W '2H K) BULLETIN No. 27. SAN FRANCISCO, JANUARY, 1908. THE QUICKSLVER RESOURCES OF CALIFORNIA. (SECOND EDITION.) ISSUED BY THE CALIFORNIA STATE MINING BUREAU, FERRY BUILDING, SAN FRANCISCO. UNDER THE DIRECTION OF LEWIS E. AUBURY, - - State Mineralogist. SACRAMENTO. W. W. SHANNON. - - - SUPERINTENDENT OF STATE PRINTING. 1908. LIBRARY UNIVERSITY OF CAUFORNIA DAVIS LETTER OF TRANSMITTAL. To Hon. George C. Pardee, Governor of the State of Cali- fornia^ and the Honorable the Board of Trustees of the State Mining Burea^i : Gentlemen: I have the honor to transmit the results of the recent work of the State Mining Bureau in investigating the Quicksilver Resources of California, and which are embodied in Bulletin Xo. 27. This is the third of a series of bulletins, issued under my direction, on special features of the mining industry in Cali- fornia, and in which will be found a description of the geology of all the deposits of economic importance in the State, together with maps and such data as it was possible to obtain. The geological field work for this bulletin was performed by Mr. William Forstner, Assistant in the Field, of the State Mining Bureau. No description of any mine or prospect, nor of the geology of any part of the territory, has been given except after personal investigation by Mr. Forstner. In treating of the geology and the genesis of ore deposition, subjects of which differences of opinion exist, endeavors have been made to present as briefly and clearly as possible the different opinions, and some suggestions have been added which have resulted from Mr. Forstner's personal observation. In the chapter on the metallurgy of quicksilver, it has been the aim more to give the general principles upon which the different methods of treatment are based than to make a mere detailed description of the different installations. The courtesy generally shown by the owners and superin- 91575 4 LETTER OF TRANSMITTAL. tendents of the difierent mines deser\'es special mention. With only one exception, at every mine all information which would be of value from a technical and often from a commercial standpoint was given with the greatest courtes}-. This is the more appreciated, as quicksilver is a product for which the demand is to a certain extent limited, and it is only natural that operators do not feel inclined to disclose all the facts per- taining to their business. I wish to extend m}- thanks to Mr. J. W. C. Maxwell, who assisted in the revision of the technical and descriptive portions of the bulletin; to Mr. Charles G. Yale, for assistance in the editorial part of the work; and to Mr. E. B. Preston, for the classification of specimens of ores and formations submitted. To the many owners and superintendents of quicksilver mines and prospects who lent their assistance, I wish also to extend my thanks, for without their valuable aid it would have been impossible to present the full results of the work as herein set forth. Ver>- respect full}', LEWIS E. AUBURY, State Mineralogist. San Francisco, June 30, 1903. CONTENTS. Page. CONDITION OF THE INDUSTRY .-..(» GEOLOGY OF THE QUICKSILVER BELT IN CALIFORNIA 12 ORE DEPOSITS ------- 23 GENESIS OF QUICKSILVER ORE DEPOSITS - - 26 COST OF MINING AND REDUCTION - - - - 34 DISTRICTS NORTH OF SAN FRANCISCO: Mayacmas District ------ 35 Clear Lake District ----- 39 Sulphur Creek District - - - - - 40 Knoxville District . - - - . 42 QUICKSILVER MINES IN THE COUNTIES OF CALIFORNIA: Colusa County ------ 43 Lake County ------- 46 Napa County - - - - - - 72 Solano County - - - - - - 93 Sonoma County ------ 97 Yolo County - - - - - - - 117 Fresno County ------ no Kings County - - - - - - - 122 Monterey County ----- 123 San Benito County ------ 125 San Luis Obispo County ----- 144 Santa Clara County ------ Kjg Stanislaus County ----- igg El Dorado County ------ 190 Trinity County - - - - - - 190 Other Counties ------ 195 METALLURGY ------- 197 ELEVATIONS - - - - - ' . - - 254 LIST OF ILLUSTRATIONS. SKETCHES. Figure. Pagk 1. Section of northwest slope of Pine Mountain, Sonoma County 38 2. Sulphur Creek District, section over Abbott ridge 40 3. Abbott mine, Lake County, section over the serpentine 46 4. Abbott mine, Lake County, plan near intersection of Reardon tunnel and first level 47 5. Plan and elevation of Abbott mine . _ faces 48 6. Big Injun group, Lake County 50 7, 8. Sections of Chicago mine 52 9. Cross-section of Great Western mine 54 10. Section over Great Western mine . 55 11. Cross-section of Helen mine. Lake County -- -.- -- 56 12. Plan of Lucitta mine 59 13. Section of Bullion mine (Standard Quicksilver Co.) _. 61 14. Sulphur Bank mine faces 62 15. Sulphur Bank mine, elevation of Upper Wagon Spring Cut at X, . 63 16. Sulphur Bank mine, section and plan of Herman shaft 67 17. Sulphur Bank mine, ore formation in Herman shaft tj8 18. Sulphur Bank mine, section of Diamond shaft 69 19. Front vievr of the Wall Street mine, from opposite hill.side 71 20. ^Etna Consolidated mines 72 21. .Etna Consolidated mines, eleva- tion at mouth of Tunnel No. 2.. 74 22. .Etna Consolidated mines, basalt dike, Silver Bow claim 74 23. iEtna Consolidated mines, section of Washington shaft... 75 24. Boston mine, section over the min- eralizedzone 78 25. Corona mine .faces 78 26. Corona mine, section showing formation. Dip S. W. 30' 79 27. Areal geology, Manhattan mine, faces 80 28. Manhattan mine, section over the works at (f,) 87 29. Napa Consolidated mines, general trend of veins 89 Figure. Page. 30. Napa Consolidated mines, crossing of two veins . . . 91 31. St. John mine, section east and west over main tunnel shaft 93 32. St. John mine, plan showing main tunnel west of shaft ... 96 33. St. John mine, plan of works in main tunnel shaft 96 34. Cloverdale mine, section over works. Mount Vernon claim 99 35. Cloverdale mine 100 36. Cloverdale mine, plan and section of Murphy tunnel . 101 37. Plan of Crown Point and Pacific mines _ . 103 38. Section of Culver-Baer mine... ... 104 39. Eureka mine 107 40. Great Eastern mine, general plan, faces 108 41. Section over the Great Eastern mine 108 42. Great Eastern mine, plan showing the form of the ore bodies 111 43. Socrates mine 116 44. Plan of Mexican mine, Fresno County 120 45. Workings, Bradford mine 132 Cerro Bonito mine . 134 46. Elevations open cut (6), Cerro Bo- nito mine 136 47. New Idria mine 140 48. Plan of New Idria mine 141 49 Section west end of fifth level. New Idria mine 142 50. Open cut, San Carlos mine 144 51. Section at Gray buck shaft, Stayton mine 148 52. Plan of .\lice and Modoc mine 1-55 53. Libertad tunnel No. 2 160 54. Lower Ocean View tunnel. Pine Mountain Mine 164 55. Section near R R. B. shafl, New Almaden property. 170 56. Section on road above Randol shaft, New Almaden mine ... 170 57. Ore bodies in the New jVlmaden mine .faces 174 58. Section of Mine Hill, New Alma- den 178 LIST OF ILLUSTRATIONS. Figure Page. 59. Section over Santa Rita West, Giant Powder stopes, New Al- maden 178 60. Plan of the clay walls, New Alma- den mine (from Atlas, Mono- graph XIII, V. S. G. S.) ./aces 184 61. Section in Enriquita mine, New Almaden -._ 185 62. Sketch of works in the Santa Teresa mine _ 186 Trinity County quicksilver districts 191 6.1a . U nderg^ound workin gs of In tegral „- mine 194 63y Plan and elevations of concentrat- @ing system, Manzanita mine 199 Pipe retort furnace, by G. V. Northey 201 65. Condensing plant, soot retort, Bos- ton mine 202 66. Johnson & McKay furnace 203 67. Continuous retort, quicksilver fur- nace 204 68. Exeli furnace - _ 209 69. Knox & Osborne coarse-ore fur- nace.. ._ 211 70. Coarse-ore furnace, John Neat's patent 212 71. New Idria coarse-ore furnace 213 "i*. Longitudinal section, modified Livermore quicksilver furnace.. 215 73. Knox & Osborne fine-ore furnace. 216 GURE. Page. Plan of Hiittner & Scott 8-tile fur- nace 220 Tilings of Furnace No. 3, New Al- maden 221 Tiling of Cermak-Spirek furnace.. 221 Ore-drier, utilizing exhaust steam . 225 Ore-drier, special furnace at Abbott mine 227 New Idria fine-ore furnace — meth- od of conveying fumes from top. 228 Top of the modified Scott furnace. 229 Top of Hiittner & Scott furnace ... 230 Discharge Scott furnace. 2.32 New Idria fine-ore furnace, details of drawing door 234 General plan of reduction works (from Mineral Industry, Vol. 7), between 234-235 Sketch showing method of hand- ling ore at Abbott mine. Lake County 236 . Plan of works 237 Details of condensers 237 , Installation to save flour mercury. New Almaden 240 Scott's brick condenser plant 248 Knox ironclad condenser _. 249 Watertank condenser.. 250 The Baker flue 251 Wooden condenser box, Corona mine.. 252 Soot-cleaning machine 253 PHOTOGRAPHS. No. Page. 1. Chicago plant 51 2. Great Western quicksilver mine .. 53 3 Western cut. Sulphur Banks 62 4. .^itna quicksilver mine 73 5. Boston quicksilver mine 77 6. Manhattan quicksilver mine 81 7. Oathill quicksilver mine . 90 8. St. John mine and furnace 94 9. St. John quicksilver 'mine 94 10. Great Eastern quicksilver mine. . 109 11. Thin section of sandstone and ser- pentine from New Idria district. 127 12. View of New Idria 1:59 1:'.. Los Picachos mine (Ramirez Con- solidated) 146 14. La Libertad mine 159 15. General view of New Almaden mine 175 ir>. Dump of New Almaden mine works 179 17. Durapof Grey shaft and Mine Hill, New Almaden 180 18. Victoria shafl, New .\lmaden 181 P.4.GE. Santa Isabel shaft. New .\lraaden . 182 Randol shaft. New Almaden. 183 Entrance Castella development tunnel. Integral mine 193 Pipe-retort furnace. Manzanita ^ mine, Colusa County ^200 Corona furnace 207" Tufa furnace in course of construc- tion. Corona quicksilver mine. . . 207 New Idria quicksilver mine, show- ing new SO-ton coarse-ore furnace 214 Cloverdale reduction plant 217 Great Western Quicksilver Mining Company's reduction plant 217 Manhattan furnace 218 Altoona quicksilver mine 219 Furnace plant, Integral mine, Trinity County 222 Karl furnace, San Luis Obispo 224 Great Eastern mine, drying ore in sun "226 Reduction works at New Almaden, Hacienda 231 8 LIST OF ILLUSTRATIONS. No. Page. 34. General view of reduction works at New Almaden, Hacienda 233 35. Furnace Nos. 1 and 2, New Alma- den, Hacienda 233 36. Reduction plant in cour.se of con- struction, Silver Creek Quick- silver Mining Company, Santa Clara County 235 37. Reduction plant, Silver Creek Quicksilver Mining Company, Santa Clara County 238 38. Great Eastern furnaces 239 39. New Idria mine, showing Scott fur- nace _ _. 241 40. Boston quicksilver mine, quicksil- ver furnace 242 41. Flues connecting furnace with con- denser plant. New Almaden, Hacienda - 242 No. Page. 42 Oceanic quicksilver reduction plant, San l,uis Obispo County. 243 43. Interior view of reduction works. New Almaden. Hacienda 245 44. New Idria, showing round wooden flue and wooden tanks used for condensers 245 45. Retorting soot, Great Eastern 246 Ferry building, San Francisco, one half of which is occupied by the State Mining Bureau 261 Mineral Museum, California State Mining Bureau __. 263 Library and free reading-room, Cali- fornia State Mining Bureau 265 Laboratory, California State Mining Bureau 267 Draughting department, California State Mining Bureau 269 MAPS— (Folders). P.\GE. Geological map of portions of Napa, Sonoma, and Lake County quicksilver districts, California _ ._ _ 35 Geological map of Napa, Sonoma, Lake, and Yolo County quicksilver deposits 39 Map of Sulphur Creek District _ _ . 40 Map of Little Panoche Mining District _ 118 Geol ogical map of quicksilver districts in southern portion of San Benito County . . _ 126 Geologfical map of Stay ton Mining District. ._. 129 Geological map of quicksilver districts northwestern portion of San Luis Obispo County ... 149 Map of the New Almaden Mining District 168 THE QUICKSILVER RESOURCES OF CALIFORNIA. By WM. FORSTNER, E.M. Assistant in the Field. CONDITION OF THE INDUSTRY. Quicksilver has been produced in California since 1850. The table published in the report of the Eleventh Census (1890), page 188, compiled bj' Mr. J. B. Randol, giving the annual pro- duction of the various mines from 1850 to 1889, indicates that in the decade 1850 to i860 the Xew Almaden mine was about the onl}- producer. In the latter part of the 6o's, the New Idria, Redington, and i^tna mines began to produce. The greatest number of mines were in operation between the years 1874 and 1880. This activity was due to the high price of quicksilver obtained in 1874, when the prices per flask in San Francisco were: highest, $126.22; lowest, $84. 15. In 1875 the price dropped to $49.75, and until 1883 the average price was about $30. The lowest price was in this period for awhile, $25. For years the price remained rather low, but in the last few 3-ears it has maintained a figure which gives the operators a fair remuneration. These low prices in 1879 and 1880 caused the closing of a number of quicksilver mines, and for some years quicksilver mining was carried on only at a few of the large mines. In later years the price of quicksilver has risen, although by no means to that of the prosperous times, and graduall}- the old mines, closed for years, are being reopened. In the meanwhile the older mines, which have been steady producers for many years, appear to have worked out their bodies of high-grade ores, and are all now working what in (9) 10 QUICKSILVER RESOURCES OF CALIFORNIA. years past would have been classed as poor ores. In the well- managed properties, however, where they have availed them- selves of the more economical methods of mining and especially of reducing the ores, a fair interest on the investment is earned from these low-grade ores. The yearly production of quick- silver in California has been as follows: TABLE GIVING YEARLY PRODUCTION OF CALIFORNIA MINES AND AVERAGE PRICE PER FLASK IN SAN FRANCISCO. Flasks Year. Produced. 1850 [a) 7,723 1851 27,779 1852 20,000 1853 22.284 1854 3O1OO4 1855 33,000 1856 30,000 1857 W 28,204 1858 31,000 1859 13,000 i860 10,000 1861 35,000 1862 42,000 1863 40,531 1864 47,489 1865 53.000 1866 46,550 1867 47,000 1868 47,728 1869 33,8x1 1870 30,077 1S71 31,686 1872 31,621 1873 27,642 1874 27,756 1875 50,250 1876 75,074 1877 79,396 1878 63,880 Average Price per Flask. V $99 45 I 66 93 I 58 33 1 55 45 I 55 45 I 53 55 I 51 65 I 48 73 I 47 83 I 63 13 I 53 55 I 42 05 I 36 35 I 42 08 1 45 90 I 45 90 I 53 13 I 45 90 I 45 90 I 45 90 Ic 57 38 II 63 10 K 65 93 IC 80 33 I( 105 18 I( 84 15 K 44 00 K 37 30 It 32 90 Flasks Produced. 1879 73,684 1880 59,926 il 60,851 £882 52,732 1883 46,725 t884 31,913 [885 . 32,073 [886 29.981 1887 (^ 42 50 45 00 52 50 45 25 40 71 36 75 30 70 37 04 34 96 37 28 38 23 47 70 44 94 48 46 43 20 42 25 37 62 35 94 36 50 (<7) Report nth Census. 1850 to 1865, great bulk of quicksilver produced by the New .\ltQaden mine. 16) The New Idria mine begins to produce 1857. (c) From 1887 to 1893, Dr. Day's Report, U. S Geol. Survey. (rf) 1893 to date. Annual Statistical Bulletins, California State Mining Bureau. Quicksilver furnaces are great consumers of wood, and even those mines which are located in well-timbered regions find the cost of their fuel steadil}' increasing. Only in exceptional cases can mines get their cordwood delivered for $3.50 per cord; generally the price is higher, in some cases double that figure. Hence most of the quicksilver mine managers are eagerly looking for a substitute for cordwood as fuel in CONDITION OF THE INDUSTRY. 11 their furnaces. Up to the present time, however, this has not been found. As mentioned above, many of the quicksilver mines have been idle for some years, and of these it is very difficult to obtain either reliable historical data, or details of the old work- ings or of the output of mercury. Even in the mines which have been in continuous operation, large portions have been worked out and abandoned, and it is nearly impossible to get the desired information regarding these portions of the mines. In regard to several of the principal mines of the State, belong- ing to the Napa Consolidated and affiliated companies, these data were to a great extent destroyed in 1898, in which year the main office in Oathill was burned and most of the mine maps, etc., were destroyed. Whatever information of this character it was possible to collect, is inserted in the descriptions of the respective mines. It may here be stated that in accordance with the general scheme of this Bulletin, its contents are confined strictly to the occurrence of quicksilver in the State of California, for which reason all reference to mines and works in other locali- ties is omitted. GEOLOGY OF THE QUICKSILVER BELT IN CALIFORNL\. The quicksilver deposits in California are, with a few scat- tered exceptions, located in the Coast Ranges. There is a ver>' marked difierence of opinion among the geologists who have made a special study of this territory, regarding two points: First, as to the age of the metamorphic series which form such a prominent part of the rocks in this territory; and secondly, as to the origin of the serpentine. Thej^ all agree that violent geological disturbances took place in this region at some period within the Mesozoic age. These disturbances were sudden and sharp, resulting in the crushing and fracturing of the strata rather than their uplifting and folding [Whitnej', Auriferous Gravels, page 15], and gave this series a characteristic struc- ture, which serves to its identification. The epoch of this revolution is placed by Becker at the end of the Xeocomian or Lower Cretaceous, while Fairbanks and others place it at the close of the Jurassic epoch, hence as pre-Cretaceous. The rock series metamorphosed b}- the revolution is called by Becker the Xeocomian, and also occasionally the Metamorphic series; by Fairbanks, the Pre-Cretaceous or the Metamorphic series; by Lawson, the Franciscan series. These rocks rest upon a basement complex consisting of crystalline limestones and schists and granites. The granite does not appear at the surface north of the bay of San Francisco, except on the coast twenty miles north of San Francisco at Point Tomales; but south of San Francisco there are two ages of granitic uplifts. The granite is intrusive in the older strata. The crystalline rocks of the basement complex are only found at a few points; the granitic uplifts brought them within a zone of such efiective erosion that the granite was almost entirely denuded before the next period of subsidence and deposition of the Franciscan series set in. The age of the crystalline rocks of the basement complex is either Carboniferous or older. [See Bulletin Geological Society of America, vol. VI, pages 79-81.] (12) GEOLOGY OF THE QUICKSILVER BELT. 13 Intimately mingled with the rocks of the Franciscan series are large masses of serpentine. Becker holds that these are prominently altered sedimentaries [see Mineral Resources, 1892, U. S. G. S., page 144]; while Fairbanks holds these serpen- tines to be exclusivel}^ derived from eruptives. A. C. L,awson is of the same opinion, so far as the serpentines in the penin- sula of San Francisco are concerned. Apparenth' the latter views as to the origin of the serpentine in the Coast Ranges are entertained by all the geologists on the Pacific Coast. The serpentine bodies occur in different forms and the rocks them- selves vary very sensibly in structure in different regions and in the various bodies of serpentine. In places the serpentine occurs in bodies indicating an original dike formation and showing intrusive phenomena; while in other places large areas of serpentine occur which can hardly be conceived to be derived from eruptive masses, and wherein are found small areas of sandstone and occasionally shales, indurated but slightly altered, in places even unaltered. In other places the serpentine overlies or underlies the sandstone and shales with- out any intrusive phenomena. During the investigation in the preparation of this Bulletin, in the neighborhood of New Idria [see general description of the New Idria district, page 125] and near Cambria, San Luis Obispo County, sandstone and serpentine were found intimately associated. Samples of these occurrences are in the museum of the State Mining Bureau, and a slide of the first mentioned has been prepared and photographed. Both views of the origin of the serpentine can be sustained by microscopical examination. [See, for instance, Becker, Mon. XIII, U. S. G. S., page 275, and following; A. C. Law- son, 15th Ann. Report, U. S. G. S., pages 417, 433, and 447; etc.] It may be argued that both views are correct and that probably the serpentine is an alteration product of both sedi- mentaries and eruptives in this region, as is the case elsewhere. This view is that of the majority of geologists. In 1888 this question was submitted to the American Committee of the International Congress of Geologists [.see American Geologist, vol. II, page 180], in the following form: Question N — Is serpentine (i) sometimes, (2) always an alteration product, (3) of eruptives, (4) of sedimentaries, (5) of either? 14 QUICKSILVER RESOURCES OF CALIFORNIA. Thirteen answers were received, which can be summarized as follows: Twelve declared serpentine to be an alteration product, and one characterized it as an original aqueous rock. Three of the first twelve took the view that it is exclusively an alteration product of igneous rocks; one exclusively of sedi- mentar\' rocks; two, generalh' of igneous rocks, but could also be such of sedimentarN' rocks; and five that it is an alteration product of both eruptive and sedimentary rocks, while one leaves this part of the question unanswered. Professor van Hise remarks, in his Principles of North American Pre-Cambrian Geology [i6th Ann. Report, U. S. G. S., Part I, page 68g] : "Actinolite, serpentine, and magnetite "have been observed to replace quartz. In the case of the two "former minerals their relation to the quartz suggests that the "other constituents, with the exception of silica, were at hand "or were furnished b}" the percolating water out of which the "serpentine and actinolite formed; and that the quartz itself "ma}' have furnished the necessary silica to produce these "minerals." [On page 691:] "Among basic sedimentan,- rock "serpentine very often develops." E. S. Dana [Mineralogy, 1898, page 477] states: "Microscopic "examination has established the fact that serpentine is largely "produced by the alteration of chrysolite; in other cases it has "resulted from the alteration of pyroxene or amphibolite." [See also Williams, Lithology, page 254.] A. C. Lawson, in describing the deformations of the earth- crust which have influenced the geology of the San Francisco peninsula [15th Ann. Report, U. S. G. S., page 466], mentions "an invasion of the upper portion of the Franciscan series by "peridotite magma, which solidified in the form of dikes or "laccolitic lenses." The granites of that part of the Coast Range which contains the quicksilver belt appear only at the surface south of San Francisco. Lawson has carefully studied granite in two places: the Montara granite in the San Francisco peninsula [above cited, page 411], which he describes as a coarse gray hornblende, biotite granite, which originally was a hornblende granite; and at Carmel Bay [Bulletin Geological Department, University of California, vol. I], which he describes as a coarse porphyritic granite. Similar granite rocks are found in the Santa Lucia Peak, and in the San Jose range. GEOLOGY OF THE QUICKSILVER BELT. 15 Fairbanks has studied extensively the granites in the Coast Range south of San Francisco, and considers them as true mica feldspar quartz granites, difiering from the granites in the Sierra Nevada, which are usually hornblendic. [Bulletin Geo- logical Society of America, vol. VI, page 79.] H. W. Turner [Am. Geol., vol. XI, page 324] supposes these granites to be of Carboniferous age. Fairbanks thinks this may be true or they may be older. Accepting the suggestion of Becker that the entire Coast Range is underlaid by granite [Mon. XIII, page 140], a source of ferro-magnesian silicates other than the suggested post- Franciscan peridotite intrusions is present in this region. Law- son [above cited, page 434] calls attention to the fact that the entire period of accumulation of the Franciscan series was a period of volcanic activity, and that the lower portions of this series were traversed by igneous rocks, which arriving at the surface, became constituents of the upper portion of the series. It appears most probable that all of these materials have contributed to the formation of the bodies of serpentine found in this region. As van Hise remarks [above cited, page 691], " Material for the serpentines maybe furnished in part or in "whole by minerals present, or the material of the serpentine ''may come from an extraneous source. Also, widespread for- "mations may be extensively serpentinized, so as to give for "considerable areas almost solid masses of serpentine." The pressures which caused these deformations produced great heat from dynamic action, which was increased by that obtained from the intruding magmas; consequently both pressure and temperature were raised during the deformations, causing an increased chemical activity of the circulating waters, and it appears only reasonable to assume that all available sources for the formation of serpentine masses were called upon. The later intrusions, forming the dike and laccolitic lenses, can be generally defined by the phenomena of contact meta- morphism accompanying them; while the large, widely-dis- tributed ma.sses of serpentine were probably formed by magnesian solutions acting upon the rock material. [Mon. XIII, pages 1 21-127, ^^^d 273-278.] The ferro-magnesian silicates are probably derived from the basal granite, and per- 16 QUICKSILVER RESOURCES OF CALIFORNIA. haps from intrusives, which would explain the entire lack of contact metamorphism phenomena at the contact of many ser- pentine bodies with the other rocks. This lack of contact metamorphism and intricate mixture of serpentine with the sandstones and shales of the Franciscan series, and even probabl3' with the schists of the basal complex, can be exten- sively studied in the New Idria district. As already stated above, there is a great diversit}' of opinion as to the historical geology of the Coast Ranges. The accom- panying table of comparison will set this forth. [See American Geologist, vol. XL] AGE. Period. Gabb — CALI- FORNIA. WHITE AND ' °STAVTOn''° C^Li'f'oRnTa NORTHCrLIPOR- I'^-^^-' CALIFORNIA. ^.j^ ^^^ OREGON. Cenozoic. Miocene. Eocene. Chico Tejon. Probable place of the Wallalla. Tejon. Monterey Series. Light color'd Sandstone? Upper Cretaceous. Tejon. Martinez. Chico. V, .a 'C V m o ■I (J 5 7. Hiatus and nconformity. ^ r. : '*- 'Chico. j « o N O Ol Lower Cretaceous. Shasta. Hiatus of White. Unconformity of Becker. . fHorsetown. i i Knoxville, j: including '"^ L Mariposa. Horsetown. t Knoxville. a a u •s a 1 Jurassic. Mariposa. Mariposa. This difference of classification is closely related to the above- mentioned difference of opinion as to the period wherein took place the disturbances which caused the metamorphism of the rocks deposited after the first-recorded intrusions. J. S. Diller says [Bulletin Geological Society of America, vol. IV, page 2o6] : " The Cretaceous of north California, embracing the " Chico, Horsetown, and Knoxville beds, are essentiall}^ con- " formable, hence the upheaval must have been pre-Neocomian." Becker places the upheaval after the Horsetown series, refer- ring to it as post-Xeocomian. Fairbanks indorses Diller's opinion, and names the Metamorphic series the Pre- Cretaceous series. GEOLOGY OF THE QUICKSILVER BELT. l7 Whatever may be its age, this Franciscan series presents some distinguishing characteristics which facilitate its identification from the underlying crystalline limestones and schists of the basement complex, and from the overlying younger rocks. This series consists mainly of sandstones, associated with some shales, cherts, and occasionally limestone. The sandstones are rather massive; the bedding planes have often intercalated beds of shale. They are very generally altered through a process of recrystallization and cementation by silicification. All grades of alteration can be observed, from nearly unaltered arkose sandstone to compact jasper, or jaspilite (a term sug- gested by Wadsworth). [See i6th Ann. Rep. U. S. G. S., Pt. I, page 702.] Interbedded with the sandstones are lime- stones, cherts, and volcanic rocks. The chert beds form a very characteristic member of this series, but are much more prominent in the districts north of San Francisco than in those south. They have been exten- sively discussed by Becker, Fairbanks, and Lawson. The first named refers to them as schistose rocks which have been subjected to a process of silicification, and classes them as phthanites. Blake supposed that they had resulted from the metamorphism of shales and sandstones by igneous action. J. J. Newberry [General Geology of California, page 66] says: " Whether the material of which they are composed is thrown " up from below, or, as is more probable, it is a metamorphosed " form of the associated rocks, it is evident that the material " has been subject to great heat." Fairbanks [Bulletin Geo- logical Society of America, vol. VI, page 71] classifies this formation as jasper. Lawson [above cited, page 420] as Radiolarian cherts, which designation appears the most correct. The following is a concise statement of Mr. Lawson's study of this formation : "These beds consist of alternate thin sheets of chert, rang- "ing generally from one to four inches in thickness, only " exceptionally having a much greater thickness, with part- "ings of shale from one eighth to one half inch thick. Some- " times the regularity is much less marked, and in the less ''ferruginous varieties of the chert beds the sheets of chert "assume occasionally a lenticular form. The difference of "opinion as to the proper classification of this formation is 2— QR 18 QUICKSILVER RESOURCES OF CALIFORNIA. "due to the fact that petrographically these cherts are not "uniform. In many cases they are true jaspers; in others "the silica is chiefly amorphous, and the rocks have a flinty "character; in still other cases the proportion of iron oxide "is so great that the cherty character disappears and the "beds become locally very soft. All gradations between "cherts composed almost wholly of amorphous silica, to those "which are a holocrystalline aggregate of quartz granules, "are found. The amorphous silica differs, however, from opal, "in that it has a much higher specific gravity and contains "much less combined water. The cherts are, then, minutely "granular aggregates of cr^^stalline silica, tending more toward "the chalcedonic than to the quartz variety, with varying pro- " portions of amorphous silica, mixed with ferric oxide and "ferric hydrate, sometimes uniformly distributed, or again in "patches or streaks. The mass is intersected bj' numerous "small, often microscopical veins, the smaller filled with chal- "cedonic, the larger with quartzose silica, and occurring in two "sets of fissures crossing at high angle. Zoisiteis often found "in the vein filling. These chert beds contain round or oval "spaces, occupied by chalcedony, which are the residual casts "of Radiolaria. The intervening shale consists of silica, iron, "considerable magnesia, and a small amount of alumina with- "out any clastic material. The association of chert beds with "the sandstone precludes the possibility of their formation "under deep-sea conditions, which would be indicated by the "absence of fragmental material." The most probable hypothesis of their formation is, as sug- gested by lyawson, that the silica was derived from siliceous springs and precipitated in the bed of the ocean in local accu- mulations, in which Radiolarian remains were imbedded. The alteration of the beds of chert with partings of shale may perhaps be ascribed to an intermittent action of the springs. These chert beds occur throughout the Coast Range in a spo- radic manner, and are especially of interest, as in some mines they form the ore-bearing zones. Associated with these rocks of the Franciscan series are metamorphic schists which appear to represent stages of alteration of rocks of very diverse origin, and may be principally the result of contact metamorphism, which, as H. W. Turner remarks, "is, however, yet to be fully demonstrated." As already stated above, the rocks of this GEOLOGY OF THE OUICKSIL\^R BELT. 19 series are further associated with many and various igneous intrusives, entirely separate from the later Tertiary and post- Tertiary igneous ejections. There must have been a considerable difference in the geo- logical history of the northern and southern part of the quick- silver belt. South of San Francisco the Franciscan series were elevated and eroded to such an extent that the Tejon is found resting directly on the granite and a second elevation, and post-Miocene erosion must have followed, as the Pliocene is also found resting direct on the granite. North of the bay of San Francisco, the erosion of the Franciscan series has been much less, so that between the bay and Clear Lake the granite does not appear at the surface and the younger formations all rest on this series. The metamorphism of the Franciscan series was eminently a process of recrystallization of the clastic sediments into holo- cr^'stalline feldspathic rocks, carrj'ing ferro-magnesian silicates, and in the formation of vast quantities of serpentine. [See Becker, above cited, page 57.] The serpentinization was pos- terior to the former process, which included a silicification which altered part of the shales to jaspery masses and formed in these and in other rocks innumerable minute veins of quartz. \_Ibid., page 393-] There are reasons to believe that the metamorphism of this series took place at no great depth. The rocks were often crushed into a confused mass of rubble by dynamic action [see above, page 12], which is often recemented bj- metamorphic process. The readjustment of the strata under pressure hence took place largely through fracturing, rather than through flowage and flexure of the rocks, consequently they can not have been buried at great depths. A much later silicification process took place attendant upon or just prior to the ore deposition and of a distinct character from that above mentioned, in many cases resulting in the formation of a black opal rock. This opal replaces constitu- ents of the rock masses, particularly but not exclusively serpen- tine. The opal is often deep black, resembling some varieties of obsidian, and is accompanied by small amounts of crystal- line silica, quartz, and chalcedonite — the name suggested by Dr. Becker [above cited, page 390] for a mixture of opal and cr>'stalline silica ; sometimes it contains a small amount of 20 QUICKSILVER RESOURCES OF CALIFORNIA. calcite. A perfect network of minute bands of quartz often traverses the opal, resulting from infiltration into fissured opal. This material is seldom, if ever, free from sulphides of iron, occasionally of nickel, and at least traces of cinnabar are inva- riably found close to it (hence its local name of "quicksilver rock"), showing its close relation to metalliferous solutions. While some of this opaline rock has certainl}- been deposited in pre-existing openings, a large part is a substitution product. The silica solutions seem to have permeated more or less frac- tured rocks, principally serpentine, dissolving the bases and depositing the opal. This silicification process is closeh' related to the deposition of cinnabar ores and to the later igneous phenomena. As above stated, cinnabar is often found in the filling of minute cracks in the opaline rock, accompanied bj' quartz and chal- cedonite, but seldom if ever imbedded in the opal. Hence this silicification process must have preceded the ore deposition; but the effects of the two processes are so closeh' related that the former must have been an earlier stage of the latter. The fact that mercuric ores are hardly ever found in direct contact with the opal is hard to explain, as it would suggest that the siliceous solutions during that period of the process were entirely barren of mercuric sulphide. The solutions during the ore deposition were, however, also certainl}- siliceous, and hence it is hard to understand wh}' the former should have been entirelj' barren. Dr. Becker ofiers as explanation the hypothesis that the cinnabar was separated from the solutions in the fissures when the siliceous fluids permeated the rocks, through a mechanical process more or less analogous to dialysis. The difficulty is, however, that metallic salts are cr3'stalloid bodies and pass readilj' through membranes, while silica is colloid. In the Manhattan mine, Xapa Count}^ sulphide of mercury- is, besides, found intimately mixed with the chalce- donite. This silicification process was directly connected with the later igneous eruptions and intrusions. Perhaps the greater heat during the first part of the period covered by this process may ofier an explanation for the absence of mercuric sulphide in the opal then formed. [See, on this point. Genesis of the Quicksilver Deposits, page 26.] Calcite and dolomite form besides the silica the gangue min- erals accompanying the cinnabar. Sometimes these carbonates GEOLOGY OF THE QUICKSILVER BELT. 21 are in direct contact with the cinnabar. The associated metallic minerals are in nearly all cases pyrite and marcasite; very often arsenious and antimonious minerals, and sometimes copper minerals. Cinnabar ores are nearly exclusively depos- ited in pre-existing openings. Ore bodies precipitated b}' substitution are very rare. Where cinnabar deposition can now be observed the same rule holds good. The later igneous eruptions, to which the ore deposition is related, are of Tertiary or later date. Becker [above cited, page 152 and following] cites three different periods: The first, pre- Pliocene, during which large masses of andesite were ejected — a bluish-gray rock, containing pyroxene and feldspar crystals imbedded in a ground mass of feldspar and magnetite. A later andesitic eruption, very late Pliocene or at the close thereof; the ande- sites belonging to a special group having a trachytic character, for which Becker proposes the name Asperites. Rhyolite, probably younger than the andesites, is found near New Alma- den and in the northwestern part of San Luis Obispo County. Basalt eruptions, belonging to the Quaternary and more recent periods. These eruptions are closely related to the fissure system of the former upheavals, which had established lines of weakness, along which the strata adjusted themselves to the posterior deformations. The ore depositions were most prob- ably formed by mineral springs connected with the volcanic activity of the post- Andesitic period; hence the3' belong to the post-Pliocene period. According to Becker, this is indicated by the usual association of cinnabar with basalt, or as in New Almaden with rhyolite, and also by the unimportance of cin- nabar deposits in andesite. It is a striking fact that most of the prominent mines north of San Francisco are in close prox- imity to basaltic or relatively recent eruptions, as for instance: The .^tna mines, a basalt dike on the Silver Bow claim, and basalt in the Star claim; the Oathill mine, a large basalt body in close vicinity to the mine; the Corona and Twin Peaks mines, between the basalt of Oathill and that of the Howell Mountains; the Great Western, a body of basalt south and in close proximity to the mine; the Sulphur Bank, basalt all around the mine; the Manhattan, surrounded by basalt to the east and north; the Boston, within half a mile of the basalt in the Manhattan ground. In the southern field the geological conditions vary very 22 QUICKSILVER RESOURCES OF CALIFORNIA. much. In the New Idria district no definitive!}^ post-Tertiarj' igneous rocks can be found, and those rocks which show indi- cations of igneous origin are so altered that it requires micro- scopic stud}' of the rocks to determine whether they are altered eruptives or sedimentaries. In the Stayton district, the country rock near the ore deposition is prominently basaltic, sometimes closely related to Becker's asperites. In San Luis Obispo County, in the Pine Mountain, Adelaide, and Oceanic districts, the scattered exposures of igneous rock are of rhyo- lite. In Santa Clara County the only eruptive rock in the neighborhood of the ore deposits is rhyolite. ORE DEPOSITS, The peculiar characteristics of quicksilver, so different from those of all other metals, render the study of the conditions governing the genesis of quicksilver deposits an intricate problem; in fact, some of the phenomena occurring in those deposits have as yet not been fully explained. Quicksilver occurs in nature principally as a sulphide, occasionally to a small extent associated with the native metal. The compounds of mercury with chlorine, selenium, tellurium antimony, etc., are all rare minerals, and probably the result of secondar}' concentration. Quicksilver differs in many characteristics from gold, which occurs in nature principally as native metal, though occasion- ally as a telluride. Gold is soluble in solutions of alkaline sulphides and iodides, ferric sulphate, and carbonate of sodium above 200° C. Chlorine is a prominent solvent of gold, especially in desert regions. In whatever form gold may be transported, it is precipitated either as a telluride, or as metallic gold associated with tellurides and sulphides; whether gold is precipitated in nature as a sulphide is, as yet, uncertain, because the existence of a sulphide of gold in nature has not been definitely established. At all events, this sulphide of gold would be an unstable compound, while sulphide of mercury is a very stable compound. These differences are here presented, because the fact that gold is present in cinnabar deposits has been used as a strong argument in the discussion of the genesis of those deposits. Quicksilver also differs greatly from silver in its chemical behavior toward other elements. The original forms of silver deposits are, besides sulphides, sulphantimonious and sulph- arsenious salts. In the zone of oxidation, silver occurs to some extent in the native state, but much more commonly as a chloride, cerargyrite. Mercuric sulphide is not found intimately associated with the sulphides of lead, zinc, and iron, as is the sulphide of silver. Sulphide of iron is often found in contact with mercuric (23) 24 QUICKSILVER RESOURCES OF CALIFORNIA. sulphide, but no mixtures of the sulphides, like argentiferous galena, etc., have been found. Oxidation products of mercuric sulphide, similar to those of the sulphides of lead, zinc, copper, and iron, are also unknown. Quicksilver dififers further materially from all other metals in its behavior toward heat. Nearly all metals have high melting and boiling points, but mercury becomes a solid at — 39-5° C., and boils at 357" C, even vaporizing to a certain extent at ordinar}- temperatures. Following is a list of the known quicksilver ores: Amalgam. — A compound of silver and mercury, AgHg or Ag,Hg3. Arguerite, from Coquimbo, Chili. AgioHg. Kongsbergite, from Norway. AgisHg. Color silver white, in isometric crystals and massive. Ammiolite. — A compound of mercury containing antimony and copper, also a little sulphur and iron. An earthy powder; color deep red or scarlet. Possibly antimonate of copper mixed with mercuric sulphide. Rare. Arguerite. — See Amalgam. Barcenite. — Related to Ammiolite, but contains no copper. Possibly antimonate of mercury. Rare. Calomel, or Horn Quicksilver. — Mercurous chloride, Hg2Cl2. Color light yellowish or gray; luster adamantine, translucent or subtranslucent. Tough and sectile. Not abundant. Cinnabar. — Mercuric sulphide, RgSorHgiSi- Color bright red to brownish-red and brownish-black. Streak,. scarlet-red. Subtransparent to nearly opaque. Cr^^stals often tabular, sometimes acicular; also massive and in earthy coatings. Cinnabar is the principal mercurial ore. Hepatic Cinnabar^ or Liver Ore, contains some carbon and clay; color and streak brownish. Metacinnabarite^ or black sulphide of mercury, HgS or HgsSs. Amorphous, color black, resembling graphite, streak same color. Fracture like tetrahedrite. Recrys- tallizes on slow cooling into cinnabar. CocciNiTE. — Iodide of mercury. Color red to yellow, some- times green and greenish-gray. In acicular crystals or mas- sive. Rare. ORE DEPOSITS. 25 CoLORADOiTE. — Telluride of mercury, HgTe. Color gray- ish-black. Rare. GuADALCAZARiTE. — Sulphide of mercury; closely allied to metacinnabarite. Part of the sulphur is replaced by selenium, some zinc is also present, although these latter two metals are probably no essential portions of the mineral. Rare. KoNGSBERGiTE. — See Amalgam. Lehrbachite. — A combination of selenide of mercury and of lead. Rare. Leviglianite. — A ferriferous guadalcazarite. Rare. LiviNGSTONiTE. — A Combination of sulphides of mercury and antimonium, HgS, aSbiS;;. Color grayish-black, generally fibrous, also massive, resembling stibnite. Rare. AIagnolite. — Mercurous tellurate, HgTe-;04. Rare. Mercury, Native. — Occurs to some extent in many quick- silver mines, exceptionally in large quantities, generally in dis- seminated fine globules. Metacinnabarite. — See Cinnabar. OnofriTE. — A sulphide of mercury, wherein the sulphur is partly replaced by selenium, Hg (S, Se), often associated with tiemanite. Rare. TiEMANiTE. — Selenide of mercury, HgSe. Color dark steel gray, resembling galena. Rare. TerlinguaiTE. — Oxychloride of mercury. Rare. TocORNALiTE. — Iodide of silver and mercurj'. Color pale yellow; granulaf and massive. Rare. The hydrocarbons Idrialite and Aragotite in places carry cinnabar. Rare. In Hungary a copper ore, consisting of sulphides of copper, iron, zinc, mercury, antimony, and arsenic, is found, often rich enough in mercury to warrant the special extraction of that metal as a by-product. This list shows that mercury combines in nature almost exclusively with sulphur, which in rare instances is partially or totally replaced by its closely related elements, selenium and tellurium; and that mercury also, but rarely, combines with the halogens chlorine and iodine. From a practical point of view, sulphide of mercury and native mercury are the only products requiring consideration, the others being of no commercial importance. GENESIS OF QUICKSILVER ORE DEPOSITS^ The majority of the geologists who have treated the subject of ore deposits consider them, as they exist to-day in situ, as principall)^ the result of precipitation from aqueous solution. [See Genesis of Ore Deposits, pages 57 and 73, F. Posepny; ibid., page 284, C. R. van Hise; ibid., page 658, Prof. J. H. L. Vogt, etc.] More especially in reference to quicksilver deposits. [Monograph XIII, U. S. Geological Sur\'ey, page 416, G. F. Becker; x\merican Journal of Science, vol. XVII, 3d series, S. B. Christ}-; Genesis of Ore Deposits, page 596, W. Lindgren.] A concise exposition of the modern views of the genesis of ore deposits is required to explain the special phenomena obser^-ed in quicksilver ore deposits, and the deductions to be derived therefrom. There is no reason for supposing that the heavj- metals of ore deposits come from the enormously compressed centro- sphere; hence the conclusion that the ore deposits are derived from the crust of the earth. Indeed, a notable number of ore deposits may be referred to eruptive processes connected, not with the heavj- interior, but with the crust of the earth, which must be regarded as being at least 50 kilometers in thickness. This crust can be divided into zones from two different standpoints: {a) The zone of fracture. The intermediate zone of combined fracture and flowage. The zone oi flowage. These zones are delimited b}- the manner in which the rocks j'ield to deformation. In the upper zone of fracture, the strata yield to deformation by fracturing; in the deepest zone, onh* spaces of microscopic size can exist, and the deformation process is similar to that of mashing or kneading. The maximum depth (assuming no lateral pressures occur) be3''ond which the strongest rock material will yield to defor- mation by flowage can be placed at 12,000 meters. In regions of orogenic and eruptive actions, the lateral stresses may (26) GENESIS OF QUICKSILVER ORE DEPOSITS. 27 materially reduce this depth, which probably may have to be further reduced, because of the greatly increased plasticity of the rocks saturated with superheated water. It therefore follows that all fissures must disappear at a certain depth. As rocks are of varying strength, and as lateral pressures materially influence the conditions under which the rocks exist, there must be a zone of combined fracture and flowage below the zone of fracture. This belt has a considerable thickness, possibly over 5000 meters. The earth crust may also be subdivided from a physico- chemical standpoint, controlled by the relations between chem- ical action and heat and pressure, into: (d) The Upper Physico-cJiemical zone, resubdivided into: . Upper Belt — Belt of weathering. LrOwer Belt — Belt of cementation. The Lower Physico-chemical zone. Near the surface, where temperature and pressure are low, the preponderating reactions are heat-developing. In the lower zone the heat-absorbing reactions preponderate, accord- ing to van Hoff's law. [W. Nernst, Theoretical Chemistry, page 583.] Two important reactions separate these zones: First, tne reactions between oxygen and sulphur. In the upper zone oxygen replaces sulphur, resulting in great liberation of heat and expansion of the volume of the solid compound. In the lower zone sulphur replaces oxygen with condensation and great absorption of heat. This reaction is the more important when considering that oxide of iron, in the form of magnetite, is one of the constituents of eruptive rocks (rocks of deep- seated origin). Secondly, the reaction between carbon dioxide and silica. In the upper zone, especially in the belt of weather- ing, carbon dioxide replaces silica, acting specially upon sili- cates; the liberated silica passing into solution in a colloidal form and not ionized [Kahlenberg and Lincoln, Journal of Physical Chemistry, 1898, page 88], and carried downward into the belt of cementation. In the lower zone silica replaces car- bon dioxide, with great absorption of heat and with condensa- tion; the carbon dioxide entering into the solution. The depths at which these reactions reverse for different compounds, and for the same compound under different con- 28 QUICKSILVER RESOURCES OF CALIFORNIA. ditions, are very variable, and are greatly affected b\- the fact whether the latter are mass-static or mass-dynamic. The water circulation through the earth crust represents a cycle, caused chiefly by gravitation stress, and is due to the fact that the water entering the ground at a certain level, after a short or long underground journey, issues at a lower level. From the point of view of the genesis of ore deposits, only the water that enters that part of the earth crust situate below ground-water level is of importance. Its temperature increases with depth, and below 3000 meters, in the zone of fracture, it is in the form of superheated water, having consequently great chemical activity. There is a strong tendency for water entering through an indefinite number of small openings to converge into larger openings which are located on the lines of weakness in the formations. These waters reach, in the lowest part of their course, where they possess their highest chemical activity, the zone wherein sulphur is the more active agent, so that they dissolve prominently sulpho-compounds out of the rocks, through which they percolate in capillary and supercapillary openings, until saturated, and hold them in solutions in ion- ized form. The precipitation out of these solutions is the result of supersaturation due to several causes, among which the most prominent are dilution and loss in temperature and pressure. It is more than probable, from the intimate association of igneous rocks with a large majority of ore deposits, that they are the main source of the metallic ores; and that there is a direct genetic relation between ore deposits and eruptive processes. A number are, in fact, intimately connected with eruptive magmas, especially through eruptive after-action, as sublimation, gaseous action, igneous-aqueous action, etc., by which the heavy metals were in great part extracted from such magmas. As the eruptive magmas, at least those of deep origin, are admitted to contain a more or less notable admixture of water, with other constituents of hydrous or gaseous character, the formation of minerals on cooling and the subsequent cycle of solution and reprecipitation, as above described, will take place. In this connection the following quotation is important: "It is thought highty probable that under sufficient pressure GENESIS OF QUICKSILVER ORE DEPOSITS. 29 "and at a high temperature there are all gradations between "heated water containing mineral material in solution and a "magma containing water in solution. If this be so, there "also will be all stages of gradation between true igneous "injection and aqueous cementation, and all the various phases "of pegmatization may thus be fulh' explained." [C. R. van Hise, 1 6th Ann. Rep., vol. XI, page 647.] The foregoing explains the reason that the metals are origi- nally deposited principally in the form of sulpho-compounds; which, in the upper portion of the earth crust, in the belt of ' weathering, under the action of the various gases, especially carbon dioxide and oxygen, and of organic bodies, are trans- formed into various oxidation products thereof, including the native metal. [See on this subject more particularly: F, Posepny, Genesis of Ore Deposits; C. R. van Hise, Principles of North American Pre-Cambrian Geolog}', i6th Ann. Rep. U. S. Geological Sun'e}^ Pt. I; ibid.^ Physico-Chemistry of Metamorphism, Bulletin Geol. Soc. of Am., vol. IX; J. L. H. Vogt, Problems in the Geology of Ore Deposits, Genesis of Ore Deposits, page 636 and following; etc.] The opinion that quicksilver deposits are formed in accord- ance with the general principles above described is based upon obser\^ations at Steamboat Springs and Sulphur Bank, and finds confirmation in the associated minerals within those deposits which bear evidence of precipitation out of aqueous solutions. The following observations on this subject are of sufficient importance to be shortly discussed: Most of these deposits show that at some time during their history they have been the scene of intense solfataric action, and a great many are in contact or in close proximity to eruptive phenomena. Mercury boils at 357*^ C, but volatilizes to some extent at ordinary temperatures. Liquid mercury combines with sulphur in the manufacture of vermilion in the dry way, below the melting point of sul- phur, 120° C. ; in the wet waj', sulphide of mercury forms between 45° and 50° C. Hence the combination of mercury and sulphur takes place between liquid mercury and sulphur. That in the wet process a heat below 50° C. is insisted upon would indicate that the combination of liquid mercury and sulphur can only take place within the immediate vicinity of 30 QUICKSILVER RESOURCES OF CALIFORNIA. the surface, as the proximity of igneous-aqueous action to the quicksilver deposits during some time of their history will cause the increase of heat in depth to be much more rapid than the ordinary static rate of i° C. per loo feet. (At Sulphur Bank, Dr. Becker gives the heat of the water of the Herman shaft at the surface 128° F., and at a depth of 300 feet 176° F.) In vapor form mercury combines with sulphur at high tem- peratures, proof of which can be found in the bricks of old furnaces wherein cinnabar and native mercury are often found in large quantities; the mercurial vapors must have recombined with free sulphur in vapor form and recr^'stallized as cinnabar. The agency which causes the recombination of these disso- ciated vapors, at practically the same temperature, is as yet undetermined. All these considerations have caused a great number of operators of quicksilver mines to retain the old theory of ore formation by sublimation, and to hold the opinion that mer- cury is brought into the lithosphere, and possibh' even into the belt of weathering, in the form of mercurial vapors. These, under favorable conditions, form mercuric sulphide, which then follows the cycle of solution and precipitation indicated by Messrs. Becker and Christy, namely, a solution of a double sulphide of mercury and sodium (HgS, nNaiS) in waters holding in solution: alkaline-sulphides, -sulph5'drates, and -h3-drates, or neutral or acid sodium carbonates partially saturated by hydrogen sulphide; and a precipitation mainly due to decrease in temperature and pressure or to dilution. Dr. Becker [Mon. XIII, U. S. G. S., above cited, page 419 and following] thoroughly discusses this subject and gives extensively his reasons for considering the cinnabar deposits as exclusively formed by precipitation from solutions. Prof. S. B. Christy [Am. Journal of Science, vol. XVII, 3d series, 1879, page 453 and following] had previously given his reasons why he arrived at the same conclusion. He made several tests as to the solubility of mercuric sulphide in different solutions under varying conditions of temperature and pressure, and regarding its precipitation out of those solutions. A short extract from his article will be of great interest: "The tests were made at temperatures varying from 200"^' to "250° C, and pressures varying from 260 to 500 pounds per GENESIS OF QUICKSILVER ORE DEPOSITS. 31 " square inch. The duration of the tests varied from three to ten "hours, and in each case the cooling was allowed to take place "gradually and undisturbed. Their result proved that waters "containing solutions of alkali sulphides and some natural min- "eral waters to which sulphydric acid had been added, will, "under certain conditions of temperature and pressure, dissolve "mercuric sulphide; that increase in pressure aids rather than "retards this solution, and that cinnabar is deposited from such "solutions in the crystallized form when temperature and pres- "sure are slowly lowered, while the occasional occurrence of " metacinnabarite, or black amorphous sulphide of mercury, was "explained by the sudden dilution or cooling of the depositing "waters, or the local mixing, during crystallization, of agents "causing rapid precipitation." Professor Christy in the course of these tests obtained out of a solution of potassic sulphydrate wherein amorphous mer- curic sulphide was placed, a coherent mass of crystals of cinna- bar, perfectly simulating the crystals which occur in nature. He further argues that while the deposition of cinnabar from mercury in vapor form occurs in the masonry of furnaces, condenser walls, etc., the same can not account for the same action in ore deposits, because the high temperature required to volatilize mercury and cinnabar would destroy the gangue minerals almost invariably associated with the ore in nature, such as dolomite, calcite, bitumen, and pyrites, which besides are never found in the occurrences of cinnabar and mercury in the masonr}^ of furnaces and condenser walls, directly traceable to volatilization and sublimation. There are some fundamental differences between quicksilver ore and gold ore deposits, which must be noted. All the quick- silver deposits worked up to the present time show a lack of persistence in depth, and at a rather shallow depth in the different deposits their cinnabar content becomes too low for commercial purposes. The approach of this impoverishment is in nearly every case accompanied with the occurrence of native mercury, while in gold deposits generally, once the sulphide zone is reached, the character of the ore remains nearly permanent. Dr. Becker attributes this phenomenon to the precipitation of native mercury by dilution of the solution, or by the action of decomposition products of organic matter; the latter causing 32 QUICKSILVER RESOURCES OF CALIFORNIA. the presence of hydrocarbons so often found accompanying quicksilver ores. [Mon. XIII, U. S. G. S., page 437.] That the native mercury is mainly found in the lower parts of the mines is ascribed by him to the fluidit}' and high density of the metal. [Ibid., page 388.] As to the precipitation of native mercury b}- dilution, when the precipitation is caused suddenly, the product is a black mass of metacinnabarite with a very small quantity of native mercury [ibid., pages 429, 430, and 436] ; hence the copresence of cinnabar and native mercury would involve a re-solution and precipitation and slow cooling of the metacinnabarite without affecting the native mercun- present. The reduction of mercuric sulphide through decomposition products of organic matter would relegate the locus of this reaction to the upper portion of the deposit, and as those agents are active at the present time, native mercury ought to be found, at least to some extent, in the upper horizon of all quicksilver deposits. Prof. S. B. Christy remarks on the occurrence of native mercury: "Unless w^e regard it as an efiect of local oxidation "of a very stable compound, its appearance is well nigh inex- "plicable upon either h3'pothesis" of production by sublimation or deposition from solution. [Am. Journal of Science, vol. XVII, 3d series, page 463.] The oxidation of mercuric sulphide takes place at high temperature; mercuric sulphate being formed in the condensers nearest the furnaces, but not having been found in nature. Whatever may be the cause of the formation of native mercurs', its fluidity and density can hardly account for all phenomena of its occurrence. In the Socrates mine, Sonoma County, native mercury is found in fine globules within com- pact rock, while in the fracture planes of the same rock cinnabar is found associated with the native metal; if the cinnabar was the original form wherein the metal was deposited, some traces of it ought to be found in the compact rock, where the decom- posing agents can not have been as active as in the fracture planes. Original deposition as native metal and subsequent transformation into sulphide appear here more probable. The quicksilver deposits are closely connected with eruptive phenomena — either the presence of eruptives, or intense solfa- taric action. As Professor Vogt states: "In the exceedingly GENESIS OF QUICKSILVER ORE DEPOSITS. 33 "numerous deposits in some way connected with eruptive "processes, the nearness of igneous rocks must have caused "increase of temperature (and also of pressure?). This is "often so great as to exceed for heavy compounds the critical "temperature." [Genesis of Ore Deposits, page 659.] The source of the great heat in most of the quicksilver mines can, in many cases, be traced directly to the chemical reactions taking place at the present time. Chemical activity being increased by temperature and pressure, it is only reason- able to suppose that, at no great depth, conditions exist which would keep the mercury in a gaseous state. The suggestion of Professor Vogt: " With regard to younger "veins especially, we must keep in mind a possible extraction "from laccolitic magma in depth" [ibid., page 656], may in many cases offer an explanation for the genesis of quick- silver deposits, where no extrusive igneous rocks are found in their vicinity. Erosion is the cause of the absence of quick- silver deposits in older formations. This erosion is much more considerable than generall)- taken into account. [See ibid., page 670.] Professor de Launay, comparing ore deposits oc- curring relativel}- near the surface in less denuded regions with those deep below the surface in strongly denuded regions, takes as instance of the former quicksilver deposits, "which occur "chiefly in recent rocks near volcanic eruptives, while from "older ranges, partly destroyed by erosion, they have disap- "peared with other debris." The cinnabar deposits are in many cases connected with alteration zones in the country rock, caused by silicification, forming by preference in those zones. The latter, however, do not uniformly contain cinnabar, and the same form of altera- tion of the rocks is found throughout the Neocomian outside of the quicksilver belts. This process of silicification is more especially characteristic of the belt of cementation. [See above, page 27.] The term cementation designates the binding to- gether of the rock particles by infiltration of mineral materials in solution, and their deposition as minerals in the interstices of the rocks. The process of serpentinization resembles that of silicifica- tion. The material for the serpentine may be furnished partly, or in whole, b}- the minerals present in basic sedimen- 3— QR 34 QUICKSILVER RESOURCES OF CALIFORNIA. tary rocks, which are altered through this process, or the material may come from extraneous sources. [Van Hise, i6th Ann. Rep., Part I, page 691.] As serpentine may replace quartz, the presence of cemented and indurated sandstones, chalcedonite, phthanite, and serpen- tine may represent various phases of the physico-chemical process of cementation in the belt of fracture. This silicification process forms different materials in different localities. It forms a great quantity of black opal, containing some quartz and chalcedonite (a mixture of opal and crystal- line silica). A considerable portion of the sandstones of the Coast Ranges show the effects of this silicification process, in varying degrees. The cinnabar forms in the cracks, seams, and fissures of the silicified material. The richness of the cinnabar ore is to a great extent dependent upon the size of the cavities favorable for deposition and consequently upon the compactness of the fissure-filling; hence rich ore bodies are principally found in those parts where the fissure-filling has been crushed and distorted. COST OF MINING AND REDUCTION. The cost of mining and reduction of quicksilver ores differs very sensibly in the various mines. The nature of the ground is one great cause of this difference. In some mines the ground is such that little or no timbering is required. In others, the ground is so bad that the stopes have to be tim- bered and filled. In some mines the air is generally good, while in others the heat is so great that the men work under disadvantage. The cost of timber and cordwood also varies very much, some districts being well provided with timber, while others are at considerable distance from the source of suppl)-. '• I--?/ YTVTJOO Geology by Win. Forstner, E.M. MAYACMAS D I — Sunrise. ") lo — Geyser, Sulphur, 2 — Cloverdale. Il — Black Bear Group. 3— Mercury. 12— Pluton Den. 4 — Manzanita. j 13 — Clyde. 5 — Albian. /■ Cloverdale Mine. 14 — Culver — Baer Group. 6 — Mattole. 15— Rattlesnake. 7 — Mount Vernon. 16 — Tunnel Site. ) 8 — Philadelphia. 17 — Incandescent. '- 9 — Waterloo. J 18 — Almaden. ) No. Name OF Mine. NO. N.4ME OK MINE. 19— Mate. 1 29 — Socrates. 20 — Eureka Nos. i and 2. [Eureka Con. 30 — Mercury. 21— Captain. f 31— Great Northern. 22- 1 23 — Cedar. 32-Hope.j. p^„^,,, p^^i,,^ ^ 24— Quicksilver. ( Crown Point 34-Denver. 25— Queen Group.! Q. Mining Co. 35-) 26 — Lookout. 1 36 — V Lucky Stone Group 27 — Diamond. \ 37—) 28 — Mercury. 38— Hurley. N.AaiE OF Mi: 39 — Pacific. 40 — Hercules. 41 — Sonoma. 42— 43— 44— 45 — Pontiac. 46- " 47 — Boston. 48— Empire. rn Point Quick- ver Mining Co. 49 — Double Star. 50 — Occidental. 51 — Healdsburg. 52— Edith. 53— Cinnabar King Group. 54-Eugenie. ) 55— Maud. [■ Bacon Con. 56— Dragon. ' 57— Napa. DISTRICT. 58— St. George, i 59— Golden Gate. ■ Bacon Con. 60— Eagle. \ 61— Helen. 62 — Young America. 63 — Chicago. 64— Wall Street. 65 — ^Jewess. 66 — Middletown. 67- Nameof mi: 68— Gem. 69 — Great Eastern. 70 — Hope. 71 — Iviverpool Con. 72 — Eureka Con. ) 73— " Great Western -Standard Q. Co. 5 74- 75— 76- 1- Napa Consolidated. 1 — Eureka Con. 79— " 80— " I— Contention. 82 - Minnesota. 83 — Manzanita. S4 — Mercury. S5 — Bone. 86 — Fanny. Napa Consolidated. 88— South Side.' 89 — Corona. 90 — Napa Con. 91— 92 — Beecher. 93 — New Granada 94— Twin Peak. 95- " Xi.. Namk of Mink. 96 — Ida Easly. 97— Old Discovery. 98— Twin Quartz. 99— Good Enough. 100 — Silver Bow. ') loi— Phrenix. j 102— Red Hill. [ :jj(^jj ^^Q„ 103— Starr. j 104— Pope. I (05 — Washington. J 34 tary rockj material n Ann. Rep. As serp( and indurj tine may process of This sili localities, some quar line silica) Coast Ran varying de The cini silicified n great exte: for deposit fissure-filli those part distorted. qAK J rri- 'Tj ./d/iHOTlIJAO COS The cost ver>' sensil is one gn ground is others, the bered and while in ot disadvanta The cost districts be considerab A 3TATe - c.tW3J Obi •ej3»*.« - i DISTRICTS NORTH OF SAN FRANQSCO. MAYACMAS DISTRICT, The Mayacmas District, as defined b}- Dr. G. Becker [see Mon. XIII, U. S. G. S., page 368], embraces parts of Napa, Lake, and Sonoma counties, along the Mayacmas range, of which Mount St. Helena and Mount Cobb are the most promi- nent mountains. [See geological map of portions of Napa, Sonoma, and Lake counties quicksilver districts, in this Bul- letin.] Quicksilver deposits are found on both sides of the range; the main belt, however, lies in its eastern part north of the range, crosses it near Pine ^Mountain (between Mount St. Helena and Mount Cobb), and lies principally south of it, west of Pine Mountain in Sonoma County. The general trend of the belt is northwest. In its south- eastern part, in Napa Count3', it is in very close proximity to a region of very intense and probably prolonged eruptive action, covering Tertiarj- and post-Tertiary periods. The center of eruptions in this region was probably' in the territory bounded b}- Mount St. Helena, the Twin Peaks (or Sugar Loafs), and High Peak; the flows have, however, spread over a large adjoining territory. Outside of this are found a great many other eruptive bodies in this district, of which the more prominent are: The basalt body on Oathill, some smaller ones in the territory of the ^-Etna Consolidated Company, an andesitic eruptive body northeast of Oathill, Pine Mountain, Col)b Mountain, and others. This district is hence a region of intense eruptive action. Large masses of lava have covered parts of it, and while partly eroded, extensive sheets of tufa cover at present parts of it to a greater or less depth, and make it ver>- difficult to determine the limits of the cores of igneous rocks. The present deeply car\-ed topography of the region is largely governed by the erosion of this capping. The older rocks are mainly represented by sandstones, some- times nearly unaltered, sometimes thoroughly altered into (35) 36 QUICKSILVER RESOURCES OF CALIFORNIA. schists, with all intermediary gradations. Serpentine is very prominent, mostly a hard, dry variety, in places disintegrated and pulverized b}- weathering, showing as large bare spots along the ranges. Even where not bare, the serpentine can be detected at a distance by a sparse vegetation, w^hile on the balance of the surface a ver>' close growth of brush or grass is found. The relation of the serpentine to the quicksilver deposits is not clear. Most of these are associated with, or in close proximity to, serpentine; but others, like those at Oat- hill and Cloverdale, are entirel}' away from the serpentine; and where the serpentine is verj^ prominent and continuous over a certain width, no deposits of any value have been found; as, for instance: between Oathill and the Mirabel around the head of Bucksnorter Creek; on the ridge between Bear Creek and Drj' Creek ; on the main ridge between the headwaters of Dry Creek and Briggs Creek. Neither are workable quick- silver deposits found in the serpentine. Where serpentine is associated with any deposits, these are always contact deposits, while both the Oathill and Cloverdale mines are in the sand- stone. The quicksilver deposits appear from their association with the opaline rock, which is presumably an alteration product of serpentine by silicification, to be related to the serpentine to a certain extent. The fact that, where it is A-ery wide, no paying deposits have been found, would indicate, however, that either the sandstones contain the primary disseminated metal, which is concentrated through some process of second- ary concentration, or else in the large bodies of serpentine the concentration took place only in those parts affected by contact metamorphism. While this holds true only for the south- eastern part of the district, it must be remarked that in the northwestern part, in Dry Creek and Pine Flat districts, there is in many cases an undoubted relation between the quicksilver occurrence and igneous actions. In the Dry Creek district the only deposit of any ascertained consequence is the Helen, which lies very close to the tufas of Pine Mountain. There are undoubted signs of igneous rocks in the Pine Flat district on both sides of Big Sulphur Creek; some of these igneous dikes run, as far as determined, in a direction which would bring them near the ore deposits of the Eureka mine; others were found near the Cloverdale mine. For a great number of MAYACMAS DISTRICT. oi deposits, these relations are not yet determined. Considering the intimate relation of quicksilver deposits and aqueo-igneous actions and the general geological conditions in this region, it may, however, be expected that, at least, laccolitic relations exist there. Between the Corona and St. Helena Creek, a distance of four miles in an air line, along the headwaters of Bucksnorter Creek, the belt of serpentine is verj- wide. Between St. Helena Creek and Bucksnorter Creek the Standard Quicksilver Min- ing Company- has in the last few years spent a considerable sum of money prospecting, but so far without any favorable result. To the west of the Great Western mine are the headwaters of Dry Creek, a bowl-form basin nearly encircled bj' the main ridge and by a ridge dividing Dry Creek from the drainage of Putah Creek. Serpentine is very prominent in a great portion of the Dry Creek basin, and again barren of any workable deposits of cinnabar, notwithstanding some very prominent, peculiar croppings, standing out boldly in the serpentine. These croppings, especially prominent in the Wall Street and Jewess grounds, consist of a network of white quartz seams, mostly thin amorph quartz, with occasional concretions of botryoidal form; the ground mass is a light yellow-brown, ochreous mass; this material is locall}- called "dry bone," and so far as yet observ'ed, never indicates a w^orkable ore deposit. The same is found on the Bacon Consolidated and Cinnabar King ground (Pine Mountain), and also in the Double Star mine (Pine Flat). (Lawson's silica-carbonate sinter.) Pine Mountain is a mass of andesitic tufa, most probably with an eruptive core, of small dimensions and very steep sides, and entirely disconnected from the Mount St. Helena and the Mount Cobb groups of eruptives. Its main ridge is not over 25 feet wdde, and about 300 feet long; elevation, 3475 feet. The tufa is of a light grayish color, and has spread over a part of the adjacent ravines. No signs of basaltic rock could be found on the ridge. The Helen mine is situated on the eastern slope, near the edge of the tufa, and on the south- western, western, and northwestern slopes are located a series of mines, comprising the Cinnabar King and Bacon group of mines. The northwestern slope is very steep and partly cov- ered by tufa, which covers alternate beds of serpentine and 38 QUICKSILVER RESOURCES OF CALIFORNIA. Fig. I. Section of uonhwest slope of Pine Mountain, Sonoma County. metamorphosed sandstones. At the contacts wide belts of croppings show, partly in place, partly covering the side hill with large bowlders. These croppings resemble very much those of the Wall Street and Jewess. In the caiion continu- ing below the old road from Middletown to Pine Flat a very well-defined cropping on the contact of serpentine and sand- stone is seen. [See Fig. i.] A great amount of work has been done here; remnants of old shafts and tunnels are found everywhere on the hillsides, but all work is now abandoned. Sev- eral pockets of very rich cinnabar ore were found at diSerent points at the surface, but none appear to have been found persist- ent in depth. The headwaters of Putah Creek are situated in a basin on the south slope of Mount Cobb. In this basin are a great number of hot springs, of which Anderson Springs are by far the most prominent. These springs generally contain a great amount of sulphur, and in several places sulphur deposition and rock decomposition b}- sulphurous fumes are taking place. Here, as in other parts of the district, cinnabar deposition does not occur in or close to those places where hot waters and vapors reach the surface. There are no cinnabar mines in this basin — only a few prospects, which can scarcely be said to give, up to the present, much promise of turning into mines; a condition partly due to insufficient development. The mines around Mount St. Helena have a considerable supply of timber in their vicinity, although the ^Etna, Oathill, Corona, Mirabel, and Great Western mines have made serious inroads on the supply. The Oathill mine is the only one having a sawmill. The other mines must use round timbers, or get their timbers from the sawmills in Lake County at the foot of Mount Cobb. In the Pine Flat district, the timber supply is rather scant. There is one sawmill in the district. Round timbers cost per set, including lagging, from $2.50 to $2.75; timbers, 7 cents per linear foot; lagging, 3^ cents apiece; -TT- An i^' r^ v., f^. .-J- ^^Sr 5-y V? ^ L\ ''K^, \\jO\v4v Lake \ /^hur»lpi(Lake \ Gehnatdl lake ,Y