhead, made to Prof. Swallow previous to 1861, and $9,000 for printing the report on work done in 1872. The printing of the first-mentioned work was undertaken by Messrs. Regan & Carter, State Printers, at Jefferson City ; but it was found that the large number of maps and illustrations in the text accompanying the report of 1872, rendered it impossible to have the work done for $9,000 by any western house. A contract was finally made with Mr. Julius Bien, of New York, whose exten- sive facilities for the use of photo-lithographic and photo-relief pro- cesses enabled him to undertake the work. In justice to Mr. Bien, it should be added that he has exceeded the requirements of the specifications in several of the most costly items. R. P. CONTENTS. PART I. PAGE CHAP. I. Notes on the Geology of Pilot Knob and its Vicinity. By Raphael Pumpelly 5 CHAP. II. Analyses of Fuels, etc. By Regis Chauvenet 31 Analyses of Iron-Ores and Pig-irons. By A. A. Blair 39 CHAP. III. The Iron-Ores of Missouri. A. General Distribution. By Adolf Schmidt, Ph.D 45 CHAP. IV. The Iron-Ores of Missouri. B. General Description. By Adolf Schmidt, Ph. D 50 CHAP. V. The Iron-Ores of Missouri. C. Modes of Occurrence and De- scription of Deposits. By Adolf Schmidt, Ph.D 93 a) Deposits of Specular Ore in Porphyry. b) Deposits of Specular Ore in Sandstone. c) Disturbed Deposits of Specular Ore. d) Drifted Deposits of Specular Ore. e) Beds of Red Hematite. f) Disturbed or Drifted Deposits of Red Hematite. g) Deposits of Limonite on Limestone. h) Disturbed or Drifted Deposits of Limonite. CHAP. VI. The Iron-Ores of Missouri. D. List of Deposits of Iron-Ore in Missouri. By Adolf Schmidt, Ph.D 193 PART II. CHAP. I. Area and Topographical Features of the Coal-Field. By G. C. Broadhead 5 CHAP. II. Lower Coal-Measures. By G. C. Broadhead 1 1 CHAP. III. Middle Coal-Measures. By G. C. Broadhead 45 CHAP. IV. Upper Coal-Measures. By G.. C. Broadhead 88 CHAP. V. Economic Geology of the Coal-Measures. By G. C. Broadhead 135 CHAP. VI. Geological Report on the Country Adjacent to the Pacific Railroad, from Sedalia to Kansas City. By G. C. Broadhead 157 CHAP. VII. Geology of Lincoln County. General Geology. By W. B. Potter, 217 xvi Contents. PAGE CHAP. VIII. Geology of Lincoln County. Economic Geology. By W. B. Potter 263 CHAP. IX. Geology of Livingston County. By G. C. Broadhead 290 CHAP. X. Geology of Clay County. By G. C. Broadhead 317 CHAP. XL Geology of Platte County. By G. C. Broadhead 327 CHAP. XII. Geology of Buchanan County. By G. C. Broadhead 344 CHAP. XIII. Geology of Holt County. By G. C. Broadhead 359 CHAP. XIV. Geology of Atchison County. By G. C. Broadhead 376 CHAP. XV. Geology of Nodaway County. By G. C. Broadhead 388 APPENDIX A. Report on the Strength of Building Materials. By C. A. Smith 403 APPENDIX B. Notes on such Rocks of Missouri as admit of a fine polish. By G. C. Broadhead. . . 414 APPENDIX C. List of Fossils from the Coal-Measures. By C. J. Norwood 416 PART I GEOLOGY OF PILOT KNOB AND ITS VICINITY BY RAPHAEL PUMPELLY ANALYSES OF IRON-ORES, PIG-IRONS, AND FUELS BY REGIS CHAUVENET AND A. A. BLAIR IRON-ORES OF MISSOURI BY ADOLF SCHMIDT, PH.D. CHAPTER I. NOTES ON THE GEOLOGY OF PILOT KNOB AND ITS VICINITY. BY RAPHAEL PUMPELLY. THE region represented on the topographical map of Pilot Knob and its vicinity (PI. I., Atlas) consists of a group of four masses of porphyry, separated from each other by valleys of the lowest Silu- rian Limestone known in Iron County. The porphyry forms the entire substructure of the region.* It had been eroded into hills and valleys before the deposition of the limestones. By reference to the map it will be seen that the limestone does not often rise above the 2OO-foot contour-line. But in places, as in the north-west extension of Cedar Hill, we find a heavy deposit of clay, with chert and mammellated quartz (" mineral blossom") and sandstone lying over the limestone and rising to the 35O-foot line. This level (350 feet above the datum of the map) is about the normal height for these clay and chert terraces through this portion of the country ; but they have generally, within the area of this map, been removed by erosion, except where they remain in place as terraces and patches on the slopes of the hills. The porphyries are older than the Silurian, and belong to the Archaean (Azoic) formation, of which they may be the youngest member in Missouri. They are the near equivalents in point of age of the great iron-bearing rocks of Lake Superior, New Jersey, and Sweden. They are stratified on an immense scale, but owing * No granitic rocks occur within the area of the map ; but a few miles to the eastward there is an extensive development of granite, apparently chiefly chloritic and syenitic, in Madison County. The few observations, bearing on the question of relative age, made by both Dr. Norwood and myself, should seem to indicate that the granitic rocks are older than the porphyries. In the north-western part of Madison County several granite hills are capped with porphyry. The red granites may be an exception to this, supposed, rule. The fact that the granites contain numerous dykes of hornblendic rocks, while none are known to occur in the porphyries, may go toward proving the greater age of the granite. 4 GEOLOGY OF PILOT KNOB AND VICINITY. to the rarity of interstratified beds of other rocks, the unravelling of the internal structure of the district is a difficult problem. On Pilot Knob the strike of the formation is S. 50 E. from the true meridian, and throughout the southern half of the map the strike may be generally assumed to vary between S. 40 E. and S. 60 E., and the dip of the strata to be to the south-west. While all the porphyries of Iron County probably contain a greater or less percentage of free silica, this is not always visible to the naked eye, nor do all the varieties exhibit the feldspars in dis- tinct crystals. While it would be difficult to make an absolute classification cov- ering all the transitional forms, we can recognize (within the area of Map, PI. I.) three very distinct varieties characterized by external features. a. Porphyry with few or no Crystals. Gray, pink, flesh-color, and brown are common colors in this variety ; the rock is compact, very hard, striking fire abundantly with the steel, and breaking with a conchoidal fracture. It frequently contains grains of smoky or limpid quartz, and sometimes very isolated minute crystals of either pink or white feldspar, the latter generally striated and ap- parently oligoclase ; the rock is frequently banded in very thin lay- ers, and may be very massive or have a columnar or tabular struc- ture. It weathers through pink to a dirty yellow or white. b. Porphyry containing Crystals of Feldspar without Grains of Quartz. The usual colors are light and dark brown and purple, more rarely black, gray, and pink ; the matrix is very compact and tough, breaks with a conchoidal fracture, strikes fire with the steel, and is often banded. Its distinguishing characteristics are the absence of quartz in grains, and the abundance of crystals, one-sixth to one-fourth inch long, of white or pink feldspar, which is gene- rally triclinic. Although quartz is not present in the form of grains, it sometimes predominates in the alternate layers of the banded varieties. c. Porphyry abounding in Grains of Quartz and Crystals of Feldspar. The matrix of this variety varies in color from purplish gray to dark purple or black, and the feldspar crystals are usually white and triclinic. Feldspar and quartz appear to be the only primary constituents in any of the porphyries of this region. But there are several PORPHYRIES AND DOLOMITES. 5 accessory minerals which occur frequently, and are evidently secon- dary products. The most common among these is epidote, and a soft, greenish substance resembling steatite, apparently an alteration product of the epidote. A chlorite-like mineral occurs frequently in the first stages of weathering, both impregnated in the matrix and traversing the feldspar-crystals. Magnetite and specular iron-ore occur in minute impregnations, sometimes imparting a decided po- larity to the fragments of the rock. Fluorite, of a beautiful ame- thystine color, is found, not unfrequently, in small cavities and seams. The Silurian rocks of the district are probably the Third Mag- nesian Limestone of Swallow, with, in places, remains of the Second Sandstone capping it. At the contact of this series with the porphyries there are very generally beds of calcareous sandstone and conglomerate. These limestones are dolomites, in which the process of dolomi- zation has in many places run its course to completion. The beds are generally from a few inches to six or eight feet thick. The thinner beds contain 10 per cent, to 20 per cent, of impurity, in the form of clay, and sometimes of chlorite, which gives a greenish tinge, often mistaken for a copper mineral. These thinner beds are also often pyritiferous. The more compact beds often contain layers of chert, but aside from this the insoluble im- purities, in the form of clay and free silica, seem to range consider- ably below 10 per cent. These heavier layers have generally a buff tinge, and contain numerous small cavities lined with beautiful crystals of dolo- mite. Sometimes crystals of calcite and of copper pyrites and iron pyrites occur in these cavi- ties. The annexed section, and the corresponding analyses by Mr. Chauvenet, refer to the lower beds of the dolomite at Mr. Mace's quarry, Sec. 8, T. 33, R. 4, E. GEOLOGY OF PILOT KNOB AND VICINITY. ABC Silicious matter 5.11 3.85 2. 06 Iron, as peroxide ^4.67 1.07 none Carb. Lime 47-5 52.50 54.32 Carb. Magnesia 42.19 42.56 43.82 99.47 99.98 100.20 In order to compare these limestones with true dolomite, we compare the per cent, of carbonate of lime in each with that of the carbonate of magnesia, the atomic ratio being 54.35 : 45-65- The following figures show the amount of carbonate of magnesia required in each to make it equivalent to the carbonate of lime : ABC 39-89 44.09 45-^2 Bed "A," therefore, contains more magnesia than the dolomite ratio calls for ; the others somewhat less. On the same property a pyritiferous limestone, from a thin bed somewhat shaly and colored green by the presence of chlorite, was examined by prospecting shafts, some years since, by persons look- ing for nickel-ore. This rock was analyzed by Mr. Chauvenet, with the following result : Silicious matter 17.88 Iron, as peroxide 3.75 Carb. Lime 43-52 Carb. Magnesia 34-25 The annexed section (Fig. 2) is taken at the quarry near Iron Mountain, from which the furnaces derive their flux. A specimen from this quarry was analyzed by Dr. Litton, with the following result : f Residue, insoluble in dilute hydrochloric acid 6.97 Alumina, with peroxide of Iron i.n Carbonate of Lime 50. 38 Carbonate of Magnesia 41-74 * Alumina, with a little iron. f Second Annual Report of the Geol. Surv. of Missouri, Part II. p. [78. 1855. DOLOMITES. Fig. 2. 8. Stiff, dark, brown, foliaceous clay. 7. Highly-weathered dolomite. 3? ft ? T"* 6. Brown and gray dolomite, with very irreg- *jj N 6 ular cavities, lined with crystals of dolomite. 5. Very compact, hard, and fine-grained dol- \T W oj omite. f 4. Similar to No. 6, with crystals of calcite "j MAGNESIAN LIMESTONE QUARRY N. W. OF IRON MOUNTAIN. An average sample of the rock from this quarry was taken at the Iron Mountain furnace, and analyzed by Dr. Wendel, of Troy, N. Y., for Dr. Schmidt's Report on the Iron Metallurgy of the State,* with the following result : Silica 5.30 Lime 27 48 Magnesia 1 8.37 Phosphorus 0.003 Sulphur 0.09 An average sample, taken in the same manner and for the same purpose, from the quarry at Pilot Knob, was analyzed by Dr. Wendel, with the following result : Silica 3.93 Lime 29.40 Magnesia 19-27 Phosphorus O.O2 Sulphur o. 16 * To be published in the next volume. 8 GEOLOGY OF PILOT KNOB AND VICINITY. The magnesian limestone, in some of the more massive beds, con- tains many cavities, from less than an inch to several feet in diame- ter. These have very ragged outlines, as though formed by the running together of numerous smaller cavities. They are gene- rally lined with crystals of dolomite, but in many places, in certain horizons, and especially in the upper beds, the walls are covered with a continuous lining of crystalline quartz resting on concentric agate-like layers of quartz. This geode quartz is called " mineral blossom." Galena and zinc-blende also occur very extensively in this rock, in some localities disseminated through it, in others occupying gash- veins and narrow caves, and in others again forming extensive interstratified layers. Residuary Deposits. The Archaean (Azoic) rocks of south- eastern Missouri are the exposed portions of the skeleton of the eastern part of the Ozark range. They appear as knobs 1,400 to 1, 800 feet above the sea, and rising 300 to 700 or more feet above the valleys at their bases. They form an archipelago of islands in the Lower Silurian strata which surround them as a whole, and separate them from each other. These rocks, consisting, as has been already remarked, chiefly of granites and felsitic porphyries, reach their most extensive surface- development in the region forming the northern part of Madison, Iron, and Reynolds, and the southern part of St. Francis and Wash- ington Counties. The rocks overlying them belong to the oldest known members of the Silurian, and they may be the deep-sea equivalents of the Pots- dam sandstone, or even older. As has been already stated, they are true dolomites, frequently underlaid by gritstone beds, and often covered by heavy masses (50 to 1 20 feet thick) of clay and chert in loose aggregations. This region of porphyries, as well as the Ozark range, generally, through southern Missouri, has apparently been above the level of the sea from a very early period to the present time. The higher portion of the elevation does not seem to have been submerged since before the Upper Silurian period ; while broad areas on the flanks of the range have apparently been dry land since the Carbo- niferous. The absence of the finer and coarser detrital material due to glacial action, as well as of all evidence of the direct mechanical RESW UAR Y DEPOSITS. 9 action of ice, prove that the region in question remained undis- turbed by the various surface-modifying agencies of the Glacial period. The rocks of the Ozarks, thus exposed to the undisturbed action of atmospheric agencies, present to us in their present con- dition one of the most instructive records of geological history one that is full of important facts. Both the Archaean crystalline rocks and the Silurian strata have undergone immense changes in volume, and in other respects, under this long-continued influence. The gradual removal of the soluble constituents has left important residuary deposits of such substances as were insoluble, especially in the Silurian strata as clay, flint, crystallized quartz, sulphuret of iron, galena, etc. The more conspicuous instances of this kind among the pre-Silurian rocks are residuary occurrences of iron-ore. The constituents of the granitic and porphyry rocks offered a far greater resistance to the action of this process of removal than the limestone strata. Still, the amount of disintegration and of full decomposition has been very great in these older formations, although it would not be easy to say what proportion of the change has taken place since the deposition of the Lower Silurian limestones. The porphyries and granites had undergone an enor- mous amount of erosion before the limestones were formed ; an amount at least several times as great as that they have suffered since that remote time. In the porphyries as well as in the granitic rocks of the region we find the destructive action developed in two marked directions, respectively the resultants of influences due to local external causes, and to the structure, texture, and mineral composition of the rocks. These directions are (a) The forming of polygonal blocks on the surface, and the gradual disintegration and decomposition of these in place and on the talus. This is the case with most of the porphyry exposures. A layer of 3 to 4 feet of this detritus covers the residuary clay- deposit of the Silurian limestone on the west flank of Pilot Knob ; it lies on a slope of 1 1. On the ridge of red granite at Ex-Governor Brown's quarry, the polygonal blocks are of great size, and their surface-disintegration in place has left picturesque, rounded masses hundreds of tons in weight. 10 GEOLOGY OF PILOT KNOB AND VICINITY. (b} Disintegration and decomposition in mass. This, among the porphyries, is best illustrated in Iron Mountain, where the entire porphyry-hill is changed to a clay. It is well shown, also, in Madison County, among the gray and green (chloritic) granites, where, over considerable areas, complete disintegration has taken place to a depth of certainly more than 50 feet, and possibly several times that depth. The formation of residuary deposits of iron-ore, having their origin in the gradual removal of very resisting crystalline rocks, is one of the local results of this weathering away and decomposition of the rock, and is well illustrated in the "surface-ore" at Iron Mountain. This hill, which rises about 250 feet above its base, is wholly covered by a mantle of ore-detritus, associated with some clay. The only knowledge we possess of its internal structure is gathered from Fig- 3- SECTION " I - IRON MOUNTAIN- the mining excavations at and near the summit and on the spur called Little Iron Mountain. The appearances in these indicate deposits of the most irregular form, and which should seem, from the results RESIDUARY DEPOSITS. II of magnetic observations, to lie in zones extending north-north- east. In all the excavations the porphyry is decomposed, generally to a clay. At the summit an immense mass of solid ore is exposed, while the decomposed porphyry adjoining this is traversed in all direc- tions by veins of all sizes and of the most irregular shapes, form- ing a reticulated network of ore and rock. The foregoing figure (Fig. 3), from a sketch by Mr. Guy, represents the exposed face of one of the great excavations. The shaded portion on the right is a part of the great ore-mass, about 50 feet high. D P is the decom- posed porphyry. One of the numerous " faults " is also shown in the sketch. Similar irregular veins and masses of ore exist in Little Iron Mountain. A remarkable dyke is exposed here, which traverses a vein of ore, and has all the appearance of resulting from the decom- position of an independent porphyry-dyke ; but in its prolongation it is seen to carry in its middle plane a vein of comby quartz. Fig. 4. UlTTuE IRON MOONTAI N A, DYKE PORPH. 8 . DE CO M P. PO R P H, C.IRON ORE The smaller seams and veins of Iron Mountain frequently contain crystals of apatite, which seems to be a more rare occurrence in the larger ore-bodies. In the surface-ore, and in the veins near the surface, the apatite has been removed, leaving the impressions only of the crystals ; and these honey-comb cavities are frequently lined with delicate quartz-prisms. .This accounts for the greater freedom of the surface-ore from phosphorus, as is shown in the com- parative analyses. That the ore-seams existed before the decomposition of the en- 12 GEOLOGY OF PILOT KNOB AND VICINITY. closing rock, is shown by the existence of similar occurrences of ore, on a smaller scale, in many of the hills of unaltered porphyry. The surface of Iron Mountain, when discovered, was covered with a layer from four to twenty, or more, feet thick, of bowlders of pure ore, associated with ore-pebbles and ore-sand, and but little clay. The ore-detritus represents all the varieties of structure, texture, and mineral associates peculiar to the different forms of ore-masses, veins, and seams of the mountain. As the volume of the ore-veins represents but a small percent- age of the volume of the hill, the amount of the decomposed por- phyry that has been wholly removed to cause such an accumulation of ore, from broken-up veins, must have been proportionately great. But the present mantle of ore-detritus represents only a portion of the concentration caused by the removal of porphyry, for the ex- cavations at the base of the hill show heavy stratified deposits of de- trital ore, having exactly the same origin, and which was washed down the slope and concentrated by the waves of the Silurian ocean. While the present ore-mantle represents a concentrating process which has been in operation since the deposition of the Lower Silu- rian limestone, the bedded ore-detritus shows that the process was active before that time, and inferentially that the porphyry was even then wholly decomposed to a considerable depth. The instance of Iron Mountain is an extreme case, where the de- composition of the porphyry in mass facilitated the separation of the ore from the rock and the mechanical removal of the latter. There are very many points where sand and bowlders of the finest iron-ore occur on the surface, to a considerable extent. In most instances of this kind these fragments were originally isolated impregnations, segregations, or the filling of small gashes in the rock, and are the residue of a large amount of disintegrated porphyry. In the Silurian limestone of this region, as of the Ozark range generally, the formation of residuary deposits has attained an ex- tensive development. The long-continued wastage of strata, con- sisting of dolomite containing a considerable amount of insoluble substances in the form of clay, both diffused and in shaly layers, and of silica in chert-layers and nodules and quartz-geodes, has left its record in heavy masses of residuary material which cap many of PILOT KNOB. 13 the dolomite hills, and, in the porphyry region, form terraces upon the flanks of the knobs of older rocks. On the west flank of Pilot Knob a shaft was sunk, to a depth of about 70 feet, wholly in a residuary mass of clay containing frag- ments of chert, geodes of quartz, and masses of brown hematite pseudomorphous after pyrites. On the tops of many of the flat dolomite hills there are immense quantities of mammellated crystalline quartz which originally formed the lining of the intricate geode cavities of the dolomite, and which is known as " mineral blossom," from its very general association with lead and zinc ores. There are numerous deposits of iron-ores on the flanks of the Ozarks, which owe their origin to this process of residuary concentration, and which are very uncertain as regards extent. In many places these beds of loose quartz-geodes are asso- ciated with extensive accumulations of limonite, which is, at least to a large extent, pseudomorphous after pyrite. Again, over areas of hundreds, or even thousands, of square miles, this "mineral blossom " has workable accumulations of galena and carbonate of lead for its associates in the residuary clay deposits.* Pilot Knob. Pilot Knob is a conical hill, nearly circular, with a north and south diameter, at the base, of about one mile. Its top is 662 feet above the datum of the map; 1,112 feet above the St. Louis directrix ; 1,521 feet above tide. On its eastern side it is connected with another group of por- phyry-hills, by a neck a little more than 200 feet higher than the western base. The rock skeleton of Pilot Knob is composed chiefly of more or less massively-bedded porphyries, porphyry conglomerates, and beds of hard, specular iron-ore. All these strata are somewhat tilted up ; their strike is N. 50 W. ; S. 5 E. from the true meridian, and their inclination is S. W. by S. In the eastern cut, near the summit, the inclination or dip is 21. In the lower or westernmost cut it is 14 . By levelling between the points along the line of the greatest dip, I find the mean inclination of the ore-bed to be 13, and shall as- sume this for the whole hill. * Prof. Whitney was, I believe, the first to call attention to the occurrence of residuary de- posits of clay, in explaining the origin of the red clays of the upper Mississippi lead-region. 14 GEOLOGY OF PILOT KNOB AND VICINITY. The top of the Knob consists of stratified porphyry conglom- erate, with an actual thickness of 140 feet (150 feet in a vertical line). This rock is made up of small and large, more or less angular, pebbles of porphyry cemented together by iron-ore, and contain- ing also frequent layers and bodies of ore. Fig. 5. TCocroL ajoec. ore . Slate Porph. cony I. vr'ifh ore -** Po rph conyl. irilhore in mctfriic. P.C Porph.. conyt. ivi/h t ore R. P. fled for^h SECTION IN THE 'GREAT CUT 8 7 2 The upper portion of the series a purple conglomerate more or less mottled with gray has the pebbles and matrix nearly equally divided. The pebbles are rarely more than one inch in diameter, and are of brown porphyry and gray quartz, with others of a yel- lowish-gray substance, easily scratched, and apparently an altered porphyry. The matrix is generally a very fine-grained iron-ore, containing small grains of limpid quartz. Although the only visible PILOT KNOB. 15 crystalline forms of the iron-ore are those of specular ore, this con- glomerate matrix possesses decided polarity. A compass held close to the rock, and moved gently a few inches in any direction Fig. 6. SECTION OF WEST CUT ^Pl LOT. KNOB ^ parallel to the rock-surface, will have, alternately, its north and south poles strongly attracted. But the needle is not perceptibly affected at a height of four or five feet above the surface, nor does the conglomerate series, as a wliole, affect the needle appreciably. Toward the bottom of the conglomerate series the conglomerate structure is less marked in the eastern openings, and the lower beds have only isolated pebbles. The matrix here consists mainly of finely-divided specular ore, with a soft, greenish-white mineral, either a steatite or a clay ; in this lie small grains of porphyry and of quartz. This is more properly an ore ; indeed, it assumes in places a workable character, while in others it contains little ore, and becomes a nearly brown, homogeneous rock, with small grains of quartz. Below this lies the ore-bed, with a vertical thickness of 46 feet. It is divided into two beds by a slate-seam 10 inches to 3 feet thick. This seam, which is very persistent, lies in the great cut 31 feet above the foot- wall of the lower ore-bed. The upper ore-bed is more variable in thickness, having in the slate-seam a regular foot-wall, but having no very well defined hanging-wall, the ore often rising into the overlying rock. The upper ore-bed is so distinctly stratified as to be a well-char- acterized flag-ore, and is considerably leaner than the lower bed. The slate-seam which divides the two ore-beds is variable in char- acter, having in places the appearance of a clay-slate, in others of 16 GEOLOGY OF PILOT KNOB AND VICINITY. talcose-slate. while it not unfrequently has all the characteristics of a porphyry. The great ore-bed which lies below the slate-seam is a very com- pact, dense, and hard ore, very finely stratified in layers from I line to y 2 inch thick. In places the alternate layers are somewhat sili- cious. This ore frequently cleaves in joint planes at right angles to the bedding-planes. The ore-bed is underlaid by a purple-brown, indurated, clay schist, traversed by numerous threads of a steatite-like mineral. Immediately below this lies a very compact red and brown jas- pery porphyry, with minute grains of quartz, and free from feldspar- crystals. It is very hard, but contains numerous irregular-shaped patches one-eighth inch to several inches in diameter, of a soft, green- ish and brownish mineral resembling steatite, which is possibly an alteration-product of the porphyry. Below this, on the eastern slope, is a compact red jaspery por- phyry, with a decided tendency to spherulitic structure. The spherules are from the size of a pin-head to that of a pea ; they are of the same color as the matrix, and usually contain a small nucleus of a soft, greenish-white mineral probably steatite. The same substance that forms the nuclei, coats also the surfaces of the spherules, and is distributed very generally through the rock in such a manner as to give it a brecciated appearance. The matrix contains very isolated minute grains of limpid quartz. Further down the eastern declivity are outcrops of a compact, pinkish-gray porphyry, rarely containing visible grains of quartz. It contains an iron-ore, both minutely disseminated and also more concentrated in dark, irregular streaks. This rock has a tendency to tabular cleavage, and weathers through pink to yellowish white. Underlying this we find, on the neck which connects the Knob with the hills to the eastward, a pinkish-brown porphyry with con- choidal fracture, containing grains of limpid quartz and scattered small crystals of feldspar. A few hundred feet further east, and forming the next lower rock, is a very hard, flesh-colored porphyry, slightly mottled through the presence of irregular spots containing steatite and minute grains of iron-ore. The rock contains small grains of quartz and crystals of feldspar, which are more or less riddled with holes containing a chlorite. PILOT KNOB, 17 The next lower rock is that which forms the western declivity of the hill next east of the Knob. It is a pinkish-gray, slightly-banded porphyry, containing innumerable small cavities filled with a chlo- rite, and has a well-marked columnar structure. The inclination of the strata forming Pilot Knob being nearly the same as that of the surface of the western slope, we should expect to find the same series and thickness by boring at any point on the west slope. But there have been disturbances, which probably ren- der this impossible, on the lower half of the western declivity. Below the 4OO-foot contour-line, the rock-surface has a steeper slope than that of the hill. A shaft sunk at about the 325-foot con- tour, after going through about 3 feet of loose rubble of ore and porphyry, was sunk through nearly 64 feet of clay without striking rock ; whereas, if there had been no disturbance, the shaft should have been wholly in the conglomerate beds which overlie the ore, and the present bottom of the shaft should be very nearly in the hanging-wall of the upper ore-bed. The absence of these rocks is due to the erosion which the south-west flank of the hill had suffered before the deposition of the Silurian rocks. There are evidences of another disturbance. This is a zone of fracture visible in both the great cut and in the lower cut. Its course is about S. 30 W., and it is marked by a breccia of broken-up and re-cemented fragments of ore and porphyry. It does not ap- pear to have " faulted" the ore-beds. From the foregoing data, taken in connection with the form of Pilot Knob as determined by the topographical survey, we can de- lineate on the map the shape of the remaining portion of the ore- bed, assuming, of course, that the dip and strike remain the same, respectively, as in the upper part of the hill, and that the ore-beds are also persistent, and neither replaced by other rock material nor thrown out of position by faults. As the western limit is probably buried beneath 75 to 90 feet of clay and chert, its delineation is only roughly given. The south- western and northern limits are probably near the truth. The area thus indicated is about 200,000 superficial yards as a maximum for the extent of the ore-bed. The indication of the limit on the map may be of service in de- termining the best points to attack the ore-bed on the west or south- ern flank. 2 1 8 GEOLOGY OF PILOT KNOB AND VICINITY. The two best points for exploration are : 1. On the north-west, where the ravine intersects the limit-line, about 200 feet north of the incline and near the 375-feet contour. 2. On the limit east and south-east from Station 6, on the survey- line running south from the summit, there is (west of Station 6) an old opening in the conglomerate series that belongs above the ore. No line of levels was run to it ; therefore, in placing its position at 20-40 feet above the ore-bed, I am making an estimate only. The great thickness of the clay-deposit on the south-west flank would render it undesirable to attempt to approach the ore from this direction, before proving the bed near the two points above indicated. The shaft that was started for exploration, about 500 feet south- east of the western turn-table, has its collar a little more than 60 feet above where the ore-bed should be. Befure leaving Pilot Knob, I \vill remark that the clay-deposit on the west flank may have a technical value. It consists of a very pure white variety and a rusty variety. The two kinds could prob- ably be separated. Their composition, as shown by the accom- panying analyses made by Mr. Chauvenet, should give, especially to the white, a very decided value as material for the fabrication of chinaware : ANALYSIS OF CLAYS. I. Opalescent White Clay. II. Brown Clay. Silica 63.50 57-22 Alumina 24.55 22.89 Peroxide of Iron none 7.81 Lime 1.60 i.io Magnesia 0.48 0.46 Water of composition 7-3 7-95 Hygroscopic Water 2.20 2.90 99.63 100.33 Cedar Hill The rocks forming the south-western flank of Cedar Hill are the north-western extension of the conglomerates and ore- beds of Pilot Knob. CEDAR HILL. 19 At the time of my visit to this point, the working had not pro- gressed far enough to indicate with certainty whether the ore after being taken out corresponds to the ore-bodies distributed irregu- larly in the conglomerate on Pilot Knob, or to the great ore-bed proper. It is quite possible that the real equivalent of the Pilot Knob ore-beds has not yet been reached on Cedar Hill. I collected a thoroughly average sample of the stock-pile at the mine, which was analyzed by Mr. Blair, with the following re- sult : Insoluble silicious matter $.62 per cent. Peroxide of Iron 93-54 " Sulphur none Phosphoric Acid 0.090 " Equal to ; Metallic Iron 64.47 " Phosphorus 0.039 " Sulphur none The ore opened in the cuts on Cedar Hill, at the time of my visit, is very hard, dense, and heavy, and very uniform in character. It breaks in prisms, with sharp edges, owing to a well-marked columnar structure. The ore contains minute grains of limpid quartz. It has all the appearance of a porphyry in which the matrix has been wholly replaced by iron-ore ; and the irregularity of its mode of association with the porphyry heightens the resem- blance. The annexed cut, taken in one of the openings, will show what irregular forms the deposit assumes : Fig. 7. SECTION OF CUT ON. C E P A R H I U L 20 GEOLOGY OF PILOT KNOB AND VICINITY. The shaded portions are ore. P* is the mottled, altered porphyry associated with the ore. In the N. W. % of the S. E. % of Sec. 28, east of Pilot Knob, there is another zone of iron-bearing beds. At one point, shown to me by Mr. Crane, there are beds of jaspery slate, containing more or less specular ore. The indications are such as would make it desirable to have some exploration done. We found at another point (half-way between Station 4 on line 12 and Station 7, line 14), a bed or beds of ore, which deserve some work in the way of " proving." It is a rich granular ore, somewhat resembling that of Shepherd Mountain. The outcrop is not sufficiently exposed to enable one to give an opinion as to the extent of the deposit. All that can be seen without digging are what seem to be two beds, one and one- half to two feet thick, of rich ore, more or less mixed with some- what decomposed porphyry. The deposits of manganese-ore and of manganiferous iron-ore form a very interesting feature of the porphyry region, and promise to be of considerable economic importance. So far as I can judge, in our present limited kno.wledge of the porphyry district, these deposits belong considerably higher in the series than the Pilot Knob beds. The most characteristic occurrence is that of ftie Cuthbertson- Buford hill, which, beginning in Sec. 19, T. 33, R. 4, E., runs W. N. W. into Sec. 13, T. 33, R. 3, E. The northern side of this hill, near the top, seems to consist of a very dark, almost black porphyry, with numerous small crystals of white feldspar and grains of quartz. The southern declivity, the rocks of which overlie those of the northern side, consists of a much-altered bedded rock of fine CUTHBERTSON TRACT. 21 grain, which has in places the appearance of an indurated sand- stone, in others that of an altered porphyry. It contains nume- rous broad and flat cavities partially filled with a red, ochreous sub- stance. Fresher fragments exhibit a brown, fine-grained rock, consisting largely of minute grains of quartz cemented together by a quartz or porphyry matrix. There are no natural exposures of the rock in place, but on the Cuthbertson tract the surface is bestrewed with large and small fragments of manganese-ore, and, in places, of specular iron-ore. A cut in the Cuthbertson tract exposes a bedded deposit consisting of exceedingly ragged tabular masses of manganese-ore, separated by a red, ochreous clay. The following are analyses of this ore and of the specular ore, by Mr. Chauvenet : Manganese Ore. Insoluble silicious matter 0.44 Peroxide of Iron 3.30 Manganese as protoxide.. 68.02 The manganese exists in the ore as sesquioxide, with a probable admixture of binoxide. Metallic manganese 52.47 Specular Ore. Insoluble 2.45 Peroxide of Iron 97-85 Manganese trace It lies upon the bedded rock described last above. Fig. 9. MANGANESE DEPOSIT ON CUTH BERT SONS HI L L SECTION 19 T. 33. R. 4-E.t 22 GEOLOGY OF PILOT KNOB AND VICINITY. Further west, at the Buford bank, a larger cut gives a better ex- posure. Fig. 10. SECTION OF CUT ON BUFORD MOUNTAIN. Here we find a bedded deposit of the same nature as that on Cuthbertson's tract, with the difference that this one is a mangan- iferous iron-ore of a very superior quality. The cut exposes a stratified deposit of a ragged black iron-ore, overlaid by beds of pink, altered porphyry. The whole thickness of the ore-bed was not visible, but I esti- mate it at nearly 14 feet in the cut, though it thins out at the out- crop on the hill-side. A sample consisting of a large number of chippings was taken by myself as a close average of the ore. This was analyzed by Mr. Chauvenet, with the following result : Insoluble 8. 54 per cent. Peroxide of Iron 68.30 " Manganese as protoxide I5-S4 " Sulphur 0.017 " Phosphoric Acid 0.102 " Equal to Metallic Iron 47.81 " Metallic Manganese 12.32 Sulphur 0.017 " Phosphorus 0.044 " This is a remarkably fine ore for the manufacture of Spiegeleiscn. Of the extent of the deposit nothing can be known until more work is done. MANGANESE DEPOSITS. 23 Near this point there is a very irregular deposit, apparently a pocket, of ore nearly free from manganese, as appears in the an- nexed analysis by Mr. Chauvenet : Insoluble 13.42 Peroxide of Iron 5-76 Manganese as protoxide trace Metallic Iron 60.03 Near Cuthbertson's, but apparently belonging, geologically, a little higher, is the manganese deposit on Mr. Marble's land. It forms an interstratified layer, 3-5 inches thick, in a decomposed porphyry. A specimen of this was analyzed by Mr. Chauvenet, with the following result : Insoluble 10.35 Peroxide of Iron 14.22 Manganese as protoxide 5 1 .06 Lime 2.75 Magnesia 0.43 Water 3.89 Mr. Marble also sank a pit in his wood-lot, near the last-named locality, and after passing the soil, found about 3 feet of the ore in ragged masses, and below these a reddish, manganiferous, soft hematite (I.), associated with another variety (II.) containing less manganese. In samples of these Mr. Chauvenet made the follow- ing determinations : I. II. Insoluble 17.66 35-96 Peroxide of Iron 49. 34 58. 70 Manganese as protoxide 21.18 3-77 Metallic Iron 34-53 Metallic Manganese 16.44 This is a soft, maganiferous hematite of excellent quality. At all of the points mentioned on this hill the strike of the beds is N. 65 80 E., and the dip, more or less gentle, toward the south. Overlying these manganiferous beds we find a metamorphic lime- 24 GEOLOGY OF PILOT KNOB AND VICINITY. stone. This remarkable occurrence, which was first brought to my notice by Mr. Gage, is well exposed on Mr. Huff's land ; it is a more or less thinly-stratified rock, with essentially two characteris- tic constituents. In one extreme we have a pink to greenish-pink, crystalline limestone, containing irregular layers, one-sixtieth of an inch to several inches thick, of a dark-brown, fine-grained material, which strikes fire readily, and shows under the glass a large per- centage of quartz in minute grains, cemented by a quartz or por- phyry matrix. While the limestone bands effervesce strongly with acid, the dark bands are not acted upon except where they contain very thin layers of the limestone. The limestone is, in places, tinged green, probably from the presence of a chlorite.* In the other extreme, the main body of the rock consists of the silicious material just described, containing very subordinate layers of the carbonate. In places, this laminated structure is highly con- torted ; the carbonate layers are often broken up, and the fragments distributed very irregularly in the brown silicious rock. On the weathered surface the removal of the limestone gives rise to the same flat cavities, filled with ochrey earth, that we found in the rock accompanying the manganese-ores on Cuthbertson's tract. On the south-west ^ of Sec. 20, T. 33, R. 4, E., and over a considerable portion of the valley between this point and Huff's, there is a very compact, dark-brown, almost black porphyry, con- taining small crystals of white feldspar and grains of quartz, with some disseminated magnetite. In places the feldspar and quartz are abundantly crystallized, but more generally they are hardly visible except under the glass. The surface weathers dirty yellow, and then displays a distinctly-banded structure, which is rarely apparent on fresh surfaces. This is probably either the equivalent of the banded rock at Huff's, or it is younger. Another interesting instance of the occurrence of manganese-ore in porphyry was examined by assistant P. N. Moore, on Section 16, T. 33, R. 2, E., in Reynolds County. It occurs in one of the members of a series of bedded porphyry rocks, which may be here briefly described. 1st. A flesh -colored porphyry with a very compact matrix, * For an analysis of this limestone, see p. 26. MANGANESE IN PORPHYRY. 2 $ abounding in grains of smoky quartz and crystals of feldspar, is overlaid by 2d. A black porphyry with very hard matrix, abounding in grains of smoky quartz and crystals of a triclinic feldspar. In this occurs the black oxide of manganese ; it is in narrow, comby strings, which are in places isolated, in others united to form a reticulated net- work throughout the mass ; in this form the rock resembles a con- glomerate, the ore representing the cement. In other instances the manganese has wholly replaced the matrix, the crystals of feldspar and grains of quartz alone remaining intact. Finally, in portions of the rock the replacement has been complete ; here no traces of the porphyry, either crystals or matrix, remain, while a more or less porous, semicrystalline mass of the manganese-ore takes their place. A specimen representing an intermediate variety of this series was analyzed by Mr. Chauvenet. It is very compact and hard, striking fire with the steel. The matrix is jet black, with metallic lustre, and has the same texture and fracture as the parent por- phyry, and, like this, contains grains of quartz and crystals of feld- spar in this instance not striated. The whole appearance of the specimen is identical with that of the adjacent porphyry, except as regards the color and lustre of the matrix. Insoluble 45 5 5 Peroxide of Iron 5.48 Manganese det. as protoxide 37-O4 Lime 2.73 Magnesia o. 8 1 The analysis of the insoluble portion gave Silica 74-9 Alumina 14.69 Iron none Lime and Magnesia traces Potash 9.64 Soda 0.67 99.98 The insoluble portion is very clearly a typical felsitic porphyry with orthoclase for its feldspar. It is evident that the manganese 26 GEOLOGY OF PILOT KNOB AND VICINITY. and the other soluble constituents take the place of more than half of the porphyry in this specimen. That the resemblance of the ore to the porphyry is not merely accidental, is shown by other instances of a similar nature. On the land of Mr. Ackhurst (Sec. 19, T. 33, R. 4, E.) is a dark porphyry containing grains of quartz and abundant crystals of white feldspar ; the matrix is frequently, in places, a compact manganese-ore. It would seem that we have, in these occurrences, instances of replacement ; but it is difficult to imagine a direct substitution of manganese oxides for the decomposition products of a porphyry, and all the more so, in this case, from the fact that the analysis shows the remaining porphyry, which is intimately associated with the ore, to have its normal constitution. In this connection the metamorphic limestone at Huff's (near the manganiferous ores on Cuthbertson's, Marble's, and Ackhurst's land) may be of additional interest. As was mentioned before, this is nearly wholly changed into a porphyry or jasper rock, it having here a schistoid structure, in which the alternate laminae are an impure, compact carbonate of lime, having, according to Mr. Chauvenet's analysis, the following constitution : Insoluble 35-Si Peroxide of Iron 5-35 Lime 3 1 .62 Magnesia i.io Carbonic Acid 2 5-&3 99.71 Here is a member of the porphyry series which was originally, unquestionably, a limestone, but in which the original physical and chemical characteristics have almost wholly disappeared. It should not seem impossible that the manganiferous rocks which have been described may have had a similar origin, and that the manganese and iron oxides owe their present existence to a former replacement of the lime-carbonate by iron and manganese salts. The porphyry, which now surrounds these ores, may be due to a previous contem- poraneous or subsequent replacement of the lime-carbonate by silica and silicates. PORPHYRY CONGLOMERATE. 2 J But there is so strong a resemblance between the mode of occur- rence of these ores and that of certain of the iron-ores that of Cedar Hill, for instance that any hypothesis explaining the one must probably satisfy the requirements of the other. 3d. Geologically above this manganiferous bed lies a porphyry conglomerate or breccia, consisting of pebbles of a red, compact porphyry, containing grains of quartz and crystals of feldspar, ce- mented by porphyry of a similar character. This rock resembles very strongly the Calumet conglomerate on Lake Superior. Overly- ing this is 4th. A bright, red, compact jasper, apparently an altered sandstone which passes upward into 5th. A dark-brown, compact, banded porphyry, abounding in mi- nute crystals of feldspar and equally small grains of quartz. This rock contains here and there layers of very small pebbles, parallel to the bands. Still higher this rock becomes darker colored, while some of the bands become green, from the presence of epidote. Higher in the series occurs a mottled-red and greenish-white rock. The red portions are easily scratched, and the white are still softer, having about the hardness of limestone. Grains of quartz occur indif- ferently through the red and white spots, while crystals of triclinic feldspar are frequent in the red spots and rare in the white. At first sight, the rock has the appearance of a variegated marble. The greenish-white substance was analyzed by Mr. Chauvenet, with the following result : * Silica 65.61 Alumina 20. 52 Protoxide of Iron 1 .99 Lime . 1.97 Magnesia 2 -37 Potash (trace of Soda) 7.93 100.39 This rock is clearly an altered porphyry, and the white portion represents the more advanced change. It is interesting as an instance in which the change appears to have been accompanied by a removal of silica and of iron, while the alkaline constituents were apparently not affected. 28 GEOLOGY OF PILOT KNOB AND VICINITY. Next above this comes 6th. A porphyry with brown matrix, containing crystals of triclinic feldspar, with few or no grains of quartz, but with numerous ^ to y^ inch spherical, crescent-shaped and irregular cavities filled with quartz, often showing free crystallization in the centre. REPORT OF MR. REGIS CHAUVENET. ' PROF. RAPHAEL PUMPELLY, Director Missouri Geological Survey : DEAR SIR : I herewith submit the results of such of this year's chemical work as is fit for tabulation, together with a brief descrip- tion of the methods of analysis used, and a short discussion of some of the more important coals, in regard to their prominent chemical and physical characteristics. Respectfully yours, REGIS CHAUVENET, Chemist of the Geological Survey, ST. Louis, April-i^ 1873. CHAPTER II. ANALYSES OF FUELS, IRON-ORES, AND PIG-IRONS. BY REGIS CHAUVENET AND A. A. BLAIR. THE analyses of coals given in these tables are what are com- monly known as " proximate " analyses. The four constituents, viz., Water, Volatile Matter, Fixed Carbon, and Ash, can be subdi- vided into all the elementary bodies contained in the coal, but in most instances no more elaborate analysis was undertaken. We may class these four into combustible and incombustible material. Water and ash coming under the latter head, their sum will repre- sent the percentage of weight of the coal unavailable for heating purposes. The method followed in these examinations was one which has received the approval of the best experimenters. A weighed quan- tity of the coal, reduced to powder, was placed in a platinum cru- cible, and kept at a constant temperature of 110 C. until it ceased to lose weight. An hour was always sufficient time for this opera- tion. The loss indicated water. The crucible being now closed, though not tightly, it was heated in a Bunsen gas-burner until the flame of the escaping gas was no longer seen. The full heat of a gas blast-lamp was then directed upon it for three minutes. After cooling, the loss of weight gave the volatile matter. In estimating ash, a fresh portion of coal was sometimes taken, but more fre- quently the coke left from the last operation was ignited in the same crucible, with free access of air. The loss of weight by this ignition gave fixed carbon, and by deducting the weight of the empty crucible from the last weight, the amount of as/i was ob- tained. The color of the ash was noted, as a rough indication of its composition : the white is usually calcite ; reddish-browns are due to iron ; slate and chocolate indicate shale. A few coals were analyzed by the combustion furnace (organic analysis) for total carbon and hydrogen, as well as nitrogen in a 32 ANALYSES OF FUELS, IRON-ORES, AND PIG-IRONS. few instances. In the table giving the results, the last column is headed "Deficiency." The sum of the total carbon, hydrogen in the volatile matter, water, and ash, will always fall short of 100 per cent, by a figure varying greatly in different coals. This is called the " deficiency," since it cannot.be all ascribed to oxygen, though probably oxygen and sulphur (and nitrogen in those cases where it is not given) would fully supply the "deficiency." The low defi- ciency of the coals used at the St. Lours Gas-works is worthy of notice. The only Missouri coals besides these which seem to prom- ise well are, unfortunately, found in very small seams. Westlake's coal, in Pettis County, has been used for gas at Sedalia. As coking gas-coals, this coal, Linn's (Chariton County), George's (Cass County), and possibly Munn's (Henry County), promise tolerably well. But no coal in the whole number of those examined is equal to that now in use at the St. Louis Gas-works. In using the combustion furnace, bi-chromate of lead was substi- tuted for oxide of copper, and with good results. The few nitrogen determinations were made by mixing the sample with soda-lime in the tube, and collection of the ammonia in hydrochloric acid, which was then treated in the usual manner, the result always being cal- culated from the metallic platinum obtained from the double chloride of platinum and ammonium. Sulphur was not determined in many coals. In fact, in order to get a correct idea of the amount of sulphur, especially when it is in the form of pyrites, large samples are necessary, representing various parts of the bed, and these should be broken up and tho- roughly mixed. Such elaborate sampling was not possible in the case of these coals. After a few determinations of sulphur, the system was followed of examining, for sulphur, only those coals in which no pyrites, or very trivial quantities, were visible to the naked eye. The impression being very common that sulphur in coal exists only in the form of iron pyrites (FeS 2 ), several experiments were made with a view to testing the accuracy of this idea. A table will be found illustrating these experiments, and the single example of the " Baker" coal will show the fallacy of the belief. Mr. John W. Meier, of St. Louis, who has made trials of various coals, states that there are other coals similar to the "Baker" in containing sulphur and no iron. The question is one of some interest for coke-manufacturers. While a large proportion of the ANALYSES OF COAL. 33 pyrites in coal-slack can be removed by washing, it is not probable that sulphur not united with iron could be thus eliminated. The method adopted for the determination of sulphur was as follows : One gramme of the coal, well mixed and finely powdered, was mixed with twelve grammes of carbonate of soda, and from four to six of nitre. (With bituminous coal, four is enough.) The mixture is made in a capacious platinum crucible, and heated in the flame of a Bunsen burner until in a state of tranquil and complete fusion. After cooling, the mass is dissolved in water, the solution acidulated with muriatic acid, and evaporated to perfect dryness, to render any silica insoluble, re-dissolved in very dilute muriatic acid, filtered, and the filtrate treated with chloride of barium, and allowed to stand for twenty-four hours. It may here be stated that the very best brands of " C. P." carbonate of soda contain sul-. phur in some form ; hence it is absolutely necessary to make a sepa- rate test of that re-agent, and the simplest way is probably to repeat the operation, without the coal, and subtract the result from that first obtained. This method is also the best for sulphur in coke, a determination which is frequently of importance. The only difference is, that six or seven parts of nitre should be used instead of four, as with bitu- minous coals. Specific Gravity was determined by the bottle. The sample was always left in contact with the water for not less than twelve hours, before weighing, in order to thoroughly expel the air. In glancing at the general results obtained, a few coals seem to call for special notice. The Pacific Coal Company's mines, near Knob Noster, Johnson County, are extensive, at least as compared with most of the developments in that region, and the coal, of which large and well-averaged samples were obtained, is remarkably free from sulphur, being in this respect superior to most Illinois coals. This coal is much used on the Mo. P. R. R., and although its ash never falls below eight per cent, and sometimes exceeds ten, it is probable that the trouble this would cause in burning it in locomo- tives, is more than counterbalanced by its freedom from sulphur, and the consequent saving in boiler-repairs. Over this coal is a curious shale, decomposing rapidly upon exposure to the air, and consequently never left in the workings. It is very bituminous, is used to run the hoisting-engine, etc. at the mine, and when thrown 3 34 ANALYSES OF FUELS, IRON- ORES, AND PIG-IRONS. in heaps, heats and finally takes fire spontaneously. It is of small value as a fuel. Near Warrensburgh are some excellent coals, but in thin seams, and not worked upon any extensive scale. As a class, these coals show a very low ash. South of the town, and some miles from any other opening, is Grove's coal, which, from the character of its " top," its somewhat greater thickness, and its analysis, seems to belong to a different seam from the other Warrensburgh coals, but when visited was just opened, and but little could be determined about it. Linn's Coal (Chariton County) is quite remarkable for its low percentage of ash (1.64), being the best coal examined in this re- spect. Equally curious are some of the Ray County coals in their high per cent, of water, one sample from Hayson's (Swanwick) mine giving 12.55 per cent. No true " cannel" coal was examined. Many bituminous shales are known as such in their respective neighborhoods, but their ash (25 to 40) is too high, and their use must remain very limited. Several analyses of ores, clays, and limestones are appended to these tables. Though these are given in the text, under their pro- per heads, it may be convenient, for some purposes, to have all the analytical results brought together. While the tables here given do not include all the chemical work done during the past year, it is believed that no result of interest or importance has been omitted. RAY COUNTY. NAME OF COAL. Water. Volatile. Fixed Carbon. Ash. COLOR OF ASH. Smith's .10.05 38.55 45-40 6.00 White. Howell's . 8.05 41.85 45.80 4-3 Do. Oberhultz . 11.02 32.48 46.30 IO.2O Gray. Hughes . 8.IS 37.60 46.35 7.90 Light brown. Godfrey . 7.20 30.30 37.30 25.2O Brown. Camden Mines .10.33 37-73 42.04 9.90 Gray. Swanwick Hayson's, top . 10.00 37.85 48.30 3-85 Light brown. Do. middle. . . . .12.55 37-05 46.65 5-75. White. Do. bottom. . . . 1 1. 20 38-50 46.70 3.60 Nearly white. Coke made from Camden coal. . . . 3-25 4.88 83.37 8.50 * PETTIS COUNTY. Newport's , 3-95 33-iQ 46.26 16.69 Red. West lake's , 4-47 39-19 51-73 4.61 Gray. * This coke was from " Collins' s" coal. ANALYSES OF COAL. 35 SAINT LOUIS COUNTY. NAME OF COAL. Water. Volatile. r Fi f d Carbon. Ash. COLOR OF ASH. Parker & Russell ... 9.17 38.49 43.19 9.15 Light gray. Do . ... 9.55 38.28 42.99 9.18 Do. HENRY COUNTY. Jordan, top ... 3.47 42.18 45.85 8. 50 Purple gray. Do. bottom S-H 37-91 4 6 -82 10. 13 Do. Owens, near Clinton ... 8.30 36.95 48.65 6. 10 White, faint purple. Do. middle ... 7.14 38-66 48.35 5.85 Nearly white. Williamson ... 7.76 44.77 43.32 4.15 Dark purple. Munn's 7-50 37-30 50-75 4.45 Red. H. Neff ... 5.89 38.01 39.97 16.13 Light chocolate. Ogan's ... 8.48 33.96 43.16 14.40 Chocolate. Britt's, top ... 2.89 28.55 50.71 17.85 Reddish. Do. middle ... 3.88 43.67 43.42 9.03 Light gray. Osage Coal Co 5-65 36.95 41-87 15-53 Uo. Do. bottom ... 4.86 41.74 37.24 1 6. 1 6 Light chocolate. LA FAYETTE COUNTY Franke's 5-55 42.95 44-08 7.42 Light brown. Payne's, top ... 8.85 37.25 44.80 9.10 Cream. Do. middle ... 7.02 37.67 39.66 15.65 Very light brown. Do. bottom ... 7-75 34-05 4-3 18.17 Light chocolate. Ennis & Cundiff, top ...6.95 42.61 43.42 7.02 Do. Do. near bottom . .. 7.03 40.72 47.11 5. 14 Chocolate. * Lexington Coal Co., top . . ... 5.79 36.03 47.31 10.87 Light brown. Do. middle.. ... 8.15 34.71 47.29 9.85 Do. Do. near bottom 6.36 36.28 47.80 9.56 Yellow brown. Do. bottom. . ... 6.25 35.03 50.04 8.68 Very light brown. *Tilden Davis . .. 8.21 37.56 46.84 7.39 Nearly white. *Graham's 6 -53 35.I9 47-46 10.85 Very light brown. JOHNSON COUNTY. Mrs. Wingfield's . .. 7-31 41-88 46.36 4.45 Pale red-brown. Sylvester Orr's ... 5.87 40.06 43.45 10.62 Dark gray. Bruce's 5-31 43-65 43-12 7.92 Pale gray. Tapscott's ... 3.30 36.85 33.05 26.80 Light slate. B. Owsley . .. 7-40 43-7 38.37 1 1. 1 6 Pinkish gray. Pacific mines . 4 28 40.30 47.22 8. 20 Nearly white. Do ... 4-29 40.24 47.27 8.20 Do. Do ... 4.85 39.85 45.30 10.00 White. Do . .. 4.60 42 50 44.55 8.35 Do. iZimmermann's . .. 6.77 45.10 44.01 4.12 Very pale slate. : Do. bottom .... . .. 7.09 42.14 47.15 3.62 Pale brown. iZoll's, top 5-39 45-89 -45-56 4. 1 6 Pale gray. : Do. bottom 6.32 45.38 44.98 3.32 Do. :Grove's .. 7.80 34.90 51.20 6.10 Reddish slate. :Gillum's . . 7.29 42.27 46.95 3.49 Slate. :Goudy's . . 5.60 44-95 44-45 5.00 Pale brown. ^Mineral charcoal i-59 15-63 71-28 11.50 Reddish slate. LINCOLN COUNTY. Link' s, top .. 8.17 32.58 46.50 12.75 Light gray. Do. next top 7-85 32-75 46-25 12.65 D' Do. middle .. 8.40 35.22 46.33 10.05 D- Do. below middle 8.25 34.55 47.50 9.70 Do. Do. bottom 7-9 33-9 49.0 9.20 Light brown. * From the Lexington coal-bed. $ Warrensburj;h coals. t Near Knob Noster. From Zoll's bank, Warrensburgh. 36 ANALYSES OF FUELS, IRON- ORES, AND PIG-IRONS. NAME OF COAL. Water. Volatile. p 'u C Ash. COLOR OK ASH. Baker's 8.50 39-5o 46.45 5.55 White. Meadows's, top 6.30 39.20 44-30 10.20 Light brown. Do. bottom 6.75 36.80 42.00 14.45 ^- Upson's 1.15 41.25 49.60 8.00 Very pale brown. Mine's 6.75 36.40 45-75 n.io Light red-brown. CARROLL COUNTY. Jas. Goodson's 2.97 36.36 47.83 12.84 Light brown, [specks. Jos. Meddlin's 2.07 29.94 47.03 20.96 Dark brown, white " Little Compton " 4.37 44.58 47-21 3.84 Reddish brown. SALINE COUNTY. L. Bohn 6.02 40.33 42.09 11.56 Pink. Haynie [Miami] 2.58 31.22 35-i8 31.02 Deep red. [specks. "Cannel"* 3.53 48.30 42.39 5.78 White, with brown PITTSBURGH (PA.). (ST. Louis GAS-WORKS.) Average sample 1.31 36.61 54. 17 7.91 Faint gray. BIG MUDDY COAL (ILL.). Sample No. i 5.86 33.08 57.48 3.58 Do. 2 5.88 32.81 57.66 3.65 CHARITON COUNTY. Linn's 5.82 38.01 54-53 1.64 Salmon. ANDREW COUNTY. Niagara Creek 8.94 34-75 45-38 10.93 Red brown. LIVINGSTON COUNTY. Graham's 5.38 42.27 44.98 7.37 Pale brown. NODAWAY COUNTY. J. C. Smith's 3.53 42.72 40.71 13.04 Very light brown. CASS COUNTY. George's 7.80 33.20 55-75 3-25 Rich brown. MACON COUNTY. "Bevier" 12.05 4-75 43-5 3-7 Pinkish gray. CALLAWAY COUNTY. Fulton Coal Co 7.43 38.90 45.85 7.82 Pink. Nesbitt's 5.00 33-95 40.73 20.32 Dark purple slate. NEBRASKA (STATE), NEAR NEMAHA. Omaha Coal Mining Co 4.93 38.17 49-44 7-46 Red brown. SULPHUR AND IRON COALP. Sulphur required c NAME OF COAL. IRON. SULPHUR. by iron to form Gravit Fe Sz. Smith's, Ray Co 0.84 2.41 0.96 .249 Godfrey's, Ray Co 2.83 4-179 3-23 .293 Newport's, Pettis Co 3.99 4.406 4.56 .347 Zoll's, Johnson Co 1.05 2.916 1.20 .243 Pacific Mines, Johnson Co 0.49 0.759 -56 -35o Link, Lincoln Co 0.70 2.036 0.80 .255 * Locality not known. Used at St. Louis Gas-works'. ANALYSES OF COAL. 37 NAME OF COAL. IRON. SULPHUR. Hines, Lincoln Co 5.21 2. 230 Meadows, Lincoln Co 4-44 4.910 Baker, Lincoln Co none 2.632 Pittsburgh (St. Louis Gas-works) 0.56 0.770 Howells, Ray Co 2. 702 Oberhultz, Ray Co 4. 609 Hughes, Ray Co 4-17 Mrs. Wingfield's, Johnson Co 4. 504 Westlake's, Pettis Co 2.670 Sulphur required by iron to form Fe Sz. Specific Gravity. 5-95 5-07 .... none 1.165 0.64 .... 1-257 .... 1.277 .... 1.328 1.252 SPECIFIC GRAVITY OF A FEW COALS. NAME. Sp. Gr. Smith's, Ray Co i . 249 Howell's, Ray Co x -257 Oberhultz, Ray Co 1.277 Hughes, Ray Co 1.328 Godfrey, Ray Co 1 . 293 Newport, Pettis Co J-347 Westlake, Pettis Co i. 319 Groves, Johnson Co 1.312 Goudy's, Johnson Co 1.228 Zoll's, Johnson Co 1.243 NAME. Sp. Gr. Zimmermann's, Johnson Co 1.225 Mrs. Wingfield's, Johnson Co 1.252 Sylv. Orr's, Johnson Co 1-377 Bruce' s, Johnson Co Tapscott's, Johnson Co. . . Pacific Mines, Johnson Co. George's, Cass Co Link, Lincoln Co.. 271 529 350 ,261 255 Baker, Lincoln Co I- 165 Mineral charcoal 1.803 ULTIMATE ANALYSES OF COAL. NAME OF COAL. a T3 X fa Combined Carbon. Total Carbon. 1 . " e 3 '" '4 o "a c ti Nitrogen. , 1 i Ik % Q 11.08 11.09 6.90 10.70 8-77 6-35 11.05 18.35 6.01 7-03 Pacific Mines, Johnson Co. Mrs. Wingfield's, " Tapscott's shale, known as " cannel" 47-22 46.38 33-05 45.56 44.01 46.95 51 .20 51.73 54.17 42.39 23.11 25.98 24.96 28.72 30.75 29.56 17.32 10.50 17.50 23-45 35-27 70.33 72.34 58.01 74.28 74-76 76.51 68.52 66.25 69.23 77.62 77-66 0.47 0.81 0-37 0.60 0.75 0.81 0.86 0.86 0.50 0.14 -39 4.66 4.81 5-47 4.80 4.81 4-35 4-99 6.00 5 '1 3 5.62 6.07 6-33 5-6i 5.67 5-49 6-39 1-45 i.56 1.72 1.84 4.28 7-31 3-30 6.77 7.29 7.80 7.80 4-47 1-31 3-53 8.20 4-45 26.80 4.16 4.12 3-49 6.10 3-25 4.61 7.91 5.78 Zoll's, Johnson Co., (War- rensburgh) Zimmermann's, Johnson Co Gillem's, Johnson Co. . . . Grove's, " .... George's, Cass Co Westlake's, Pettis Co Pittsburgh, used at St. Louis Gas-works Saline Co. "Cannel," used at St. Louis Gas- works HYDRAULIC LIMESTONE, LINCOLN COUNTY, OVER MEADOWS'S COAL. Silica. . . ....... .21, 35 Peroxide of iron i. 79 Lime 42. 1 6 Magnesia 0.66 Carbonic acid 34-14 38 ANALYSES OF FUELS, IRON-ORES, AND PIG-IRONS. CLAYS FROM LINCOLN COUNTY. Under Coal in Baker's Shaft. Morris's Shaft. Colbert's. ^. llca : 34-40 72.35 65.35 Alumina *i8.6a 18.11 23.25 Lime. . I5-27 1-09 0.52 Magnesia 6.25 1.48 1.27 Hygroscopic water 1-4 6 2.14 Water of composition 123.09 3.05 4.83 LINCOLN COUNTY IRON-ORES. PARTIAL ANALYSES. Morris's Morris's Morris's Morris's Shaft, i. Shaft. 2. Shaft. 3. Shaft. 4. Humphrey's. Murphy's. Insoluble silicious 26.98 15-42 7.74 n.66 4.10 Peroxide of iron 4.72 63.12 79-64 84.30 86.56 95-32 (Metallic iron) 3.30 44-i8 55.75 59.01 60.59 66.72 A BOWLDER OF RED HEMATITE FROM T. 49, R. i, E. Section 12, Lincoln County, gave Insoluble silicious 7-55 Peroxide of iron 9 J -95 (Metallic iron) 64.36 Sulphur 0.017 Phosphoric acid 0.023 (Phosphorus) o.oio CLAYS FROM PILOT KNOB. Brown. White. Hygroscopic water 2.90 2.20 Water of composition 7-95 7-3 Silica 57-22 63.50 Alumina 22.89 24.55 Peroxide of iron 7.81 none Lime i.io 1.60 Magnesia 0.46 0.48 100.33 99-63 LIMESTONE OF ST. JOSEPH BRIDGE. Silica ................................................................... 4. 25 Peroxide of iron .......................................................... I. oo _ ............................................................... 3055 M agnesia ................................................................ 1 9. 09 Carbonic acid ............................................................ 44- 6l 99.50 Per cent, of magnesia less than in dolomite. LIMESTONES. IRON COUNTY. ABC Pyritiferous. Insoluble silicious 5.11 3.85 2.06 17.88 Peroxide of iron 4.67 1.07 none 3.75 Carbonate of lime , 47-5 5 2 -5o 54-32 43-52 Carbonate of magnesia 42.19 42.56 43-82 34-^5 If the percentage of carbonate of lime in these analyses is assumed as one equivalent, and the corresponding amount of carbonate of magnesia calculated according to the formulae for dolomite, CaO, CO 2 , MgO, CO S , we have ABC Pyritiferous. MgO, CO 2 39.89 % 44.09 45.62 36.55 * With some peroxide of iior. t Total loss by strong ignition, including a little carbonic acid. \ Iron and alumina. ANALYSES OF IRON-ORES. 39 by which it appears that A has more magnesia (in proportion to its lime) than dolomite the others less. METAMORPHIC LIMESTONE. (Sec. 19, T. 33, R. 4, E.) Insoluble silicious 35- 81 Peroxide of iron 5-35 Lime 3 1 - 62 Magnesia 1. 10 Carbonic acid 25.83 99.71 MANGANIFEROUS IRON-ORES. lUiford Kuford Mt. A 239 A 240 Marble's Mountain. Upper cut. Marble's. Marble's. Field. Insoluble silicious matter 8.54 13-42 17.66 35-96 J o-35 Peroxide of iron 68.30 85.76 49-34 58.70 14.22 Manganese (reduced to protoxide) 15.84 trace 21. 18 3-77 S 1 - ^ Lime 2. 75 Magnesia .... .... .... 0.43 Sulphur 0.017 Water 3.89 Phosphoric acid 0. 102 .... .... .... Metallic iron 47-8i 60.03 34-54 41.09 9.95 Metallic manganese 12.22 16.34 2.91 39-38 Cuthbertson's Cuthbertson's Manganese-ore. Iron-ore. Insoluble silicious 0.44 2.45 Peroxide of iron 3. 30 97-85 Protoxide of manganese , 68.02 trace of Mn. Metallic manganese 52.47 "SHUT-IN" ORES. A 27. A 29. A 29. Insoluble silicious matter 1. 75 2. 10 .... Peroxide of iron 93-9 98-50 .... Sulphur o. 078 .... Phosphoric acid 0.057 0.062 ANALYTICAL LABORATORY OF CHAUVENET & BLAIR, 218 Pine St., Saint Louis, April 21, 1873. PROF. R. PUMPELLY, Director Missouri Geological Survey : DEAR SIR : At your suggestion I hereby submit, in a tabulated form, for convenience of reference, the analyses of iron-ores and pig-irons made by me for the survey, from samples taken by Dr. Adolf Schmidt. These analyses were made for the immediate use of Dr. Schmidt, and are incorporated in his exhaustive report. There are also a number of analyses made for private parties and published by their permission. In determining the amounts of sul- phur and phosphorus in the ores and pig-irons, 5 grammes of the material was always used; consequently "a trace" of sulphur or phosphorus means a trace in 5 grammes. It had been my intention to devote some space to the chemical 40 ANALYSES OF FUELS, IRON- ORES, AND PIG-IRONS. action of some of the iron-ores in the blast-furnace, and the nature of this action especially in relation to silicon in the resulting pig- metal ; but the impossibility of getting perfectly reliable data in many cases, and the objections of iron-masters, in others, to make public the results of their experiments, oblige me to defer it to some future time. Yours, very respectfully, ANDREW A. BLAIR. Insol. silicious matter. 2ft. IRON MOUNTAIN ORES. 2ft. 2b. 2b, 27. 6.76$ 127- 3 1 - 5- 128. Peroxide of iron Protoxide of iron 2. 34 86.75 96.78$ 1 72 95.15$ 95.04 Alumina O.Q3 O. 71 Lime 0.41; Oil Magnesia . . O. IQ Manganese. . . none .... none Sulphur . . none none none none 0.016 o 008 0.003 o 5 O OI2 Phosphoric acid 0.212 0.248 0.081 0.073 o 119 o. 1 12 o 125 o 071 o 067 100.322 - 100.586 Insol. silicious matter. Silica 3.00$ 3.28$ 4. 14.$ I 175! Alumina 0.47 Lime 0.06 Magnesia 0.03 4-55 1.6 5 Metallic iron Phosphorus. . . 65.78 o. no .... 65.17 .... 67.75$ 0.108 0.031; 0.030 0.012 66.60$ 68.63 0.04Q 0.017 0.031 O.O2Q 2<7, zb. Specular ore from enclosed conglomerate mass in the backbone-vein, cut A, on south side of Iron Mountain. 20. deflects the compass-needle ; 2b does not, yet 2l> is more magnetic and contains more magnetic oxide than za. These two samples being practically the same, the great difference in the amounts of phosphoric acid seemed unreasonable. The analyses were therefore repeated, and the results were practically as before. 27. Specular ore from backbone-vein, cut II, north side of mountain. 127. Average sample of quarry-ore taken by Maj. Brooks. 31. Average sample of surface-ore from western slope. 5. Average sample of surface-ore from south-east slope. 128. Average sample of surface-ore taken by Maj. Brooks. All the samples, except 127 and 128, were taken by Dr. Schmidt. NOTE. The samples Nos. 127 and 128 were collected by Maj. T. B. Brooks with great care, and represent thousands of chippings, in 127 from the quarry-ore, and in 128 from the loose surface-ore. After being thoroughly powdered, portions were sent by Maj. Brooks to three chemists, viz. : Prof. Allen, of Yale College, Mr. Otto Wuth, of Pitts- burgh, and Mr. A. A. Blair, of St. Louis. As the determination of phosphorus and sul- phur in perfectly average samples of this great ore-deposit, is a subject of considerable technical interest, the results obtained are here given : ANALYSES OF IRON- ORES. 41 No. 127 Quarry-Ore. WUTH. Phosphorus 0.016 0.043 Sulphur .... No. 128 Surf ace- Ore. Phosphorus 0.016 0.025 Sulphur. .... PILOT KNOB ORES. ALLEN. Double determination. 0.042 O.O26 47- Insoluble silicious matter 14.75$ Peroxide of iron 84.33 Protoxide of iron o. 15 Alumina - 75 Lime o. 2 1 Magnesia o. 14 Manganese none Sulphur traces Phosphoric acid -35 45- 5-57$ 90.87 1.67 0-53 1.76 0.13 none 0.078 0.069 45 (Rep.). 36. BLAIR. 0.049 O.OOS 0.029 O.OI2 [R. P.] 16. 67. 62.88$ 0.063 o.co6 0.092 0.079 O. IOI 100.365 100.677 Insoluble silicious matter. Silica 13.27 Alumina and trace of oxide of iron ... i .44 0.36 Metallic iron 59. 15 64.91 Phosphorus 0.015 0.031 0.027 47.16 0.041 44.01 0.044 50. 46. 4?. 40. Peroxide of iron 87.18$ 83.28$ 77.02$ 52.18$ Metallic iron 61.03 58.29 53-91 36.52 47. Soft ore from central cut (B). 45. Hard ore from central cut (B). 36. Ore from lower strata eastern cut (C). 16. Average sample from upper strata eastern cut. 50. Specular ore from western cut (A). 46. Hard ore from central cut (B). 48. Ore in conglomerate central cut. 40. Average sample of better ore on refuse-heaps. All taken by Dr. Schmidt. SHEPHERD MOUNTAIN, ETC. Insoluble silicious matter. , 20. s.is$ 21. 23. 6.76$ 68. C.H. 5.62$ L.M. IZ.T.T.% Peroxide of iron Q4.84. 88. 56 96. 70$ 70. -3q$ 07. C4. 84.60 Protoxide of iron . 1. 80 2. 07 14.22 Alumina O.^2 Lime 0.35 0.^8 Magnesia O.O4. o. 15 Manganese none none minute trace none Sulphur none none none none none O.O2I Phosphoric acid o. 02 < 0.039 -32 0.0^8 O.OQO o. 06 s 1 00.866 Insol. silicious matter. Silica 4.o^$ 5.98$ 14.45$ Peroxide of iron O.O7 none Alumina ... c 46 -5l Lime ... O 12 .... 0.06 Magnesia o.oz 0.04 6 68 i;.o6 Metallic iron . 66. ?2 64..3I 67.6q 66.61 6s. 47 59.22 Phosphorus. . O.OII 0.017 0.014. 0.017 0.039 0.027 42 ANALYSES OF FUELS, IRON- ORES, AND PIG-IRONS. 20. Average sample upper part of central vein (B). 21. lower " 23. Soft ore from " " " " 68. Ore from eastern vein. The above all taken by Dr. Schmidt. C. H. Sample of Cedar Hill ore taken by Prof. Pumpelly, and representing average of vein . L.M. Sample of Lewis Mountain ore taken by Prof. Wm. B. Potter, and analyzed for Pilot Knob Company, by whose permission it is published. SPECULAR AND RED HEMATITE ORES. 6. Insoluble silicious matter. . 11.19^ 9.30.^ ..... 0.87^ Peroxide of iron 85.95 76.45 27.40 87.92 97-23 98.96 Protoxide of iron - 77 4. 1 1 .... Alumina o. 97 Lime 0.12 36.01 Magnesia 0.07 Manganese none Carbonic acid 0.48 29. 51 Water 0.46 13-65 2.45 0.03 0.47 Sulphur 0.126 0.052 0.044 none none trace Phosphoric acid. . 0.116 0.478 0.09^ 0.089 0.092 0.062 loo. 252 Insoluble silicious matter. Silica 9-78$ 6.78$ 0.27$ 11-32^ 2.06% Alumina 1.33 Lime none ..... Magnesia 0.12 11-23 .. Metallic iron 60.76 53-51 22.38 61.54 68.08 69.27 Phosphorus 0.051 0.208 0.043 -39 0.040 0.027 i. Purple paint-ore from Meramec mine. 2. Oclirey ore from do. 3. Red ore and yellow rock, with spathic ore, from do. 4. Hard, silicious specular ore from do. 5. Average sample best specular ore from do. I, 2, 3, 4, and 5, taken by Dr. Schmidt. 6. Blue specular ore from Orchard bank, Salem District, Dent County, analyzed for Mr. O. A. Zane, and published by permission. Now worked by Salem Iron Company. SPECULAR AND RED HEMATITE ORES. 7*. Silica . . . . o. 69,1 Peroxide of iron 97-94 Protoxide of iron trace Alumina 1.17 Lime . . 97.08 0.31 1.50 1,9% 37 835^ 78.38^ Hygroscopic water 0.02 Combined water o. 19 Carbonic acid none Sulphur none Phosphoric acid 0.068 0.08 | 0.23) 0.21 none 0.079 3-09 trace 0.207 Insoluble silicious matter Metallic iron 68.56 68.19 61.86 Phosphorus 0.029 -34 0.091 0.079 I7-05 0-034 0.083 0.205 5-73 63.02 0.036 14-13 54-86 0.089 7#, 7$. Piece of ore from Iron Ridge, partly blue specular and partly red paint-ore ; fa, blue specular, "jb, soft, red paint-ore. These samples were taken for a comparison of the ANALYSES OF PIG-IRONS. 43 two kinds of ore, and is particularly interesting on that account. 8. Average sample from Iron Ridge mine. The above taken by Dr. Schmidt. 9. Blue specular ore from Beaver Branch. 10. Partly decomposed ore from same. n. Soft paint-ore from same. These Beaver Branch ores were analyzed for Missouri Furnace Company, and are published by permission. BROWN HEMATITE ORES. i. 2. 3. 4. 5. 6. 7. 9. Insol. silic. matter 8.66$ 7.17$ 7.42$ 8.35^ Peroxide of iron 84.02$ 77.42$ 82.02$ 84.10$ 81.96 78.73 79.82 79.53 Water 10.98 12.49 12.80 11.60 Sulphur 0.171 0.147 0.015 0.084 none none 0.009 trace none Phosphoric acid. ... 0.861 0.076 0.091 0.084 0.077 Manganese none Silica 3.08 8.05 5.13 3.59 Metallic iron 58.81 54.19 57.41 58.87 57.37 55.11 55.87 55.67 Phosphorus 0.376 0.034 0.041 0.037 0.034 0.058 0.081 0.061 0.071 10. n. 12. 13. 14. IS- I 6- Insol. silic. matter. . 4.88$ 3.60$ 6.97$ 4.34$ 9.41$ 39.22$ 7.08$ Peroxide of iron 82.27 8 5-9 80.98 78.38 80.35 49-12 75.42 Water 8.87 Sulphur trace trace none none trace o.oor 0.035 Phosphoric acid 2.891 0.249 0.206 0.859 Metallic iron 57.59 59.55 56.68 54.86 56.24 34.38 52.79 Phosphorus 0.074 0.028 0.123 1.262 0.109 0.089 0.375 I. Brown and red hematite from Marmaduke bank. 2. Limonite from Sheldon bank. 3. Do. from White bank. 4. Do. (pipe-ore) from Elm Hollow bank. 5. Do. do. from Indian Creek bank. All on the Osage River. 6, 7, 8, 9, 10, II. From Camden Co. Analyzed for Mr. H. S. Reed, and published by permission. 12. From Perry Co. Analyzed for Mr. Reed, and published by permission. 13. From Perry Co., opposite Grand Tower. Analyzed for Big Muddy Iron Company, and published by permission of Mr. Jas. E. Mills, Vice-President. 14. From Indian Ford, Bellinger Co. Analyzed for Mr. Win. B. Spear, and published by permission. 15. From near Irondale, and used in the furnaces there and at Iron Mountain. Ana- lyzed for Messrs. E. Harrison & Company, and published by permission. 16. Analyzed for Wm. E. Romer, Esq., of Grand Tower, and published by permission. I, 2, 3, 4, and 5 samples were taken by Dr. Schmidt. PlG-lRONS. I. 2. 3. 4- 5- 6. 7. 8. 9. Sulphur 0.024$ 0.017$ 0.005$ trace none trace 0.016$ 0.026$ Phosphorus 0.133 0.062 0.116 0.165$ 0.098$ 0.116$ 0.136 0.196 .... Combined carbon Graphitic carbon. . . 3.293 Silicon 3.230 2.624 1.329 0.942 1.389 1.354 0.630 1.347 4- 8 5 10. ii. 12. 13. 14. 15. 16. 17. 18. j Sulphur none 0.045$ 0.006$ o. 103$ o. 134$ o. 141$ 0.061$ none Phosphorus o. 168$ 0.147 - l 53 0.097 0.141 0.107 0.141 o. 116$ Combined carbon 0.810 . ...) .... 0.625 0.850 Graphitic carbon 3.000 ....) 2.775 2.500 Silicon 1.517 3.840 3.325 3.425 5.898 3.443 2.847 2 - 2 34 2.770 I. Made in the fall of 1872, at Vulcan Iron Works, from Iron Mt. ore alone; i Big Muddy coal, | Connelsville coke. 2. Made at Pilot Knob Iron Co.'s furnace, from f Pilot Knob and Shepherd Mt. ores, charcoal and hot blast. 3. Made at Scotia Iron Works, from Scotia ores, charcoal, and hot blast. 4. Made at Meramec, from Meramec ores, 44 ANALYSES OF FUELS, IRON- ORES, AND PIG-IRONS. $ half hard and | soft, charcoal and cold blast. 5. Made at Iron Mountain, from Iron Mt. ores, with 8$ of limonite. 6. Irondale, hot blast. 7. Irondale, cold blast ; both charcoal, and same ores as 5. 8. Made at Moselle, from Iron Ridge and St. James ores, with 8$ Moselle limonite, charcoal and hot blast. 9. Made at Pilot Knob Iron Co.'s Works, from all Pilot Knob ore, charcoal and hot blast. 10. Made at same, f Shepherd Mt. and ^ Pilot Knob, charcoal and hot blast, n, 12, and 13. Made at Big Muddy Iron Co.'s furnace, at Grand Tower, n and 13 from \ Pilot Knob ore, \ Iron Ridge and St. James red hema- tites, using f Connelsville coke, f Big Muddy coal. 12. Same, except that the Illinois Patent Coke Co.'s coke was substituted (using a larger proportion) for the Connelsville coke. These analyses were made for Big Muddy Iron Co. and published by permission of James E. Mills, Esq , Vice-President. 14, 15, 16, 17, and 18. Made at South St. Louis Iron Co.'s furnaces. Analyzed for them, and published by permission of Mr. H. S. Reed, President. 14. Glazed pig, made from all Pilot Knob ore. 15 and 16. No. i and 2 Foundry, from all Iron Mt. ore, made in summer of 1872. 17. Made from Iron Mt. with some Iron Ridge soft, red hematite. 18. Made from all Iron Mt. ore, spring of 1873. All with Connelsville coke and Big Muddy coal. i, 2, 3, 4, 5, 6, 7, and 8 were samples taken by Dr. Schmidt or sent to him for the use of the survey. CHAPTER III. THE IRON-ORES OF MISSOURI. BY ADOLF SCHMIDT, PH.D. A. General Distribution. MISSOURI is one of the richest States in iron-ores on the North American continent. These ores are, however, very unequally dis- tributed over the State. Very little iron-ore is found in the whole northern part of the State north of the fiftieth township-line, and in a range of counties on the western border. These districts are covered by the coal- measures, which, although containing clay-ores and carbonates of iron, do not contain them in such quantities and in such positions as to make them workable. According to Mr. G. C. Broadhead's statements, these ores in the coal-measures of Missouri occur either as single nodules, or as thin beds, varying from one to twenty inches in thickness, imbedded in the carboniferous clays and slates. They lie, generally, deep below the surface, from 20 to 60 feet, and not close enough to the coal-beds to be mined conjointly with the latter. These ores are, besides, not very rich in themselves. The only point where the region of workable iron-ore reaches, north of the Missouri River, is in Callaway County, where red, earthy hematite occurs as a stratum in the ferruginous sandstone of the subcarboniferous system. South of the Missouri River there are, between this river and the fortieth township-line, valuable deposits, mostly of limonite, in Franklin, Osage, Morgan, and Benton Counties. This kind of ore also occurs nearly over the whole central and southern part of the State. In the southern part the counties of Stoddard, Bollinger, Wayne, Ozark, Douglas, Christian, and Greene, contain considerable deposits of it. But by far the richest portion of the State in iron-ores is that between the 3Oth and 4Oth township-lines. Within this zone, iron- 46 IRON-ORES OF MISSOURI, ores abound in the greater part of the counties situated between the Mississippi in the east and the Upper Osage River in the west. Limonite banks are scattered over the whole of this vast region, being, however, somewhat concentrated in three districts. The most eastern of these is composed of Bellinger, Wayne, and the southern part of Madison Counties ; the second but smaller con- centration is in the south-eastern part of Franklin County ; while the third and most important one of this ore is found on the Middle Osage River, between Warsaw and Tuscumbia, in Benton, Morgan, Camden, and Miller Counties. This latter district extends also to the Upper Osage, above Warsaw, into St. Clair and Henry Coun- ties. But while the limonites are deposited on the Second and Third Magnesian Limestones in the rest of the State, they here lie on the subcarboniferous limestone. The Upper Osage district also contains good deposits of subcarboniferous red hematites, occurring, here in the same way as in Callaway County. The specular ores are much more concentrated in certain parts of the State than either the limonites or the carboniferous hematites, and also occur in much larger masses. There are two important specular-ore districts, different by their geographical positions, dif- ferent entirely by the mode of occurrence and the geological posi- tion of their ores, but quite similar, on the other hand, in the mineralogical character and the chemical composition of these ores. The one of these districts is the Iron Mountain dis- trict in the east, extending only over a small area, in southern St. Fran9ois and northern Iron Counties, but containing two enormous deposits, besides numerous smaller ones. The ore is here in veins, beds, and other less regular forms in the porphyry. The second specular-ore district lies more toward the centre of the State, yet mainly in its eastern half. Its principal deposits, as far as known at present, are concentrated in three counties, Crawford, Phelps, and Dent. The occurrence of the specular ores, however, extends somewhat into the surrounding counties of Washington, Franklin, Maries, Miller, Camden, Pulaski, and Shannon. The spe- cular ore in this central ore-region is always more or less distinctly connected with the Lower Silurian Sandstones, especially with the so-called Second Sandstone. Many of these deposits are disturbed and broken, and altered in regard to their position and contents. From all that has been said, we may infer that, according to our IRON- ORES. 47 present knowledge, there are three principal and important iron- regions in Missouri, namely : 1. The eastern region, composed of the south-eastern limonite district and the Iron Mountain specular-ore district. This region has its natural outlet, at present, over the Iron Mountain Railroad. 2. The central region, containing principally specular ores, and having its commercial outlet over the St. Louis, Salem & Little Rock and the Atlantic & Pacific Railroads. 3. The western or Osage region, with its limonites and red he- matites. This region will have to establish an iron industry of its own, because it is too remote from the present ore-markets. Its present connection with these markets is down the Osage River to Osage City, and from there either over the Missouri Pacific Railroad or down the Missouri River. A railroad from Jefferson City, through Cole, Moniteau, Morgan, Benton, Henry, St. Clair, Bates, and Vernon Counties to Fort Scott, which would touch the Upper Osage districts, is partly in construction, partly under consider- ation. These three principal regions, combined, form a broad ore-belt, running across the State from the Mississippi to the Osage, in a direction about parallel to the course of the Missouri River, from south-east to north-west, between the thirtieth and fortieth town- ship-lines. The specular ores occupy the middle portion of this belt, the limonites both ends of it. The latter are, besides, spread over the whole southern half of the State, while the subcarboniferous he- matites occur only along the southern border of the North Missouri coal-field, having thus an independent distribution, and being prin- cipally represented in Callaway, St. Clair, and Henry Counties. To make this distribution of ores more apparent and clear, I have added to this report the accompanying " Preliminary Map, showing the Distribution of Iron Ores in Missouri." Atlas, Plate IV. This map contains about 280 deposits. Its title indicates that it does not pretend to be complete. It represents only a first effort toward a more complete map, and contains the results of informa- tion obtained during the summer of 1872. Such a map can, in fact, hardly ever be entirely complete, because new ore-banks are con- tinually being discovered and opened. Neither does this map pretend to show the exact relative char- acter and size of the single ore-banks. It is only intended to show, 48 IRON- ORES OF MISSOURI. in a generally correct and clear manner, the general distribution of the ores. For this purpose it was necessary, however, to mark every single deposit that has come to my knowledge, and to indi- cate those deposits which, according to their present appearance, seem to be more extensive than others, by larger sizes. This led to the adoption of five sizes, with a respective estimate of yield of smeltable ore. Below 20,000 tons, for size, I. 20,000 to 100,000, " 2. 100,000 to 500,000, " 3. 500,000 to 2, 000,000, " 4. Above 2,000,000, " 5. To distinguish the different kinds of ores, I use three colors, thus : Red, for red hematite. Blue, for specular ore. Brown, for limonite. As regards the character of the deposits, those which, like veins and beds, are generally supposed to be more or less continuous, are marked by squares. All the other deposits, which are supposed to be either decidedly limited or very irregular, are marked in a cir- cular form. Another distinction made on the map is that between undisturbed, disturbed, and drifted deposits. This distinction was unavoidable, on account of the very frequent occurrence of disturbed deposits, especially in the central ore-region. In the following chapters of this report the ores and deposits will be described under the following geographical arrangement : Eastern Ore-Region. ORE-DISTRICT ALONG THE MISSISSIPPI RIVER. IRON MOUNTAIN DISTRICT. SOUTH-EASTERN LIMONITE DISTRICT. FRANKLIN COUNTY DISTRICT. SCOTIA DISTRICT. Central Ore-Region. STEELVILLE DISTRICT. ORE-DISTRICT ON THE UPPER MERAMEC AND ITS TRIBU- TARIES. GEOGRAPHICAL ARRANGEMENT. 40 SALEM DISTRICT. IRON RIDGE DISTRICT. ST. JAMES DISTRICT. ROLLA DISTRICT. MIDDLE GASCONADE DISTRICT. LOWER GASCONADE DISTRICT. CALLAWAY COUNTY DISTRICT. Western Ore-Region. LOWER OSAGE DISTRICT. MIDDLE OSAGE DISTRICT. UPPER OSAGE DISTRICT. South-western Ore-Region. WHITE RIVER DISTRICT. OZARK COUNTY DISTRICT. 4 CHAPTER IV. THE IRON-ORES OF MISSOURI. BY ADOLF SCHMIDT, PH.D. B. Description of Ores. General Description. IT may be inferred, from the contents of the preceding chapter, that there are principally two species of iron-ores in Missouri, hematite and limonite. These can be easily distinguished from each other by their exterior appearance, the hematite being either grayish black, with a slight bluish or reddish tint, or red in various shades ; while the limonite is always brown or yellow. But the best and least deceptive distinction is made by the streak of these ores that is, by the mark they produce when rubbed against a rough, white porcelain-plate. The streak is invariably red with the hematite, and yellowish brown to yellow with limonite. If the ores are not too hard, the color of the streak can also be discovered, though less plainly, by scratching the ores with a knife. The hematite occurs in two very different and distinct varieties, the specular ore and the red hematite. Specular Ore is bluish-black to steel-gray, with a more or less metallic lustre, and a more or less crystalline structure. Its mine- ralogical hardness is about 6, which is also about the hardness of hardened cutlery-steel. Thus an ordinary pocket-knife will not scratch the hardest specular ores ; but it will scratch the softer kinds, though not without some effort, there being no great differ- ence in their respective hardness. The streak of pure specular ore is cherry-red to dark-red, with a purple tint. Its magnetic quali- ties vary considerably in the same kinds of ore and in the same localities. Most specular ores are, however, slightly magnetic. This description refers to specular ore in its pure and natural con- dition, being then composed chemically of nearly pure peroxide of iron, containing about 70 per cent, of metallic iron. But this ore is LIMONITE. 5 1 sometimes found mixed with foreign substances, as quartz, sand, flint, porphyry, clay, pyrites, apatite, etc., which generally change somewhat its qualities and diminish its value. Specular ore also frequently undergoes physical and chemical changes by a gradual alteration under the influence of air, water, or mineral solutions. These alterations, which will be spoken of more fully hereafter, some- times change the character of the ore completely. We find the spec- ular ore to pass, under certain conditions, into compact red hematite, and into soft red hematite, by other influences into limonite, by others into carbonates. These various ores, as far as they are merely the products of such gradual alterations, will be described together with the specular ores from which they are derived. It is a very remarkable fact, that all the Missouri specular ores, with but a few exceptions, have pretty nearly the same mineralogical and chemical character, whether they occur in the porphyry or in the Silurian sandstone. Red Hematite, when not produced by transformation of specular ore, but occurring as an original mineral in the subcarboniferous strata of Missouri, has a dark-red color, either with a yellowish or more frequently with a bluish tint. The fracture is uneven and dull in the earthy, somewhat conchoidal with a slight lustre in the compact, varieties. The structure is never crystalline, but either earthy and more or less porous, or compact and fine grained, or coarse grained to oolitic. The hardness is less than that of most specular ores. It varies from 5 to 6, but rarely reaches the latter figure. The streak is cherry-red to yellowish red. This ore is unmagnetic. Red hematite, when exposed to atmospheric influence, seems to become more porous, and is altered gradually into brown and yellow limonite. These subcarboniferous hematites consist of a somewhat clayish peroxide of iron, and contain from 50 to 60 per cent, of metallic iron. Limonite, also known as "brown hematite," has a dark, grayish- brown color. Nearly all the limonite occurring in Missouri is dull, and sometimes earthy in the fracture, amorphous. It occurs partly in porous masses, the irregular pores and cavities being filled with yellow ochre, partly in botryoidal and stalactitic forms. The hardness of compact limonite is about 6, and pretty uniform. The streak is yellowish brown. Limonite is unmagnetic. It is chemi- 52 IRON- ORES OF MISSOURI cally composed of peroxide of iron, and water in varying quantity, and contains from 45 up to 60 per cent, of metallic iron. It is sometimes clayish, and in several localities mixed with broken chert. It is invariably accompanied by soft, yellow ochre, distributed in small cavities throughout its mass, but also occurring in larger accumulations occasionally. Limonite does not seem to undergo any material changes by exposure. SPECIAL DESCRIPTION OF MISSOURI IRON-ORES. a. SPECULAR ORES. I. Specular Ores in Porphyry. Iron Mountain Ore. The iron-ore of the Iron Mountain corre- sponds in its mineralogical qualities to the general characterization of Missouri specular ore as given above, and may be considered as a type. It is very uniform in its character in the various parts of the vein. Also the surface-ore has the same appearance and qualities, with the only exception that it is in the great average a little softer, its hardness being generally slightly below 6, while that of the vein-ore is slightly above 6. The color of both is steel-gray, with a slight tint of blue. Their streak is dark red to purple. Both have an uneven fracture, a nearly metallic lustre on fresh-broken faces, a subcrystalline to massy structure. The structure is occasionally inclined to become lamellar. In this case the ore is brittle, and breaks in long flat splinters with very thin and sharp edges. The surface of fracture of such pieces is very bright, and shows indications of a coarse crystallization, the single indistinct crystals being flattened and drawn in length in the direc- tion of the long axis of the splinter. Many of these splinters are strongly magnetic, some less so. The former show a distinct po- larity. The magnetic axis, however, never coincides with or ever lays parallel to any one of the three main axes of the splinter, but it is always in an inclined position to all of them. Marks of dis- tinct crystallization are very rare in the Iron Mountain ore. Wher- ever distinct crystals occur in holes or fissures, they are mostly small and micaceous. These small micaceous crystals are some- times also distributed throughout the mass of the softer ore, filling IRON MOUNTAIN ORE, 53 the very finest pores. This is more frequently the case in the sur- face- than in the vein-ore. All Iron Mountain ore is magnetic. I have not been able to dis- cover a single piece entirely free from magnetism. Some of it, besides the special variety above mentioned, is strongly magnetic with distinct polarity, the north pole of a compass-needle being attracted by one side and repulsed by the other side of the same piece, producing very strong declinations. The greater part of the Iron Mountain ore acts, however, but slightly on the needle, but shows, nevertheless, frequently distinct polarity. Some of it does not seem to act at all on an ordinary compass-needle. But when reduced to a fine powder, some parts of it are invariably attracted by a magnet of ordinary power, while other parts, although equally fine, are not attracted. This remark, which is correct even for the impure ores from the small veins of but one to two inches' thick- ness, as they occur in the so-called " bluff," proves the universal distribution of magnetism in the Iron Mountain ore, and besides indicates that this magnetism is a quality inherent in certain small particles only, while others are free from it. This is one step, un- fortunately but a small one, toward the explanation of the ine- quality existing between the magnetic strength of one piece of ore and that of another. This inequality exists to such an extent that sometimes a piece of ore, whose largest dimension does not exceed one inch, is found to be in part strongly magnetic, in part very weak, as may be seen when the piece is broken and the single frag- ments tested. This inequality seems to be independent of the location, and shows itself in the same manner and degree in the large vein, in the smaller veins, and in the surface-ore. Pieces in- clined toward a crystalline structure are more generally strongly magnetic than others, also those containing secretions of mica- ceous crystals. Small differences in the chemical composition do not seem to influence the magnetism. The latter seems espe- cially not to be dependent on small variations in the amount of protoxide the ore contains. We see from the following analyses that the sample No. 3, al- though strongly magnetic, contains only 2.34 per cent, of protoxide, while the sample No. 4, which is very little magnetic, contains 5.72 per cent, of it. The magnetism of these samples was tested by approaching the single pieces to the north pole of a compass-needle. 54 IRON- ORES OF MISSOURI. Afterward, however, some of them were reduced to a powder, and were tested by approaching a magnet to the powder. Tested in this way, the powder of No. 4 seemed to be attracted more lively and more copiously than that of No. 3. A repetition of these tests showed the same results. These facts would invite to a closer investigation of these matters. The axis of polarity in single pieces of Iron Mountain ore is never either parallel nor rectangular to the cleavage or to the surface of fracture, and runs very frequently from one point near the edge to another point near the centre of the piece on the opposite side. No ore with active magnetism, constituting a natural magnet, and attracting iron-filings, was found on the Iron Mountain. The following analyses, made by Mr. A. A. Blair, of St. Louis, will show the chemical composition of the Iron Mountain ores : VEIN- I. 2. Insol. silicious matter Peroxide of iron . . - 06.78 ORE. 3- 4.71 91-45 2-34 o-93 0-45 0.19 o.oo O.OO 0.252 4- 6.76 86.75 5-72 SURFACE-ORE. 5- 6. 1.88 95.04 2.57 0.75 0.15 o. i 7- 95-15 Protoxide of iron . . . Magnesia Manganese o.oo 0.081 O.OI2 0.067 0.00 0.005 0.071 0.003 O.I25 66.60 0.057 4-54 4.029 Sulphur 0.008 0.016 Phosphoric acid 0.112 0.119 Metallic iron 100.322 65.78 65.16 o. no 0.035 0.029 Insoluble Silicious Matter. 3-99 6.16 0-47 0.06 0.13 0.03 S.I49 4-934 100.586 68.53 0.031 i-57 0.04 O.O2 0.017 4.835 67.75; Phosphorus . O.OAQ O.CK2 Silica 3.28 Alumina Lime . O. I4Q Magnesia Specific gravity. . 1. Average sample of the vein or quarry ore from all parts of the mountain, sampled by Major T. B. Brooks, of Marquette, in May, 1872. 2. Average sample of ore from the eastern part of the principal vein (cut D). 3 and 4. Average sample of ore from the western part of the principal vein (cut A). 3. Decidedly magnetic pieces. IR ON MO UNTAIN ORE. 5 5 4. Pieces not acting on a compass-needle. 5. Average sample of the surface-ore from all parts of the moun- tain, sampled by Major T. B. Brooks, of Marquette, in May, 1872. 6. Average sample of surface-ore from the south slope of the mountain. 7. Average sample of surface-ore from the north-west slope. The metallic iron in samples I and 5 was determined by Dr. Otto Wuth, of Pittsburgh, as follows : i . Vein-ore 66.049 P er cent. 5. Surface-ore 67.416 per cent. From the above analyses we may conclude that the Iron Moun- tain ore is very rich and very uniform, in general ; that the surface- ore is a little richer in metallic iron, and less phosphoric than the vein-ore ; that both are nearly free from sulphur ; and that the per- centage of phosphorus is variable, though never running very high. A comparison made between the analyses 3 and 4 on the one hand, and 2 on the other hand, might indicate that the vein-ore grows richer toward the west. The number of analyses is, how- ever, too small to warrant the correctness of such a conclusion. It will be noticed that the specific gravity, as given above, agrees well with the results of the analyses. The Iron Mountain ore is in the whole very pure and nearly free from mechanical admixtures of foreign matter. A few minerals, however, occur in it occasionally, namely, porphyry, apatite, and quartz. Admixtures of porphyry never occur in such a manner as to in- jure the ore, the enclosures having so large a size that the porphyry is easily separated from the ore. This is therefore more of geologi- cal than of mineralogical interest. Fine clay, probably of porphyric origin, is sometimes intimately mixed with the ore in the smaller veins in the " bluff." The thicker veins are entirely free from it. Apatite must have been very fre- quent formerly in those parts of the veins which are in immediate contact with, or at least in pretty close vicinity of, the porphyry- walls, to judge from the numerous large and small holes of crystal- line shape to be found in the ore in such places. These holes occur generally in larger or smaller groups, in some parts of the 56 IRON-ORES OF MISSOURI. principal vein, as well as in the " bluff" veins and in the surface- ore. The crystals which originally filled these holes were hexago- nal prisms of varying sizes, from the smallest up to a length of 3 inches and a diameter of I inch. They generally start at the wall of the vein, or at the wall of some fissure existing in the vein, and reach into the ore, sometimes perpendicular to the wall, but more frequently at some angle to it, and often nearly parallel to each other. The prisms are distinct and sharp near the wall, where they start from, but the more they reach into the ore the smaller is their diameter and the less distinct and sharp their edges. Many run out into a sharp point and look almost like sharply- pointed pyramids, or, when rounded off, as they frequently are, like needles or lances. Some, however, show indications of the basis of the prism, also at that end of the crystal which lies free in the ore. All these crystallic holes are very likely impressions of crystals of apatite formerly present in the ore, and some of them, though fortunately but few, are yet filled with nearly fresh apatite. The empty holes are generally clad out with a very thin layer of a fine ferruginous clay. The third mineral found in the Iron Mountain ore is quartz. It occurs but rarely, and nearly always near the walls of the veins, especially in disturbed places, or near large enclosures of broken porphyries in the interior of the principal vein. This quartz is there evidently the result of a process of infiltration, which has taken place long after the formation of the ore. It fills small fissures or irregular cavities, or the crystallic cavities above described, which were left after the removal of the apatite. It is always more or less distinctly crystalline, and sometimes foims drusy aggregations of crystals, slightly covered with yellow hydrated peroxide of iron (yellow ochre). Pilot Knob Ore. The Pilot Knob ore differs somewhat in its qualities from most of the other specular ores in the State. Its color is steel-gray to pearl-gray, with a very marked tint of sky- blue. Its lustre is so faint that it can scarcely be called submetallic. Its structure is crystalline to granular, with a very fine grain barely to be seen with the naked eye. Its fracture is either even or sub- conchoidal. It shows a plain stratification, and splits parallel to it into plates ^ to 2 inches in thickness. These plates break in par- PILOT KNOB ORE. ' 57 allelopipeds with sharp edges and with surfaces that are sometimes at right angles, but more frequently inclined to each other. The faces parallel to the stratification are generally even, or nearly so ; the others are either subconchoidal or irregular, with sharp edges and corners. The general flight of two faces situated opposite each other is always more or less parallel. The hardness of the Pilot Knob ores is very variable, and the faces parallel to the stratifi- cation are always perceptibly harder than those lying in other directions. The former are mostly near 6^, the latter near 6. There are, however, a few places in the Pilot Knob mine where the ore is considerably softer, about 5^. The hard ore passes gradually into the soft. All Pilot Knob ores are very brittle. Their streak is uniformly dark red. Also the poorer ores show this streak. None of the Pilot Knob ores from the main body of the deposit, neither below nor above the slate-seam, disturb an ordinary com- pass-needle, with the exception of the uppermost layers of poor ore, in the eastern cut, immediately below the conglomerate which forms the summit of the mountain. Also, most of the fine ore which is mixed with this conglomerate has polaric magnetism. The greater part of it acts on the needle very strongly. This con- glomerate has indications of stratification, and the magnetic axes run either at a right angle or parallel to it. The ore found in loose pieces in the conglomeratic detritus covering the western slope of the mountain is also polaric-magnetic, some of it strongly so. Mag- netic pieces of thinly-stratified, poor ore are also found loose in the creek north-east of the mountain. All ores on the Pilot Knob, those in the deposit as well as those in the conglomerates, are slightly attracted by a magnet, when they are ground fine, and those which, as above mentioned, act strongly on the needle, are not attracted by the magnet with any greater power or in any larger quantity than those which do not seem to act on the needle at all. The chemical composition of the Pilot Knob ores from different parts of the mine is very different, as may be seen from the follow- ing analyses, made by Mr. Andrew A. Blair, of St. Louis : IRON- ORES OF MISSOURI. Insoluble silicious matt< Peroxide of iron ORES IN THE MAIN ORE-BED BELOW ORES ABOVE THE THE SLATE-SEAM. SLATE-SEAM. i. 2. 3. 4. 5. 6. 7. 8. ;r 14-75 ^-^ 87.18 83.28 84.33 90.87 67.38 77.02 1.67 , 62.88 S2.I8 Protoxide of iron O. I? Alumina 0.71; O. ^ Lime 0. 2 1 1.76 . Magnesia O. 14 O. IT, O. OO Sulphur trace 0.078 O.OO6 O.O7Q .. Phosphoric acid O.O'K 0.069 O.O92 O. IOI Metallic iron . 100. 16s 100.677 . . 61.01 "?8.2Q so. i <; 64.91 47.16 53.91 O.O1I O.O4I . 44-01 36.52 O. O44 . . Phosphorus. . . o.oi<; Insoluble Silicious Matter. Silica 13-27 5.18 30.10 28.16 Alumina (with a trace of per- oxide of iron) 1.44 0.36 1. Average sample of ore from the main ore-bed below the slate- seam, in the western cut (A). 2. Hard ore from the central portion of the main ore-bed, below the slate-seam, west of the soft ore (analysis 3), in the central cut (B). 3. Soft ore from the central portion of the main ore-bed, below the slate-seam, in the central cut (B). 4. Hard ore from the central portion of the main ore-bed, below the slate-seam, east of the soft ore (analysis 3), in the central cut (B)- 5. Average sample of ore from the main ore-bed, below the slate- seam, in the eastern cut (C). 1 6. Ore in conglomerate, 5 feet above the slate-seam, in the cen- tral cut (B). 7. Average sample of ore from the strata above the slate-seam, in the eastern cut (C). 8. Average sample of the better ore on the refuse-heaps of the eastern cut (C). This ore is not smelted, nor shipped, but thrown away with the rock-refuse. We may conclude from these analyses that there is a great differ- ence between the richness of the ore in the main bed below the slate- seam, and that of the ore above the slate-seam, the former showing, in the lower and central parts of the deposit, an average of about 60 per cent, of metallic iron, while the latter contains only PILOT KNOB ORE. 59 53 per cent., or, as this latter ore is very variable in itself, we may say from 45 to 55 per cent. The ore from the upper part of the deposit, from the eastern cut (C), is decidedly poorer than that from the central and western cuts. It contains only 47 per cent, below the slate-seam, and 44 per cent, above it, and the uppermost and poorest layers stand as low as 36, and some would analyze considerably lower than this. The ores from the last-mentioned uppermost layers, in the eastern cut, are thrown away now. But a considerable part of them could undoubtedly be smelted with profit in the Pilot Knob furnace. They could not be shipped, being too poor to pay for both the transport and the smelting. But they would give a fair profit, when smelted in place, especially when mixed with some of the richer ores or with limonites, or, better, with both. As the metallurgical and commercial value of ores increases very rapidly with their richness, I have no doubt that a great gain would result for the Pilot Knob Company, in money and in reputa- tion, if the 60 per cent, ores from the lower and central part of the main bed would be kept and sold separate. These could be shipped to Indiana, Ohio, and Pittsburgh, and command high prices, while the 50 per cent, ores could be used in Missouri and Illinois, mixed with other Missouri specular ores and limonites, and while the 35 to 40 per cent, ores would be smelted at Pilot Knob. We see from the above analyses that the Pilot Knob ores contain very little sulphur and phosphorus. Their principal impurity is silica. This silica is either chemically combined, or, more likely, inti- mately mixed with the ore in microscopic particles or grains. Mr. Blair's analyses show it to vary from 5 to 13 per cent, in the richer ores, and to be as high as 30 per cent, and over in the poorer ores. The upper part of the ore above the slate-seam is often inti- mately mixed with porphyry. The main bed is entirely free from it. Besides these two kinds of admixtures, a few minerals occur occasionally in very small quantity in fissures, as the micaceous oxide of iron* and a yellowish-white, lamellar, crystalline, translu- cent heavy-spar. These two minerals occur rarely, but generally together and mixed with each other, in fissures, in the eastern por- tion of the central cut (B), below the slate-seam. A mineral re- sembling the last described, probably also heavy-spar, sometimes 60 IRON- ORES OF MISSOURI. forms a thin film, composed of many crystalline lamella:: of a vitre- ous lustre, over the even faces of separation of the ore, especially over those which have a nearly vertical position in the bed. This film is, in some instances, very pure and transparent ; in others it is more grainy, of a reddish color, opaque, and up to one-eighth inch thick. In the latter case it is not pure, but seems to be mixed with loose and extremely small grains or crystals of quartz. Mr. Chauvenet found the specific gravity of the sample No. 3, which is soft ore from the central part of the main bed, = 4.386, and that of sample No. 4, which is hard ore from the same place, = 5-OI9- These results agree with the results of the chemical analyses, which show much more silica and less iron in the soft ore than in the hard. Shepherd Mountain Ore. The ore from Shepherd Mountain, in its mineralogical qualities and chemical composition, resembles a little more a magnetite than any other ore in Missouri. It is, how- ever, in the main a specular ore, very similar to that of the Iron Mountain, as above described. Its color and streak are slightly darker than those of the latter. Its hardness is considerably less, being about 5/^ m the average. Its lustre is less bright. It has no stronger tendency toward a crystalline structure. The crystal- line faces, though equally indistinct, are rather smaller. Splendent lamellae of micaceous crystals, disseminated through the mass, as they occur rarely in the Iron Mountain ore, are quite general in the Shepherd Mountain ore, and the ores from these two localities may generally be distinguished exteriorly from each other by this characteristic, as well as by the marked difference in their lustre. The Shepherd Mountain ore is also much tougher and less brittle, and breaks with less sharp corners and edges. In some places in the depth of the northern vein (A), the ore gets nearly black in color, finely granular, and fully black in the streak, thus approaching a true magnetite. A very soft, black ore occurs in irregular masses of limited extent in the upper part of the central vein (B). These masses show a more distinct crystallization, and sometimes aggregates of lamellar crystals of specular hematite in the forms of the rhombohedric system. The glittering; small crystals of micaceous ore are very numerous in some parts of these soft masses, while other parts are quite dull. The ore in the small southern outcrop (C) has a distinct, coarsely crystalline structure, with a pretty bright metallic lustre. SHEPHERD MOUNTAIN ORE. 6 1 When inspected through a magnifying glass, the Shepherd Moun- tain ore appears to be composed, on the one hand, of crystalline parts, with a color and a lustre very similar to that of the Iron Moun- tain ore ; on the other hand, of a dull, dark-red, ground mass sur- rounding the crystalline parts. Sometimes the one prevails, some- times the other. I found a specimen in which these two distinct kinds of ore form alternate, undulating layers about one-eightieth of an inch in thickness, giving the piece a striated appearance. The magnetic qualities of the Shepherd Mountain ore are much more pronounced than those of either the Iron Mountain or the Pilot Knob ores. Here again we have to distinguish two different modes of action of magnetism, which seem to be independent of each other in certain respects and within certain limits ; first, the magnetic influence of the ore on a compass-needle, and second, the attractive influence of a magnet on small particles of ore. The influence on the needle is much less dependent on the chemical composition and on the structure of the ore than on its position in the vein. The specimen No. I, amongst the following analyses, contains 1.8 per cent, of protoxide, and is much more magnetic than the No. 2, which contains 2.97 per cent. There is no decided and regular difference between the magnetic strength of hard and soft, of dull and bright, of fine-grained and coarse-grained ore ; but all the ore in the upper part of the vein, from the outcrop to a depth of 30 or 40 feet, acts strongly on the needle, while the action of the ore from the lower part is much weaker, though very differ- ent in different places. Besides being stronger magnetic, the upper ore is also decidedly polaric, the axis of polarity being nearly par- allel to the cleavage. Regarding the lower ore in Shepherd Moun- tain, it is a remarkable fact that, although acting on the needle invariably, it is, with rare exceptions, entirely unpolaric, while the Iron Mountain and Pilot Knob ores, although mostly weaker, are nearly always polaric. A piece of this lower Shepherd Mountain ore repels the north pole of a magnetic needle, and attracts its south pole, and, when the piece is turned over, instead of acting in a reversed manner, it allows the needle to return to its natural position, and does not produce any deflection whatever. In the northern vein (A) the strongly magnetic and polaric ore is more frequent, and reaches deeper than in the central vein (B). There also occurs some ore (analysis No. 4) which contains a large amount of pro- 62 IRON- ORES OF MISSOURI. toxide, and has most of the mineralogical characteristics of a true magnetite, especially a deep-black streak. All Shepherd Mountain ore is strongly attracted by a magnet of ordinary power, when either pulverized or ground coarsely. No decided difference can be discovered in this respect between the ore which strongly disturbs the needle and that which affects it but little. Neither can a difference be discovered in this respect be- tween the polaric and the unpolaric ore. When a polaric piece is broken or ground, the single fragments are polaric. From a strong- ly polaric piece, I broke off some particles from the north pole and also some from the south pole. Each of these particles had itself two poles, when tried by approaching it to a compass-needle, and all these particles were attracted by both poles of a magnet. The position of each single particle, when attracted by the north pole, was however reversed, when compared to the position of the same particle when attracted by the south pole. When the ore is finely pulverized, only a part of the powder is attracted, while the rest seems to be unmagnetic. This fact shows that the magnetism is inherent in certain very small particles only, while others are free from it, and explains the difference between the two modes of magnetic action. A piece of ore containing comparatively but few though strongly magnetic particles, may not disturb the needle ; nevertheless, when the ore is pulverized, a magnet will exert a lively attraction on the magnetic part of the powder. Bowlders of ore are sometimes found on the Shepherd Moun- tain which are strong natural magnets, possessing active magnet- ism, and attracting iron-filings. A piece of iron, when rubbed against such a natural magnet, becomes itself a magnet. The chemical composition of the Shepherd Mountain ore may be seen from the following analyses made by Mr. Andrew A. Blair, of St. Louis : i. 2. 3- 4- Insoluble silicious matter 5.15 6.76 Peroxide of iron 94.84 88.56 96.70 79-39 Protoxide of iron 1. 80 2.97 . 14.22 Alumina 1.55 Lime o. 35 Magnesia 0.04 Manganese o. oo Copper trace in 5 grins. o.oo Sulphur o.oo o.oo o.oo o.oo Phosphoric acid 0.025 -O39 0.032 0.038 100.269 SPECULAR ORES FROM IRON COUNTY. 63 Metallic iron 66.52 64.31 67.69 66.63 Phosphorus o.on 0.017 0.014 0.017 Insoluble Silicious Matter. Silica 4.05 5.98 Peroxide of iron 0.07 Alumina o. 46 Lime o. 12 Magnesia 0.05 Specific gravity 4-714 1. Average sample of ore from the upper part of the cen- tral vein (B) ; magnetic ; streak dark red. 2. Average sample of ore from the lower part of the central vein (B), about 80 feet below the outcrop; slightly magnetic; streak dark red. 3. Soft, friable ore from the lower part of the central vein (B) ; slightly magnetic ; streak dark red. 4. Hard, black ore from the northern vein (A) ; strongly mag- netic ; streak black. These analyses show that the Shepherd Mountain ore is very uniform in its chemical composition, very rich in iron, and almost entirely free from sulphur and phosphorus. It is very nearly as rich as the Iron Mountain ore, and much purer than either this or the Pilot Knob ore. It is, besides, nearly free from mechanical admixtures, small specks or thin seams of a soft, white clay, probably decomposed porphyry, being the only foreign matter generally found in it. The northern vein (A) contains, in a few places near its outcrop, some crystalline iron pyrites. This mineral, however, occurs very rarely, and does not injure the general quality of the ore in the northern vein, as the above analysis, No. 4, shows. The Shepherd Mountain ore is perhaps the best iron-ore in Missouri. Specular Ores from the smaller Deposits in Iron County. These ores are very variable, approaching partly the Pilot Knob ore, partly the Iron Mountain ore, in their general character. Mica- ceous ore is of very frequent occurrence in most of these smaller deposits. On Buford Hill, 2^ miles west of Iron Mountain, mica- ceous oxide is found almost exclusively. It occurs in consider- able irregular accumulations, mixed with quartz. The crystalline lamellae have a black color, a bright lustre, and variable sizes, up to one-fourth inch diameter. The ore is strongly magnetic, with distinct polarity. The ore from Cedar Hill, north-west of Pilot Knob, resembles the 64 IRON-ORES OF MISSOURI. Pilot Knob ore externally. It has a grayish color, with but little lustre, and is very dense, hard, and brittle. The streak is red. This ore is distinguished by the absence of all magnetism. It does not affect the needle, and is not attracted by a magnet, after being crushed or pulverized. It is sometimes mixed with specks and seams of brown porphyry. Most of it is pure and very rich in iron. Mr. Blair found in an average sample, taken by Prof. Pumpelly from all parts of the mine Insoluble matter 5.62 Peroxide of Iron 93-54 Sulphur o.oo Phosphoric Acid 0.090 Metallic Iron 65.47 Phosphorus 0.039 The ores found imbedded in stratified porphyry in some localities, one-half mile east of Pilot Knob, are more like the Iron Mountain ore, having a darker color, a brighter lustre, and a less degree of brittle- ness than the Pilot Knob ores. They are mostly softer than 6. All the specimens I found there have a pretty strong magnetic polarity. The ore from Lewis Mountain, near Arcadia, is very variable in its mineralogical qualities. Most of it looks like the Cedar Hill ore, and is unmagnetic. Other parts are softer and tougher. Wherever crystallization appears, the ore is micaceous and magnetic. The following analysis, made by Mr. A. A. Blair, of St. Louis, shows this ore to be about equal in quality to the better ores of Pilot Knob. This analysis was kindly furnished to me by Hon. Thomas Allen : Insoluble silicious matter .... 15.33$ Peroxide of Iron (including a small amount of protoxide) 84.60 = Metallic Iron. .59.22$ Alumina 0.32 Lime 0.38 Magnesia o. 1 5 Manganese o.oo . Sulphur 0.021 Phosphoric Acid 0.065 = Phosphorus. .0.027 (Excess due to the presence of protoxide.) 100.866 BUFORD MOUNTAIN ORE. 65 INSOLUBLE SILICIOUS MATTER. Silica 14.45 Alumina 0.51 Lime 0.06 Magnesia 0.04 What has been said of the Lewis Mountain ore may also be applied to that of Hogan Mountain. Masses of soft, coarsely crys- talline, semi-micaceous, slightly magnetic ore, are, however, more frequent in the latter than in the former. The Buford Mountain ore is dull, dark-colored, soft, in part earthy. It is partly massy, with indications of stratification, partly in irregular botryoidal forms, and frequently mixed with specks and seams of decomposed porphyry, of white and red clay, of hydrated peroxide of iron, and of black peroxide of manganese. The streak is therefore very variable, being red where the iron-ore prevails, .and black where the manganese-ore prevails. The ore has a strong polar magnetism. An average sample, taken by Professor R. Pumpelly from all parts of the lower or main cut, was analyzed by Mr. Regis Chauvenet, of St. Louis, and gave the following result : Insoluble matter 8. 54 per cent. Peroxide of Iron 68.30 " Peroxide of Manganese 19.46 " Sulphur o.oii " Phosphoric Acid o. 102 ' ' As this ore is rich in both iron and manganese, and as the oxides of both these metals are, to all appearance, intimately mixed, this ore is likely to prove a very valuable material for the manufacture of Spiegeleisen, now so extensively used in the Bessemer process. Ores with little iron and much manganese were found by Prof. Pumpelly on Mr. Cuthbertson's land in that vicinity, and analyzed by Mr. Chauvenet, showing Insoluble matter 0.44 per cent. Peroxide of Iron 3 . 30 " Peroxide of Manganese ..83.56 " The above descriptions will suffice to characterize the specular 5 66 IRON- ORES OF MISSOURI ores occurring in the porphyries of the eastern iron-region of Missouri. 2. Specular Ores in Sandstone. I have mentioned above, that the specular ores occurring in the Silurian sandstones in the cen- tral ore-region, have nearly the same mineralogical and chemical properties as the specular ores just described. They differ, how- ever, considerably in one respect. I have alluded to.the alterations which specular ores often undergo, passing either into soft, red hematite, or into limonite, or into carbonates. These alterations have not been spoken of in the special description of the specular ores in the porphyry, because they never take place there. We may find these specular ores, which have originated in the porphyry, in their original position as veins, beds, etc., in the solid porphyry ; we may find them in veins, in the clayish " bluff" of Iron Moun- tain, or broken up into large and small fragments, imbedded in loose detritus in the same locality, or in outcrops, or as surface-ore being exposed to the atmosphere during an incalculable length of time. In no case can we find these ores to have undergone any material changes in their chemical or mineralogical character. On the other hand, those specular ores which have originated in the sandstone are invariably altered when broken up, or when exposed to external chemical influences. These alterations will be more fully spoken of in the following special description of the ores in which they occur, especially in that of the Scotia Iron Ridge and St. James ores. I will however say here, that they take place in three distinctly different directions, depending in each case on the character of the external influence which causes them. First. When certain specular ores are directly exposed to the influences of the atmosphere, or when they are in such a position 1 that both air and water may have access to them alternately, the ores become gradually changed into brown and yellow limonites. Second. When these same specular ores are broken up in larger or smaller blocks, and covered with sandy detritus, so that water or mineral solutions have access to them, while the atmospheric air is more or less completely excluded, the ores become gradually changed into a soft, red hematite, which is in many instances greasy to the touch. Third. When these same specular ores are broken up and in a =tate of gradual transformation into soft, red ores, or else when they SPECULAR ORES. 67 ,are already transformed into soft, red ores, certain mineral solutions containing carbonic acid seem to dissolve the iron under certain circumstances, and to depose it again as carbonate in fissures and cavities, either in the ore itself, thus changing the latter gradually into spathic ore, or in the adjacent rocks. The last-mentioned transformation occurs but rarely, and on a small scale ; the first is more frequent, though not generally very extensive ; but the second is quite common, and has produced thorough-going changes in several important deposits, while no broken-up or disturbed deposit is entirely free from it. The fact that these transformations do not occur in the specular ores which have originated in the porphyry, leads us to consider more closely the dissimilarity, however small it may be, between these ores and those originally imbedded in the sandstone. In doing so, we find that the latter are in the average somewhat softer, their hardness varying from 5^ to 6. They are also a little less silicious, less compact, and more porous. The small, irregular cavities and cracks which are occasionally found in the former are quite universal and more equally distributed in the latter. When sufficiently large, these cavities are also clad with numerous small crystals of peroxide of iron, but they are less frequently filled with quartz or other minerals. Regarding their form, these cavities look somewhat different in the two different kinds of specu- lar ores. While those in the porphyry-ores seem to be produced in part by the removal of minerals formerly enclosed in them, in part by a local crystallization of the mass of the ore, and by the expansion or contraction effected by crystallization, the cavities in the sandstone-ores have more the appearance as if they were pro- duced by a very slow and uniform contraction of the ore, which may have taken place during its consolidation, perhaps by a gradual abstraction of the fluid from which the ore was precipitated. I have the impression that the above slight differences between the two kinds of specular ores of Missouri are sufficient to account for the great difference in their capability of being altered by ex- terior influences. The associated rocks or soils may, however, contribute toward effecting this difference. The porphyry-ores, when broken up or exposed, are generally associated with less pen- etrable, clayish materials, the sandstone-ores with sandy and cherty detritus, which presents an easier passage to water or solutions. 68 IRON- ORES OF MISSOURI, If the existence of numerous small cavities in the mass of the sandstone-ores is not one of the principal causes of the alterations of these ores, the fact that these alterations nearly always start in such cavities certainly proves that their existence greatly facili- tates and promotes transformation of any kind. Franklin County Specular Ores. There are a few occurrences of specular ore in Franklin County, in the neighborhood of Stanton and in the north-west corner of Washington County. The greater part of these ores is not very pure, as far as can be observed from the present condition of the ore-banks. The hard ores are either silicious in themselves or intimately mixed with sand, so much so in one locality as to constitute rather an impregnated sandstone than a real iron-ore. They have a dark, bluish-gray color, a light- red streak, and are slightly magnetic. The soft, red ores, as pro- duced by the alteration of the specular, have a light-red color and streak, are somewhat greasy, and mixed with very fine, clayish substances. They are, however, sufficiently rich for being smelted, Scotia Ores. The specular ore of the two Scotia banks, on the Meramec River, in Crawford County, occurs in various forms and in nearly all stages of transformation. The hard, unaltered ore is in bowlders imbedded in the soft, red ore. The hard ore is steel-gray, with a submetallic, and on fresh- broken surfaces frequently metallic, lustre. It has a finely-crystal- line structure, an even to subconchoidal fracture. Its hardness is 5^ to 6. It is slightly polaric-magnetic. It is pretty uniform in its appearance and structure, but contains those numerous and pretty equally distributed little cavities of which I have spoken above. The Scotia ore is, however, distinguished from all the other known specular ores in the State by the frequent occurrence of larger drusy cavities, which contain botryoidal and reticulated forms of ore, and are covered all over with small, highly-splendent crystals of peroxide of iron, which often have an irised tarnish, and play in all colors, presenting a beautiful appearance. Smaller and larger, well-formed and transparent quartz-crystals, up to one quarter-inch diameter, often of a fine yellow color and of a bright, vitreous lustre, are likewise met with in these irregular cavities, which sometimes reach a length of several inches. Occa- sionally such cavities are filled by amorphous or subcrystalline, SCOTIA ORES. . 69 wax-yellow jasper, enclosing thin seams of white quartz and fine specks of crystalline ore. The soft, red hematite which forms the greater mass of the ore in the Scotia No. I, as far as it is at present disclosed, is not a very uniform material. It breaks with very irregular surface, almost like a conglomerate, and is full of irregular streaks, running in the de- posit more or less vertical, of similar though somewhat differently colored and composed materials. Some of these are red, crystal- line, and glittering, and often silky or greasy, others yellowish brown and earthy. The main body of this ore seems to be an irregular but intimate mixture of these same two materials, which separately form the streaks just described. The hardness of the mass is only 2 to 3. Its streak is red to brownish red. It is not magnetic. Soft, yellow iron-ochre occurs also in big seams through the ore- deposit, and some large pockets of it reach into it from the surface. This ochre is generally very porous, mixed with broken chert or with red loam, and permeated irregularly by very thin seams of subcrystalline quartz. The bowlders of hard specular ore are generally surrounded by a layer of red ore, which has not fully the same degree of softness as the rest of the soft ore. Yet the transition from the hard to the soft ore is here more abrupt than in the Iron Ridge and Meramec deposits, and pieces showing this transition very plainly are com- paratively rare. Nevertheless, all appearances indicate that the red ore has been gradually formed by an alteration of the specular ore, while the ochre seems to be a later product. The deposit called Scotia No. 2 is distinguished by the occur- rence of long and fine stalactites, all of which are, in the greater part of their mass, transformed into red ore. Some of those, however, which are over an inch thick have preserved a specular kernel, though softened to about 4 in the mineralogical scale of hardness. The following two analyses, made by Dr. August Wendel, of the Bessemer Steel Works, Troy, N. Y., will show the composition of the Scotia ores, and also the chemical difference between the hard and the soft ore : I. 2. Hard Specular. Soft Ore. Metallic Iron 69.37 63.15 Silica 0.59 1.52 70 IRON- ORES OF MISSOURI. Alumina . ... o. n 0.76 Magnesia traces traces Phosphorus 0.016 O-IO5, Sulphur 0:058 0.095 Water 0.20 7.95 I. Average sample of the hardest speculur ore from the eastern cut (a) of the Scotia No. I. Looks very pure. Amorphous to sub- crystalline. Hardness, 5^ to 6^. Slightly magnetic. 2. Average sample of soft, red hematite from Scotia No. I., partly red and greasy, partly earthy and slightly greasy, partly yellow ochre, with numerous small specks of specular ore and fine seams of quartz. By calculating the peroxide of iron from the above percentages of metallic iron, we find for No. I, 99.1 per cent. ; No. 2, 90.21 per cent. These analyses show that the hard Scotia specular ore is near- ly pure peroxide of iron and nearly free from impurities, while the mixed soft, red, and ochrey ores contain some quartz, some pro- bably hydrated silicate of alumina, a considerable amount of water, nearly twice as much sulphur and six times as much phosphorus as the hard ore. Nevertheless, these soft ores are quite rich in metallic iron. The chemical changes which have taken place in the specular ore, by its transformation into soft, red ore, consist principally in the introduction of four substances, namely : of hydrated silicate of alumina, which substance very likely produces the greasiness of some of the soft ore ; of water in considerable quantity ; of phosphoric acid, and of sulphur. The three last-named substances are probably in combination with the iron. Quartz has besides been infiltrated into seams in the ochre. From the loose and porous structure of these soft ores, it must be supposed that some oxide of iron has been re- moved, and wa$ partly replaced by hydrous silicates and phos- phates. I shall come back to this subject in speaking of the Iron Ridge and St. James ores, of which similar comparative analyses have been made. The high amount of water in analysis 2 is undoubtedly due to the presence of a considerable quantity of yellow ochre in the sam- ple analyzed. SPECULAR ORES. 71 Specular Ores in the Steelville District. The Steelville ores resemble the Scotia ores very closely, and do not need a special description. Some of the banks of this district seem to be almost entirely composed of hard, specular ore, as the Cherry Valley banks, which, although not yet opened, present that appearance. The ores of some other banks are more or less broken up and altered into soft, red ore, which is here also conglomeratic in its fracture, but less streaky, and more even in its color and general character than the Scotia ore. Distinct crystallization is rarely seen. Stalactitic forms of specular ore, exteriorly converted into red ore, occur at the Cherry Valley banks. Quartz is not often found in these ores. Transformation of surface-ore into brown and yellow limonite is here very frequent, and can be well observed at the Cherry Valley and Ferguson banks. Smaller pieces are often entirely changed. Large bowlders retain a kernel of specular ore with mostly straight and sometimes almost sharp limits, which limits become irregular in such places only, where the small cavities and pores in the specular ore happen to be more numerous. The limonite is much more porous than the specular ore, and a re- moval of iron has evidently taken place during the transformation. The crystalline particles seem to resist this transformation better than the amorphous or subcrystalline ground-mass ; for the limonite contains numerous specks of small, crystalline, specular ore. But the uppermost layer of bowlders is generally free from them, which shows that also these crystals finally become altered. The porousness of the limonite increases toward the surface, and the color gets more yellow, owing to very fine seams of ochre. Close to the specular kernel, the limonite is mostly dark brown, sometimes reddish brown. The cavities in the specular ore near its limit are clad with a brown or reddish-brown, earthy film. With the formation of this film the change evidently begins. This film seems to get gradually thicker and more brown. The small cavities seem to widen and often to run into each other, thus form- ing larger cavities and spongy masses. The limonite partly re- mains brown, partly is altered into yellow ochre, permeating the brown ore irregularly in extremely fine seams. The specular ore close to the limit of the limonite is apparently as hard as ever, and no gradual softening of the ore seems to pre- cede this kind of alteration. 72 IRON- ORES OF MISSOURI. I will add here two analyses of pure specular ores from the Steel- /ille district : Steelville. Cherry Valley. No. i. No. r. Silica 1.84 1.73 Peroxide of Iron 97-49 Alumina 0.07 .... Lime o. 34 .... Magnesia 0.12 .... Phosphoric Acid o. 14 .... Sulphur o.oo o. 16 Metallic Iron 68.24 67.69 Phosphorus 0.061 9-39 The sample from the Steelville No. I bank was analyzed by Dr. Otto Wuth, of Pittsburgh, for the " Iron Mining Company of Missouri," and the result published in the prospectus of this com- pany. The second analysis was made by Dr. A. Wendel, of the Bessemer Steel Works, Troy, N. Y., from an average sample taken by myself at the Cherry Valley bank. Most of the latter sample was a pure, crystalline, specular ore. All of it was magnetic, a few pieces strongly so. These ores are, according to these analyses, very rich in iron, and sufficiently pure for any purpose. In comparing these analyses with those of the Iron Mountain, Scotia, and other ores from de- posits which are opened and mined, it must be borne in mind that the former were made with samples picked up on or near the sur- face, where they may occasionally have taken up some phosphoric acid from the ashes of the grass and brushes, which are purposely burnt off every year in many districts of central Missouri, or some sulphur from the reducing action of decaying plants on solutions of sulphates. Specular Ores on the Upper Meramee River and its Tributa- ries. None of the specular ore-banks in this district are as yet opened to any extent, and my last remark will therefore also apply to them. To judge from the appearance of the surface-ore, some of these banks, as the Winkler, Lamb, Benton Creek, Fitzwater, and Hutchins Creek banks, are likely to contain specular ore almost exclusively, although on all of them superficial transformations into limonite are developed more or less. Others, as the Grover, Ar- SPECULAR ORES. 73 nold, and Smith banks, seem to contain much red ore besides the specular. Both kinds of ore Ifave "here about the same mineralogi- cal character as those in the Steelville district. Pronounced magnetic properties are however, here, more frequent- ly met with. Some of the specular ores from Benton Creek, Fitz- water, Hutchins Creek, and Smith banks are strongly polaric, es- pecially those which are crystalline, or which contain numerous small crystals. Amorphous ores, as they sometimes occur, rarely possess magnetism in an observable degree. Also stalactitic speci- mens are generally unmagnetic. Some black sandstone, strongly impregnated with iron, but giving a light-red streak, from the Benton Creek bank, has distinct polarity. Fine stalactitic forms, "pipe-ores," occur on the Smith bank No. i. Some of these show on their upper side, which was ex- posed to the atmosphere, a beginning of a change into limonite, while a thin layer on the under side, which was imbedded in loam and sand, is changed into soft, red ore. Many of these "pipe-ores" consist of clusters of thin, hollow stalactites, regular pipes, one-eighth to one-quarter of an inch in diameter, with comparatively wide holes and thin walls. They are covered on their inside walls with crystals of peroxide of iron, and on the outside with a thin film of dark-yellow limonite. The struc- ture of these thin stalactites, whether hollow or massive, is generally crystalline and granular, rarely radiated. But they are sometimes surrounded concentrically by larger stalactites, in whose hollow in- terior they lie like a casting in the mould. These larger surrounding stalactites have always a radiated structure. They never close tight to the kernels which they surround. There is always a cylindrical space between the inner wall of the large and the outside wall of the small stalactite. This space is either empty, in which case both walls are covered with small crystals of oxide of iron, or it is filled with soft, red ore, perhaps produced by the alteration of such crys- tals. This cylindrical space is sometimes very narrow and nearly filled up with splendent crystals. Thus the fracture of the stalactite shows sometimes a small, round, crystalline surface in the centre, surrounded first by a thin, annular layer of more loose and much more splendent crystals, and outside of this by a thick layer of less bright ore with a radiated structure. These formations sometimes 74 IRON- ORES OF MISSOURI. repeat themselves. A specimen I found on the Cherry Valley bank, where they are, however, less frequent, has five layers of radi- ated ore, alternating with thin layers of either splendent crystals or soft, red ore. The whole stalactite, thus composed, is divided in two halves by a thin crack, running across all the layers and through the thin central kernel, and being filled with the same splendent crystals which form some of the annular layers. The whole stalac- tite is exteriorly converted into soft, red ore, and lies loose in a con- formable cavity in a piece of specular ore, the wall of which cavity is also covered with a layer of red ore. Stalactites split lengthways, by a thin crack, partly filled with fine crystals of oxide, have also been found at the Scotia No. 2 bank, of which I have spoken before. I add two analyses of ores from the upper Meramec district : I. 2. Silica 0.98 17-97 Peroxide of Iron 98.62 .... Alumina 0.05 .... Lime 0.19 .... Magnesia 0.08 .... Phosphoric Acid 0.076 .... Sulphur o.oo 0.21 Metallic Iron 69.03 56.01 Phosphorus 0.033 0.098 Analysis I was made by Dr. Otto Wuth, of Pittsburgh, for the " Iron Mining Company of Missouri," and published in their pros- pectus. The specimen was taken from one of the Smith banks, and was evidently a very clean piece of specular ore. Analysis 2 was made by Dr. A. Wendel, of Troy, N. Y. , from an average sample of the various kinds of rich and poor surface-ore, taken by myself at the Benton Creek bank. This sample consisted only of one half-inch good specular ore. The other half was mostly a dull, black, uncrystalline, very hard, brittle, and silicious ore, mixed with some hard, grainy, and sandy ore of a black color and of a weak, resinous lustre. The object of this analysis was principally to see whether these silicious materials, which sometimes occur, especially at the outskirts of specular ore-banks, are worth smelting, as I sup- SPECULAR ORES. 75 posed they were from their color and weight. The result of the analysis shows that these materials are yet quite rich in iron, though less pure in regard to phosphorus and sulphur. Clean spec- ular ore, from this and all other localities in this district, would un- doubtedly analyze as favorably as the above specimen I. Specular Ores in the Salem District. Most of the ores of this district seem to be unaltered specular, corresponding in their pro- perties to the general characteristics of this ore. The small, irregular cavities are very distinct and numerous in them, having sometimes the form of short cracks, wider in the middle and thinning out to- ward both ends. Alterations into soft, red ore can be observed on the Arnold, Jamison, Pomeroy, and Taylor banks, and very fine alterations into limonite on the Simmons Mountain, and on the Arnold, Taylor, and Pomeroy banks, in the latter two on a pretty large scale. Fine specimens of specular ore with a mossy and reticulated structure are sometimes found on Simmons Mountain. The following observations I made in this district will throw some light on the paragenesis of the various materials connected with the specular-ore deposits in sandstone : I found on the Arnold bank botryoidal and mammillary forms of specular ore, clinging directly to a slightly ferruginous but other- wise unaltered sandstone, composed of coarse, loose grains with hardly any cement. The grains are slightly red, apparently from a thin film of red ore deposited on their surfaces. The specular ore is superficially converted partly into red ore, partly into brown limo- nite. A specimen from the Taylor bank shows wax-yellow jasper of the same description as that observed at the Scotia bank, filling ir- regular and reticulated cavities in the ore. Other cavities in the , same specimen are filled with transparent quartz. A specimen from the Jamison bank represents a conglomerate of irregular grains of ore, each of which is either partly or wholly surrounded by a variable layer of fine-grained, yellow sandstone adhering to it. They are cemented together by a coarse crystalline, transparent or white quartz. Infiltrations of transparent quartz in the massive specular ore are frequent on the Jamison bank and on the Simmons Mountain. This infiltration seems to be accompanied or followed by a recrys- 76 IRON-ORES OF MISSOURI. tallization of the ore, or by an alteration of enclosed particles of specular ore into loose aggregates of splendent ore-crystals. The limonite on the Simmons Mountain is, as most metamorphic limonite, full of pores and of large holes. These holes frequently contain infiltrations of crystalline quartz. Splendent ore-crystals, of a flat, rhombohedric form, are found lying on the quartz. Such ore-crystals are also seen there, lying on films of limonite which cover specular ore. Some of those rhombohedric crystals are themselves again exteriorly, or thoroughly, changed into brown limonite. The porous limonite on the Pomeroy bank contains yellow ochre in its seams and cavities. When these observations are held, together with others mentioned previously, and with the following that the Scotia ores contain seams of wax-yellow jasper in specular ore, seams and specks of crystalline, transparent quartz and of splendent ore-crystals in the yellow jasper, seams of crystalline quartz in yellow ochre, and rhombohedric ore-crystals lying on drusy, crystalline quartz we come to the conclusion that the order in which these various min- erals have come into existence, beginning with the oldest, is as follows : 1. Sandstone, white or yellow. 2. Sandstone, colored by, or impregnated with, oxides of iron. 3. Massy specular ore. 4. Yellow jasper, perhaps simultaneous with the latter. 5. Soft, red, and greasy ore. 6. Brown limonite. 7. Yellow ochre. 8. Transparent, crystalline quartz. 9. Rhombohedric, splendent ore-crystals. 10. Red and brown incrustations of these crystals. The specular ores of the Salem district are decidedly more mag- netic than any I have mentioned, with the only exception of those from Shepherd Mountain. As the ores in the Upper Meramec district are more magnetic than those in the Steelville district, it is evident that there is a gradual increase of magnetism in the ores, from north to south, from the northern boundary of Crawford County toward the central part of Dent County. Here, however, as in the Iron Mountain and Shepherd Mountain, the magnetism SPECULAR ORES 77 seems to have its seat principally near the surface of the ground. Specimens taken from the south-eastern ore-shaft on Simmons Mountain, about twenty feet below the surface, are nearly unmag- netic, while the ore near the surface in the same locality is dis- tinctly polaric, some of it so strong that pieces two or three inches thick act on the needle from a distance of one to two feet. Pieces from the surface, which are, in the greatest part of their mass, con- verted into limonite, and contain only irregular and rough seams of specular ore, cropping the limonite in various directions, show nevertheless distinct polarity. Wholly converted pieces are un- magnetic. Magnetic but unpolaric pieces are comparatively rare, and generally attract the south pole and repulse the north pole of a compass-needle. Also stalactitic specimens possess polarity, the polar axis being parallel to the position of the stalactites. The specular ores from the Pomeroy, Taylor, Orchard, Jamison banks, and the " pipe-ore " from the Wiggins bank, have mostly a very strong polarity. Quartz-infiltrations seem to diminish the mag- netism. In the Salem district, as everywhere else in Missouri, unaltered specular ores contain very little sulphur and phosphorus, besides being very rich in metallic iron. The following analyses are proofs of this very important fact : i. 2. 3. 4 . 5 . Arnold Simmons Jamison Wiggins Huzzah Bank. Mountain. Bank. Bank. Bank. Silica 4.12 1.41 0.94 0.87 2.64 Peroxide of Iron. ... 95.24 98.14 98.62 98.96 97.26 Alumina o. 1 1 0.06 0.06 Lime 0.33 0.24 0.23 Magnesia 0.15 o. n 0.08 Sulphur o.oo o.oo o.oo trace trace Phosphoric Acid .... 0.052 0.038 0.07 Metallic Iron 66.66 68.69 69.03 69.27 68.08 Phosphorus 0.023 0.016 0.031 0.027 -3 All these analyses were evidently made with clean specular speci- mens. Protoxide of iron was not determined, although undoubt- edly present in determinable quantity, to judge from the mineralo- gical properties of these ores, and from the fact that it is invariably ;8 IRON- ORES OF MISSOURI. found in such ores when sought. Analyses I, 2, 3, and 5 were made by Dr. Otto Wuth, of Pittsburgh ; analysis 4 by Messrs. Chauvenet and Blair, of St. Louis. The three first analyses were made for the " Iron Mining Company of Missouri," and published in its prospectus ; the last two for Mr. O. A. Zane, of St. Louis, who kindly put them at my disposal. Iron Ridge Ores. Unaltered specular ores from Iron Ridge are similar to the Scotia and Steelville ores in their general mineralogi- cal character. They are rather more porous, and contain frequently enclosures of crystalline, transparent quartz. They are less mag- netic than the Steelville ores, and as Iron Ridge is situated north of Steelville, they present a further proof that the magnetism of the ores in the central ore-region decreases toward the north and in- creases toward the south. Pieces of over three inches' diameter do not deflect a compass-needle. Fine ore-powder is, however, some- what attracted by a magnet, especially the crystalline and glittering particles. The red ore is unmagnetic. By far the greater part of the ore from the Iron Ridge No. I is softened, and altered into a red and frequently clayish hematite. The transition from the specular to the red ore can be observed in the bowlders which are imbedded in the soft mass of ore, which principally constitutes the deposit. When these bowlders, which are sometimes two or several feet in diameter, are broken, the interior is seen to consist of a some- what porous but pretty hard specular ore, of bluish-gray color, and composed of a subcrystalline matrix with little lustre, and of nume- rous very small and splendent crystals. Toward the outside of the bowlder the matrix gets softer, more porous, and disappears by degrees, leaving finally a spongy agglomeration of glittering black crystals. This black, crystalline zone in the section of a bowlder is from one-eighth to one-half inch thick. It is surrounded by and passes into a similar crystalline and glittering zone of red color, one-half to one and a half inches thick, which itself gets gradually less bright, then more and more greasy, then mixed with specks and flakes of white clay, and finally turns into a soft, clayish, dull and pale, red hematite, of which a considerable part of the deposit is composed. The gradual disappearance of the matrix, and the appearance of the clay, are in many bowlders very plain and unmistakable. These two changes are, however, not simultaneous. The white clay is never IRON RIDGE ORES. 79 seen in the black crystalline, and rarely in the red crystalline, zone. The following analyses, made by Mr. Andrew A. Blair, of St. Louis, will show the chemical changes accompanying this interest- ing transformation : i. 2. 3. Silica 0.69 O.68 8.39 Peroxide of Iron 97-94 97.08 88.37 Protoxide of Iron trace 0.31 .... Alumina 1.17 1.50 .... Hygroscopic Water. . . . 0.02 0.08 .... Combined Water 0.19 0.23 3-O9 Carbonic Acid o.oo 0.21 .... Sulphur o.oo o.oo traces Phosphoric Acid p. 068 0.079 0.207 Metallic Iron 61.86 Phosphorus .... 0.091 The samples I and 2 are taken both from the same bowlder, which had a diameter of over 3 feet. Sample I is specular ore, pure, porous, very little softened, from the centre of the bowlder. Sample 2 is from the outside of the bowlder, more than a foot from the central part, where sample I was taken, and consists of soft, crystalline, glittering, and somewhat greasy red ore. Sample 3 is an average sample, taken from all parts of the mine, and containing some specular but mostly soft ores of all varie- ties. We see from the first analysis that the unaltered specular ore from Iron Ridge is free from sulphur, and has but little phosphorus, and is very rich in iron. The second analysis shows an increase in protoxide of iron, alu- mina, water, and phosphorus, and a small amount of carbonic acid. The latter is probably combined with the protoxide of iron, being just about as much as is necessary to make carbonate of iron. This would indicate that carbonic acid might have something to do with this transformation, perhaps by dissolving and removing the ma- trix. As the alumina has increased, while the silica has not in- creased, we must suppose that either some alunv'na was added and 80 IRON- ORES OF MISSOURI. combined with some of the silica already present, or that some silica was removed and replaced by water, so as to form a hydrated silicate of alumina, which, I think, produces the greasy appearance and touch. Some of the alumina may be or may have been in combi- nation with phosphoric acid. The analysis 3 proves that the soft and fully transformed ore is not nearly as pure as that in the bowlders a conclusion which we had already drawn from the comparative analyses made with the Scotia ores. Specular Ores in the St. James District. The ores in the St. James district are, when fresh and unaltered, very similar to the unaltered Scotia and Iron Ridge ores. They are, perhaps, a little less porous and a little more magnetic. They occur in very vari- able conditions and alterations. The Meramec bank is especially interesting in this respect. There we find very pure and clean ore, generally somewhat soft- ened ; we find very hard and silicious ore, containing in its cavi- ties transparent, crystalline quartz and yellow jasper ; we find soft, red hematite in all stages of transformation ; we find greasy paint- ores in various colors, from light red to dark purple ; we find brown and yellow ochres, and porous, soft limonites, with seams of a very fine and uniform reddish-brown clay ; we find the spathic iron- ore in specks and seams in red ore and in a peculiar, very dense, yellow, ferruginous limestone ; we finally find ferruginous chert-conglome- rates and sandstones, impregnated with iron-ore, or intimately mixed with brick-red and yellow ochres. As the Meramec bank was found to contain so many varieties of ore, it seemed to present a fine opportunity for comparative analyses. As, however, time and means would not allow to have a large series of analyses made, five of the most characteristic specimens were selected for this purpose. They were analyzed by Mr. Andrew A. Blair, of St. Louis, with the results given in the following table, under I, 2, 3, 4> 5- The two analyses 6 and 7 are taken from a pamphlet, entitled " Contribution to a Knowledge of the Iron-Ores of Missouri," published in 1872 by Prof. Charles P. Williams, Director of the School of Mines of Missouri. They refer to other ores from this district. ANALYSES OF SPECULAR ORES. 81 Insoluble silicious matter. Peroxide of iron i. 97-23 MERAME 2. c BANK. 3- 11.19 85-95 0.77 0.97 0. 12 0.07 0.48 0.46 O.I26 o. 116 o.oo 100.252 60.76 0.0; i 4- 9-30 76.45 I3-65 O.O52 0.478 5- 6. 7- 27.40 4.II 36.01 29-5I 2-45 0.044 0.098 84.463 0.783 7.278 trace 0.114 trace trace 0.050 0-153 0.360 49-245 1.203 none 0-374 o.ooo 0-530 0.087 0.022 0.109 O.2I3 Alumina Lime Water, combined 0.47 o.oo 0.092 0.03 O.OO 0.089 Sulphur Phosphoric acid Manganous oxide Metallic iron . 68.06 61.54 0.0^9 53-51 0.208 22.38 0.047 59-733 0.066 35-397 0.047 Phosphorus . . , , o. 040 Silica 2.06 Alumina Lime Magnesia Insoluble Silicious Matter. 11.32 9.78 6.78 0.27 6.686 46.330 o. oo .... .... 0.12 11.23 1. Is an average sample of the best ore found in the Meramec mine. It is a somewhat softened and slightly altered specular ore. 2. Is a hard and silicious specular ore from bowlders in the cen- tral and upper part of the Meramec bank. 3. Is a soft, greasy paint-ore of purple color, from pockets in the Meramec bank. 4. Soft and ochrey, porous limonite, brown and yellow, with some thin seams of very fine, brown clay from the outside of some of the bowlders in the Meramec bank. 5. Pretty dense but soft, red ore, and hard, yellow limestone, mixed, both containing crystalline, spathic ore in numerous specks and seams, from the lower part of the Meramec bank. 6. Is an ore from T. 38, R. 6, Sec. 33, probably the " Santee and Clark's bank." Prof. Williams describes the specimen thus : " Mammillary and concretionary, with concentric layers, the cen- tral one being the blue-specular variety, the second of the brownish- red hematite, and the outer one a thin coating of brown hematite, probably limonite." 7. Is from T. 38, R. 6, Sec. 29, probably the "James bank." Prof. Williams describes the specimen as " finely granular, com- pact, brownish-red ore." The analysis I shows that the clean specular ore, although in this 82 IRON-ORES OF MISSOURI. case slightly decomposed or altered, is very rich in iron, free from sulphur, and does not contain much phosphorus. Analysis 2 shows that the harder and more silicious ore, when it has the natural color and brightness of a true specular ore, does not contain any more sulphur and phosphorus than the ore which is not silicious. A complete analysis has been made of sample 3, principally for the purpose of finding out whether the supposition, made above, that the greasiness is produced by a small admixture of very fine and perhaps hydrated silicates of alumina, holds good, or what else may cause it. The result of the analysis does not suggest any other cause, but seems to support the above supposition. As in the 2d of the Iron Ridge analyses, we also meet here with a small amount of carbonic acid, and with a corresponding amount of pro- toxide of iron, so as to suggest the probability of the presence of carbonate of iron, and to lead us to the belief that carbonic acid is one of the agencies which effect, or at least prepare, the transform- ation of specular into red ore. Another interesting feature in this analysis is, that the percentage of phosphorus is increased but little, when compared to analyses I and 2, and that the increase is about in the same proportion as that from No. I to No. 2 of the Iron Ridge analyses. It seems therefore probable that the paint- ore is nothing else but the crystalline and glittering red ore (similar to the Iron Ridge sample 2), in a crushed and compressed condi- tion. The comparatively large amount of sulphur in analysis 3 is also remarkable, and explains the purple color, which is undoubted- ly produced by sulphides of alumina, lime, magnesia, and perhaps of alkalies in minute quantities. Analysis 4 gives the practically important result that the yellow ochre contains a very large amount of phosphorus, much larger than any of the other hard or soft ores. Analysis 5 proves that the peculiar hard, yellow rock in which the spathic iron-ore frequently occurs, is a very dense carbonate of lime, probably mixed with some silicate and phosphate of lime, and with some peroxide of iron. This rock, as well as its enclosures, would deserve a repeated chemical examination, separate from that of the red ore, with which it was mixed in sample 5. Analyses 6 and 7 are interesting, because, considering the min- eralogical description of the specimens, they fully agree with and ANALYSES OF SPECULAR ORES. 83 confirm the results of all the analyses of ores given in this report, and lead to the same conclusions and views regarding those ores. Specular Ores in the Rolla District. The Rolla ores are nearly all more or less altered, or at least softened, though many not so much as to lose entirely their specular appearance. Most of them consist of specular and of soft red particles intimately mixed. They do not attract the needle perceptibly, but are attracted by a magnet partially, when powdered fine. Their porosity is very unequal in different parts of a piece or bowlder. Some parts are dense, while others contain irregular cavities up to an inch in length and one- quarter of an inch in width, clad with crystals, or, more frequently, with a film of red ore. Such ores are those from the banks on Big Beaver Creek. They pass into red ores, softening at first, and then changing their color into dark red, and finally getting earthy and lighter red. The ores in the immediate vicinity of Rolla are mostly thus transformed, and besides frequently mixed with spathic iron- ore in specks and seams. This spathic ore sometimes occurs in larger masses, and is then accompanied by white or light-gray clay, enclosing well-formed crystals of iron pyrites, either single or in bunches. The following analyses were taken from Prof. Charles P. Wil- liams's " Contribution to a Knowledge of the Iron-Ores of Mis- souri " : Fe ide C ofIro d n). ! Pe X . } **** 97*572 45*968 77*905 83*275 Ferrous Oxide (Pro- j ^ Q ' ' 684 a4 l8 '9 88 2 - 2 5i 1.206 toxide of Iron) . . . Manganous Oxide ...... 0.252 0.265 ...... o.ooo 0.715 Alumina .............. O-I99 0.802 ............ traces Lime ................. 2.097 0.568 0.289 ...... traces Magnesia ............. trace o. 166 trace ...... traces Silicic Acid (Silica) ..... 2.951 1.144 I-I59 ...... 3-99 Carbonic Acid .......... ..... trace ................. Phosphoric Acid. '. ..... 0.249 -35 0.281 0.033 -3i5 Sulphur ............... trace 0.009 trace 0.094 o.ooo Combined Water. . trace 100.981 Metallic Iron 63.306 68.6n 46.944 56.283 59.220 Phosphorus 0.109 0.015 0.122 0.014 0.137 The empty spaces in the above table, as well as in all the pre- 84 I RON- ORES OF MISSOURI. ceding ones, indicate in each case that the respective substance was not determined. The various specimens are described by Prof. Williams as follows : 1. From T. 36, R. 7, Sec. 26 (perhaps the Hyer bank). " Blue specular mixed with brownish-red hematite, and containing some limonite and spathic iron." 2. From T. 37, R. 8, Sec. 33 (perhaps the Beaver Creek bank). " Blue specular ore, finely granular and compact ; powder gives particles attracted by the magnet." 3. From T. 37, R. 8, Sec. 20 (perhaps the Buckland bank). " Mixed spathic iron and limonite, with some blue specular ore ; powder slightly magnetic." 4. From T. 37, R. 8, Sec. 21 (perhaps the Kelly bank, No. 2). No description of this sample is given. It was probably a silicious specular ore. 5. From T. 37, R. 8, Sec. 15 (perhaps Taylor's Rolla bank). " Brownish-red hematite, somewhat cellular, slightly magnetic." In comparing these descriptions with the above analyses, we see that the samples I, 3, 5, which enclosed some red hematite, limonite, and spathic ore, contain much more phosphorus than the pure specular ores 2 and 4. Analyses I and 2 show that the specular ores from the Rolla district are as rich in iron as any in central Missouri, and analysis 2 shows that, in an unaltered state, they are nearly free from injurious ingredients. As the same observations have been made regarding the ores of all the other districts, we may infer that these observa- tions are generally true, and generally applicable to all specular ores that have originated in the Silurian sandstones of Missouri. Gasconade and Miller County District. The specular ores on the Gasconade River, and in Miller and Camden Counties, are similar to those above described. Some ores near Linn Creek are almost entirely unmagnetic. The specular ores found south of Tuscumbia seem to be very pure, to judge from the following analysis made by Messrs. Chauvenet and Blair, of St. Louis, of a sample from the west bank. This analysis was kindly furnished to me by Mr. M. S. Cartter, of St. Louis : CALL A WA Y CO UNTY HEM A TITES. 8 5 Insoluble 1 1.077 Peroxide of Iron 88. 52 Sulphur trace Phosphorus trace Metallic Iron 61.96 b. RED HEMATITES. A general description of the red hematite found in the carbonif- erous formation of Missouri has been given in the introduction to the third chapter of the present report. According to that descrip- tion there are three varieties of this ore, namely : one, dull-red, soft, earthy, and frequently coarsely porous to spongy, and uneven in the fracture ; another, dark, bluish gray, sometimes with a slight submetallic lustre, hard, dense, and compact, with very fine grain, and with a subconchoidal fracture ; a third, coarse grained to oolitic, the grains being of the compact ore, and surrounded and cemented by the earthy ore. The earthy variety is the most common. The other two varieties have only been observed in Callaway County. The earthy ore sometimes encloses spathic iron-ore. When ex- posed to atmospheric influences it is altered into limonite. Callaway County Hematites. The red hematites in the sub- carboniferous strata of Callaway County occur in the most variable forms. The "Old Digging" and "Murphy's Hill," five miles south-east of New Bloomfield, contain some handsome, coarsely oolitic ore, besides the earthy hematite. The ores from the vicinity of New Bloomfield are mostly com- pact and heavy, some bluish gray, others dark red. They frequently show a thin stratification. They are also found in concretionary forms, and seem occasionally to pass into the earthy hematite. They sometimes enclose spirifera and other fossils. Some of the ore on the Henderson bank has an earthy or a finely oolitic struc- ture. The ore on the Knight bank, near Fulton, is in part dense and concretionary, in part earthy. The latter has a light-red color and streak, and is especially distinguished by the admixture of a large amount of spathic iron-ore in ^specks and seams. Concretions of this ore are hard, and sometimes reach the mineralogical hardness 6. Spongy hematites are rarely found in Callaway County. 86 IRON- ORES OF MISSOURI. The following analyses were made by Mr. F. Emmerton, of the Joliet Iron and Steel Works, and were put at my disposal through the kindness of Mr. A. B. Meeker, of Chicago : ^NEW BLOOMFIELD ORES. KNIGHT BANK. i. 2. 3. Compact Earthy Variety. Variety. Metallic Iron 63.87 61.17 53-o Silica 5.80 8.63. Phosphoric Acid o. 10 0.165 1-87 Sulphur 0.017 0.018 The specimen 3 was of the red, earthy kind, mixed with spathic iron, as above mentioned. This ore is probably altered, and has taken up a considerable percentage of phosphorus, besides the car- bonates. The analyses I and 2 show that the dense as well as the earthy varieties of these ores, when unaltered and free from carbo- nates, do not contain a large amount of injurious ingredients, and are very rich in iron. Hematites in St. Clair and Henry Counties. The red hematites in the north-eastern corner of St. Clair County, and those in the southern and eastern portions of Henry County, seem to belong ex- clusively to the soft, earthy, and spongy variety, and are very fre- quently and extensively altered into soft, spongy, brown or yellow limonites, as far as can be judged from the present appearance of the banks, none of which are as yet opened. The following analysis was made by Mr. A. A. Blair, of St. Louis, from a mixed sample of soft, spongy, partly red but mostly brown hematite, from the Marmaduke bank : Peroxide of Iron 84.02 Silica 3.08 Phosphoric Acid 0.861 Sulphur 0.171 Water 10.98 Metallic Iron. .'.' 58.81 . Phosphorus o. 376 This ore has a high percentage of metallic iron, but is not very pure in regard to sulphur and phosphorus. As the specimen had LIMONITES. 87 to be taken from the surface, where the ore had been in contact with the soil and its vegetation for a long period, and as it was al- most entirely altered into limonite, it may be expected that the ore to be found in the hematite banks of this district, when opened, will contain a much smaller quantity of these substances, and will prob- ably also prove richer yet in iron. C. LIMONITES. I have given a general description of the Missouri limonites in the introduction to the present chapter (III.), to which description I must here refer. From that it would seem that two different varieties could be distinguished, the porous and the stalactitic. This is, however, not really the case. Indeed, if we inspect those limonites, which apparently consist of one coherent though porous mass, more closely and more carefully through a magnifying glass, we find them almost invariably composed of single, but densely- packed, round, stalactitic columns, and we find also that the pores, which are seen by the naked eye, are generally interstices left between such stalactites, or between less regular mammillary or botryoidal forms. These pores are distinguished from those found in the specular ores of central Missouri, by sharper and smoother outlines, curved toward the inside of the cavity, thus forming very sharp angles, which point, not in two opposite directions only, but always in several directions. We may therefore say, in general, that all the Missouri limonites, with the exception of some of those produced by transformation of specular ores, are of stalactitic structure and origin. The appearance of the pores and cavities does not, however, present a perfectly reliable means by which the original limonites might be distinguished, in all instances, from those produced by the alteration of specular ores, for two reasons : first, because the specular ores occur themselves not unfrequently in stalactitic forms, similar to those of the original limonites ; second, because both kinds of limonites, and especially those produced by alteration, often lose their original structure entirely, through the influence of atmospheric agencies, both kinds becoming thereby either irregu- larly streaky or more or less spongy. Ores in the South-eastern Limonite District. Several limon- ite deposits, situated along the Mississippi River, have been favorably 88 IR ON- ORES OF MISSO URL reported on by Dr. B. F. Shumard, in his geological reports on St. Genevieve, Perry, and Cape Girardeau Counties, which reports will be found in the second volume of the present (third) Annual Report of the Geological Survey of Missouri. I have inspected but one locality in this district, namely, the Col- lins bank in Perry County. The limonite which occurs there is very dense, hard, and apparently silicious, and is frequently mixed with fine chert-breccia. It is also found as an impregnation of sand- stone. The ores in the vicinity of Irondale, Washington County, are in part hard and botryoidal or reniform, in part soft and ochrey. They sometimes contain splendent quartz in seams. The richest part of the south-eastern limonite district is in the southern portion of Iron, Madison, and Bellinger Counties, and in Wayne County. Most of the limonites, which are found abundantly in these counties, are hard', compact, and massive, yet showing dis- tinctly their stalactitic origin in the structure. The Cornwall limo- nites are softer and more ochrey than the others, but pretty free from foreign mechanical admixtures. The ores found east of Marquand and Marble Hill are hard, and in many places very pure, while in others they seem to be more silicious, and enclose fragments of white chert, and then resemble somewhat the above-described limonites of Perry County. The following analyses will show the chemical composition of the south-eastern limonites : I. 2. 3. Peroxide of Iron 72.58 81.40 80.98 Silica 5.84 3.01 1.98 Sulphur 0.17 0.07 o.oo Water 14.96 11.78 Metallic Iron 50.81 56.98 56.68 Phosphorus 0.34 0.15 0.123 The two first analyses were made by Dr. August Wendel, of the Bessemer Steel Works, Troy, N. Y., the third by Messrs. Chauve- net & Blair, of St. Louis. I owe the latter to the kindness of Mr. H. S. Reed, of St. Louis. Sample I was an average sample taken at the Ford bank, near Cornwall, and consisted of one-third hard limonite, and two-thirds soft limonite, mixed with some ochre. LIMONITES. 89 Sample 2 was a hard, dense ore of stalactitic structure, from the Francis bank, 6 miles south of Marble Hill. Sample 3 was a hard limonite, from the vicinity of Marble Hill. We see that these ores, although less rich and less pure than the specular and red ores, are, however, good and valuable. We also see that the hard limonites are purer than the soft, ochrey ones. Franklin County Limonites. The Moselle limonites, and the brown ores south of Stanton, have mostly a dark color, and are partly hard and dense, partly soft and not unlike a fine sponge. A few banks in the vicinity of the Moselle Iron Works are distin- guished by the reniform structure of their ores. These are com- monly called " kidney-ores." The single kidneys are sometimes several inches in diameter, and have walls, half an inch thick, of very hard, dark-brown limonite, passing, toward the outside, into an ochrey clay. The hollow space inside these kidneys frequently contains rounded pieces of a very fine, hardened clay of white or yellowish color. Admixtures of chert are not often seen in this district. But in some localities heavy-spar is mixed with the ore. Also pseudo- morphs after pyrites occur, some of which contain undecomposed masses of this mineral in the centre. The following analysis was made by Dr. August Wendel, of Troy, from a specimen of hard, dark-brown limonite, containing fine, irregular pores, evenly distributed, from the Bowlen bank, south-east of Moselle : Peroxide of Iron 81.38 Silica 2.88 Sulphur 0. 13 Water 1 1 . 70 Metallic Iron 56.97 Phosphorus o. 1 2 This analysis has a great resemblance with that of the Francis bank ore, as given above. A good specimen from the Blanton limonite bank, 10 miles south of Stanton, was analyzed by Mr. A. A. Blair, and con- tained 90 IRON-ORES OF MISSOURI. Peroxide of Iron 84.16 or Metallic Iron 58.91 Limonites in the Central Ore-region. A look on the ore-bank map which accompanies this report will show that the central ore- region contains a number of limonite deposits, besides its numerous deposits of specular ore. These limonites resemble those of Frank- lin County very closely. Some such ores in the Steelville district are very clean and uniform, while some on the tributaries of the Upper Meramec are occasionally mixed with white chert. Heavy- spar has not been found with the limonites of this region. Also pyrites occurs rarely. Limonites on the Osage River. The western ore-region of Missouri, on the Osage River, contains almost exclusively limonites. Those on the Lower and Middle Osage River, nearTuscumbia, Linn Creek, Boulinger Creek, and Warsaw, are mostly fine, pure ores of medium hardness and of a very favorable degree of porosity. Their structure is very distinctly stalactitic, and true stalactites are frequently met with on some banks in considerable quantities ; as, for instance, on the Indian Creek, on the Elm Hollow, and on some banks near Tuscumbia. These stalactites are generally round in section, long and thin. Their diameter varies from --$ to inch. They are always massive, and are formed of a dense and hard, grayish-brown ore. They do not show a crystalline structure in their fracture; but the surface is almost invariably covered with small pseudomor- phous crystals after pyrites or after marcasites. In some in- stances these crystals are larger, up to ^ inch in diameter, and con- stitute the main portion of the stalactitic individuals, which then appear externally to be altogether composed of aggregated crystals. The single stalactites are themselves aggregated either in bunches or in wavy sheets. The inside of bunches sometimes consists of sulphide of iron ; in most cases, however, they are entirely changed into limonite. That ore, which forms large coherent bodies, and which is much more common than the true stalactites, is also of stalactitic origin, to judge from the shape and distribution of its pores and cavities, and was undoubtedly deposited in caves, from solutions which have been infiltrated from above. The Osage ores are mostly free from foreign matter. In a few LIMONITES, gi localities only, chert is found mixed with the ore. The walls of the small cavities are generally covered with a layer of brown and yellow ochre. Larger masses of ochre have not been discovered. While the ores on the Lower and Middle Osage, which I have just described, occur on the Silurian limestones, the limonites on the Upper Osage, above Warsaw, are found on the subcarboniferous limestones, and are also somewhat different mineralogically. They have a very dark, sometimes nearly black, color. The stalactitic structure is less common and less distinct than many of the other limonites occurring on limestones in Missouri. On the other hand, botryoidal and mammillary forms, consisting of numerous thin and parallel layers of dark-brown ore, are very frequent. The single layers peel off from each other easily, and are sometimes naturally separated from each other by fine, empty fissures with rough sur- faces. The massy ore, which is more common, is often spongy in the fracture, and is mixed irregularly with small botryoidal masses and seams of a soft but splendent limonite, of nearly black color and of vitreo-metallic lustre. The chemical composition of the Osage limonites will be seen from the following analyses, made by Mr. Andrew A. Blair, of St. Louis. The first analysis was kindly furnished to me by Mr. M. S. Cartter, of St. Louis : Middle Osage. PP er Osage. Osage. I. 2. 3. 4. 5. Peroxide of Iron. ... 67.07 82.02 84.10 ..... 77-42 Manganese .............. ..... ..... ..... o.oo Silica .................... 5.13 3.59 ..... 8.05 Phosphoric Acid ......... 0.091 0.077 0.084 0.076 Sulphur ................. 0.015 -OO 0.084 0.147 Water ................... 12.80 11.60 ..... 12.49 Insoluble matter.... 14.27 ..... ..... ..... .... Metallic Iron ....... 46-95 57.41 58.87 ..... 54-19 Phosphorus ............. 0.041 0.034 0.037 0.034 1. Soft, earthy limonite, from the Laclede bank, near Tuscumbia. 2. Hard limonite, with a stalactitic structure, the pores filled with yellow ochre ; from the White bank, near Boulinger Creek. 92 IR ON- ORES OF MISSO URL 3. Loose pipe-ore, broken stalactites, from the Indian Creek bank, near Warsaw. 4- Stalactitic aggregate of pseudomorphous crystals of limonite after marcasite, from the Elm Hollow bank, near Warsaw. 5. Average sample of ore from the Sheldon bank, on Bear Creek ; in part a moderately hard, brown limonite, containing some yellow ochre in its pores ; in part a very dark, nearly black, mammillary limonite; in part a spongy limonite, with dark-brown, submetallic seams. All these ores are rich in iron, and contain but little sulphur, while the percentage of phosphorus is so low that they can, in this respect, almost be compared with the specular ores. These limo- nites on the Osage River are indeed remarkable for their chemical purity. It is also apparent, from the above analyses, that there is no difference in this respect between the stalactites and the massy ore. Analysis 4 was made for the purpose of investigating whether pseudomorphs after sulphides do not contain a considerable amount of sulphur. The result shows that such pseudomorphs may be as pure as the rest of the ore. As a part of sample 5 looked nearly black, it was supposed that it might contain some oxide of manganese. The analysis, however, showed that this is not the case. CHAPTER V, IRON-ORES OF MISSOURI. BY ADOLPH SCHMIDT, PH.D. C. Modes of Occurrence and Descriptions of Deposits. WE have seen in the preceding chapters, II. and III., that two principal mineralogical species of iron-ores are represented in Missouri - the hematite and the limonite and that the hematite occurs in two very different and distinct varieties, the specular ore and the red hematite. We have, moreover, seen in section A that the specular ore occurs either in porphyry or in sandstone ; that the red hematite forms strata in the carboniferous system ; and that the limonite is generally deposited on limestone. This gives us four classes of original ore-deposits. I have mentioned, in the same connection, that the deposits of specular ore in sandstone are very frequently found to be disturbed and broken, and altered in regard to their position. Some of them, according to their present appearance, seem to be broken up entirely, and their parts and fragments seem to be drifted some distance, and to be deposited a second time, either irregularly or in alternate layers, with the sandy and cherry detritus produced by the destruction of sandstones and limestones. Such is the present appearance of many specular-ore banks, as well as that of some deposits of red hematite and of limonite. Very few deposits of this character, however, have been opened, and none of them are as yet sufficiently opened and worked to allow a clear insight into their structure and formation. It is not impos- sible, in some instances perhaps probable, that the working of such deposits will lead to the discovery of original deposits in the interior of the same hills on which the former appear, and that these will prove to be only outliers of such original deposits in their vicinity, and not to be beds of far-drifted ore. Their present appearances, however, do not generally indicate this, and we have to judge them 94 IRON- ORES OF MISSOURI. by what we can see, to avoid losing ourselves in bold suppositions and speculations. Therefore, as long as the internal structure of these deposits is not better known, we must place them in a sepa- rate class, as " drifted deposits." Thus, for the purpose of a systematic description of the modes of occurrence of iron-ores in Missouri, we are led to assume the exist- ence of the following eight kinds of deposits : a. Deposits of specular ore in porphyry. b. Deposits of specular ore in sandstone. c. Disturbed deposits of specular ore. d. Drifted deposits of specular ore. e. Strata of red hematite. f. Disturbed or drifted deposits of red hematite. g. Deposits of limonite on limestone. h. Disturbed or drifted deposits of limonite. a. DEPOSITS OF SPECULAR ORE IN PORPHYRY. The deposits of specular ore in the porphyries of eastern Mis- souri, especially in St. Fra^ois and Iron Counties, occur in the most varied sizes and shapes. There are very large deposits side by side with those scarcely workable. There are regular veins, as in Shepherd Mountain and Iron Mountain ; there are regular beds, as in Pilot Knob and in some localities east of it ; there are irregular deposits, some of which somewhat approach veins by their shape, as on Lewis Mountain ; while others have proved to be isolated pockets, as on Hogan Mountain. The principal and most common kind of porphyry of which the greater portion of the hills in the vicinity of the ore deposits, and in general most of the porphyry-hills in that whole region, are com- posed, is chocolate-brown to brownish-black in color, and contains numerous small feldspar-crystals, pretty evenly distributed in the matrix. These feldspar-crystals are generally not over one-eighth inch long and about one-half as wide. Some of them are color- less and transparent, others red and opaque, the latter being mostly thicker, without being longer than the former. The red crystals have the appearance of orthoclase, the transparent ones that of oligoclase. These two kinds of feldspar-crystals occur sometimes separate, sometimes together. I will call this porphyry the brown or normal SPECULAR ORE IN PORPHYRY. 95 porphyry. It is very hard and brittle. It breaks in thin and flat splinters with very sharp edges and with a subconchoidal fracture. It breaks very suddenly under the hammer, and the splinters fly off with great rapidity and vehemence. This porphyry sometimes contains quartz either in light-gray grains or in transparent crystals, colorless or slightly yellow. Also specks of a green mineral, perhaps chlorite, and iron and copper pyrites occur in it. Large masses of a brown feldspathic rock of a dirty-brown color, containing no crystals, and being tougher and softer than the surrounding rock, are frequently met with in this normal porphyry. So are also smaller streaks and masses of red porphyry. The latter are of very variable and irregular shapes, and seem to be produced by accidental infiltrations which changed the color of the rock. The brown or normal porphyry occurs in some localities flaked and banded, with black, brown, and red, parallel, undulating, thin stripes ; the crystals cutting through the stripes in the matrix. But this porphyry is always massive, never stratified. By gradual de- composition the transparent feldspar turns opaque and white, the red feldspar light brown and yellow. When the whole mass of the porphyry is gradually decomposed by the dissolving action of the atmosphere, or of acid waters on its alkalies, it turns at first pale brown, then light red, then light yellow, and finally white. It gets at the same time more and more soft and friable, and is finally changed into a white or gray or light-yellow, loose, clayish mass, in which sometimes the original feldspar-crystals can be indistinctly recog- nized, the transparent ones as very white spots, the red ones as yellow spots of a darker shade than the surrounding clay. Another kind of porphyry, which is less frequent than the former, but occurs in immense bodies, so that large portions of certain hills are composed of it, is the " red porphyry." This porphyry has a light flesh- red color, and contains generally no feldspar-crystals. In very rare instances, however, small, red crystals of a darker shade than the matrix are found in it, either single or irregularly distribu- ted. This porphyry, when entirely intact, is nearly as hard and brittle as the normal porphyry, and breaks then with a subconchoi- dal fracture. It is, however, rarely found thus probably owing to its being much more liable to be decomposed than the normal porphyry. As mostly found, it is much softer, rather tough in 96 IR ON- ORES OF MISSO URL breaking, and presents, when broken, an even to irregular frac- ture. The red porphyry is very frequently inclined to assume a stratified appearance, and in several localities forms regular strata, apparent- ly extending, in uniform thicknesses, over considerable areas. The thickness of the single layers varies from one-quarter of an inch to several inches. These stratified porphyries seem to contain some- times transparent feldspar-crystals, though very rarely. But they are principally distinguished by the more frequent, though irregu- lar, occurrence of quartz in grains and specks. The red porphyry passes by gradual decomposition and under removal of the alkalies, at first into a peculiar, light-yellow, soft rock, somewhat resembling an uncrystalline limestone, and finally into a more or less white, loose, clayish mass. Such a clayish mass is the so-called "bluff" on the Iron Mountain. The red porphyry, at its lines of contact with the brown porphyry, either mixes with the latter irregularly, or passes into it gradually by taking up feld- spar-crystals and by assuming a darker color. Both porphyries must therefore be considered to be of a similar and simultaneous geological origin. The red porphyry seems, however, to be in a certain relation, though not a very plain one, to the ore-deposits, and to be in a closer connection with them than the normal porphyry. The lat- ter contains very seldom veins'or seams or specks of ore, while all such are very common in the red porphyry. Large masses of red porphyry occur in close proximity to the ore-deposits on Iron Mountain, Pilot Knob, Shepherd Mountain, and Cedar Hill. Cer- tain enclosures in the Iron Mountain veins, the distinct stratifica- tion of the ore-bed on Pilot Knob, and other facts to be mentioned hereafter, indicate that both these hills were originally composed of red porphyry. It might be supposed from this that red porphyry owes its exist- ence to a mere change of color produced by the same influences which caused the deposition of the ore. This is, however, not so ; for the red porphyry, besides being somewhat different lithologi- cally, occurs very frequently without ore, and veins and seams of ore do occur sometimes in the brown porphyry without producing in the latter a decided and uniform change of color. We also see from this that the existence of ore-deposits, although evidently fa- SPECULAR ORE IN PORPHYRY. 97 voring the vicinity of the red porphyry, is by no means dependent upon its immediate proximity. The question, how iron-ore deposits like those which are found in such variable shapes in these porphyries may have been formed, is one which is treated in a general way in all manuals of geology, and more specially in numerous other geological publications. I will, however, say a few words on this subject, with special reference to these East-Missouri deposits. It seems to me, in the first place, that these deposits of specular ore, being all of a very similar mineralogical character, being all associated with the same kind of rock, and all situated within a small area of territory, must have been produced by one and the same kind of geological action, although the chemical action may have been different in different localities. Regarding this geolo- gical action, we may consider whether the specular ores can have been brought into their present places and shapes by injection in a melted condition, or by distillation in a gaseous state, or by segre- gation from the adjacent rocks, or by infiltration of chalybeate waters and springs and precipitation from the same. 1 . The descriptions of the various deposits which I shall give here- after will show the impossibility of supposing that the ores were injected in a melted condition. There is no sign of the action of very high heat on the associated rocks. All the enclosures found in the veins and beds of ore are of such a character that they would combine and smelt in a very short time, when in contact with such large masses of melted ore. The ore is found in very thin fissures, of such an extent that a force capable of filling them with melted ore would certainly have opened the fissures, and would have pro- duced thicker Veins. Smelted and chilled ore has a very different appearance from that existing in these deposits. 2. A distillation could rather be thought possible. But distil- lations of iron-salts occur only in volcanoes, and are then mixed with other distilled matters, and never form large deposits. Here, on the contrary, the deposits are very extensive, the ore very pure, and neither lavas nor any other volcanic rocks are found in the ore- region, nor does the configuration of the ground indicate the for- mer presence of any kind of volcanic action. 3. These specular-ore deposits cannot be derived from segrega- tion, by waters penetrating the adjacent porphyries, dissolving iron 7 98 IRON-ORES OF MISSOURI. out of their mass, and depositing it in the fissures ; for, such an action would have altered these porphyries uniformly along the veins and beds, which is not found to be the case. Such segrega- tion could, besides, hardly have produced such immense deposits as on Iron Mountain and Pilot Knob, and would certainly have caused a less uniform structure and frequently stalactitic forms. 4. The specular-ore deposits of eastern Missouri, therefore, must all have been formed by infiltration and precipitation from chalybeate or iron-bearing waters, similar to those which occur still in all parts of the world in the form of chalybeate springs, and are now forming ore-deposits in numerous localities. All rocks of which the earth is composed are more or less pene- trable by water ; all are more or less broken or permeated by wide or narrow cracks and fissures ; nearly all of them contain iron, some in very small, others in larger quantities. The iron can be dissolved and extracted from these rocks by certain solutions at certain tem- peratures. From the bottom of the sea, of the lakes, of the riv- ers, from the surface of the ground all over, waters continually fil- trate into the rocks below. These waters all contain more or less carbonic acid and other substances which they take up from the atmospheric air and from the soil. As they descend they dissolve various other matters under various circumstances, from the rocks through which they flow. They follow the easiest and widest chan- nels. They grow warm, and sometimes hot, partly by the natu- ral warmth of the rocks, partly through the heat produced by chem- ical reactions. The higher temperature and the higher pressure increase their capacity for dissolving mineral matters, with which they become charged as much as the existing circumstances allow. They may contain chlorides, sulphates, silicates, carbonates ; they may contain silica, alumina, alkalies, lime ; they may contain zinc, lead, iron, etc. When these solutions have reached a sufficiently high tempera- ture, and happen to find sufficiently easy channels, upward, they will rise through such channels, driven by the pressure of the colder and therefore heavier solutions which follow them, and frequently assisted by the development of gases through chemical reactions. In this course upward they will again follow the preexisting na- tural channels, wide fissures, small cracks, irregular holes and pockets. When they reach porous or loose strata, they will pene- IR ON MO UN TAIN. 99 trate and impregnate them. When they come in contact with strata of materials which they are apt to decompose chemically at the existing temperature, they will alter, transform, metamorphose them. When these materials are such as to precipitate oxides of metals from the solution, these oxides will be precipitated and ore- deposits will be formed. The same effect may result when solutions of different chemical composition meet. The same effect must result when such metallic solutions approach the surface, where their pressure and temperature, and therefore their dissolving capacity, is diminished or altered. As the circulation of waters and watery solutions just described, although locally variable, has existed during the whole geological history of our globe, as it exists still, it is evident that the largest fissures and cavities, when kept filled with however dilute yet con- tinuously renewed metallic solutions for hundreds and thousands of years, under otherwise favorable conditions, will finally become filled with deposits of ores. It also appears evident from the above, that the same mineral solutions can, under different local conditions, produce very differ- ent kinds of deposits veins in one place, pockets in another, beds in a third. I have no doubt that the various deposits of specular ore in porphyry, which I will now proceed to describe, were formed in this wise. Iron Mountain. T. 35, R. 4, E., Sec. 31, north-east quarter, St. Francois County. The Iron Mountain is undoubtedly the largest ore-deposit in Missouri. For the size and exterior description of the Iron Mountain hill, I may refer to page 75 of Prof. G. C. Swallow's Second Annual Report, where Dr. A. Litton mentions and describes it in a very lucid manner. This report was published in 1855, at which time the main part of the hill had not been opened, and no accurate knowledge < could then be had of its internal geological structure. The openings which have been made meanwhile enable me to give a more detailed account of it. The accompanying topographical sketch, Fig. n, of the Iron Mountain and its surroundings, shows the surface-geology, the dis- tribution of the porphyries, the extent of the surface-ore, and the position of the cuts or openings made by mining operations. The surrounding hills are composed mainly of the normal brown IOO IRON- ORES OF MISSOURI. Fig. ii. S,K T C H O F {.IT.V-K.LS ABOVE ZERO. LI A ISi'' E _2otf B - I7S'* . F _ 130' C ~ IBOVIZO' H - 6O' O i- 145" _ K _ 80' THE IRON < E r ERENC.ES: MOUNTAIN B. P. .BROWN PORHtRY R . P. . R E D B.C.. B L O E CONGLOMERATE a. x .. . . . SURFACE. ot ~~~ . LIMITS Or CuTfc porphyry. A zone of red porphyry, frequently mixed with ore in larger and smaller seams and specks, runs along the north side of the Iron Mountain, across the ridge which connects the latter with the hill north of it. This zone of red porphyry thus separates the ore-deposit from the brown porphyry on the north side. The red porphyry in places becomes paler and takes a reddish-gray color. In the eastern portion of the zone the porphyry is half decomposed, forming a soft, yellow rock, which in one place, near its contact with the blue porphyry, is in distinct layers or strata from one to several inches thick, and has sometimes been taken for a limestone. The red porphyry in the western portion of the zone seems to pass into the normal porphyry, in some places gradually, while in IRON MOUNTAIN. IOI others it mixes irregularly with the latter, constituting a rock of a conglomeratic appearance and of a dull-brown or bluish color, with irregular flesh-red enclosures. This is the case in the place marked B C on the sketch. The whole surface of the Iron Mountain itself is covered with surface-ore, which also extends over the south-western knob, called the Little Iron Mountain, and reaches into the valley south and west, and across the valley north-west of the mountain, and over a part of the slope of the opposite hill. This surface-ore, which, according to the preceding chapter of this report, is of the same character and composition as the vein-ore, occurs in more or less rounded bowl- ders and pieces, of very variable sizes, from a diameter of several feet down to a pretty fine sand, all irregularly mixed with each other, as well as with a fine, clayish or sandy detritus of a yellow or red color, and with single bowlders of half-decomposed porphyry. Pieces of a coarse-grained sandstone are sometimes found with it on the south-west slope. The surface-ore generally lies directly under a few inches of soil, and varies from one to five feet in thick- ness, which is, however, considerably exceeded in some places, especially on the south side, below cuts B and C, where it attains a thickness of 40 feet and over. The main body of the hill, as far as opened, consists of a loose clay- ish mass, undoubtedly decomposed porphyry, known amongst the miners under the name of "bluff." This "bluff" and its origin have been described above. It is in the north-western half of the mountain, to the west of the principal ore-vein, of a very uniform and purely clayish character, while on the south-eastern half it has a more conglomeratic character. In this latter half, especially in the northern part of it, the " bluff" contains masses, which, from their partly preserved darker tint and from the numerous decom- posed feldspar-crystals they contain, must be considered as being altered normal porphyry, while the north-western bluff seems to be exclusively altered red porphyry. A large mass of entirely fresh and unaltered, thickly stratified, red porphyry has been struck by the lower cut C, made on the east side through the " bluff." (See Fig. 6.) This mass, which is .uncovered to a height of about 30 feet, contains numerous fine ore-seams, and evidently is not in its original position,, as the stratification dips about 40 toward the 1 02 IR ON- ORES OF MISSO URL east. Large disturbed masses of unaltered brown porphyry have been struck in cut D, on the north-east side. (See Fig. 17.) The whole immense clayish mass of decomposed porphyry or " bluff," forming certainly the upper part if not the whole of the Iron Mountain, is cut in two pretty nearly equal halves by an enormous vein of specular ore, from 40 to 60 feet thick, striking N. 53 E., which direction may be observed on the sketch by drawing a line through the cuts A E D F. Whether the main portion of this vein is in a vertical or somewhat inclined position cannot now be ascertained. It seems to be rather irregular in thickness and shape, to be split up in two branches for a part of its length, and to enclose large bodies of broken ore mixed with porphyry. This large and principal vein is called the " backbone " of the Iron Mountain. The " bluff" contains, however, besides the backbone-vein, nu- merous other veins of various and very irregular thicknesses, from less than one half-inch up to 6, and in places, 10 feet. These smaller veins cross the bluff in various directions, not subject to any definite rule. The limits between each of these veins and the "bluff" are very sharp, and there is nowhere a gradual transition from the ore into the " bluff." A line drawn through the cuts A E D F along the backbone, when prolonged in both directions, will pretty nearly touch the cut H on the Little Iron Mountain in the south-west, and the cut K on the hill across the valley in the north-east. As both these cuts have struck large bodies of ore, it seems probable that the principal vein extends over the whole distance from H across the hill to K, which is not much less than a mile. The Iron Mountain ores have been described in the preceding chapter of my report. To make the mode of occurrence of the specular ore in the Iron Mountain more plain, I will illustrate the above general description by a few sections taken in the different mining-cuts, adding expla- nations as far as required or desirable. The position of these cuts, as well as their elevation above the zero-line of the topographical survey, are given on the sketch, Fig. n. The cut H, near the blast-furnaces on the Little Iron Mountain, is not worked now ; but much ore has been taken out of it and more seems to be left, especially in depth. This place is, however, at IRON MOUNTAIN. 103 least near the surface, greatly disturbed, and the formation is to a great extent composed of displaced materials. The following two sketches present some interesting features : 4RON MOUNTAIN Fig- 13- IKON MOUNTAIN We see in Fig. 12 four irregular masses of decomposed porphyry, (D P) surrounded by formerly massive, but now broken, specular 104 IRON- ORES OF MISSOURI. ore. Such enclosed masses of rock are, however, rarely entirely surrounded on all sides by ore, although it looks so in the present section. In digging or blasting, perhaps only a few feet further, an entirely different section would present itself, and the apparently floating masses would be found to be in connection with, or sup- ported by, other masses of the same nature. From the parallelism of the contour-lines of the three enclosed pieces, situated on the left side in the sketch, it must be supposed that they formed originally one mass, but were broken up and the interstices filled with ore. The breaking may have begun by the formation of thin cracks, produced by the contraction of the porphyric mass during its drying or cooling, or both. These thin cracks may have been widened, afterward, gradually by the crystallization of the ore. The jointed structure of the ore is very instructive. The arrangement of the joints shows that the ore has been formed round the preexisting porphyry, and that the latter has offered a strong resistance to the contraction of the former, and consequently that the porphyry was still hard and fresh when the ore contracted, and that its decompo- sition took place afterward. Wherever there was an equal resist- ance on both sides, the ore separated in nearly parallel plates. In the lower part, where no resistance existed, the ore contracted and separated into blocks of irregular shape but nearly equal size. Fig. 13 represents an undoubtedly disturbed formation. That portion of it which is to the right of the thin clay-seam (Cl) may have been formed as it is. We see here an upright, ramified ore- vein, having on the right side solid porphyry, on the left side, be- tween the vein and the clay-seam, decomposed porphyry. The mass to the left of this clay-seam, between it and another thicker clay-seam, to be seen on the utmost left of the sketch, was evi- dently not formed in its present position, but must have slid into this position long after its formation. At the time when the thick mass of ore enclosed in this part was formed, the stratification in the porphyry was undoubtedly horizontal, while it is now vertical. When afterward brought in its present position, and when, owing to the gradual decomposition and consequent contraction and soft- ening of the porphyry below, the ore lost its support, it broke off in plates corresponding to the porphyry-strata. It is not unlikely that its natural jointed structure has predisposed it to that effect. Fig. 14 represents a cross-section through the backbone-vein in JR ON MOUNTAIN. Fig. 14. ** 105 S.E & ECTION OF CUT. A cut A, the working-level of which is about 60 feet below the summit of the Iron Mountain. The vein is here divided in two branches, from 12 to 1 8 feet thick each. These branches join above, enclosing a mass of broken ore and porphyry, mixed with quartz and apatite. This mass seems to be the product of destruction of numerous smaller ore-veins in porphyry, formerly existing in this same place or close by. The porphyry may have been broken up by the crystallization of the ore in its seams, and the ore by contraction and by the decomposition of the porphyry. All the pieces of ore have sharp edges and corners. All the porphyry is more or less decomposed. P is slightly decomposed, but yet pretty hand, porphyry, passing into the loose, clayish " bluff" above it. The " bluff " on the south- east side of the vein is all a loose, soft clay of a yellow color. The surface of the big vein is wavy and very smooth. The small ore- veins which cross the "bluff" in all directions vary from one-fourth to 3 inches in thickness, a few near P are up to 12 inches thick. The " bluff" does not contain any ore outside of these veins. Fig. 15 gives a section of a characteristic part of cut B. This section shows in what a varied and often peculiar manner the smaller ore-veins cross the mass of the " bluff," enclosing larger and smaller pieces and blocks of decomposed porphyry, frequently changed into soft clay. Most of these veins strike about east- west in this place. The ore has the same mineralogical character as that of the backbone-vein. It contains perhaps a little more s. 106 I RON- ORES OF MISSOURI. Fig- 15- VIE.W OF CUT-B- quartz and more apatite, or crystalloid holes formerly filled by apatite. These holes are generally sitting on the walls of the veins. The ore resembles the surface-ore closely. The smaller the veins are, the more impurities they contain in proportion to the quantity of ore. The "bluff" is here very plainly a decom- posed porphyry, sometimes imperfectly decomposed, in which case it is composed of a bluish-gray or bluish-brown matrix, enclosing white, decomposed feldspar-crystals. It seems from this appearance that a large part if not the whole of the "bluff" in this cut is derived from the normal porphyry. Fig. 1 6 represents a section through both the cuts C C, which lie about in one vertical plane, on the south-western slope of the Iron Mountain. The upper cut is about 60 feet, the lower one 120 feet, below the summit. The upper cut shows another character- istic section of veins running through the " bluff." What is marked as "detritus" is composed of blocks and pieces of colored clays Fig. 1 6. IRON MOUNTAIN. 1 07 (decomposed porphyries), mixed with ore in pieces, the latter also somewhat softened by partial decomposition. Irregular holes and cracks in this mass are filled with yellow and red loam. This must be a part of a hole or crack which was opened after the complete solidification of both the porphyry and the ore, and was filled with broken porphyry and ore before the decomposition of the former. The section of the lower cut likewise presents some very peculiar features, indicating disturbances on a larger scale. An immense block, at least 35 feet in thickness, of thickly-stratified, red por- phyry, lies here in the " bluff" in an inclined position, abruptly cutting off the ore-veins. This flesh-red porphyry is hard, and entirely fresh in its fracture and color, and encloses numerous ore- seams, one-quarter to 3 inches thick. This block was evidently exposed to the influence of the solution that deposited the ore, but not exposed to those influences which produced the decompo- sition of the rest of the porphyry. To explain this satisfactorily, we must suppose that this decomposition- was not effected by at- mospheric influence exclusively, but that it was effected partly, or at least prepared and begun, by acid solutions, and that this block would have occupied an isolated or elevated position, while this, perhaps, preparatory action took place, and that it could not then be reached by the solutions. Afterward this block may have fallen over on the slope of the hill, sunk into the " bluff" gradually, cutting off the ore-veins, and may finally have been covered by a layer of bluff-clay washed down from the hill. The somewhat irregular character of the "bluff" overlying it seems to support this theory ; otherwise the strange position of this block could only be explained by assuming that it was raised from below after the decomposition of the overlying porphyry. However this may be, the presence of this intact, red porphyry with ore-seams, proves that the geological action by which the veins were filled was not the same as that which decomposed the porphyry, but that the latter took place much later than the former. For it might be supposed that the decomposition of the porphyry and the deposition of the ore had been effected, if not by the same solution, at least by a simultaneous chemical action. Another fact, however, besides the above, speaks against these suppositions. We find on Iron Mountain no instance of a total or partial replacement of porphyry by iron-ore, which replacement would have been the IRON- ORES OF MISSOURI. unavoidable consequence of such a simultaneous chemical action, as I propose to show in my description of the Pilot Knob deposit. s w N.E .VIEW or CUT'D" In Fig. 17, which represents a section of cut D on the north- east slope of Iron Mountain, we find the brown or normal porphyry in a disturbed position, similar to that of the red porphyry in Fig. 16. We also see a cross-section of the north-east part of the back- bone-vein, which is here -in one solid mass, about 30 feet thick, and inclined toward the north under an angle of about 50 degrees. P is a part of an immense solid mass of hard and intact normal por- phyry, underlying the backbone-vein and being in close contact with it. This porphyry frequently contains specks and thin seams of green chlorite (?). Thin seams of ore also occur, though very rarely. The porphyry overlying the vein, in three flat pieces of a rather vari- able thickness from 3 to 10 feet, is very nearly of the same descrip- tion. These three flats of porphyry, however, are not in close contact either with the backbone-vein, or with each other, or with the flat mass of ore that overlies them. All these masses lie loose over each other, being in contact at certain points only, while separated by clay-seams or empty spaces at other points. The " bluff" contains here no continuous ore-veins, but only single pieces of ore in such positions and so distributed as indicated in the above illustration. This locality, as well as the whole north-eastern portion of the Iron Mountain, has evidently been subjected to great disturbances long after the formation of the ore and after the decomposition of the porphyry. The fact that the backbone-vein has not, so far, been struck by the cut F, which is situated on the line of its strike, and the presence of the above-mentioned conglomerates a little farther east, support this view, besides the appearance of cut D. PILOT KNOB. 109 In the neighborhood of cut K, on the hill north-east of Iron Mountain, we find both the red and the normal porphyries. Ac- cording to Dr. Litton's description (see Second Geol. Report, 1855) of a well bored near the furnaces, porphyries and large masses of ore exist there to a depth of more than 1 50 feet, overlaid by some magnesian limestone and sandstone. This shows that the por- phyries are pre-Silurian, which fact is verified by numerous observa- tions made in other localities. When we look over all that has been said about the Iron Mountain, the geological history of this deposit naturally presents itself as follows : The whole Iron Mountain was composed originally of porphyries, which also filled the valley east and south of it. A great portion of these porphyries, especially on the north-west side, were of the red, the others of the brown or normal variety. These porphyries, either from the effects of contraction or from other causes, contained numerous large and small fissures. These fissures were kept filled with constantly renewed chalybeate waters for a very long period, during which these waters, through various chemical and physical influences, deposited the oxides of iron, which they contained in solution. The oxides of iron thus deposited were undoubtedly at first loose and soft, and mixed with water, but became denser and harder and less watery as their mass increased. As the fissures were gradually filled, the access of the solutions became more difficult and more scarce, and was finally stopped. Then the ore dried in the veins, undergoing thereby a small con- traction, which cracked and broke most of the veins without dis- placing their disconnected parts. After this had been done, the por- phyry was acted on by atmospheric or other waters, probably con- taining carbonic acid, which decomposed the porphyry, removing the alkalies, and leaving a silicious clay. By this process these porphyric masses became so soft that rain and flood waters washed them off readily, the consequence of which was that, simultaneous with the erosion of the valleys, the cracked and disjointed ore-veins lost their support, and fell to the ground in single bowlders and pieces, thus forming the beds of surface-ore which now cover the slopes of the hill, and which fill a part of the now-eroded valleys. Pilot Knob. T. 34, R. 4, E., Sec. 29, Iron County. For the IIO IRON- ORES OF MISSOURI. dimensions and the external appearance of Pilot Knob, I refer to Dr. A. Litton's description, given on page 79 of the " Second An- nual Report of the Geological Survey of Missoui : ." I give hereby, in Fig. 18, a topographical plan, showing the sur- face-geology of the Pilot Knob : SURFACE GEOLOGY Although the surface-geology does not always give perfectly reli- able indications regarding the interior geological structure of a mountain, it generally allows us to draw certain valuable conclu- sions. The ore on Pilot Knob is not in veins, but forms a regular PILOT KNOB. Ill bed in the porphyry. The top of the Pilot Knob, according to our sketch, is composed of" blue conglomerates." These consist of a dark, bluish-gray, porphyric matrix, enclosing large and small, but mostly sharp-edged, pieces of a light-gray, or reddish-gray to red- dish-brown, porphyry. No distinct feldspar-crystals are visible in it. But the blue matrix contains numerous small, almost microscopic, crystals of iron-ore, more or less equally distributed through its mass. These conglomerates are all strongly magnetic with polarity. They have frequently a distinct though wavy stratification. They form large groups of rocks on the summit, and compose the upper part of the mountain itself, directly overlying the ore-bed, into which they pass by degrees, becoming more and more im- pregnated with ore and mixing with ore irregularly above the bed. They also lose their conglomeratic character in this direction, and a few feet above the ore-bed constitute a uniform bluish-gray por- phyry, strongly impregnated with ore, and containing thin layers of a fine conglomerate. Their maximum thickness, measured to the top of the rocks, may be estimated at an average of about 100 feet ; that of the ore-bed at about 40 feet. Immediately below the ore-bed we find the same uniform bluish-gray porphyry, which directly overlies it, also mixed with small ore-crystals, although in a less number. These " blue porphyries " are likewise found on the surface for some distance down the slope of the hill, as is indicated on the above sketch. All of them contain a little ore in very minute, isolated crystals, not often visible to the naked eye. A B and C represent mining excavations or cuts made in the ore- bed itself, but cutting also through the porphyry and conglomerate above it. Lower down on the slopes of the hill, especially on the northern and eastern sides, we find the red porphyries cropping out in masses of such a size and position as to leave very little doubt that a large portion if not the whole of the middle and lower parts of the hill must be composed of them. They are mostly hard and un- altered, and correspond in their appearance to the general descrip- tion given above, containing but rarely admixtures of feldspar- crystals or of quartz. Such is the distribution of the rocks on Pilot Knob. We notice, however, two streaks of "blue conglomerates with ore," running 112 IR ON- ORES OF MISSO URL down the hill, one on the north-east and one on the west side. These conglomerates, with specks and impregnations of crystalline ore, are similar to those found on the summit. They are all broken up, in pieces and bowlders, partly decomposed, and are evidently washed down from above. This seems to have taken place on quite a large scale on the west and south-west sides, where these broken and either partly or entirely decomposed masses are spread in consider- able thickness over a large area, and reach down to the foot of the hill. The ascent of the Pilot Knob is much less steep there than on the northern and eastern slopes. These loose masses are to a great extent altered into white or yellow clay. Several shafts have been sunk into them to a depth of near 70 feet without reaching the solid rock. We find another, though smaller accumulation of broken and decomposed materials along the foot of the hill on the north side. There we find also feldspathic rock, feldspar mixed with quartz, quartz without admixture, and pieces of stratified porphyry. In a few places at the foot of ( the north-eastern and north-west- ern slopes we find deposits of magnesian limestone, apparently over- lying the porphyry. Fig. 19. P I LOT. KNOB AS StEN FROM TMt W O w T I s WITH SURFACE C.B.OCOGV Fig. 19, giving a side-elevation of the Pilot Knob, from the north side, with the surface-geology, will convey a clearer idea of the dis- tribution of rocks over the hill, as described. It shows the red porphyries spreading over the lower two-thirds of the hill, but part- ly covered by decomposed materials and by loose, broken porphy- ries and conglomerates. Higher up it shows the region of the blue porphyries, with the mining-cuts A B and C, which indicate the position of the ore-bed. It finally shows the conglomerates on the summit. It must be remarked that this sketch does not represent a sec- PILOT KNOB. 113 tion, but a view of the hill. It is, however, probable that it would represent a pretty correct section through the Pilot Knob from east to west, if we would mark the whole mass below the "region of blue porphyry " as "-red porphyry," leaving off the mention of the various detrital materials, which probably only cover the surface to a certain depth. The ore-bed, and the stratified conglomerates above it, dip toward the south-west from 13 to 22 degrees, according to Pro- fessor Pumpelly, who ajso found the strike to be S. 5 E. I will add here some sections through the ore-bed, as they ap- pear in the three mining-cuts A B and C on Pilot Knob, to illus- trate more fully the mode of occurrence of the ore in this deposit. The ore itself has been described in section B of this report. Fig. 20. N.E.. CUT "C PILOT. KNOB Fig. 20 is a cross-section through the highest and most eastern cut C made in the upper outcrop of the ore-bed. This section shows the following consecutive strata : I. Broken-up porphyric mass, without stratification, containing numerous irregular fissures. Its color is bluish gray. It encloses flakes of green serpentine, and small masses of white clay and of half-decomposed red porphyry. The thickness, as far as uncov- ered, is 15 feet. 8 114 IRON- ORES OF MISSOURI. 2. Seam of hard, blue porphyry. 3 inches thick. 3. Compact porphyric mass, partly bluish gray, partly reddish brown, containing some serpentine in fissures. 10 feet. Between 3 a,nd 4 is a large empty fissure, parallel to the strata, evidently produced by a sliding motion of layer 4 over layer 3. 4. Bluish-gray porphyry, distinctly stratified. Strata parallel to those of the ore. 8 feet. 5. Dark-blue, nearly black porphyry, mixed with ore irregularly. 4 feet. 6. Good-looking though silicious specular ore. 16 feet. 7. Is composed of three parts, namely, a i-foot stratum of hard, red porphyry without ore, a 1-2 feet stratum of ore, interstratified with red porphyry in very thin layers, and a i-inch seam of light- gray clay-slate. 8. Stratified ore, good strata alternating with others which are intimately mixed with fine quartz. 22 feet. Fig. 21. Fig. 21 represents the main cut B, which is about 420 feet above the valley west of the knob, and 160 feet below the highest point. This figure shows the foot-wall, consisting of a slightly ferriferous, blue porphyry ; the main ore-bed (H H) nearly 40 feet thick, con- sisting of somewhat silicious specular ore, stratified more or less dis- tinctly; a seam of light-gray clay-slate, varying from 6 to 18 inches in thickness, and containing no particles of ore whatever ; another irregular layer of ore (H H) above the seam, mixing gradually with and passing into the blue conglomerate (B C). PILOT KNOB. 115 The ore in the central part of the cut below the slate-seam is con- siderably softer than that either east or west of it. Analyses of these various ores have been given in section B. If the slate-seam in cut B, Fig. n, is the same as that in cut C, Fig. 10, as it appears to be, the thickness of the ore below the seam diminishes considerably toward the south-east, while the thickness of the ore above the seam increases in the same proportion, leaving the total thickness of the ore the same. The absence of ore in the slate-seam makes it probable that this seam is of later origin than the ore, being, perhaps, produced by a slide of the upper part of the bed over the lower part, whereby, through the irregularities of the surfaces, an empty fissure was left in places, similar to the empty fissure between layers 3 and 4 in Fig. 10, and was gradually filled up with a fine clay washed into it by surface-waters. Fig. 22. CUT 'A' PILOT. KNOB Fig. 22 is a section exposed by the mining-cut A, made on the lowest and western outcrop of the ore-bed, as may be seen on Figs. 8 and 9. We have here a disturbed locality before us. A portion of the ore-bed may have been underwashed here, broken off", and fallen down on the slope of the hill, the debris being then either carried away by floods or buried under the porphyric detritus. We see, therefore, in this cut an abrupt end of the ore-bed below the slate-seam. Above the ore and the seam, and close to the ore below the seam, is a nearly vertical streak of broken porphyric masses with some ore, permeated nearly vertically by numerous fissures mostly filled with red, yellow, and white clay or loam, washed into them from above. The porphyric parts are to a great extent converted into green steatite. Many pieces are thus altered 1 1 6 IR ON- ORES OF MISSO URL on the outside, while the inside is yet tolerably fresh porphyry. The broken ore is poor and silicious, similar to the less pure ore above the slate-seam in cut B. This whole irregular and mixed mass was evidently produced by a fall, and subjected, during a long period, to the influence of surface-waters. Adjoining it, below the seam, we find a breccia of ore, imbedded in more or less fine porphyric detritus, above the seam a mass of blue, ferriferous porphyry (B P), which is solid where the slate-seam is in its natural position, but broken up into a blue conglomerate (B C) where the slate-seam makes a sudden turn downward, indicating another break- down, produced by an underwashing of the stratum of blue porphyry. The cut A, according to this description, presents two disturb- ances or falls, which have occurred at different times. The one affected the ore-bed and all the overlying strata ; the second, of smaller extent, broke up a thick layer of porphyry only. The slate- seam runs across the first fall undisturbed, and must, therefore, have come into existence some time after the occurrence of the fall. As the latter produced ore-breccia, it must have occurred after the formation of the ore, from which it follows that the slate-seam is much younger than the ore-bed. The softness of the clay-slate that fills the seam corroborates this statement. The second fall in cut A breaks the slate-seam, and must therefore have taken place after the formation of the latter, and a long time after the occur- rence of the first fall, and after the formation of the ore-bed. As to the extent of the Pilot Knob deposit, we find, by throwing a look on the map, Fig. 8, that as far as opened at present, by the three cuts, A, B, and C, it seems to cover a triangular area, measuring 1,000 feet along the base, from east to west, and 600 feet in the height of the triangle. But the fact that the ore-bed dips in the south-western direction, at nearly the same angle as the surface of the ground, leaves the possibility of its extension over a consid- erable distance in that direction. In regard to the geological and chemical action which may have created the ore-deposit on Pilot Knob, we must recall the in- troductory remarks on the formation of the specular-ore deposits of this region in general. Referring to this deposit specially, I fully agree with Professor Pumpelly, who, by more detailed and more thorough investigations, has come exactly to the same conclusion, PILOT KNOB. namely, that it has been formed by a gradual replacement of stra- tified porphyry by ore, effected by solutions similar to those which deposited the ore in the Iron Mountain and in the other places. The stratification of the ore-bed, and of the impregnated and half-metamorphosed porphyries overlying it, is very plain and regular. Stratified porphyries are found at the foot of the north-eastern slope of the knob, and very extensively in a large district east of it ; but C, Fig. 20, shows a layer of red porphyry interstratified with ore. The general appearance of the ore-bed, especially as shown in cut B, Fig. 21, as well as the appearance of numerous single speci- mens, and the partly impure and silicious character of the ore, nat- urally suggest the idea of an impregnation and gradual replacement of porphyry by ore, besides other circumstances mentioned in my introductory remarks. Furthermore, such a replacement is not only possible, but it must be expected, at least partially, under certain circumstances. When a solution of sulphate or chloride of iron, containing also carbonic acid, remains during a long time in contact with porphyry, the carbonic acid will decompose the porphyry, com- bining with its alkalies and dissolving them. The alkaline car- bonates will almost simultaneously precipitate oxides of iron from the solution, and these oxides will fill the pores produced in the porphyry by the removal of the alkali. The silica is thereby set free, and will perhaps also to a small extent be dissolved, but the greater part of it will remain mixed with the ore, and make the latter silicious. The removal of the silicate of alumina contained in the porphyry is more difficult to explain. It has been shown, however, by Bischof, in his Lehrb. d. chem. und phys. Geol., ed. 1863, vol. i. p. 86, that silicates of alumina can be decomposed by bicarbonate of iron in solution, and removed in the form of a soluble bisilicate of alumina and iron. Considering, in our present case, that the solutions producing the transformation did not act perhaps on silicate of alumina pre- viously existing as a free substance, but that they may be supposed to have acted on silicate of alumina which was undergoing at the same time its separation from the alkalies, and therefore, quasi in 1 1 8 IR ON- ORES OF MISSO URL statu nascendi, various other modes of decomposition or solution may be thought of. This is not, however, the place to discuss such questions. My only purpose in touching them was to show the possibility of a chemical action, by which the formation of the Pilot Knob deposit by replacement may have, and undoubtedly has, taken place. Another question regarding the formation of this deposit, is, whether the solutions from which the ore was precipitated were conveyed to this locality through fissures, and whether, therefore, veins of iron-ore will be likely to exist below or in close proximity to the ore-bed. It is very probable that the solutions were con- veyed through either small or large fissures ; but from this it does not follow necessarily that these fissures must contain deposits of ore ; for the deposition of ores or of other substances, in fissures or cavities, is not alone dependent on the presence of the cavities and of the solutions which contain these substances. It is also dependent on various other circumstances, as temperature, un- limited or limited access of air, presence of other mineral solu- tions, facility of renewal of the matters to be deposed, rapidity of motion, and others. It is therefore not to be expected, with any degree of certainty, that cavities through which chalybeate waters flow, or were flowing, should contain deposits of iron-ore. Also a temporary deposition, and subsequent re-dissolution under altered circumstances, is possible and frequently met with. Thus, the existence of ore-veins below or close to the Pilot Knob bed is possible, but by no means certain. Shepherd Mountain, T. 34, R. 4, E., Sec. 31, N. E. i^, Iron County. This hill is named after Professor Forrest Shepherd, of St. Louis, who made the first investigations regarding the valuable ore-deposits it contains. Dr. A. Litton, Professor at Washington University, St. Louis, has given an excellent description of the Shepherd Mountain, in Professor Swallow's second annual report of the Geological Survey of Missouri, to which description but little has to be added, be- cause the mining operations which have been carried on there since that report was published, seventeen years ago, have proved the correctness of Dr. Litton's views, in nearly all their details. Although Shepherd Mountain is but little over one mile distant from the Pilot Knob, its ore-deposits are of an entirely different SHEPHERD MOUNTAIN. IIQ character, being unquestionably veins, which, if they do not cut through the hill in its whole width, certainly extend over consider- able distances. I give, in Fig. 23, a small map showing the relative position of the Pilot Knob, Shepherd Mountain, and Cedar Hill, also indicating the surface-geology of that district. Fig. 23. BUZZARD MOU N T. y M A P ~ SHOWING THE SURFACE 6EOL06Y r w i VICINITY on PI LOT.K NOB Shepherd Mountain is principally composed of normal porphyry, of a pretty uniform brown color, and containing either transparent or red and opaque feldspar-crystals, evenly distributed. This por- phyry sometimes contains seams or small irregular masses of red 120 IRON- ORES OF MISSOURI. porphyry, which look as if produced by changes caused by infiltra- tions of some kind. The brown porphyry is in places beautifully banded, but never stratified. Some of it, on the upper part of the hill, is magnetic with distinct polarity, and is then found to be inti- mately mixed with single, microscopic particles of ore, absolutely invisible to the naked eye. The porphyry close to the ore-veins is considerably decomposed, quite soft, and mixed with large masses and veins of red and white clay. These clayish masses are sometimes impregnated with ore, or permeated by small veins of ore, which veins also penetrate more or less into the solid and in- tact porphyry. On the summit of the hill, south-east of cut B, we find a zone of red porphyry, about 50 feet wide, running across the hill from east to west, as indicated in Fig. 13. Three places have been opened on Shepherd Mountain, marked respectively A, B, and C on.the map. Cut A has disclosed a vein of specular ore, with some magnetite, IO to 20 feet wide, nearly vertical, striking N. 62 E. (true). This cut is about 500 feet long. Cut B on the west side has opened a length of about 1,000 feet of a quite similar vein, striking N. 68 E. (true). This vein, how- ever, contains very little, if any, true magnetite, but is almost ex- clusively composed of specular ore. The southern cut, C, is hardly opened enough to see its charac- ter. It looks thus far like a vein striking pretty nearly in the same direction as the other two veins, and containing a coarsely crystal- line, specular ore, crossed by numerous thin seams of red por- phyry. It will be noticed that the strike of these veins is directed toward the Pilot Knob. These deposits have undoubtedly originated in the same manner as those on Iron Mountain ; but the surrounding porphyry has been very little altered, while most of that on Iron Mountain is en- tirely decomposed. Smaller Deposits of Specular Ore in Porphyry, Cedar Hill, T. 34, R. 4, E.,Sec. 30, Iron County. The position of Cedar Hill can be seen on the map, Fig. 13. This map shows that the surface-geology, on the south-eastern slope of Cedar Hill, is very similar to that of Pilot Knob, the red porphyry at the foot passing into bluish and conglomer- atic porphyries toward the summit. In the place marked A, however, CEDAR HILL. 121 where a mine has been opened in summer, 1872, the porphyry is red again. This red porphyry, however, takes a bluish color in the proximity of the ore, and the walls of the ore-deposits are in some places composed of a blue, porphyric conglomerate, similar to that on Pilot Knob. This seems to indicate that the blue color, and per- haps also the conglomeratic to spherulitic structure, might be due to infiltrations of the same ferriferous solutions which deposited the ore. The Cedar Hill is not sufficiently opened to allow a judgment regarding its ore-deposits. In September, 1872, about two acres of ground were freed from the soil, and showed two parallel, vein-like segregations, I to 4 feet in width, and about 100 feet in length, cropping out on the surface. Their strike was about 60-70 north-west. A shaft 10 feet deep was sunk on one of them, but showed it to be of an irregular section, so as to leave some un- certainty regarding its continuation in depth. These small segre- gations, surrounded by hard and solid porphyry, are not always workable in themselves, but they may be offshoots of some larger deposit, to the discovery of which they might lead. Occurrences of specular ore were observed in some other locali- ties in that vicinity, namely, in T. 34, R. 4, E., Sec. 18-19, 1 7~2O, andT. 34, R. 4, E., Sec. 19, S. W.i< S. W.%. One and one-half miles east of Pilot Knob, in T. 34, R. 4, E., Sec. 28, N.^, coarsely crystalline specular ore is found in seams through a red, banded, and stratified rock, of the appearance and fracture of jasper, overlying a series of stratified porphyries. The succession of strata which presents itself there, with a south-western dip, is from south-west to north-east, as follows : Slates of red, banded porphyry. Stratified quartz-porphyry. Slates of red porphyry. Green porphyry. Banded jasper. Jasper, with specular ore. Buford Hill, T. 35, R. 3, E., Sec. 26, two miles west of Iron Mountain, in Iron County, is a pretty high and steep hill, consist- ing principally of brown porphyry, occasionally mixed with a brown, jasper-like, feldspathic rock, and with light-red porphyry in some places. These three kinds of rocks seem to be mixed there 122 IR ON- ORES OF MISSO URL irregularly. Some micaceous iron-ore, mixed with quartz, is found in a depression between the hill itself and a low spur on its north- eastern side. Red porphyry occurs at a short distance south of it. The quartzeous ore is spread in large and small pieces over the ground, and extends along the slope of the hill over a distance of more than one hundred feet, in a line striking north-east to south- west. A little lower down on the same slope a streak of greenstone may be observed, running about parallel to the direction of the ore. This greenstone, which occurs in loose fragments, is fine grained, of a dark-green color, with white specks. It has the appearance of a diorite. It contains numerous black, microscopic crystals, of a metallic lustre, probably peroxide of iron. The same kind of ore, accompanied by the same kind of green- stone, is said to exist in some places on the west side of the hill. Nowhere, however, are plain indications of the presence of larger masses of ore. Buford Mountain, N. E. ^ Sec. 24, T. 33, R. 3, E., Iron County, contains a bed of manganiferous specular ore in decomposed por- phyry, apparently of a not inconsiderable extent. Big Bogg Mountain, S. E. ^ Sec. 13, T. 33, R. 3, E., the Rus- sell No. i bank, E. ^ Sec. 3, T. 33, R. 3, E., and the Shut-in bank, N. ^ Sec. 2, T. 33, R. 4, E., all in Iron County, are also deposits of specular ore in porphyry, and have been mentioned and described by Dr. A. Litton in the second geological report. Lewis Mountain, S. ^ Sec. 6, T. 33, R. 4, E., Iron County, one and one-half miles south-west of Arcadia, is a small porphy- ry-hill, at the foot of which magnesian limestone is deposited in nearly horizontal strata. The slopes of the hill are covered with red and yellow clay and loam, 30 to 40 feet thick, mixed with half- decomposed pieces of porphyry. Above this is 2 to 4 feet of soil, mixed with rounded pieces of hard, specular ore, some pure, some mixed irregularly with brown porphyry in such a way as to indi- cate a gradual replacement of porphyry by ore. Indeed, in some specimens the brown porphyry, containing feldspar-crystals and brown quartz-grains, passes imperceptibly into specular ore; where- by the feldspar- crystals disappear, while the brown grains of quartz are preserved, and lie in exactly the same manner in the ore as in the porphyry. An irregular vein, varying from I to 5 feet in thickness, HOG AN MOUNTAIN 123 strikes across the hill about N. 75 W. This vein contains in some places specular ore, while in other places, where the vein is thinner, it is filled with red loam. This fact seems to show that the vein, which was originally of a more limited extent, has been opened more and extended by the crystallization of the ore, or by freezing water, and that the cracks thereby produced were after- ward filled with loam washed into them from above. Some red, blue, and conglomeratic porphyries occur near the ore, and also small accumulations of micaceous ore-crystals, accompanied by quartz. Cuthbertson bank, north-west quarter Sec. 19, T. 33, R. 4, E., and Ackhurst bank, south-west quarter Sec. 18, T. 33, R. 4, E., are deposits of manganiferous specular ores and magnetites and man- ganese-ores. Hogan Mountain, south-east quarter Sec. 14, T. 33, R. 3,E., Fig. 24. CUT ON HOGAN MOUNTAIN 124 IRON- ORES OF MISSOURI. Iron County, contains irregular pockets of mostly soft, coarsely crystalline or micaceous, specular ore, in a peculiar, light-red, granular quartz-porphyry, which in the immediate vicinity of the ore is de- composed, and assumes a blue color when mixed with the ore. Fig. 24 represents a section of such a pocket as opened by a cut. The massive, red porphyry on both sides of the cut is of the above description, and is covered by a dry soil, containing many pieces of broken porphyry. On both sides of the pocket we find the red porphyry half decomposed to a thickness of several feet. We fur- ther find, in immediate contact with the ore, a blue porphyry, mixed with some ore. The pocket itself is filled in its lower part with a blue porphyry conglomerate, strongly impregnated and mixed with ore, and in its upper part with pure, soft, crystalline, specular ore. This pocket, getting smaller below, runs out into a fissure, which splits in several branches, enclosing a large fragment of half-decomposed red porphyry, and a mass (C) of a gray conglomerate, mixed with pieces of a jasper-like porphyry and with quartz. The fissures are filled with a soft, loose, chloritic clay, undoubtedly a product of the decomposition of adjacent porphyries. R P is a dark, reddish- brown, very hard and massive porphyry. It seems probable, from this section, that the solution which has deposited the ore has come from the side, or from above, out of fissures in porphyries which have since been destroyed and washed away, and that the cracks below the pocket were opened either by the crystallization of the ore or by the freezing of water, and after- ward filled with fine clay. There are several small deposits of a similar character on Hogan Mountain. b. DEPOSITS OF SPECULAR ORE IN SANDSTONE. The valuable and, in part, extensive deposits of specular ore in sandstone, the ores of which have been described in Chapter III. of the present report, occur in the eastern part of central Missouri, south of the Missouri River, especially in Crawford, Phelps, and Dent Counties, and constitute, together with the two following cate- gories c. and d. of ore-banks, that iron-ore region in the State which in Chapter II. I have called the " Central Region." It has been mentioned there that many of these deposits have undergone great disturbances in their position. I shall describe under the present SPECULAR ORE IN SANDSTONE. 125 head, b., only such deposits of specular ore in sandstone as are either entirely undisturbed, or which have been broken in place by being underwashed, or by a contraction of underlying strata or of their own mass, without subsequent removal of any great portion of their mass. Those deposits which were broken and separated into two or several parts, the single parts being shifted or moved to a greater or less distance, I shall describe under the two following heads, c. and d. All these deposits belong to the Lower Silurian formation, and more especially to those strata which have been designated and described by Prof. G. C. Swallow, in the Second Annual Report of the Geological Survey of Missouri, page 125, as ' ; Second Sand- stone." Wherever I have been able to trace distinctly the geolo- gical position of these specular-ore banks, I have found them to be associated with this second sandstone, which has its place above the third and below the second " Magnesian Limestone." As the second sandstone is represented more or less extensively in the whole central part of southern Missouri, a great portion of which has been very little investigated as yet, we may hope that numerous other deposits will yet be discovered in the State, besides those to be described hereafter, and besides all those to be mentioned in our ore-bank list in Chapter V. These deposits of specular ore have generally a lenticular shape, with either circular or elliptic outlines. They are frequently found in an inclined position, in which case they usually dip with the slope of the hill. Sometimes the ore is cut off abruptly at the out- skirts, by nearly vertical walls, consisting of nearly vertical layers of clay, chert, and sandstone. In this case, these deposits appear like large, round, somewhat lenticular pockets in the sandstone, clad with layers of clay and chert, and filled with specular ore, which is often more or less altered into soft, red hematite. The thickness of these deposits is in the average about one-fifth to one- sixth of their average diameter. The ore is directly surrounded and underlaid by formerly continuous, but now broken and discon- nected, strata of green or gray chert or flint, sometimes mixed with a fine, silicious, white clay, or with red loam. Below these chert- layers we find alternating strata of chert, sandstone, and of chert- breccia cemented by sandstone, sometimes continuous, but mostly broken. Below these are the regular strata of the second sand- 126 IR ON- ORES OF MISSO URL stone, running parallel with the above, and forming a circular or elliptic depression, in which the deposit lies. At the outskirts of this depression, where the sandstone strata suddenly change their nearly horizontal position, to curve downward and to run beneath the ore-deposit, the upper strata are frequently broken off, and form an annular outcrop round the deposit. All these various rocks surrounding and underlying the specular- ore deposits, have in some cases their original and natural color and appearance, while in other cases they are ferruginous, or colored and impregnated by iron-ore, whereby the sandstone turns brown or black, and glittering with numerous fine ore-crystals throughout its mass, while the chert is colored green or red, and the clay or loam is transformed into a reddish-brown, sometimes pretty hard, ferruginous clay-rock. In the Meramec bank we find regular layers of clay, chert, and sandstone, not only under but also above the ore-deposit. In most other places the ore is either covered with loose detritus, bro- ken chert, and soil, or else it lies bare, in which latter case the specu- lar ore is often changed into limonite near the surface. The above description gives us the following two series of suc- cessive layers of rocks lying above, in, and under the specular-ore deposits in sandstone : 1. Sandy and Ckerty Soil. ( Sandstone with solid chert-layers. Same, impregnated } chert d etr i tus an( j L ;. 2. K with iron-ore. Sandstone, loam, and chert, broken v ( and mixed. Solid chert. Broken chert and clay. ) 3. Soft Red Hematite. 4. Hard Specular Ore. ^. White clay or red loam. Ferruginous clay-rock. 6. Clay and broken chert. Ferruginous chert -breccia. ... , ,., , ( Sandstone, colored or im- 7. Broken sandstone and chert with layers of solid chert, -j pregnated by i ron . ore . 8. Second, Lower Silurian, Sandstone. Not all these strata are equally and invariably represented in all the deposits. All the beds of rock thus associated with the ore-deposits seem to be in the same relative position in which they have originated, but to be in part broken, in part half-destroyed and altered. It seems that these specular-ore deposits were originally formed in a lenticular shape, and imbedded in or on a sandstone containing layers of chert, and that they were afterward partially or wholly underwashed, some of the softer sandstone being thus removed, LIMESTONE IN HENRY COUNTY. 127 while the harder cherty parts and layers remained. In consequence of this action, a slight shifting of the whole mass of ore may have taken place, which somewhat crushed and mixed some of the un- derlying materials, and brought the deposit in a more or less in- clined position. In some instances large caves, which are so com- mon in all limestones, and which are undoubtedly formed by the dissolving action of acid waters, may have existed in the Third Magnesian Limestone, below the ore-deposits, and may have caused either a gradual or a sudden sinking, without which the origin of the pockets with almost vertical walls, in which such deposits are sometimes found, cannot easily be explained. The original len- ticular masses of ore may have been formed either by deposition from chalybeate waters in depressions on the surface of the sand- stone, and afterward covered by other strata, and condensed and altered by pressure and higher temperature, or else they may have come into existence by a gradual replacement of lenticular limestone- deposits formed in the above-described manner in the sandstone. While the first supposition appears as the more simple and as the more natural and intelligible one, the second one is supported by the two following facts : Irregular rounded masses of a very dense and hard orange-yel- low, subcrystalline limestone, interspersed with pretty large gray crystals of carbonate of iron, are sometimes .met with in the midst of the ore, and passing into the latter. Mr. G. C. Broadhead found, in the lower coal-measures of Henry County, a stratum of limestone from 3 to 6 inches thick, which is partly converted into red hematite, containing no carbonic acid. This transformation has taken place from both the upper and the lower surfaces of the stratum, and has reached a thickness of three- quarters to one inch, from either surface, while the interior consists yet of the unaltered gray limestone. Another fact, however, which speaks in a certain measure against the second of the above two suppositions, is this, that lenticular deposits of limestone have nowhere been observed in the Silurian sandstone of Missouri. I will not attempt to decide whether any such deposits have existed and have all been metamorphosed into ore-deposits, or whether the supposition is incorrect. These undisturbed or slightly-disturbed deposits may be recog- nized by the following external characteristics : 128 'IR ON- ORES OF MISSO URL 1. They mostly occupy a high topographical position, lying on summits of hills or of ridges if undisturbed, or on the upper part of slopes close to the summits if somewhat disturbed. 2. They have a circular or elliptical outline, inside of which the ground is covered all over with surface-ore of various sizes, partly specular, partly limonite, more or less rounded and smoothed, es- pecially on the upper side, from being exposed to rain and storm. The larger the size of these pieces and bowlders on the surface, the more confidently a good deposit may be expected. 3. They are surrounded by annular outcrops of solid or broken red clay-rock, chert-breccia, black or brown impregnated sand- stone, and finally of yellow or white sandstone. These annular sandstone outcrops are frequently very conspicuous. 4. The slope of the hill shows also, outside of these annular out- crops, streaks of smaller and more rounded surface-ore, evidently washed down from the original deposit, the main body of which always lies inside the sandstone outcrops. The surface-ore is some- times spread over the whole hill. In other localities it is concen- trated in depressions and ravines, the soil and sandstone being con- tinually washed away, while the heavy ore is left and concentrated. In other not unfrequent instances the surface-ore on the slopes covers swellings of the ground, encompassed or cut by two or more diverging ravines. In such cases the surface-ore lies generally pretty thick and close, and thus protects the underlying softer ma- terials from being washed away as rapidly as the less protected por- tions of the same slope. It is obvious that these swellings have been produced by such an unequal protection of the ground. When opened by shafts, these swellings are then found to consist of loose, sandy detritus, with little or no ore, overlying the solid sandstone. The extent of the surface-ore, however thick and close it may lie, when outside of the annular outcrops of sandstone, is therefore no proof of a corresponding extent of the deposit. I will now proceed with the special description of a number of ore-banks belonging to this category of undisturbed or slightly- disturbed deposits of specular ore in sandstone. Scotia No. 1, Sec. I, E. y 2 S. E. ^, T.' 38, R. 3, W., Crawford County. This deposit lies in a low sandstone-hill, which forms a spur on the southern end of a higher limestone-hill, and is separated by two SCOTIA MINE. 129 narrow valleys from the surrounding high hills, composed of Third Magnesian Limestone at the base, and of Second Sandstone in the upper part. Fig. 25. The Second Sandstone on which the ore is bedded occupies a much lower level than the Second Sandstone which caps the sur- rounding hills. It has undoubtedly sunk down gradually into its present location, which is at the level of the limestone, by which it is surrounded on three sides. The whole ore-bank sank down with the sandstone, and by its weight may have kept the latter in place, and protected it against destruction by the waters which effected the erosion of the valleys on both sides. S and L, on Fig. 25, mean that pieces of sandstone and limestone are found there, mixed, on the surface. Distinct outcrops and openings of both these kinds of rocks are found on the other two hills, east and west of the ore-hill. The broken line across the ore-hill shows the probable limit of 9 130 IRON- ORES OF MISSOURI. the ore. The annular outcrop of sandstone round the ore is also indicated. The surface-ore extends over an area about 1 80 feet wide and over 200 feet long, a, b, c, are cuts made for the purpose of mining the ore. Fig. 26. Ill |SP n n 5 i o o H > to m o O Z 2 5 CA U> il ^5: o -< Z (0 f EAST The foregoing, Fig. 26, represents a section through the cuts a and *, showing the interior structure of the upper part of the ore- deposit. SCOTIA MINE. 131 We see here nearly corresponding strata on both sides of the ore, all dipping toward and apparently under the ore. There is the Second Sandstone (S), yellowish-white, dipping about 40 on the west side, and considerably more on the east side. Next to this sandstone is, on the east side, a stratum of breccia of green, red, and yellow chert, mixed with pieces of sandstone, and cemented by red loam 8 feet thick (B S). This same stratum, with the same thickness, is represented on the west side ; but it is there separated from the white sandstone by a stratum, 5 feet thick, of Sandstone impregnated with fine, greasy ore (S and H), probably pro- duced by an accidental and local infiltration into the regular Second sandstone. Then follows, on the east side, a stratum (F), 2 feet thick, of green and brown flint or chert, in solid and nearly un- broken but very irregular layers. These strata will undoubtedly meet below the level of the present section, and thus form a pocket, in which the ore is placed. The ore itself consists of large, irregular masses of hard, blue, specular hematite (H H), getting more soft and light-colored out- side, and passing into the soft, red hematite (S H), which surrounds them, and which constitutes the greater part of the bank, as far as opened at present. The soft, red ore is mostly greasy to the touch. It contains sometimes streaks of broken chert and of clay, and is in its upper part mixed with streaks and irregular masses of yellow ochre. All this ore must have been formerly one solid mass of specular ore, which was broken, and gradually softened, and sub- jected to such transformations as I have described in section B. Scotia Bank No. 2, S.E. %, Sec. 28, T. 39, R. 2, W , Crawford County. This seems to belong to this category of ore-banks, although its exterior characteristics are not very plain, and although it is not sufficiently opened to allow an exact judgment regarding its char- acter. To judge from the surrounding hills and from the surface- rocks, the hill seems to be composed of limestone capped by sand- stone, or else of sandstone exclusively, and to contain a considera- ble mass of ore, situated above the sandstone on the summit of the hill. The ore is thickly covered by detritus on the north-east side, while it is but a few feet below the surface on the south-west side, near the summit. Its presence there has been proved both by a shaft and by a ditch, which are from 80 to 90 feet apart. 132 IRON- ORES OF MISSOURI. At the foot of the hill, which is about 150 feet below the summit, a tunnel was made, and struck immediately under the soil, the soft, red ore enclosing pieces and bowlders of specular ore, and numerous broken stalactites of specular, partly converted into red, ore. This ore, several feet thick, dips with the slope, and is underlaid con- formably by a layer of green chert, 2 feet thick, which itself lies on a mass of broken chert and sandstone, mixed with clay and loam. All these materials that were struck by the tunnel are undoubtedly detached parts of the main ore-bank on the summit. Cherry Valley, No. 1, E. V 2 S. W. ^, Sec. 4, T. 37, R- 3, W., Crawford County, 6 miles east of Steelville. JP. H . H . SPECULAR ORE B.H. BROWN HEMATITE CHERRY VALLEY BANK . i Fig. 27 gives a topographical sketch of the two Cherry Valley banks, neither of which is as yet opened. Nevertheless, the west- ern or No. i bank will readily be recognized as a very distinct and characteristic example of a nearly undisturbed deposit of specular LAMB BANK. 133 ore in sandstone. The lower part of the hills in that region is com- posed of Third Magnesian Limestone, the upper part of Second Sand- stone. On the summit we observe an annular outcrop, several feet thick, of white and yellow Second Sandstone, having in part the ap- pearance of a vitreous quartzite, and dipping toward the centre, but so steep that the strata are in most places nearly in a vertical position. Inside of this outcrop of light-colored sandstone, and placed conformably to it, is an annular outcrop of a sandstone col- ored or impregnated by oxides of iron. The circular space inside of these outcrops, 150 feet in diameter, is entirely covered with ore, the numerous large bowlders consist- ing principally of specular ore, while most of the smaller pieces are altered partly into limonite, partly into soft, red hematite. This space marks the position of the regular deposit, and a pocket of con- siderable depth, filled with ore, will certainly be disclosed here by future mining operations. There is a gap in the sandstone outcrop on the south side, and there the surface-ore is spread in considerable quantity down the slope, outside the outcrops, in a streak 50 to 60 feet wide and about 200 feet long. The greater part of this surface-ore is changed into limonite. An extension of the underground deposit in this direc- tion cannot, however, be expected. The eastern or No. 2 Cherry Valley bank, which is sketched in Fig 27, does not show the exterior characteristics of an undisturbed bank, although it contains very large and very numerous bowlders of specular ore and of limonite on the surface, and although very large masses of ore will undoubtedly be found there underground, especially in the upper part of the hill. But it is, from its present appearance, a disturbed deposit, belonging to the third category C, of which I shall speak hereafter. Lamb Bank, Sec. 35, T. 36, R. 6, W., Phelps County. This bank is situated in the " Upper Meramec" district, on the dividing ridge between the Benton Creek Valley and the Norman Hollow, at the head of the western branch of Benton Creek. The main part of the bank is situated close to the highest point, and is nearly round, 150 to 200 feet in diameter. No distinct annular outcrops are perceptible, however, and the limit of the body of massive ore can therefore not be determined with great accuracy. But an annular streak of ferruginous clay-rock and of 134 IRON- ORES OF MISSOURI. chert-breccia can be traced nearly all round the bank, from the loose pieces lying on the surface. LAM A BANK. A horizontal outcrop of white sandstone is found half-way down the western slope, where also large bowlders of specular ore occur, as well as in the western ravine, which is about 130 feet below the bank. The low, triangular slope south of the circular bank is covered with small and rounded surface-ore, between the road and the little ravine on the east side. This ore was undoubtedly washed down from the main deposit. Benton Creek Bank, Sec. 32, T. 36, R. 5, W., Crawford County. On Benton Creek, in the " Upper Meramec " district. The sketch (Fig. 29) shows a large hill, 150 to 200 feet high, cover- ed with surface-ore, which is partly specular, partly limonite, partly strongly-impregnated sandstone. The surface-geology indicates yellow and white sandstone on the lower half of the hill, cropping out in several places on the slopes and dipping in each case toward the centre of the hill. On the north-west side we find a ferrugi- nous or impregnated sandstone on the surface, extending in a curved streak round the hill. All this points toward the existence GROVER BANK. 135 of a large ore-deposit inside these sandstones. A peculiar feature of this bank is a straight zone of very large bowlders of specular ore running across the hill from north-west to south-east. This bank is somewhat disturbed, but it has preserved its circular char- acter. The mass of ore will probably be found broken, but not scattered to a great extent. Fig. 29. BCNTON CREEK BANK. This is one of the largest ore-banks in central Missouri, judging from its appearance and dimensions. Grover Bank, S. W. %, Sec. 2, & N. W. j^, Sec. 11, T. 35, R. 4, TV., Crawford County. This ore-bank is situated in the " Upper Meramec " district, on the top of a high ridge, with pretty steep slopes, cut by numerous ravines, which descend gradually through lower ranges of hills into the broad valley of Crooked Creek. The ore does not lie thick, either on the slopes or^on the hill. It is more concentrated in the ravines. Fig. 30 presents an elevation, showing the various rocks met with in going from the Crooked 136 IRON- ORES OF MISSOURI. Creek valley up to the bank, namely, the Third Magnesian Lime- stone, the Second Sandstone, which becomes ferruginous near the bank, above this a thin streak of red clay with chert, and finally the ore on the summit. Fig. 30. SHAFTS G ROVER BANK This succession of rocks and the situation of the bank seems to warrant the presence of a good ore-deposit, although the surface- ore is not very copious. Six small shafts have been dug on the top of the hill, five of which were too near the outcrop of the ore, and therefore, after cutting through 5 to 7 feet of soft red and of specular ore, struck either the underlying white clay or the chert- breccia or the impregnated sandstone. The sixth shaft was made nearer the central part of the summit, and struck soft, red hematite immediately below the soil, together with bowlders of specular ore up to one foot in diameter. This shaft was brought down six feet only in the ore, and then discontinued. The presence of a large amount of soft ore in this locality proves that the bank has been broken up and somewhat disturbed. But it is not likely that a con- siderable part of the original mass of ore should have been washed away. Simmons Mountain, N. W. *^, Sec. 24, T. 34, R. 6, W., Dent County, y 2 mile south-west of Salem. This is one of the largest, if not the largest deposit of specular ore in the central ore- region. It received its name from its original owner, Mr. C. C. Simmons, of St. Louis. Fig. 32 is a view of the Simmons Mountain, which is a nearly isolated hill about ninety feet high, above the plateau south of Salem, on which' it is situated, and covering over thirty acres of ground. SIMMONS MOUNTAIN. Fig. 32. 137 if. V; / / SIMMONS MOUNTAIN . UNIT Of* 30UO ORe COVERING' A DISTRICT SOO'LONC *, UMIT or OTHER HOCKS . e 8. OVTOHOP Of SANDSTONE. The main body of the hill seems to be composed of Second Sand- stone, which is found in pieces on the surface, and has been uncovered by a digging at the foot of the north-western slope, close to the road. The sandstone on the surface is mixed with pieces of chert on the southern and south-western sides, near the base. Higher up it is mixed with specular surface-ore, which extends over a very large district, increasing in frequency and size toward the summit. Some of the surface-ore on the slopes is altered into a fine and pure limonite (brown hematite), but most of it is specular. The 138 IR ON- ORES OF MISSO URL latter occurs in bowlders, several feet in diameter. The follow- ing topographical sketch will give a better idea of the surface- geology. We here notice, in addition to the occurrences just described, an elliptic district, about 400 feet wide and 500 feet long, enclosing the summit, and being very thickly covered with surface-ore. This is the position and extent of the original deposit. As may be seen on the sketch, it is surrounded by outcrops of sandstone (S), which are especially distinct on the north and west sides, and are ferruginous in several places. On the east side some outcrops of sandstone are found lower down the slope. The dip of the sand- stone cannot now be distinctly recognized, but this rock will un- doubtedly be found to form a large elliptic pocket, filled with ore. Inside of the upper sandstone outcrops, the surface bowlders are of enormous size, evidently outcrops of an immense body of massive ore. Wherever the soil is removed between these bowlders, ore is found immediately below it. Outside of this district, the surface-ore, although very large in places and very plentiful, must be considered as being broken off from the main deposit and thrown or washed down the hill. This ore may have been at first imbedded in large masses of detritus of sandstone which was broken off simultaneously with the ore. Afterward this ore was concentrated on the surface by the slow but unavoidable and merciless action of rain-water, which mechani- cally destroyed and removed the light sandy materials surrounding and underlying the ore, while the ore itself, being too heavy to be carried off by such action, remained in place. This outside surface- ore is therefore not indicative of the existence of large bodies of ore below it. These views have been fully verified by a number of shafts which have lately been sunk on the Simmons Mountain, and which on our sketch are marked by the numbers I to 9. The shafts 5, 6, 7, 8, and 9, which are outside the elliptic district, disclosed 15 to 25 feet of loose, sandy detritus, and finally struck the solid sandstone. Shafts 5 and 6, which are the nearest to the deposit, met with more clayish materials, and streaks and masses of white clay and chert, which are so frequently found in close proximity to such deposits. The shafts I, 2, 3, and 4, although sunk quite near the limits of the deposit, but inside of them, went through 25 to 30 feet of solid, POMER O Y BANK. 1 39 pure, specular ore, without reaching the foot-walls. I was lately informed that, since my last visit, one of these shafts has struck the clay at a depth of a little less than 30 feet. This is not at all aston- ishing, on account of the proximity of the shafts to the limits of the pocket. The fact that none of these shafts has reached the clay at a less depth, proves that the walls of the pocket are nearly ver- tical, and points to a great thickness of the ore in the central por- tion of the deposit. At the foot of the Simmons Mountain, and north of it, a well has been sunk, which is marked in Fig. 32. This well is over 60 feet deep. It passed through 8 10 feet of soil and loose, sandy material. 6 7 feet of sandstone in broken layers. 15 18 feet of red, sandy loam. 6 feet of chert, in thick, broken layers. 6 8 feet of red, sandy loam. 3 4 feet of chert, in broken layers. 14 feet of chert, mixed with clay. All the materials just mentioned seem to be remnants of destroy- ed sandstones which must have formerly surrounded the Simmons Mountain. The harder cherty strata have been evidently less subject to destruction, and have therefore been left in place and concentrated, while the greater part of the softer sandstone was destroyed and carried off by the waters and floods, which effected the erosion of the valleys in that region, besides washing away whole strata of rocks. The body of the Simmons Mountain was in a great measure protected against this action by the size and weight of its ore-deposit, which seems to be nearly undisturbed, resembling in this respect the Cherry Valley No. I and the Lamb banks above described. Pomeroy Bank, Sec. 10, T. 34, R. 6 W., Dent County, three miles north-west of Salem. This quite extensive ore-bank was evidently underwashed on the west side, and broken and turned or moved in that direction, as can be easily perceived from the study of the surface-geology on our sketch. The mass of the ore does not seem, however, to be much scattered, nor to have been removed to any considerable ex- IRON- ORES OF MISSOURI. tent ; so that we may rank this bank with the disturbed depos- its (b). JP. BROWN 8*. '8LUE Oftt V\ I ' j / / ^-^^EMAT.Tt^^:^^:---- POM E ft Q Y ORE BANK The top of the hill is about 120 feet above the eastern valley; but the surrounding hills are mostly higher than the Pomeroy hill. In throwing a look on Fig. 33, we find that the principal mass of the surface-ore, although in large quantities and sizes, is here not situated on the summit, but on the western slope, where indeed, besides the cherty soil, hardly anything else but ore is seen on the surface. The summit is occupied by ferruginous clay-rock and pieces of ore altered into limonite. On the eastern slope we have a zone of the well-known breccia of white and green chert, ce- mented by clay-rock, and lower down the ordinary, white or yel- low, Second Sandstone. No regular outcrops are to be seen ; but TAYLOR BANK. 141 the succession of rocks from the east to the west, shows that a con- siderable mass of ore must exist in the western and central parts of the hill. Taylor Bank, S. W. % of S. W. ft, Sec. 12, T. 34, R. 7, W., Dent County, eight miles north-west of Salem. Fig. 34- TAYLOR BANK On this topographical and geological sketch of the Taylor bank we meet with circumstances very similar to those just described. We find about the same succession of rocks, and the whole ore- bank situated on the slope, the specular ore occupying the foot of the hill. The surface-ore extends over an area about 400 feet square. The main body of the ore will probably be found in the upper part of the semicircular space, which is surrounded by a zone of ferruginous rocks. This bank has been undoubtedly underwashed on the south side, and disturbed in its position. North ! 42 fR ON- ORES OF MISSO URL of the bank, near the summit of the hill, is one of the round sink- holes which so frequently occur on hills composed of Second Sand- stone and Third Limestone. They are, perhaps, caused by the existence of large cavities in the limestone, which have caused a sinking of the overlying sandstone. This sink-hole does not at present seem to be in any connection with the ore-deposit. Iron Ridge No. 1, N. E. %, Sec. 29, T. 39, R. 5, W., Crawford County. I give here a plan and section of the Iron Ridge mine. The ore-deposit seems to be of a lenticular shape, but curved hori- zontally, while dipping at an angle of about 40 degrees toward the east. The specular ore is all broken, and to a great extent altered into soft, red hematite, in which the remains of the specular ore are imbedded as half-converted bowlders. The deposit is entirely surrounded by loose materials, and has undergone considerable dis- turbances ; but at the time when these took place the ore-bank must have been in a solid and intact state, because its limits are sharp and well marked, and the main body of the ore, although broken up interiorly, has not been separated into several smaller bodies, nor scattered about, as far as can be seen at present. The succession of rocks may be observed as follows : 1. Cherty and sandy soil. 1-3 feet. 2. Clayish and sandy detritus, white, yellow, and light red, en- closing pieces of chert and chert-breccia in sandstone, and some- times masses of soft sandstone. 40 feet. 3. Very hard breccia of sandstone, cemented by quartz. 2-4 feet. 4. Broken chert, imbedded in red and yellow clay or loam. 1-3 feet. 5. Soft, red ore, partly greasy, enclosing bowlders of hard specular ore, exteriorly converted into red ore to a greater or less extent. These bowlders form about one-third of the whole mass, and grow larger with the depth, being apparently 5 to 8 feet in diameter at the bottom of the main shaft. The average thickness of the deposit, as far as now opened, is about 25 feet. IRON RIDGE ORE- BANK. 143 PLAN OF MINE. CUD. CrAYlSrt DETRITUS S.H. BOFTHEMATJTC YELLOW PLASTIC CLAY K.H. HARD HEMATITE Cl.+ F. CHERT IN RCO * YSLLOW CUY B.S. BROKEN SANOSTONC S.O. SANDY OCTHITU8 ? , SANDSTONE LIMIT or CUT LIMIT or ORE 1 44 IR ON- ORES OF MISSO URL 6. Yellow, plastic clay, sometimes with pieces of specular ore. 1-3 feet. 7. Red loam and white or yellow, sandy clay, irregularly mixed, enclosing large bowlders of decomposed specular ore. These bowlders are soft enough to be broken by picks and sledges, and present in their fracture a variegated appearance, red, brown, yellow, and black ore being mixed together, and containing specks of white clay and in some places seams of quartz. The original geological position of the Iron Ridge deposit cannot be safely determined from its immediate surroundings, all the regu- lar geological strata in that district being thickly covered by sandy and cherty detritus, undoubtedly produced by a very extensive and complete destruction of sandstones with chert-layers. A bore-hole, a few hundred feet south-west of the ore-bank, on the same ridge, went through 65 feet of this loose and irregular formation, without striking the solid rock. Several wells were sunk in various places in the valley to a depth of 45 feet. There, also, drifted masses were found to a depth of 12 to 15 feet, consisting of broken chert, of rounded pieces of sandstone, and of sand. Below this more solid, yet not quite undisturbed, rocks were reached, consisting of alternate strata of sandstone and more or less broken chert. Of these strata, a thickness of 30 feet was pierced, without obtaining water in desirable quantity. The ore in the Iron Ridge deposit seems to extend to a consid- erable depth. The main shaft is now over 50 feet deep, and has not reached the end of the deposit. Meramec Bank, N. W. %, Sec. i, T. 37, R. 6, W., Phelps County, 7 miles south of St. James. The Meramec bank, a section of which is given in Fig. 36, is a lenticular deposit of a nearly circular outline, lying in clay and chert beds, in the Second Lower Silurian sandstone. Its inclined position, as well as the broken condition of the ore, indicate former disturbances, probably caused by a partial destruction and removal of the underlying sandstone, especially on the south side, where a deep ravine or narrow valley has been eroded, perhaps by the same waters that may have underwashed the ore-deposit. In this valley, through which a road leads down to the Meramec Iron Works, outcrops and bluffs of the Second Sandstone are exposed. The dip of the sandstone is very irregular, mostly, however, 10 to MERAMEC BANK. Fig. 36- 145 SOUTH NORTH. s. SECTION OF MERAMEC MINE S. SECOND SANDSTONE Cl. + F. S.*F. .SANDSTONE WITH FLINT F. g.-F. Cb. 3*MO STONE WITH F I I NT& LO A M 6.H. ,*.H..r. SANDSTONE WITHORC fc. CHERT H-H, LIMIT OF OUT CLAY WITH CHE RT SOU F LI MT SOFT H EM ATITE HARD HEM ATITE 20 degrees to the north-west, about in the direction of the ore- bank. Lower down, in the vicinity of the iron works, the Third Magnesian Limestone is exposed with a dip of 10 to 15 degrees north-north-west. A large spring, discharging about 10,000 cubic feet of water per minute, of a temperature of 58 F., uniform all the year round, comes out of this limestone, proving that it must contain enormous cavities and spacious subterranean channels. The limestone is thickly bedded and contains numerous chert con- cretions. The upper strata are more irregular, and enclose layers and masses of sandstone. The Second Sandstone in the vicinity of the ore -bank occurs on the north and west sides in distinct outcrops dipping toward the ore. This sandstone is often thinly bedded, and shows sometimes a wavy striation on' the surface of the layers, similar to that which is frequently produced on loose river-sand by the waves of a shallow water. The succession of strata in a section through the ore-deposit, as represented by Fig. 36, seems to be the following : 1. Second Lower Silurian sandstone. 2. Broken chert, imbedded in red, sandy clay. 12 feet. 3. Chert-breccia in sandstone. 4 feet. 4. Soft, red hematite with many bowlders of specular ore, more or less altered on the outside ; also, in places, irregular, large 10 1 46 IR ON- ORES OF MISSO URL masses of hard, yellow limestone, with seams and specks of car- bonate of iron ; also, soft, greasy "paint-ore," red to dark purple, the latter very pure in pockets on the surface of the deposit ; also, streaks of soft, yellow ochre. The thickness of the deposit varies from 5 to 40 feet. 5. White clay, mixed with broken chert, o to 5 feet. 6. Layers of solid chert. I to 2 feet. 7. Broken sandstone and chert, mixed with loam. I to 10 feet. 8. Impure and uneven sandy rock, impregnated with oxides of iron and containing layers of broken chert. 5 to 20 feet. 9. Alternate layers of sandstone and of massive chert. 5 to 20 feet. 10. Dry, sandy soil, containing small, rounded particles of specu- lar ore. y 2 to 2 feet. All the strata above the ore are very irregular in their position and thickness. Most of them can, however, be traced across the whole mining-cut. That portion of the section, Fig. 36, which is below the limit ( ) of the cut, is imaginary, and has been added merely to give a clearer picture. The ore might, perhaps, in the central part of the deposit, extend deeper into the sandstone than is indicated in that section. James Bank and Moselle No. 9, S. ^ of S. E. y[, Sec. 29, T. 38, R. 6, W., Phelps County, 2 miles south of St. James. These two banks are situated close together, on a low ridge, on the plateau of St. James, between the Dry Fork and the Bourbeuse Rivers. The formation in that district is Third Magnesian Limestone, capped by Second Sandstone. This may be observed along the Dry Fork River, south of St. James. The two ore-deposits men- tioned are in the sandstone. The sketch on next page, Fig. 37, shows their relative position. Both these banks are nearly worked out ; the best and richest ores are all taken out, and the walls and the bottoms of the deposits are laid bare. These places, therefore, offer a good opportunity for the geologist to study the character of these pocket-like deposits in the sandstone. The ore formerly contained in these pockets was mostly soft, red, and in part greasy hematite, enclosing large bowlders of specu- lar ore. The ore filled a nearly circular depression in the sandstone, JAMES AND MOSELLE BANKS. 147 with pretty steep walls. The ore was 10 to 15 feet higher in the centre than at the circu'mference. The James bank had about 35 feet average height, and a diameter of over 200 feet, and fur- nished about 30,000 tons of ore. The Moselle bank was 20 feet thick in the average, and 150 feet in diameter, and may have contained 12 to 15.000 tons of ore, some of which is yet in place. The James bank lies at the edge of the northern slope of the hill, and dips slightly north. The Moselle bank lies at the edge of the western slope, and dips west. These last observations, made on two banks so similar in every respect, and in so close proximity to each other, go far to prove that the dip of such deposits follows the slope of the hill, and that both were produced by the same cause, namely, by erosion. The walls of these.two, now empty, banks, consist of a mixture of green and white broken chert, with yellow and red clay, partly soft, partly indurated. The face of the walls is rather uneven, the ore reaching in places into the chert in irregular masses. The limits between the chert and the ore are, however, well marked. The bottom consists of a white or gray broken chert, mixed with white clay. A shaft has been sunk into this mass, in the centre of the James bank, 22 feet deep, .without reaching the solid rock. In the lower part of this shaft, the clay turned dark gray, green and black, and 148 IRON- ORES OF MISSOURI. was mixed with iron pyrites, in small concretions or as a fine crys- talline grit. Beaver Creek Bank, S. j^, Sec. 33, T. 37, R. 8, W., Phelps County, 5 miles south-west of Rolla. I give here a plan and an elevation of the Beaver Creek bank, as far as it was opened and known in summer 1872. Fig. 38. w.TrV/JSrYii'tVT ra J . SOLID \ P 3 ~4 4 ,. v p ,i ( ORE z 9 , f 2 j 1 ttN ruHT V,^^,^^ T CROSa - SECTION BEAVER CREEK BANK. It lies on the summit of a high ridge, near the head of Beaver Creek. An excavation has been made into the ore, 7 f eet l n g> 30 feet wide, and 16 feet deep. The hill seems to consist of sand- stone, which crops out on the slope about 60 feet below the mine, as seen in the above elevation. The ore seems to be pretty solid, and in its greater part specular, but slightly altered or softened. The above plan shows that the mass of ore extends about 70 feet from north to south, being cut off on both sides by nearly vertical layers of green chert imbedded in red loam. Next to this a layer of chert-breccia may be observed on the northern wall. The extent of the deposit in other directions cannot as yet be estimated, because the ground surrounding the DEPOSITS OF SPECULAR ORE. 149 bank is covered by soil, without any plain surface-indications of either rocks or ore. Other deposits, which probably belong in this category, are the Craig bank, in the "Upper Meramec " district; the Wiggins and the Ziegler banks, in the Salem district; and the Mont Rouge, Mocassin Bend, and Hancock banks, in the specular-ore district, on the Middle Gasconade River, and in Miller County. The exact location, with a few particulars, of these banks is given in the general ore-bank list, section D. C. DISTURBED DEPOSITS OF SPECULAR ORE. The specular-ore deposits, of which I intend to speak under this head, were originally such as described under b. They were, how- ever, not only broken by contraction, or by underwashing, or by more violent geological actions, but they were also divided into two or more large portions, which portions were separated from each other by the removal of one, or of more than one, or of all of them, from their original position. We may, accordingly, distinguish two kinds of such " disturbed deposits," namely : 1. Masses of specular ore which have been removed from their original position and deposited elsewhere, in a more or less irregu- lar manner, and 2. Remaining portions of original deposits, from which other portions have been separated and removed. Such disturbances must have taken place in some instances slowly and gradually, in other instances with more rapidity and violence, which difference of action must have exercised a marked influence on the condition in which the various deposits are found at present. The more rapid and violent this action was, or the greater the dis- tance over which a certain mass of ore has been shifted, the more will the present ore-bank be broken up, and the less of those more solid rocks with which it was originally associated will adhere to it, as chert, sandstone, breccia, and the more directly will it be im- bedded in loose detrital materials. Some of the deposits, which I shall describe or mention in this category, are not yet sufficiently opened to give a final decision regarding their character. They may prove to be broken-off parts of larger deposits situated in close proximity, and may lead to the discovery of the latter. 150 1R ON- ORES OF MISSO URL FRANKLIN COUNTY ORE-DISTRICT. Thurmond Bank, N. y 2 N. W. ^, Sec. 19, T. 41, R. i, W , Franklin County. This bank is situated 2 miles north of Stanton, in a rather rough country, with steep, high hills, separated by narrow valleys and ravines. The soil is mixed with, and in places cov- ered, by broken white chert. No outcrops of regular geological strata are perceptible, nor any surface-rocks, which might give a clue to determine the formation. The Thurmond bank is as yet but imperfectly opened. The surface-indications consist of a num- ber of large pieces of limonite, and of some small, sharp fragments of a very hard and silicious specular ore. They are scattered over a surface about 50 feet wide and 200 feet long, over a slight swell- ing of the ground extending down the slope of a moderately steep hill. A shaft was sunk here a number of years ago, in a vain attempt to find copper-ores. It is said that this shaft, which is yet open to a considerable depth, passed through 37 feet of red iron-ore. Some heaps of soft, red, somewhat clayish hematite, mixed with pieces of soft " paint-ore," are seen at the mouth of the shaft. All ap- pearances indicate that this is a greatly disturbed and dislocated deposit. Old Copper Hill, E. y 2 N. E. %, Sec. 23, T. 40, R. 2, W., Crawford County. This bank is not opened. It has externally a great resemblance to an undisturbed bank, as which it would have to be considered if the surface-ore was larger, less rounded, and more concentrated on the summit of the hill. As it is, the bank has more the appearance of being the remainder of a disturbed deposit, large parts of which would have been removed. A circumstance which is very strange, and which also points to a disturbance, is, that fragments of white sandstone, in part sharp-edged, are found together with the surface- ore on the summit, while the upper part of the hill generally seems to consist of a dark-colored and ferruginous sandstone. The hill is pretty steep, and nearly isolated. The surface-ore is specular, in some places pure, in others mixed with sand, and pass- ing into a strongly-impregnated sandstone. The pieces are all rounded, none over head-size, most under fist-size. The two shafts, indicated on the annexed sketch, were sunk to a CHERRY VALLEY. Fig- 39- CILKERSON'S FORD ON GRAND RIVER, HENRY CO V!-* OLD COPPER HILL BANK !*. .V-.-J SURFACE ORE depth of perhaps 20 or 30 feet, in loose sand and clay, mixed with pieces of white sandstone. They did not reach any solid strata of rock. STEELVILLE ORE-DISTRICT. Cherry Valley No. 2, W. % S. E. ^, Sec. 4, T. 37, R. 3, W., Crawford County. This bank is represented in Fig. 27, and has been mentioned and characterized in connection with, the description of the Cherry Valley No. I bank, from which it is only ^ mile distant. It con- sists of a streak of large and copious, specular and brown surface- ore, about 20 feet wide and say 200 feet long, extending down the south-western slope of a hill into a ravine, and a short distance up the opposite slope. This bank has the appearance of a disturbed 152 IRON- ORES OF MISSOURI. though undoubtedly very valuable deposit. Ore is found in less quantity in several other places on the surrounding hills. Steelville No. 1, E. y 2 S. W. ^, Sec. 5, T. 37, R. 4, W., Crawford County, 2 miles west of Steelville. Fig. 40. WtST Ci.*r. STEELVILLE ORE BANK S ECT.ION . The above sketch gives a section through this bank, which is opened by a large mining-cut. As Fig. 40 shows, this bank represents a typical example of a disturbed deposit of the first kind. We see here an irregular mass (S H) of soft, red hematite, with bowlders of specular ore lying at the foot of a hill, imbedded in loose materials, as white clay (Cl), clay mixed with broken chert (Cl + F), broken chert and sandstone mixed (F + S), red, sandy loam (R Cl), and fine sandstone-detritus with some broken chert (S D). The red loam encloses large bowlders (S) of a fine-grained, yellow, very hard sand-rock. The position of all these materials, including the ore, makes it evident that they must have slid down the hill, some simultaneously, others at various times, and must have been thrown there one over the other, in irregular layers. Some of the loose materials round the ore are undoubtedly pro- ducts of the destruction of cherty sandstone-strata, in which the deposit originally lay. It will be noticed that the excavation made by the miners has nearly reached the solid sandstone which seems to compose the hill and which is likely to cut off the ore. There are, however, indications of specular and red ores in other places, which make it probable that other loose masses of ore have been thrown down at the foot of this hill and buried under the detritus. ARNOLD BANK. 153 ORE-DISTRICT ON THE UPPER MERAMEC RIVER AND ITS TRIBU- TARIES. Winkler Bank, S. ^, Sec. 14, T. 36, R. 6, W., Phelps County. This bank is situated on the plateau between West Benton Creek and Norman Hollow, and spreads over three flat hills, lying in a north-south line, somewhat curved toward the east. The south-eastern slope of the most northern of the three hills is covered with good and large surface-ore, mixed with some broken chert. The central hill shows scarcely any ore on the surface, but frequently pieces of sandstone. The southern hill is very wide and flat, and bears on its western slope a very extensive streak of sur- face-ore, about i, 200 feet long and 100 to 400 feet wide. Most of this ore is rounded off, and not very large, and looks as if it had been drifted. A number of pieces, however, reach and exceed head-size. The ore at the south end is very hard and silicious, that at the north end is purer and softer. This bank is untouched, and its exterior appearance does not con- vey an exact idea of its character. It is not unlikely that the ore on the northern hill forms a separate deposit from that on the southern hill, and that the latter deposit has been more disturbed and broken, and the ore scattered over a larger surface. From all appearances the Winkler bank seems to contain considerable quan- tities of specular ore. Arnold Bank, S. E. J^, Sec. 4, T. 35, R. 5, W., Dent County. This bank is not yet thoroughly opened. But it presents a very similar appearance to that of the Steelville No. I, and is un- doubtedly a deposit which was formerly imbedded in sandstone, and fell or slid down to the foot of the hill simultaneously with the erosion of the ravine, near which it lies. The hill itself is sand- stone, which has been struck by a shaft sunk 12 feet deep near the summit of the hill, about 50 feet above the ravine. The ore is principally spread over a swelling of the ground, reaching from the ravine about 40 feet up the slope, in a width of 40 to 5 feet. On this ground large bowlders and smaller pieces of surface-ore, mostly rounded, are found, together with pieces of white, yellow, and red sandstone, containing thin seams of specular ore. Also pieces of broken chert, and of an impregnated or ferruginous sand- stone, are quite frequent. Numerous bowlders of ore are deposed 154 IRON- ORES OF MISSOURI. in the ravine. The hill on the other side of the ravine is likewise sandstone. A ditch made at the foot of the hill on which the ore is found struck red clay, mixed with paint-ore and with bowlders of specular ore. A second shaft, sunk 12 feet deep into the slope, on a place about 40 feet above the ravine, passed through red, sandy clay, mixed with pieces of ferruginous and of white sandstone, and with bowlders of specular ore. The whole slope is evidently thick- ly covered with sandy detritus, enclosing irregular and unevenly distributed masses of broken ore. Other banks of this district, which are likely to belong in this category, are the N. G. Clark No. 2, C. C. Cook, Arthur, and St. L., S. and L. R. R. banks. Their location, etc., is given in the ore- bank list, in Chapter V. SALEM ORE-DISTRICT. Orchard Bank, E. y 2 S. E. ^ S. E. %, Sec. 13, T. 34, R. 6, W., Dent County, close to Salem. Fig. 41. ^SSSSWfc^S^ W-z -t=^e ==S^r JAMISON BANK. 1 5 5 This bank is remarkable for the large development of sandstone, colored and impregnated by oxides of iron, which seems to com- pose the greater part of the body of the hill, as well as for the un- usual relative position of ore and sandstone, the former occupying here an annular space round the latter. These facts, together with the flatness of the hill, the height of which is only about 30 feet, prove that this deposit has been greatly disturbed. It seems likely that the ore lay originally on the impregnated sandstone, and that both occupied a much higher level than they do now. A large part of the ore was broken into pieces varying from a pea to head- size. Another large part of it has undoubtedly been carried off. How much of the original mass of the ore is left in the hill, can only be ascertained by practical work. It may be observed in this locality, as in several others, that the white sandstone gradually passes into the yellow and into the ferruginous sandstone. The argillaceous or calcareous cement that surrounds the single sand- grains is changed into red clay and into reddish-brown iron-ore. In other places, the original cement is replaced by amorphous quartz, so that the sandstone takes the appearance of a quartzite, which itself in places loses its grainy structure, passing into a solid flint or chert. It also seems that under certain circumstances the sand-grains, when enclosed in a quartzous or ferruginous cement, have been dissolved and removed, leaving a mere skeleton of a former sand- stone, with a cellular structure. The cells and irregular holes of such masses have sometimes been filled up again, either partly or wholly, by a transparent quartz of a dark appearance, or by yellow jasper. Jamison Bank, S. W. ^, Sec. I, T. 33, R. 6, W., Dent County, 3 miles south of Salem, on the vast plateau dividing the waters of the Meramec from those of the Current River. This bank occupies the highest point on a rather flat, semicircu- lar hill, which lies round a nearly circular depression (sink-hole ?), apparently filled with fine detritus of chert, sandstone, and specular ore. The surface-geology, as given in Fig. 42, is very irregular, but nevertheless seems to be grouped in a general way round that part of the summit and eastern slope over which the largest and most copious surface-ore is spread. The ore is specular, in part 156 IRON- ORES OF MISSOURI. Fig. 42. SURFACE GEOLOGY or JAMISON BANK . pure, in part mixed with quartz. Some bowlders are 2 to 3 feet in diameter. The principal surface-ore district is separated from the ordinary light-colored sandstone by a zone of ferruginous and clayish mate- rials. Another smaller district, with rounded surface-ore, is seen about 600 feet to the north-west, another in a small ravine to the south. Both are probably drifted outliers of the main deposit, which lay originally at a higher level, above the present top of the hill, per- haps a little north of it. I view this bank in a similar light as the Orchard bank, and consider it as containing the remnants, perhaps pretty large, yet incalculable, of a former lenticular deposit in sandstone, which has been broken, and partly destroyed and removed. ST. JAMES ORE-DISTRICT. 157 The shaft marked on Fig. 42 was 10 feet deep, end September, 1872, and had not struck any solid rock, but stood in a red, sandy loam, with bowlders of sandstone and of specular ore. Other banks in the Salem district, and in Shannon County, which may be supposed to belong in the category of more or less dis- turbed deposits, are the Barksdale, Merriam, Shannon, and Cur- rent River banks. The locations, etc., are given in Chapter V. ST. JAMES ORE-DISTRICT. Thornton Bank, N. E. ^ Sec. 33, T. 38, R. 6, W., Phelps County. The situation and appearance of this bank may be seen from Fig. 43. Fig. 43- N .W. B.C. S. WHITE SANOSTOHE Cl.+ F R ED. CL A Y W ITH W HITE CMCRT 6.0. XELLOW fc ftED SANDY CLAY Ct. WHITE CLAY THORNTON BANK. The ore is soft red, with small pieces of hard specular. No large bowlders have as yet been found in it. The character and position of the ore is such that it must be considered as a bed-like or a lenticular deposit, which has been brought into its present ver- tical position by some exterior disturbance, and then broken and decomposed. The deposit can so far be traced over a small space only, and is perhaps a removed portion of some larger bank. The ore seems to be associated with the rocks in which it originally lay, or at least with their detritus. As the succession of these rocks is the same on both sides, the supposition suggests itself that the cor- responding strata might come together below the ore, and thus constitute a pocket, which is crushed sidewise, in the direction from S.E. to N.W. The hill is Second Sandstone. Santee and Clark's Bank, S. W. %, Sec. 33, T. 38, R. 6, W. Phelps County. This bank lies on a high bluff of Third Magnesian i 5 8 IRON- ORES OF MISSOURI. Limestone and Second Sandstone, on the east side of Dry Fork River. Several small openings have disclosed irregular masses of red and brown ore, imbedded in layers of chert and loam. Fig. 44. MINES m -I"' J!:*iii-' T ' CHERT .'LOAM * ORE ""jlli :JIL_II- ' S5 ' JrVTV/. "* SAND6TONE WITH LAYERS OF FLINTY SANDSTONE. 100' . SANDY LIMESTONE *<> 3 rA MAGNESIAN LIMESTONE 8ANTEE *, CLARK'S BANK The character of this bank is very indistinct and doubtful. The present digging may lead to some larger, disturbed bank, or it may disclose a drifted deposit. The materials which surround the ore are evidently of a detritic nature, and not now in the place where they were formed. Another deposit which might belong here is the South Moun- tain (see Chapter V.). ROLLA ORE-DISTRICT. Kelly Bank No. 1, E. ^, Sec. 18, T. 36, R. 8, W., Phelps County. ' Fig. 45- SOUTH KEUCY. BANK .N?l. BUCKLAND BANK. 159 This bank is situated near the summit of a hill composed of Second Sandstone in its lower part, while no solid rock can be seen higher up. The bank itself has a decided resemblance to the Thornton bank, above described, but it seems to be more extensive, and con- tains larger masses of hard, specular ore. It differs, besides, by the detritic character of the associated rocks. There is next to the ore, on each side, a thick layer (1-3 feet) of white clay mixed with broken chert, and outside of this a mass of yellow sand and red loam, irregularly mixed, and free from chert. When opened further, this deposit may be found to be a large fragment of a disrupted- layer deposit, or else an original ore-pocket, which has been pressed and crushed sidewise. The layers of clay and chert are evidently in their original position relative to the ore, but they are broken and mixed. It is doubtful whether this statement could also be ex- tended to the surrounding mass of sand and loam. Buckland Bank, S. ^, Sec. 20, T. 37, R. 8, W., Phelps County. This bank lies at the foot of a sandstone hill, in the crossing of two ravines. Fig. 46. 1 SCCTiO N B..H. s . 60fT HIKATITE Cl.f. WHITC YELLOW' CLV * I T H CMfT YELLOW iANOSTONC Cl. 81ACR BOlPHUROUfl CLAY