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ARMY. No. 18. REPORT OF THE GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEL MADE BY ORDER OF THE SECRETARY OF WAR ACCORDING TO ACTS OF CONGRESS OF MARCH 2, 1867, AND MARCH 38, 1869, UNDER THE DIRECTION OF BRIG. AND BVT. MAJOR GENERAL A. A. HUMPHREYS, CHIEF OF ENGINEERS, BY CLARENCE KING, U. 8. GEOLOGIST. DN VOLUME III. UNITED STATES GEOLOGICAL EXPLORATION OF THE FORTIETH PARALLEL. CLARENCE KING, GEOLOGIST-IN-CHARGE. MINING INDUSTRY BY JAMES D. HAGUE WITH GEOLOGICAL CONTRIBUTIONS BY CLARENCE KING. SUBMITTED TO THE CHIEF OF ENGINEERS AND PUBLISHED BY ORDER OF THE SECRETARY OF WAR UNDER AUTHORITY OF CONGRESS, ILLUSTRATED BY XXXVIT PLATES AND ACCOMPANYING ATLAS, WASHINGTON. GOVERNMENT PRINTING OFFICE. 1870. Be | B ae —_ ie _ Ww - : ee v oe —_ ‘7 a Att) Te ier io ? : i Z > — ar a on Ys <7 a - an _ ye NOTE. The following reports will constitute the series of the GEroLoGicaL EXPLORATION oF THE FortiIeTH PARALLEL: Volume I. Systematic Geology. Volume II. Descriptive Geology. Volume III. Mining Industry. Volume IV. Zodlogy and Paleontology. Volume V. Botany. The present, or Volume III, has been first prepared and published, because its subject, Mining Industry, is most directly applicable to the mate- rial development of that great extent of mountain territory opened up by the Pacific Railroad. The other volumes will be pressed to completion with all possible rapid- ity. The Atlas of Topographical and Geological maps, necessarily the latest of the publication, will be issued in 1871. CLARENCE KING, U.S. Geologist in charge. TABLE OF CONTENTS. TENET OD GLC O Rivas ORIN) 2 epee erence Sle ee oe ths oe ha see Sak oe CHAPTER JI. MINING DISTRICTS.—BY CLARENCE KING. .............-..-.- CHAPTER II. THr Comstock Lopr.—By CLARENCE KING.... .......--.-. SECTION I. GroLoGY oF THE WASHOE MINING DISTRICT... - II. STRUCTURE OF THE COMSTOCK LODE IN DETAIL. Ill. GENERAL STRUCTURE AND MoprE oF OCCURRENCE Ohmi COMSTOCK quODE 2 ces seca s-eceac e oee CHAPTER III Turn Comstock MinEs.—By J. D. HAGUE................-. SECTION I. GENERAL METHOD OF EXPLOITATION............ II. Cost AND YIELD OF ORES .................-.-.- IJ. REVIEW OF OPERATIONS OF LEADING MINES.....- OHAPTER IV. TREATMENT OF THE ComsTOock OrrEs.—By J. D. HAGUE.... Section I. GENERAL OUTLINE OF THE PROCESS .........--- Ii, DETAILS OF CRUSHING AND AMALGAMATING Ma- CUEIINIDIR Wy tects as ayaa es tarsomeres eee ee es Ill. Costs AND RESULTS OF MILLING OPERATIONS... IV. TREATMENT OFRORHE JRESIDUES -22.-<¢-— 22.2. 2.2 V. TREATMENT OF FIRST-CLASS ORE ............... CHAPTER V. CHEMISTRY OF THE WASHOE PROCESS.—BY ARNOLD HAGUE.. CHAPTER VI. CENTRAL AND EASTERN NEVADA.—By J. D. HAGUE......-. SecTIon I. MINING AND MILLING IN WESTERN NEVADA..... II. GroLocy OF THE ToyaBE RANGE.—By S. F. En- TV O INS pester ets cena ee ee ae ee a enc IIt. MIninG AND MILLING AT REESE RIVER ......... IV. GEOLOGY OF THE WHITE PINE DIStTRICT.—BY JSRNOLD) EENGUR eee esses Se sees acca See ace V. MINING AND MILLING AT WHITE PINE.........-.. VI. Eaan CANon District.—By S. F. Ennions...... CHAPTER VII. THE GREEN RIVER CoAL BASIN.—BY CLARENCE KING.... CHAPTER VII. CoLnorAno.— BY J: D. HAGUE.................--:.... IL 167 193 193 206 929 232 252 264 274 295 295 320 349 x TABLE OF CONTENTS. CHAPTER IX. GoLD MINING IN CoLORADO.—ByY J. D. HAGUE........... SECTION J. GILPIN CouNTY GOLD VEDNS.............-.--..-- I]. TREATMENT OF THE ORES......--.--..-...--..--- CHAPTER X. SILVER Minine In CoLoraApo.—By J. D. HAGUE......... SecTION JI. GEORGETOWN SILVER-BEARING VEINS ......-....- 1B eee Wien oy Mien oe MONK UMono O NAO wae Pvt oie ee Bee (ELT. SCAT, RUEVAI TR SIVETENGI Sie ec tete soe teete oa— Far me tes LIST OF PLATES. The Plates illustrating this volume, as well as those of the accompanying Atlas, were engraved and printed by JULIUS BIEN, of New York. PLATE IE, IE. Xx. XAT. XIV. XV: exeVale XVII. XVIII. XX EREXS XX. XXI. XXIT. XXIV. DOV: XXVI. 9.0 AU XXVIII. XXIX. XXX. WASH OGISCCHOUSe se mee. oa. >so eee eee Ser opposite page... peli tahiiny J ba aloyei wenysaers Ges gee ees eee Gy ees en ee ae Chon = Shaft RIM DSTI Dee mes kes 2 I INE Se do... =. Stope and Tunnel Timbering........---..--..- dopeeees SHOP SMD GUN Oras aos Aas aaa Sere ce (ile) Goose Drift-car; Ventilating appliances...... -.....- (|G ere OSI OY CAO Oe lice. cirs yale ste Mere iene cere, oe ei Om eee ers Hoisting Cage, with Eccentric Safety.......-.-- MO. 22 se Minin oPUM pS Seek ea coc eeiccete cease se dotesess Oscillating 0 tse eee cena a eee cee eee dO2222-2 iriction Gearing for Hoisting....---+....--..- @O=2ac=- Crown Point Hoisting Works: 2.t22..262 2226. cc. Oneeeen Hale and Norcross Hoisting Works..........-.--- COgsaa- Wat chino a Ghin erry oes sttns, 92s. ie Sicrctars Sie GOs eset Nava ere OISUIMO NW OLsSing. sce ee See ee ee: dOne ee Sectional View of Savage Works.............---. dos Gen. Separator or Settler..-......-.....- eee seats eat Om eee Retorting and Melting Furnaces .........-....... Owes aets Two Five-Stamp Batteries. .......--..--..-.--s6- (lOeeee a Details of Stamping Machinery ............-- G0se2sn. Grinding and Amalgamating Pans ..........-.... d0.<-2.- IMG Cone Sig aint crs ee re ee vais Sere ey tar Osesees sectional View ot Mills 22522-2586 See te cee Clone Roasting Furnace; Amalgamating Barrel ... - - d0ys 2522 Oreana WurmaceS: 2 -.2scec2c28 si Secs: secs d0-ece3: Moya eG SCCHOUS as me ae ee eee er eta pt (CLO ever IREBSEGRIVERD MINGSS a 22s oes oars cis zB eae ea ee ee 8 2 ee ca 53 |8 6 a Ss ~ ~ it oo ~ oS 2 23 Sb 5 § |2 8 ae = 3 6 se & & zs a =e 2s ss S36 as Gelvat hcg es arcs we {oe} ee fs au “ a a EO Zz in aa) a ¢ Siu 9 9 = Og OF Ss ‘og 0 Oo Oo ee ops a a &B net as =| = i Eo > & o oO Oo "fo — 2 Re) SF 3 (ey an aD gq 7 aa q n ° Solid contents, grammes*) 0.0553 0.3271 0.0615 0.0924 0.0784 0.2660 0,080 BaSeSe= ee =e Lime Lime. Lime. Lime Lime. Lime. Lime. Magnesia. Magnesia.| Magnesia. Magnesia.| Magnesia.| Magnesia.| Magnesia. Potassa. Potassa. Soda. Soda. Soda. Soda. Soda. Soda. Soda. Alumina. AGIOS (er vies es 2 Carbonic.) Carbonic. Carbonic.) Carbonic.} Carbonic.| Carbonic. Sulphuric. Sulphuric. |Sulphuric. Sulphuric. Sulphuric. Sulphuric. Sulphuric. Phospho- | Phospho- | Chlorine. Phospho- | Phospho- | Chlorine. jalan 1g Keb ric. hater Silicic. Silicic. (Trace.) | *In 100 cubic centimeters of water. A considerable series of less extended analyses is given above. In these the amount of solid matter per 100 cubic. centimeters is first given, then a qualitative enumeration of contents. station of the Savage. It will be seen that beside the elements found in the Savage water, that from the Yellow Jacket shaft contains phos- phoric acid, which also occurs in the lower Hale and Norcross and in the fifth The contents of these waters, together with their tem- peratures, illustrate nearly all the chemical agents now actively engaged in the vein. Below are given three tables: one of analyses of the clays; another of horse materials; a third contains the prominent rocks of the neighborhood, propylite and andesite. THE COMSTOCK LODE. Table of Quantitative Analyses of Comstock Clays. 89 Silica. Alumina Lime - Magnesia Potassa Soda .- Water - Pyrites - Carbonic acid Ferric oxide Phosphoric acid Yellow Jacket. Chollar. Hale and. Nor- Savage. cross. East clay. West clay. East clay. Second Station, 60.02 59.71 65.69 39-52 234 Trace. Trace. Trace 3207 6.20 12.15 17.59 15.39 15.97 4.38 5.04 2.11 4.47 (oe -73 1.66 9.20 I.40 4.41 2.85 3.40 I.23 3.98 4.64 II “45 I.O1 2.36 8.09 4.19 2.80 9-95 1.84 3.58 2.84 9.18 99.07 100.24 100.34 IOI.00 Prof. S.W. Johnson.| W. G. Mixter. | W.G. Mixter. | Prof. S.W. Johnson. Analysis of Propylite florse, by W. G. Mixter. Yellow Jacket. Silica =. < Alumina . .~ Ferric oxide ~- Magnesia . . Lime 2 = = {Potassa <= .~ aSoda .- . . ‘Water. - . sPyrites. . . Manganous oxide 830-foot level. 90 MINING INDUSTRY. Table of Quantitative Analyses of Rocks, by W. G. Mixter. Andesite. Propylite. milicaigs: sintag ey See. = 59.22 58.68 Aluming 292 2 = © = 18.20 17.90 Herriciox1de es. sasl es 6.69 Aol UU ins (oe he es peed Oe 5.51 5.87 Magnesia . 2.90 2.03 Potassa 1239 3.19 Soda Svat 2107 Waters = 42, (5 Son 2.80 6.53 100.02 100.36 From these chemical data it is seen that the propylite, waters, and iron pyrites, furnish all the materials for the chemical action now going on in the vein. ‘To the orthoclase of the propylite, with its large proportion of potassa, may be traced the potash which is found so frequently in the waters and vein- materials. The horses from various localities throughout the lode have been examined for silica and were found to contain from 68 to 85 per cent. The quantitative analysis of a propylite horse above given, represents a fair average of their chemical composition. The comparison of the tenure of silica with that of the propylite shows the important fact that all the vein-materials are more highly charged with silicie acid than is the normal propylite wall-rock. When it is considered that so basic a rock as the syenite forms the other wall, the writer thinks the conclusion inevitable that the immense masses of quartz cannot be the result of lateral secretion zm situ. The horse materials, especially, contained rather more silica than the normal propylite, and those specimens which have been taken from the immediate east country, are charged to their normal percentage with silica. Whence then is the enormous volume of this mineral? That it came from below, brought upward by the ascending currents of hot water, there seems to be little doubt ; likewise that it filled the fissured chambers with a uniform charge of quartz is evident from their internal structure. The rocks upon either side in immediate contact with the vein, and as far as we have seen in the eroded gorges of the syenite, and THE COMSTOCK LODE. 91 for a distance of at least 600 feet to the east of the vein, contain their normal equivalents of silicic acid. But after passing the zone of 600 feet to the east of the vein, the country-rock for a mile and a half is filled with seams parallel to the Comstock lode; is fissured in every direction with a net-work of minor cracks, and has lost its original texture by solfataric decomposition. Here we find the silica contents almost gone. The greater part of this wide zone lying east of the Comstock has been reduced to a more or less ochreous, earthy rock, from which almost the last traces of silica have been taken. Supposing the Comstock to continue downward, along the inclined west wall, at no great depth, the solfatarized zone would be entered. It seems most probable that the whole mineralogical contents of the lode were sent upward from that region. In the immense withdrawal of silica from the rocks of that zone is a sufficient supply for the Comstock fissures. PaRAGENESIS OF MaAvrertAts.—The only facts beside those already cited, which throw additional light upon the origin and mode of occurrence of the Comstock, are the paragenetic relations of the various mineral materials. In a large way, of course, the horses are the earliest included materials. Next to them the fissure chambers were filled with quartz. After the quartz the percolating of waters, the attrition of rolled pebbles along their sides, and the thermal decomposition of horse and wall produced those sheets of clay which, in remarkable persistence, line every surface of quartz, and define every line of fissure. That they are later than the quartz is proven by their containing pebbles of that mineral, by their cutting it in certain instances, and by their surrounding it in every direction. The following series of minerals has been observed. The main ore-mass of the bonanzas is composed of, first, quartz; secondly, an assemblage of crystalline combinations of gold, silver, silver glance, blende, galena, and copper pyrites, the latter two ordinarily in small proportion; thirdly, un- important, secondary introductions of quartz, which occur as coverings and casts of earlier quartz crystals; fourthly, polybasite and stephanite, which throughout the whole length of the lode occur sparingly in well defined crystals; fifthly, carbonate of lime; sixthly, a third occurrence of quartz covering the carbonate of lime, and in some instances remaining in the form of a shell, after that mineral has been entirely dissolved away. Iron _pyrites 92 MINING INDUSTRY. belongs to the period of the earliest formaticn of the silver sulphides, and seems to have continued to a very late period, certainly until after the formation of the latest clays, for there are no important seams which are not more or less impregnated with the small, brilliant crystals of this mineral. Carbonate of manganese occurs but once, and in that case occupies a position between the main introduction of sulphides and the latest quartz formation. The other carbonates, those of lead, lime, and copper, belong also to this same period. The oxides, of which there are only those of iron and manganese, are wholly superficial products, belonging to the phenomena of the “Tron Hat,” and result- ing without doubt from the decomposition of the carbonate of manganese and the sulphides of iron, Of the accidental rare minerals, pyromorphite, which occurred in the Ophir, belongs to the upper levels, and its relations with the other materials were never clearly understood. Horn silver was found by Kiistel in the outcrops of Gold Hill, but there is no information concerning its paragenetic relations. The sulphates are wholly later than the latest introduction of quartz. They occur, first, in the form of selenite ; secondly, in those soluble sulphates with which the waters of the lode are now so largely impregnated ; and, thirdly, in that important zone of gypsum which occurs in the east country-rock, froma depth of from 600 to 900 feet below ground. From the Ophir to the Yellow Jacket this zone is more or less impregnated with gypsum, which occurs filling the cracks and fissures of the propylite, its fibrous crystals arranged diagonally to their surfaces. The distri- bution of the gypsum or selenite is one of the most interesting phenomena of the vein. At four or five places in the middle works of the lode, such as the Gould and Curry fourth, and the bottom of the Fair View shaft, were found beautiful crystals of selenite resting upon the latest quartz, later, therefore, than any of the metallic introductions, unless it be those sulphides of iron which are found in the clays. Natrolite and chabazite, with a rare association of stilbite, occurred in the black dike of the Gould and Curry, and near the bottom of the North Yellow Jacket shaft. A second growth of selenite has also recurred, its crystals resting upon those of the zeolites. The clays were prob- ably completed before this latest introduction of quartz, since certain of their surfaces and cracks are penetrated by it. After this latest quartz the zeolites, and then the sulphates, subsequent to which we have the “Iron Hat” with its | THE COMSTOCK LODE. 93 oxides of iron and manganese. It is important to observe here that the periods of most active crushing of the quartz were prior to the introduction of the stephanite. Angular fragments of quartz, which are found imbedded in the clay, never contain that mineral, while they are often more or less charged with the silver glance ore. Mope or Continuance IN Depru.—-So far the study and consideration of the lode has been confined to its past and present history. More interesting than these, by far, is its future condition and its probable mode of continuance indepth. In some respects this is the most difficult and perplexing period for an out-look which has occurred since the working of the district. During the last three years the gradual convergence of the bonanzas, both in the Gold Hill and the Virginia group, has given an unfriendly aspect to the lower region of the lode, and cast a decided shadow upon the future. In many places, as has been seen, the lode was found to terminate in a mere line of fissure scarcely marked by even a thin parting of clay. It began to be very seriously ques- tioned by careful men whether, sooner or later, the whole of the ore-channel would not follow this unfortunate example, and close out altogether. The walls in Gold Hill decidedly converged, those in Virginia approached each other with a rapidity which bade fair, after a few hundred feet deeper, to bring them together, and it looked very much as if 500 feet at the utmost would end the productive zone of the Comstock. Against this view were the prominent facts of the immense masses of vein-material, which analysis of the various constituents proves to have been introduced from some dis- tant source. 'To suppose these poured in from the surface is an hypothesis so utterly at variance with all our ideas of the past condition of the range as to be untenable even for a moment. It is considered as certain that those vein-materials which are not either portions of the country-rock that have fallen into the chasm, or such as are clearly derived from their decomposition, have been introduced from below. This indefinite source of supply most probably lies at a considerable depth beneath that portion of the east country-rock which is most thoroughly decomposed by solfataric action. It became a matter of intense interest to discover those points where the great gashes of the ore-channel should open out into the true or deep-seated fissure, and when mine after mine worked downward and 94 MINING INDUSTRY. found the two walls coming into close contact, with nu appearance of the re-opening of a downward chamber, the very existence of such deep-seated fissure was more than doubted. The great structural puzzle of the lode for three years has been to find the vents through which the quartz ascended and filled the fissures of the ore-channel. Within the last year a new aspect has been put upon the whole question. In Gold Hill, the west clay-seam, after steadily and uniformly approaching the east quartz to within 60 feet of actual contact with it, has now opened downward into almost exact parallelism with that body. At the lowest working in the Virginia group, at a point in the Hale and Norcross, or directly within the widest eastern expansion of the Virginia chamber, the east fissure opened more and more into an inclined position, until now, in the deepest works, the walls are approaching parallel- ism, and the conditions assuming more and more those of a simple fissure. In the previous pages reasons have been given which seemed to forbid the idea of the quartz being segregated by lateral secretion zm situ. If it ascended from the depths below, as there can be no doubt it did, it must have had a very considerable channel, for its immense volumes forbid the idea of a slow seepage through a very contracted channel. It is possible for the quartz to have risen either through one general fissure, or to have found an entrance into the gashes of the ore-channel through two or three narrow chimneys. Had the former been the case it is difficult to conceive any reason for the peculiar disposition of the bonanzas. Had it been equally easy for the quartz to ascend at any part of the lode, and had the nature of the fissure given free vent to ascending currents either of water or metallic vapors, there would seem to be no reason why the bonanzas would not have been more equally distributed through the quartz. Decidedly the most remarkable feature of * the silver distribution is that, with an immense surface expansion, it focuses downward in three points, at Gold Hill, Virginia, and Ophir. This is some- what due, no doubt, to the fact that the ore-channel stands at a much greater angle than the west wall, and that the junction of these two systems of fissur- ing would naturally produce some barriers to the upward transit of material. It is dangerous to hazard a conjecture as to the mode of occurrence below; it is working altogether in the dark. The indications at present are insufhcient to warrant any well-grounded conclusion. This, of course, offers but little THE COMSTOCK LODE. 95 encouragement in a financial point of view; but the absence of bad prospects is in itself an encouraging feature, and there is certainly nothing in the present lowest developments of the lode which will at all warrant the belief that the metallic yield must necessarily cease. While it seems improbable, from the configuration of the ground and the relations of the fissures, that there can ever again be such a magnificent expansion of bonanzas, yet there is no strong reason why a total cessation of the silver minerals should be expected. The examples of other great veins, all that we know of the mode of deposition aud chemical transmutations of silver ore, rather favor the idea of a continued silver occurrence in depth. But the lode is in many respects unique, and it may be considered as established that only actual exploration can determine the important question of the future. Resumé.—The results of this long and perhaps tedious investigation may be summed up in the following statement of conclusions: The ancient Virginia Range, prior to the Tertiary period, was composed of sedimentary beds of the great Cordillera system, which, in the late Jurassic epoch, had been folded up, forming one of the corrugations of that immense mountain structure which covers the western front of our continent. Accompanying this upheaval were outpourings of granite and syenite. The erosion which followed this mountain period escarped the ancient rocks, and modeled the eastern front of Mount Davidson into a comparatively smooth surface, whose average angle of slope sank to the east at about 40°. In the late Tertiary, at the time of the volcanic era, the Virginia Range shared in the dynamical convul- sions which gave vent to successive volcanic outflows of immense volume and very remarkable character. The first and, so far as the Comstock lode is con- cerned, the most important, was of propylite, or trachytic greenstone, which deluged the range from summit to base, covering large portions of its ancient surface, and leaving here and there isolated masses, which rose like islands above the wide fields of volcanic rock. Subsequently followed the period of the andesites which, at their commencement, in the form of a thin intrusive dike, penetrated a new-formed fissure on the contact plane of the ancient syenite and the propylite. This earlier andesite period gave birth to the solfataras, which, bursting from a hundred vents, rapidly decomposed the surrounding rocks, and gradually filled the fissures of the Comstock with their remarkable 96 MINING INDUSTRY. charges of metal-bearing quartz. The latest flows of andesite poured out over the decomposed propylite: and since they are themselves unaltered, their appearance marks the period when solfataric action over wide areas had ceased. While it no longer maintained its energy through the broad zone of propylite, it still continued intensely active within the chambers of the Comstock lode. Metallic contents were introduced into the the quartz, the clay-seams were formed by a rapid decomposition of the neighboring propylite materials, the horses reduced to a spongy, semi-plastic condition, and at last the final solidi- fication of the quartz took place. Outside of the vein two events of geological interest have occurred: first, the period of trachyte eruptions, when from the ruptures of the crust, parallel to the Comstock lode, vast volumes of sanidin- trachyte overflowed the country; and, secondly, the less powerful but still important outpouring of basaltic rock, which marked the close of the volcanic era. Within the vein, and probably caused by one or both of these latter volcanic disturbances, a pressure has been exerted which has crushed and ground the masses of quartz into minute fragments. It is interesting to observe that while this force was great enough to crush quartz-masses one hun- dred and fifty feet in breadth into mere angular pebbles, the disturbances were insufficient to cause any actual faulting of importance. Both within and with- out the vein the solfataras gradually came to a close. The heated currents of water which even yet ascend into the lower levels of the mines, are evidence that at no very great depth a considerable temperature is still maintained; but this is only a faint relic of a once intense action. No chemical theory will be advanced as to the origin of the quartz, nor of those delicate questions of magneto-chemical introduction and subsequent transmutations of the metallic minerals. ‘They belong rather to an abstruse study of the theory of veins in general than to an investigation of a particular district. ‘The writer has endeavored to present the most important facts that came within his observation, in the hope that a patient reader may gain a general view of the structure and chemistry of this celebrated lode. CHAPTER III. THE COMSTOCK MINES. SECTION J.—GENERAL METHOD OF EXPLOITATION—THE VEIN—MINING CLAIMS— SHAFTS—SHAFT TIMBERING—DRIFTS—STOPES—STOPE TIMBERING—ORE EX- TRACTION—DRIFT. CAR—CAGES—ECCENTRIC SAFETY ATTACHMENT—PUMPS— VENTILATION—HOISTING AND PUMPING ENGINES AND GEAR—SAVAGE WORKS. SEecTIon I.—Cost AND YIELD OF ORES—MATERIALS CONSUMED—TABULAR STATE- MENTS OF COSTS OF MINING—STATEMENT SHOWING YIELD OF ORES—CONDITIONS OF THE FUTURE AFFECTING COSTS—VIRGINIA AND TRUCKEE RAILROAD—SUTRO TUNNEL, SECTION IJI.—REVIEW OF OPERATIONS OF LEADING MINES—SIERRA NEVADA—OPHIR —VIRGINIA CONSOLIDATED—GOULD AND CURRY—SAVAGE—HALE AND NOR- CROSS—CHOLLAR-POTOSI—IMPERIAL AND EMPIRE—YELLOW JACKET—KENTUCK —CROWN POINT—BELCHER—OUTSIDE MINES—OCCIDENTAL—LADY BRYAN— TABULAR STATEMENTS. ye Cr POW GENERAL METHOD OF EXPLOITATION. It is the object of this chapter to describe the methods by which the mines of the Comstock lode are worked, and to show the general condition of mining industry in the district of which that lode is the principal feature. Norre.—The writer takes occasion here fo express his obligation to many gentle- men, superintendents of mines and mills in the vicinity of Virginia City, and officers of mining companies, for much assistance in obtaining the information embraced in this and the following chapter. He is especially indebted to Mr. Lours JANIN, Jr., formerly superintendent of the Gould and Curry Mine, Mr. CHARLES BONNER, super- intendent of the Savage Mine, Ma. JAmes Farr, superintendent of the Hale and Nor- cross Mine, and Mr. IsAAc L. REQUA, superintendent of the Chollar-Potosi Mine; also, to Mr. LOWELL, Mr. FRANK THAYER, Captain RAwLines, and Mr. Jonn O. PLATER, officers of the Savage Mining Company, and to the Hon. F. A. Tritn His thanks are also due to the officers of Wells, Fargo & Company’s Express, not only in Nevada but elsewhere, for many favors; and to Messrs. J. H. CArMANY & COMPANY, proprietors and publishers of the Commercial Herald and Market Review, of San Francisco, for nruch statistical information. The following publications have been frequently referred to by the writer during 13 98 MINING INDUSTRY. Tur Verw.—The geological features of the vein and its inclosing rocks, its general structure, and the character and method of distribution of its ore- bodies, have been so fully discussed in the foregoing chapter that, in what follows, these matters will receive only such attention as may be made neces- sary by their intimate connection with the branch of the subject under present consideration. The course of the Comstock lode is nearly north and south, maintaining a general conformity in direction with the trend of the Washoe Mountains, in which it is contained. Its croppings extend in a broad, irregular belt along the eastern slope of the range, at an altitude of about 2,000 feet above the level of the plain to which the hills descend, and about 1,300 or 1,400 feet below the summit of Mount Davidson, the highest point in the range. The western, or foot-wall, dips to the eastward from near the surface to the greatest depth attained, at an angle varying from 85° to 55°. The east- ern, or hanging-wall, is ill-defined, especially in the upper portion of the lode, but at the depth of several hundred feet the two walls, or what are usually recognized as such, descend with considerable regularity, dipping easterly at 5 about 45°. The size of the vein is irregular, the walls being in close contact with each other at some points, and at others diverging and expanding, so as to include between them masses of vein-matter several hundred feet wide. With- in these immense spaces, filled by material of varied character, are the bodies the preparation of these chapters, and are commended to the reader as valuable sources of information: The Reports on Mineral Resources by the United States Com- missioner, Mr. J. Ross BROWNE, and his successor, Mr. Rt. W. Raymond; the Reports of the State Mineralogist of Nevada, Mr. R. H. StRErcH, and his successor, Mr. A. I, Wurtz; Reports of the Surveyor General of Nevada, Mr. 8S. H. MARLerrE; and the official reports of mining companies. The plates illustrating this volume have been prepared from notes and drawings obtained in the field during the progress of the survey; the final work of preparing them for the engraver has been done, under the supervision of the writer, by Mr. ELLSwortH DaGGETrtT, of New Haven, and Mr. A. POHLERS, of Washington, to whose skill as draughtsmen, combined with a practical knowledge of the subject, they owe much of whatever merit they possess. All money values quoted in this and folowing chapters, referring to the State of Nevada, ave, unless otherwise stated, expressed in coin. THE COMSTOCK MINES. 99 of ore-bearing quartz, whose peculiar features have been already described and the extraction of which is the object of the miner. The extent to which the vein has been clearly traced, and on which min- ing claims have been located, is about four miles. At either extremity of this ground, however, and particularly on the north, the vein has been but litile explored and has not been thus far proved to be very valuable. Its developed, and, so far, productive portions, are included within about two miles, and within these last named limits the ore-bodies have been found to occur in disconnected groups, separated from each other by long intervals of barren ground. Minine Criams.—The following is a list of the mining claims located on the course of the lode as far as its continuity has been traced with any certainty. It gives the length of ground claimed by each company or indi- vidual owner, beginniig at the north and proceeding towards the south: List of Mining Claims on the Comstock Lode.' Length of | | Length of Name of company. pants | Name of company. | es claim in feet. | claim in feet. | tae! oa hoe ~=, = ee 300 ; Winters and Kustel - - - - 30 CentraliNon22) "- sae uns 100 | Consolidated . . 2... .- 2I KSInMeyys) We, sal scars e 50 i IIGEIGTOUNG y= a sae see 1334 White and Murphy?. . 210 | Imperial, (South mine). - - - 65% Sides eae eee ce Boow same Hallen see neees yess ne 50 Best and. Belcher=. 2." - 250 jeaCOnia ence ewe mtsmrc tec) <= 130 GouldandCurry. . . . I, 200 | Burke and Hamilton - - - .- 40 Savage ye ee eS 7 lie Wellowalacket ===" = (5 fe = 943 Hale and Norcross. . - 400 [Pe cretuttelless 2 AS aeseeey coins 93% Chollar-Potosi» . .- . . I, 434 | Crown Point. . - - - - - 540 is}riNitofot es oS Gey ee SY 940 | iiss ae s) S Se Ss 940 ES Chequel === aan tia 400 | Segregated Belcher. - - - - 160 ei pha Seems | Se. oe 278% || Overman.” . ~ 2.9. 2 = ~ I, 200 Apple and Bates. .- . - 31% || NorthAmerican. - - - - - 2, 000 Imperial, (Alta) TTS | Baltimore American -. . . . 2, 000 i | 1 Report of R. H. Stretch, State Mineralogist of Nevada, 1866. ° Virginia Consolidated. 100 MINING INDUSTRY. Each claim mentioned in the foregoing table formerly represented a dis- tinct and separate ownership in the vein, originally acquired by location under the laws of the State. A few of them have since been consolidated, reducing slightly the number of individual owners. Many of these claims are very short, their length varying from 10 to 2,000 feet. The length of each claim, as given in the table, is measured along the line of the lode, or in a nearly north and south direction, covering in width the whole of the known extent of the vein between the east and west walls. ‘The difference of opinion regarding the position of these walls and the relation sustained toward each other by parallel bodies of ore, separated by country-rock, but all included between what are now held to be the main walls of the vein, was, in former years, a fruitful source of litigation, involving the expenditure of millions of dollars. Each claim, with few exceptions, is represented by an incorporated company. In most cases, formerly, the number of shares in any company was equal to the number of lineal feet contained in its claim on the lode; lat- terly, however, nearly all the more important companies have found it desirable to increase the number of their shares, and this has been done by subdividing each foot into fractional parts, usually twelve or twenty in number. The subdivision of the workable portions of the lode among so many independent owners, has not only given rise to much expensive litigation, but has doubtless increased the cost of development, multiplying the expenses of administration, the outlays for machinery, and other requisite equipment of the mines, and in various ways involving expenditures that would be avoided under more comprehensive or consolidated management. All of these companies have explored their ground to some extent, and most of them throughout the eutire length of their claim; but the number of those that have attained great success as producing mines is comparatively small. ‘These latter, whose locations fortunately covered the great bonanzas, form four or five distinct groups. The northernmost. comprise the claims of the Ophir and Mexican mines, from which a large amount of bullion was produced in the earlier years of the development of the lode.’ Adjoin- The Sierra Nevada, north of the Ophir, has latterly become a successful and profitable mine. Its product, however, has thus far been chietly gold, derived from surface rock. Its deeper explorations have not developed large bodies of silver ore. THE COMSTOCK MINES. 101 ing these on the south is a portion of the vein that, so far, has been unpro- ductive, amounting in extent to about 2,000 feet, at which point begins the next group of bonanzas, on which the Gould and Curry, the Savage, the Hale and Norcross, and the Chollar-Potosi are situated. Further south, separated from the last-named group by some 1,500 feet of ground, in which the Bullion claim has been explored with a wonderful persistence, and so far without any reward, is the next important and one of the most productive groups of ore- bodies yet developed. Here is a series of claims, some of them very short in extent, beginning with the Exchequer and Alpha and extending southerly to the Crown Point, covering, in the aggregate, some 2,500 feet of ground; this portion of the vein, excepting some slight intervals, has been very pro- ductive. Still further south, the Belcher and the Overman have found con- siderable bodies of ore, but less important than those before referred to. GerneraAL Metnuop or Operation—The earlier developments of the lode were made by sinking shafts upon it or by driving adit-levels through the eastern country-rock to cut the ore-bodies in depth. This latter method was employed by the Gould and Curry and served in the extraction of the greater portion of their workable ground. Other companies operated by means of shafts, and these, in early days, were sunk upon the croppings. At that time, before the structure of the vein had been discovered by actual work, the false pitch of the eastern wall and a slight westerly pitch of some of the ore-bodies, led to the belief that the vein would permanently dip to the west. As developments proceeded, however, the eastern dip of the western, or foot-wall, with the probable conformity of the eastern wall to it in depth, became clearly apparent. The shafts, sunk on the croppings on the northern part of the vein, reached the west wall at a depth of 400 or 500 feet, and penetrated the hard syenite below the vein. As the increasing depth of such shafts constantly increased the distance between the bottom of the shaft and the vein, and as the ground above, in the vein, was of a soft character and difhcult to sustain, the plan of locating deep shafts at 800 or 1,000 feet east of the croppings and sinking through the eastern country- rock to strike the lode at a considerable depth, was adopted, first by the Gould and Curry, and afterward by nearly all of the principal mines in the vicinity. 102 MINING INDUSTRY. Shafts of this character, designed for permanent and extensive operations, liberally planned and constructed in the most substantial manner, and furnished with the best of machinery for pumping and hoisting, are now being sunk -by the Ophir, Gould and Curry, Savage, Hale and Norcross, Chollar-Potosi, and Empire-Imperial companies. The depths attained by these several shafts vary from 700 to about 1,300 or 1,400 feet. The deep mines further south, the Bullion, Yellow Jacket, Kentuck, and Crown Point, are still working through the shafts originally sunk near the croppings of the vein, but in the vicinity of the last-vamed mines the west wall is only encountered at a much greater depth than in the more northerly portions of the lode. At the present day the greater part of the ore extracted from the vein is brought from a depth exceeding 500 or 600 feet, and the underground work of the leading mines is necessarily prosecuted through these deep shafts. As the sinking of these progresses, stations are established at successive distances, usually at intervals of about 100 feet, and from these stations, levels or tun- nels are driven from the shaft to the vein for purposes of exploration or extrac- tion. he ore-body being reached, it is stoped out overhand; that is, the level is driven under the body of ore to be worked out, and the ground over- head is thrown down and carried in cars from the stope to the shaft, where it is raised to the surface. The drainage of the deep workings must, of course, be effected by means of the shafts. The adits or tunnels, driven in from the surface to the upper portion of the lode, serve to drain the ground above them, but as operations are now carried on far below their level, the accumulating water must be col- lected at the shaft and raised to the surface or to an adit-level. For this pur- pose the deep shafts are provided with pumps of adequate capacity, and the water encountered in the various parts of the mine, finding its way to the shaft, is thus discharged at the surface. The various operations included in this work, comprising the sinking and timbering of the shafts, the construction of the drifts or tunnels, the working and timbering of the stopes, the extraction of the rock, the machinery em- ployed for hoisting, pumping, and ventilation, and the arrangement of these works on the surface, will now be reviewed somewhat in detail. Mini Suarrs.—The deep shafts of the several leading mines on the Hosting Compartnrent PURPLAG Compartiient Howsting Compartnent Hoisting: Compartment ASA ; iy Seale: as. THE COMSTOCK MINES. 103 Comstock resemble each other in general features, They are sunk vertically and, as they pass through ground of rather unstable character, require to be timbered from top to bottom. They are from 44 to 6 feet wide, and from 20 to 24 feet long, inside, between the timbers. They are usually divided into four compartments, one for pumping and three for hoisting. Of the latter, two compartments are usually devoted to the general work of hoisting from the mine, while the remaining one is exclusively used in the further sinking of the shaft. The present working shaft of the Savage mine, the description of which may serve as an example of the others, is 24 feet long in the clear between the end-timbers and 6 feet wide. It has three compartments for hoisting and one for pumping. The latter is 6 feet square in the clear; the hoisting compartments are 6 feet (the width of the shaft) by 5 feet, and the three partitions between the compartments are formed of 12-inch timbers. Saarr TIMBERING. The timbering consists of framed sets or cribs of square timber, placed horizontally, 4 feet apart, and separated by uprights or posts, introduced between them. Each horizontal set of timbers, therefore, marks about 5 feet in depth. Cross-timbers, for the partitions between the compartments, form a part of every set. The whole is covered on the outside by a lagging of 3-inch plank placed vertically. This method of timbering is illustrated by several drawings on Plates IL and III. Fig. 1, Plate UH, repre- sents the plan of the shaft, or of one horizontal set of timbers; S, S, are the longitudinal or sill-timbers; J, 7, the transverse end-timbers; P, parti- tion-timbers; 7, guide-rods, between which the cage moves; 4g, gains, cut in the sill-timbers, to receive the ends of the posts. The sheathing or lagging is seen inclosing the whole frame. Fig. 2, on the same Plate, is a transverse section through the partition ? of Fig. 1, between the pumping compartment and the adjoining hoisting com- partment, looking toward the latter. In this figure, G, Gare the posts; S the sill-timbers; P, the partition-timbers, the ends of which are framed with short tenons that are received in gains cut in the sill-timbers and the ends of the posts; 7, guide-rod ; 7, lagging or sheathing. Fig. 3 is an end view of the frame, shown in Fig. 1. The single piece 7 forms the end, while the double pieces, P, forming the partitions, are seen beyond. The other letters denote the same parts as in Fig. 2. 104 MINING INDUSTRY. The outer timbers of each set, that is, the two sides and ends of the main frame, are 14 inches square; the posts, 10 in number, four at the corners and two at each end of the three partitions, are of the same size. The dividing timbers, forming the partitions, are 12 inches square. These partitions, as may be seen in the drawing, are not close, no planking or lining being used on them, but two pieces of timbér are employed, one above the other, at each set, leaving open spaces of about 3 feet between the sets. The drawing on Plate IIL presents an isometric view of a series of these sets, forming together the timbering of the shaft. The lagging or sheathing is removed frdm the side and end nearest the observer. The ground through which these shafts pass being generally too unsettled to allow of sinking to any considerable depth without support, the work of timbering is necessarily done from above downward, as the sinking pro- gresses. The method of putting these timbers in place is about as follows : When sufficient ground has been excavated below the last set of timbers, for conveniently putting in another lower set, the long horizontal timbers, or sill- pieces, forming the sides of the set, already framed for receiving the ends, and having gains cut for the posts and cross-pieces, or ties, are lowered down and put approximately in place, being hung by chains to the last set already fixed above. The sill-pieces are usually in two parts, each about 13 feet long, butted together, at the middle, without splice or framing. The ends, cross- pieces, and posts are then fitted as nearly as possible into their proper places. This being done several long, round iron bolts, each made in two parts with a tightening screw in the middle, are passed through the new set and the one, or sometimes two or more, above. Everything being approximately in its place, the new set is adjusted exactly to its proper position, by means of the tightening screws on the bolts by which it now hangs to the set above. The lagging is then put in behind the timbers, and between the plank and the ground are inserted pieces of spiling and wedge-timber, which are driven into place or forced in by jackscrews as firmly as possible. Once fixed in this manner, everything is held by lateral pressure; the bolts by which the set was at first suspended are alowed to remain for a time and then withdrawn, for use in placing succeeding sets. The shafis on the Comstock timbered in this manner generally stand Plate Ti Seale THE COMSTOCK MINES. 105 very well and are maintained in good condition. When movements of the ground force any part of the work out of line, the disturbed sets may be taken out and replaced by new, or re-adjusted without difficulty; and, unless the ground is very bad, with a tendency to move in large masses, the perpen- dicular line of the shaft may be well preserved. When it becomes necessary to retimber a shaft or any considerable part of it, the work is usually carried on in one compartment or one-half of the shaft, while the remaining compartments are kept for use in the ordinary operations of the mine, Nearly all of the deep shafts of the Comstock mines have required more or less retimbering; this has been especially necessary in the deeper portions, near the vein, where the ground passed through is sometimes very heavy, consisting of massive clay, which exerts a tremendous pressure upon the timbers. To withstand this latter it is sometimes necessary to resort to methods still more substantial than that just described. A portion of the Yellow Jacket shaft, passing through uncommonly heavy ground, has been lately timbered with double sets, an outer set inclosing the ordinary single set, giving additional strength to the frame. The deep shafts of the Gould and Curry, Savage, and Chollar-Potosi mines have all encountered very bad ground in depth, involving large expense for the proper maintenance of the work. Several hundred feet in each of these shafts have been lately retimbered with 14-inch timbers, placed in sets not four feet apart as just described, but close together, making a solid casing 14 inches thick. In the Chollar-Potosi shaft the sill-pieces are made in two parts of unequal length, one long and one short piece, and in each succeeding set these pieces are so placed as to break joints, the joint occurring opposite one or the other of the timber partitions between the compartments. The corners of the frame are joined together simply with a mitred joint as shown in Fig. 1, Plate II; and the end pieces are placed transversely between them, in such manner that the end of each transverse piece bears with half its thickness against two adjacent sill-pieces. Figs. 4 and 5, on Plate II, illustrate this method of construction. Fig. 4 is a longitudinal section of a portion of the shaft, showing one end and two partitions. The sill-timbers are laid close together, one upon another; the end- 14 106 MINING INDUSTRY. timbers are placed in similar manner, but breaking joints with the sill-timbers, as shown in Fig. 5, which is an end view of the shaft. The partition-timbers are placed like the end-timbers, one upon another; but their ends are not let into the sill-timbers by any gain or mortice; the sills are dressed smoothly to receive the ends of the partition-timbers, which are then put in place without any framing. The cost of sinking these shafts varies with the depth and the character of the ground. The actual cost per foot is not easily ascertained, because, in most cases, the expense of sinking the shaft is involved, in the accounts, with other general expenses of the mine, so that an accurate and minute analysis of costs is almost impossible. The most carefully detailed statement concerning the costs of this kind of work are found in the books of the Gould and Curry Company. Their shaft is of the same general character as that described above. It is 24 feet long by 4 feet 8 inches wide, inside measurement. The average excavation is about 7 feet by 26. It is divided into four compart- ments and timbered, as generally indicated in the foregoing, with 12-inch timbers. From the available accounts of this work it appears that the cost, per foot, of sinking and timbering the shaft, at a constantly increasing depth, was as follows 2! Per foot. ARO AGEL MOM) SUMING e aroha sate a hchgiy ta ete «ote a Oke $70 21 200 Yeah miext tollowiOt: agarose a tobe ee eee arene 100 88 200 iéet ext dollowings=.225 252265220. hs oues onc ae eee Neyae Bi il SECS Tish SG LOY ITS wos: sicccca a sie leah cee a eet eee eee 189 50 Lee tec next followin) it P6606. eek te ete eee 224 99 Bo teet Mest, tollawink, 1m 18682606250 eis seers cen ee 342 65 120 Je6¢, costing, Orth averves < gota wa see ietc so wee ee 180 22 The shaft had+reached a depth of 1,187 feet on November 380, 1869, but the cost of sinking during that year is not published in the last report of the company. * The reader is reminded that these values are expressed in coin. THE COMSTOCK MINES. 107 The following statement shows the details of the cost of 187 feet sunk in 1867, and similar details for 879 feet, the depth attained on November 30, 1867: Cost of 187 feet | 879 feet; total sunk during depth attained 1867. Nov. 30, 1867. EEXCavatione @ Sinus (eles = ba ba @ ws a 8 oS? = $12, 865 00 $35, 189 50 ADatN aie ys rere pe Ee Cenc ees e cr anime 1,898 92 11,569 59 Jouve ye) ee a I Be Seon Set I, 163 94 6, 623 99 Framing and placing. the same - - - - - - = = = = 950 00 ) Bumpj\rods and laborthereon. - =< 2 - . = = = = & 367 31 | 0,405 88 POW Cervanc fUSn Oram cite iets eae a) Rinse ie | bene 541 25 832 25 Gandles ~-» 22 =.= Sy ede -5 -= heh Ue. 5 os 456 65 I, 510 95 Picksmandediallssseteys ve) 8 areise eee a bei ep = 716 05 275755 Carmen at surface and below - - - - - - - -- - 2,486 50 6, 016 50 Machine labor, engineers ; oil, and other material consumed in 20,626 64 46,904 52 pumping and hoisting; work in setting pumps including $5, 000 for resetting engine in 1867. 42,072 26 117,810 66 25Oreet, SUM INBOGs at m542°O5-5, =e cs uee tee Ss) ay ee fm || 2 ee ee eS 85,662 50 MotaliGOsi.of ae Lag teet ya eee ce a eee |= wa eese sate 203,473 16 Oran average cost, for that depth, of $180 22 per foot. Drirts or Tunnets—From the stations established in these shafts, drifis or tunnels are run for the purpose of reaching and extracting the ore, or for general exploration of the ground. These levels are usually 100 feet apart, vertically. In the Gould and Curry, where the deeper tunnels have been chiefly for exploring, they are 200 feet apart. The ground through which they pass is not very firm, being worked sometimes without the aid of powder. The deeper levels, however, have usually required blasting. They almost invariably need to be timbered, especially when the drift is designed for permanent use and not for the sole purpose of prospecting. Occasionally the character of the ground is very troublesome, and the most substantial methods of timbering prove inadequate to its support. 108 MINING INDUSTRY. The method employed in timbering drifts or tunnels of the Comstock mines is generally similar to that in use in other mining districts. The tim- ber, however, is all square, varying in size from 8 to 15 inches. Ordinary working drifts, such as those connecting the main shaft with the vein, are about 5 feet wide in the bottom, 4 feet wide in the top, and 7 feet high. They are usually timbered with vertical sets or frames, consisting of two posts, a cap and a sill, or spreader. In the Savage these posts are 7 feet 2 inches high, the cap 3 feet 9 inches, and the sill 4 feet 9 inches long. These sets are placed from 2 to 6 feet apart, according to the nature of the ground. 'They are covered on the outside with lagging, which is likewise varied accord- ing to the condition just named, consisting sometimes of 6-inch scantling, in pieces 5 or 6 feet long, and placed several inches apart; sometimes of 83-inch or 4-inch plank placed close together, inclosing both sides and top, and some- times the bottom. Lagging, consisting of light scantling, placed several inches apart, is often preferred in heavy, swelling ground, as the pressure breaks in the pieces of scantling before affecting the stronger timbers of the tunnel-sets; by picking down the intruding clay and relieving the pressure, the more expen- sive timbers are saved. String pieces, usually of square stuff, or 3 inches by 4 inches, are laid in the bottom on the sill-timbers and shod with flat iron 14 inches wide by 4-inch thick, to serve as track for the drift-cars, and a footway of 2-inch plank is laid between the rails. Figs. 3 and 4, on Plate IV, illustrate the method of framing the tunnel- sets. Fig. 4 is the ordinary form; Fig. 5 is a style of timbering im use in the lower level of the Gould and Curry, in passing through very heavy ground. Tn the cases illustrated, the lagging consists of plank placed closely together. The following statement, furnished from the books of the Gould and Curry, gives the details of expense in driving and timbering one of the tun- nels at the first station of their shaft, 225 feet below the surface, at mouth of shaft, and 1,465 feet in length: THE COMSTOCK MINES. 109 Cost of Tunneling in the Gould and Curry Mine, including Labor and ALaterials. (Length of tunnel, 1,465 feet, at a depth of 200 to 4oo feet below the surface.) Total cost. Per foot. BkCA VAL OU ees more ret he Vice ee ere, Fan TS. 632550. $10 87 MM DGite wae ies 8 we! ews Oars 3,120 60 rs Agebseloses BRR Se eee eee eee 549 49 a7 Spllingtapreye nya ay IS Se ee ee 807 26 55 Framing and placing timber .- - - - - - 967 15 66 Mrackiromand Screws -. = = = = = = = 322 93 22 PicksStand drillss = a= 2 So Se es es 562 75 39 Powderand iuseé <= °= 2 = % «= “= « 305 12 21 Candles. 4-82 “225 => = ae = ee 654 80 45 UNITED ORES) Wesai= SECO e oc whe! fess ict oo 337 O04 23 otal eee wee a cae Se eeate S 23,559 64 16 08 For 938 feet on the second station, at a depth of 625 feet, the cost per foot for same details as furnished in foregoing table was $16 84, the costs of excavation alone being $11 45. The above statements include nothing for costs of pumping or hoisting. These would of course vary considerably, according to the amount of other works in progress in the mine, among which the total costs of pumping and hoisting might be divided. On the fifth station, where the rock was much harder, the cost of excava- tion for 406 feet was $16 92 per foot. For details as given in foregoing, including excavation, $20 93 per foot; and adding the proportionate costs of pumping and hoisting, an aggregate per foot of $36. On the sixth station, for 297 feet, the cost per foot for excavation alone was $18 30, and for details, as stated in table, $22 94; and adding proportion- ate costs of pumping and hoisting we have an aggregate of 540 97, It should be observed that the pumping and hoisting costs are large because at that time but little other work was in progress in the mine. Sropinc or Breastinc.—The yein, or its ore-bearing portion, being reached by a drift or tunnel proceeding from the shaft, the work of extrac- tion begins and is almost invariably conducted by overhand stoping. The 110 MINING INDUSTRY. first desideratum, under ordinary circumstances, is to connect the new level or station with the one above it by a winze, usually passing through the ore-bearing ground, by which means a circulation of air is effected and the necessary ventilation obtained. The stoping then commences, the work progressing from the level of the new station upwards towards the station next above; the ore, as fast as it is removed from place, being thrown down to the track-level and transported from the stope to the shaft by means of the crift-cars. The character of the quartz composing these ore-bodies is generally soft, granular, and sometimes friable. It can generally be worked with a pick without the aid of powder, though blasting is sometimes required, The ore is very finely, almost imperceptibly, distributed throughout the mass and with a general uniformity. Formerly the workable ores of the large producing mines were divided into three classes. The first-class, forming now a very small proportion of the whole and yielding, on an average, between $300 and $400 per ton, usually occurring in bunches or pockets in the quartz, is, when so found, removed to the surface in sacks. The second-class ores were such as yielded from $75 to $150 per ton, while the third-class gave from $25 to $50 per ton. More recently, in some of the principal mines, these two classes, the second and third, have been worked together as one without any attempt at assortment. The average yield of these ores varies considerably in the differ- ent mines and will be referred to further on. In stoping the ground, there- fore, the entire mass of quartz is usually taken down and sent to mill without any classification as to quality, except in the case of first-class ores, when such occur. A rude assortment, however, for the purpose of distinguishing pay- rock from that which is too poor to send to the mill, is sometimes rendered necessary by the occurrence, within the mass of stoping ground, of belts of low-grade rock or bunches of barren quartz, which would otherwise be sent to the surface and worked at a useless cost. An experienced eye, aided, when necessary, by assays, can distinguish by inspection the pay-rock from that which is too poor to yield a profit. The latter then is assorted as well as pos- sible and retained underground for the purpose of filling up the exhausted chambers. This assortment, so far as observed, is not made by hand but by inspection of the ground before breaking, the pay-rock being picked down THE COMSTOCK MINES. ilak separately and sent to the surface, the poor being dumped into the old stopes that remain to be filled up. This is sometimes important, because the neces- sity of filling up the exhausted stopes is so great, on account of the unsettled character of the ground inclosing the ore-bodies, that when the necessary dead-work of the mine does not supply sufficient material, waste rock must be mined especially for that purpose. This may cost from $1 to $2 per ton, and, consequently, quartz that will not yield a profit exceeding the cost of obtaining waste-rock for filling is usually employed for that purpose. In the Savage mine, where this was observed, the intended minimum value of quartz sent to the surface at date of visit was stated at $23 per ton. By some others, however, ore of much lower grade, and too poor to pay under existing conditions, is taken out to surface and held in reserve, awaiting the time when it may be made available by cheaper methods or reduced prices. The material inclosing the ore-bodies, or “bonanzas,” is of a very unstable character and involves an immense cost in timbering. The great mass of vein-matter is composed of “horses” of country-rock, chiefly propylite, associ- ated with immense sheets of clay. The ore-bodies frequently have selvages of clay of considerable thickness. The whole is soft, yielding, and, owing to its clayey nature, swells on exposure to the air, exerting an enormous pressure. The extraction of such immense bodies of ore, and the opening of such exten- sive chambers with insufficient support of the country-rock or vein-matter, induces large movements of the surrounding masses. In early days, the immense stopes, though timbered at an extravagant cost of material and labor, were not filled with waste-roek but allowed to remain open. Great caves of ground were, of course, the consequence, extending, in some cases, from the surface to a great depth. It is now the custom to fill up exhausted stopes as soon as possible after the extraction of the quartz, but the necessary outlay for maintaining the mine in proper condition for work is still very large. The means of obtaining waste-rock, as observed in the Savage, where the supply from ‘he dead-work of the mine is insufficient, affords some indication of the character of the ground to be dealt with. For this purpose drifts, 30 or 40 feet long, are driven at convenient points into the country-rock, or, more properly speaking, the barren vein-matter. These drifts are securely timbered. At the end of any such drift a chamber is excavated, about 10 or 12 feet high 112 MINING INDUSTRY. and 20 or 30 feet in diameter, the roof, during excavation, being sustained by a few posts and plank. When the chamber has attained the desired dimen- sions these slight supports are removed. The roof and sides soon begin to swell and fall in, supplying the material which is wheeled out and dumped into the stopes. The loose material being removed from the chamber, the swelling and falling continues for an indefinite period, affording a supply for a long time. Srors Timpertnc.—The difficulty of sustaining ground of this nature, by any method of timbering, is not only in itself great, but is much increased by the large size of the chambers rendered vacant by the extraction of the bodies of ore. In the upper portions of the lode, worked several years ago, these cham- bers were much greater in extent than now. One in the Gould and Curry, 400 or 500 feet in depth and length, is said to have been over 80 feet wide in places, while several others had a width of 45 or 50 feet. At that time, more- over, nearly all of the quartz was removed in working and no provision made for filling the stopes with waste material to replace the ore extracted, leaving these immense spaces to be kept open by timbering, which, to be efficient, even for a time, needed to be of the most substantial sort. Methods ordinarily in use in veins of moderate width and in firm rock were found to be insufficient. To meet the necessities of the case a method of timbering was introduced, which is said to have been devised by Mr. Didesheimer, then of the Ophir mine which, though meeting with some opposition on account of its great cost, has since been generally adopted and is now used by all the mines on the lode. This consists in framing timbers together in rect tangular sets, each set being composed of a square base, placed horizontally, formed of four timbers, sills, and ecrosspieces, 4 to 6 feet long, framed together, surmounted by four posts, 6 to 7 feet high, at each corner, and capped by a frame-work similar to that of the base. These cap-pieces, forming the top of any set, are at the same time the sills or base of the next set above, the posts, as the sets rise one above the other in the stope, being generally placed in position directly over those below. This somewhat complicated system of timbering may also be described, in other terms, as a succession of horizontal floors, composed of timbers that are framed together in rectangular sets, 4 to 5 feet square, the floors being supported one above the other by posts 7 to 8 feet high. Fig. 2, on Plate IV, Fig. / . i Scale ; 360 +. am) Seale: 43 Ss ~ Q ~~ THE COMSTOCK MINES. 13 and the perspective view on Plate V, illustrate this method of timbering in stopes. Fig. 2, Plate IV, presents an elevation and a plan of a single set, showing the details of the framing; while the view on Plate V shows the general arrangement of a series of sets when put together in a stope of the mine. The timbers are usually of 12-inch stuff, square-hewn or sawed. They are framed with much care so that the various parts fit snugly together. Each piece, excepting, occasionally, the ground-sill or foundation-timber of a new series of floors, as explained further on, is cut and framed separately. This is sometimes done by hand, sometimes by machinery. ‘The latter is the case at the Savage, where a system of circular saws and planers, adjustable by set- screws, is so arranged that the piece of timber, held firmly by appliances which permit of its being easily revolved or moved to and fro, can be brought against them, the saws cutting the tenons of any desired dimensions and the planers cutting the shoulders, either square or beveled. In the Savage mine the posts of the sets, above described, are 7 feet 2 inches high, including the tenons. These latter, 8 inches square or 8 by 10, are 9 inches long on the upper end of post, and 2 inches long on the lower end; and as the caps and sills have $-inch shoulders cut for the admission of the ends of the posts, there remain 6 feet 3 inches in the clear between sills and caps of each set. The sills and caps, 3 feet 9 inches in the clear, also have short tenons on each end and shoulders cut to receive the ends of the posts and horizontal cross-pieces. In some cases this method of framing is varied to suit the varying condi- tions 6f the ground, so that, if the pressure is chiefly a vertical one, the tenons of the posts are cut as just described, bringing the ends of each post in direct contact: with its neighboring post, above and below, without introducing between them the tenons of the horizontal timbers, which would offer less resistance to a pressure at right angles to the fibre of the wood ; while if the pressure be lateral instead of vertical the tenons of the posts are made short and those of the horizontal timbers long, so that the latter may press directly against each other without the intervention of the post-teaons. The stoping is, as already observed, all carried on overhand; that is, a station, or level, is opened under the body of ore to be worked out and the 15 114 MINING INDUSTRY. progress of mining goes on from below upwards. In commencing the timber- ing of a stope, as for instance, at a new station or level, commonly called the “track-floor,” the ground-sills are usually laid parallel with, though sometimes at right angles to, the direction of the stope, or the walls enclosing the body of ore, and are frequently timbers of sufiicient length to serve as the sill for several sets. The end of a ground-sill is so framed, projecting a few inches beyond the last post, that the next adjoining sill-timber, to be laid as the stope progresses, may be spliced to the one already in position, the jomt being made under the post, as shown at sin Fig. 2, Plate 1V. The sills being laid and the cross-pieces adjusted in position, the posts are raised and the cap-timbers are fixed in their places, everything being fitted carefully and closely together. No pins, bolts, or keys are employed in the framework. The walls of the. chamber are sustained by a lagging of plank, inserted between the timber frame and the adjacent rock. This lagging consists of 3-inch or 4-inch plank, laid next the timbers and wedged, when necessary, by spiling. In time the lateral pressure of the ground holds everything firmly in place. After a set of timbers has thus been introduced and finally put in place, a floor of 38-inch planking is laid upon it, to serve as a footing for the workmen in the space above. From this comes the local term of “floor” to designate any particular place or point in the mine; the stations or levels, about 100 feet apart, being numbered from the surface down, first, second, third, and so forth, the floors being similarly numbered upward, between the several stations or track-floors. In working a stope thus the whole width of the workable ground in the body of ore is taken down at once and the timbering supplied in its place, the advancing breast of the stope being carried forward from wall to wall; in bodies of ordinary width this is from 10 to 20 or 25 feet, requiring, therefore, in cross-section from two to six sets of timber, like those just described. In commencing a stope on the level of a new station the ground-set or first floor is put iv, and as soon as sufficiently advanced in the direction of the stope the next set above is placed on the first of those below. Both then progress at about the same rate, the lower floor being kept sufficiently in advance of the upper to furnish platform and working room for the men above. As the work progresses, one set or floor is raised above the other until the Plate V. Mane \ DRAM Wat i Wh THE COMSTOCK MINES. 115 station above is reached, each floor being kept a little in advance of the one next above, as indicated in the drawings on Plates IV and V. When it becomes necessary, on account of the unsettled character of the ground, or for other reasons desirable, to extract the body of ore as speedily as possible, it is not uncommon to commence at the same time a floor on the level of the station and another floor halfway between the given station and the one above. For this purpose a winze is sunk from the upper station to the one below. From this winze the stopes are started, one on the lower station and one 50 feet higher. The lower series of floors, usually six or seven in number, rising one above the other, arrive at length directly under the 50-foot sill, as the lower floor of the upper series is termed. By this time the mass of timbering is held in place by lateral pressure with sufficient security to allow of introducing, without difheulty, the timbers to be placed directly under the 50-foot floor. Fig. 1, on Plate IV, is an illustration of this proceeding. The main body of stopes, visible in the drawing, have been started and carried on from the winze, W, that connects the upper with the lower level. The stoping on the extreme left has proceeded in similar man- ner from another winze, further to the left, the stopes advancing to meet each other. After the available ground has been exhausted the plank of the floors are removed for use elsewhere, and the vacant chamber filled with waste material. The expense of this work is, of course, very great, both for material and labor. The cost of the timber is from $30 to $40 per thousand feet, board measure, and the consumption is enormous, making the timbering one of the largest items of expense in the Comstock mines. In the Gould and Curry the costs of framing (by hand) the mining timbers just described were from 46 to 60 cents apiece for posts, 35 to 40 cents for caps, 25 to 30 cents for cross-pieces, or girths, and $1 20 to $1 50 for sills. Shaft-timbers cost, at same mine, framed by hand, about $20 per set; tunnel-timbers S1 to $1 50 per set for framing alone, not including any costs of placing under ground. In the Gould and Curry, in 1864, the supply of timber for use in the ‘These prices have been reduced since the completion of the Virginia and Truckee railroad. 116 mine cost $160,488 76, or nearly $2 50 per ton of ore produced. MINING INDUSTRY. for same purpose, were expended $14 In 1865, 7,382 92, or over $3 per ton. The following statement, prepared from the annual reports of the Savage Mining Company, shows the consumption and cost of timber used in their mine during three years: = ae Total cost of Year ending June 30— Timber. Lumber. Spiling. : materials. | : : ; i Feet, b. m Feet, b. mM. Pieces. } | 1867 1, 755, 956 499, 704 10, 307 $69, 982 59 1868 F 2,075, 507 544, 599 15,028 82,785 65 P | A 20 5 | 1869 - = - ; T, 352,710 363, 388 | 10, 057 51, 102 18 | | The cost as stated in the foregoing applies to the material alone, without including the labor of framing and putting in place. It covers the whole amount of timber and lumber used in the mine, in all the various departments of the work, and may be analyzed about as follows: Cost of Timber and Lumber consumed in the Savage Mine per ton of ore produced. ; 7 In extrac- | In prospect-| Inaccessory | In improve-| Total per During year ending June 30— : : . tion of ore. | ing work. work. ments. ton. Cents. Cents. Cents. Cents. Cents. 186 : : 63 12 13 10 98 1868. < : 51 13 24 06 94 1869 =<. 42 16 34 03 95 In the Hale and Norcross Mine the cost of timber during the past two or three years is shown by their reports to be about $1 per ton of ore pro- duced. Ore Exrraction.—The ore, as it is worked out or broken down by the miners in the stope, is thrown down to the track-level of the station below, either falling upon the floor of the drift or into a receiver or bin, whence it is loaded into the drift-car and carried to the shaft. ‘There the ear, containing Plate VI i] | LE a — sme : | THE COMSTOCK MINES. 1g BF its load either of ore or waste-rock, is placed upon the cage or platform in the shaft and raised to the surface, where it is run from the cage on to another track and so conveyed to the appropriate ore-bin or waste-dump, according to its character, and thus delivered of its load without any intermediate hand- ling. The car in general use in the Comstock mines is made of wood and has a capacity of about 1,600 or 1,800 pounds. That employed at the Savage may serve as an example. Fig. 1 on Plate VI presents an elevation of the side and front end of one of these cars. The box is made of plank 1§ to 2 inches thick, lmed with sheet-iron and strengthened with iron bands on the outside. It is 3 feet 10 inches long, 2 feet wide, and 2 feet 4 inches deep, inside measurement. The truck on which it is supported is a stout frame of four timbers, the two longitudinal pieces having their front ends beveled off to admit of the car being dumped. == Ibs 10, 796 ach) re a. & aoe, 134 44 134 44 Gandles’. “=.= “lbs 38, 500 4, 817 63 CRC w epee 2,576 30 972 05 9, 838 31 Wood - - - cds 3,456%| 19,491 43 | 13,729 20 | 15,655 70 64 50] 48,940 53 Charcoal - - Ibs 10, 228 I, 184 41 621 94 728 74 937 07 3,472 16 Stone coal - - Ibs 16, 925 24°77 I4 00 240 75 624 13 903 65 Powder. - - kgs 444 100 00 73°75 48 75 - 6 = 222 50 Tron = =. = = Ibs 78, 086 440 90 I5r 78 4, 629 10 2,080 96 208) 7A) zee eA ee A Rd EM RR tr 148 Prospecting Extracting Accessory | Improve- | Total cost Materials. Quantity. and dead ms ore work. ments. value, work. Steel. - - - Ibs 4, 854 533 40 62 65 I44 24 429 96 I, 169 65 Nails - lbs Ir; 713 239 44 82 87 223 30 796 82 I, 342 49 Bolts, nuts, &c., lbs 5,482! Gur2 An37 677 38 244 23 932 10 Pick handles No. 1, 518 308 52 114 18 748 54 5 45 576 69 Siedzes. Peau NO; oF 70 37. 28 03 12 37 IO 20 129 97 | Sledge handles No. 264 47 04 8 34 32 06 33 87 77 Saws . - . No. 32 38 61 27 08 48 80 Se II4 49 Wheelbarrows No. rE = 2 ae I2 50 x 7 I2 50 Brooms - - No. 56 1377 Io 83 20 03 at 44 13 Car wheels . No. 79 270 20 Ior 80 136 40 é 508 4o Car axles No. 10 18 00 9g 00 18 00 45 00 | Files No. 406 II2 17 47 03 97 07 9 61 265 88 Fuse: feet 4,598 142 67 87 90 74 50 ee 305 07 Rope Ibs 4, 221% 334 98 187 56 349 68 176 98 I, 049 20 anvas . yds 16614 E 26 21 49 35 - + 75 56 Lard oil gals 850 413 47 oar. 27 508 00 7 60 I, 460 34 Kerosene gals 849% 270 40 113 70 287 00 8 4o 679 50 Paraffine gals 55 35 25 a -% 26 65 $ 61 go Tallow . - - Ibs 7,598 296 94 216 59 398 47 = gI2 00 Lamp chimneys No. 185 Il 19 8 75 I2 40 = Bo 34 Lamp wick No. 74 Z s 3 04 < 3 04 Water buckets No. 83 26 89 7 15 19 19 Taye 54 95 | Gas pipe - . feet 997 a ae 220 32 329 53 a ae 549 85 Leather - lbs 215 * 7. = 64 60 19g 52 84 12 Shovels . . . No. 435 227 590 98 75 176 25 4I 25 543 75 AXES: (c No. 62 47 74 23 89 45 50 : 117 13 Axe handles No. 27 5 20 2 I 20 4 40 10 80 Gum packing - lbs 6984 9 00 3 00 Teed 639 29 686 54 Whitelead . . Ibs 187 = oe : = 38 oO 38 00 Borax . =< = Ibs 192 23 16 4 75 20 52 2, Sues 48 43 Nay- - - ~ Ibs 34, 202 - oon 949 38 - + - 949 38 Barley .- - - Ibs 5, 886 a ante ao 289 90 ae ers 289 90 Bran. = = = Ibs 4, 813 = 3 « 2c 244 31 ees 244 31 Oats. = = = Ibs II, 255 = Soe 565 53 ee 565 53 Wiateteve (2 0. iwee == 2,465 00 é : 2,465 00 S gee 4,930 00 Whiting. . . Ibs 196 8 25 3 50 4 65 S itsiseee 16 40 Sundries. = Jo). as ee 5, 45 I, 863 18 982 39 | 13,508 93 15,893 17 | 32,247 67 79, 133 89 31,551 47 | 66,530 II 28, 184 40 | 205,429 87 MINING INDUSTRY. Quantity and Cost of Materials consumed at the Savage Mine, &c.—Continued. Under the head of “Sundries” are comprised iron pipe, galvanized pipe, screws, asphaltum, stcel wire rope, copper wire, steam drum, spirit level, tar, turpentine, paints and oils, varnish, belting, pump- columns, foundery work, stone work, cement, electric signal apparatus, appurtenances to machinery, &c. THE COMSTOCK MINES. Quantity and Cost of Materials consumed at the Savage Mine 149 during the year ending Fuie 30, 1869. Materials. chirab creas =e cer Lumber =.) 2) =) feet Spiling . .= = pts Shingles - - No. Candles Se LDS Wood - - - cds Charcoal . ~- bush Stone coal - - Ibs Powder- - - kgs Powder, (Giant,) Ibs IGT eee 4k a DS Steels, t= = = Ibs Nails . - - Ibs Bolts, nuts, &c., Ibs Pick handles - No. Sledges. - - No. Sledge handles No. Shovels. - - No. Axes) =. = eNO: Saws -. - - No. Wheelbarrows! No. Brooms. - - No. @arst 2 == 42 (No; Biles «. . = No; Fuse- - - ~ feet Rope, (Manilla,) Ibs Canvas. . . yds Castor oil - -. gals Lard oil - - gals Paraffine oil - gals Kerosene . ~- gals Tallow - - - lbs Lamp chimneys No. Lamp wicks - - .~ Water buckets No. Gas pipe - ~- feet eatheraem= wacamelS White lead - - Ibs ; Prospecting . Extracting Accessory Quantity. and dead a ore. work. work. I, 352, 716 | $18,203 45 | $5,866 x12 | $13, 312 18 363, 388 4,147 50 2,230 29 3,531 66 10, 057 34 60 395 20 I, 581 60 2, 250 oN See ne 33, 440 2,924 07 I, 466 49 I, 881 82 3,333 | 21,247 50 | 11,394 00 | I4,154 50 8, 758 I,OI2 20 613 20 958 65 13, 628 32 91 35 95 382 36 108 , } 259 06 179 80 62 60 vi 19, 490 239 Io 83 43 I, 051 56 3, 903 451 29 79 55 323 56 7, 288 229 II 87 99 246 24 808 275 Io 60 II3 50 I, 587 304 97 ve Ye 185 07 39 62 25 25 75 59 00 255 50 30 14 65 35 70 312 199 21 2 34 145 I0 79 35 50 18 73 69 13 29 37 20 4 94 48 92 24 67 15 50 275 27 10 12 387 96 58 29 62 I02 75 9, 550 58 00 25 00 I5 50 2, 285 197 50 51 81 261 93 309 25 00 25 I0 DLy Yr I55 IIo 38 61 87 134 64 357 270 2 68 28 235 38 go 53 84 7 25 42 95 666 176 97 53 74 179 64 5,547 254 IL 182 I0 250 87 nr 9 94 6 51 7 52 cued 2 00 O4 83 42 18 60 2 10 ro 86 271 at et ee TIT 63 460 a veti2e 41 78 100 47 Improve- ments. Oo oH - w Total cost value. $38, 189 14 10, gOI 64 40 18 50 6,279 46, 824 2, OIL 3, 065 534 13 501 150 Quantity and Cost of Materials consumed at the Savage Mine, &c.—Continued. MINING INDUSTRY. ; Prospecting ; Extracting Accessory | Improve- Total cost Materials. Quantity. Mier and dead aes se ee work. Borax, 5= = lbs 123 20 35 7 12 I6 00 a 43 47 Hay =. «= “= lbs 20, 103 ue ee ars ery oe 450 31 « 22 450 31 Barley - - - Ibs 705 a ae = a) 40 54 =. ee 40 54 Bran. = = = bs 4, 698 =. oe. Serer 193 97 2 193 97 Oat = - = = Ibs 8,153 S é =e ire 405 86 oS 405 86 Water - - - : : z 2,510 00 A oo 8 2,510 00 cost 5,020 00 Sundries - - ee II4 63 118 11 8, 430 86 6,479 65 15,143 25 | | 53,406 61 23,394 31 51, 81I 57 9,426 00 | 138,038 49 1 Wheelbarrows and cars manufactured at the mine and cost included in the items of lumber, iron, and labor. Cost value of materials on hand, July 1, 1868 - - - - - $21,340 OL 23,527 67 Under the head of “Sundries” are comprised foundery work, repairs to boilers, pump fixtures, steam Cost value of materials on hand, July 1, 1869 .- - - - feed-pump, valves, Babbit-metal, screws, gas pipe fixtures, packing, cotton waste, sulphate of copper and of zinc, wire, hose and hose-pipes, gum coats and gum boots, tar, belting, paints and oils, jack screws, circular saws, hardware, &c. Costs or Mixrya.—The cost, per ton, of mining ore in the mines of the Comstock lode may be seen by the following statements, prepared from the reports of some of the leading companies, whose accounts furnish the desired data in the most available form. The first statement presents, in one table, the mining costs of several mines during three or four years. Thesé figures include nothing for milling or metallurgical treatment; they apply simply to actual mining costs or ex- penses incidental to carrying on the business. In this respect it must be observed that the apparently large differences between the figures of the sev- eral companies, as, for instance, the Savage and the Imperial, are chiefly due to the difference in methods of presenting the accounts, some of them includ- ing in their statement of costs nothing more than the actual expense of mining and extracting the ore in question, or of such dead work as actually applies to that part of the business, while others comprise the additional items of pros- pecting, opening new ground, repairs, improvements, office labor, and all the THE COMSTOCK MINES. 151 incidental expenses of carrying on the entire operations of the mime. It is ob- vious that if the expense of all this work, generally very large, be applied to the quantity of ore raised from the productive portion of the mine, the costs, per ton, will appear much larger than they would if only the actual expense of extraction were considered. Thus in the tabular statement here presented the lowest cost of mining, per ton, in the Savage mine, is given at 57 21; while in the Imperial the cost in one year is as low as $3 54, for the Holmes mine, and is generally less than $5. In the case of the Savage every item of expense that may reasonably be charged to the business of mining is included in the account, whereas in the Imperial the given figures apply only to work performed in reaching and extracting the quantity of ore on which the calculation is based, imcluding nothing of the cost of sinking the new shaft, unproductive work or other incidental expenses. If the ac- counts of the several mines were prepared on exactly the same basis, the differences in the figures would be but little. Another cause of difference in the cost of mining in the several mines, or between various years of the same mine, is to be found in the varying relation existing between the amount of unproductive work performed and the quantity of ore extracted. Thus in the Savage mine the costs of extrac- tion, per ton, in the year ending June 30, 1866, are stated at 518 06; while in the two succeeding years the average is about 57 55, the difference being mainly due to the fact that in 1866 the outlay for dead work, improvements, and equipment was large, while the quantity of ore extracted in that year was but little over one-third of the quantity produced in either of the two years following; the proportionate expense of this work, per ton, of course, increasing as the quantity decreases. It is difficult therefore to give a correct idea of mining costs except by minutely analyzed accounts, and these are given for some of the companies, with more or less detail, in the statements which follow. 152 MINING INDUSTRY. Statement showing Mining Costs, per ton of ore extracted, in several mines of the Comstock lode. During fiscal year ending in— Mine, 1860. 1867. 1868. 1869. Per ton. Per ton. Peritons Per ton. Gouldand'Curry <9. =< = = = = - $7 86 $11 35 ats $7 29 Sava wis ay warns ee es ens noe =) 0e 18 06 7 91 $7 21 8 go Hale and Norcross. - - - - - = = = 9g 03 Chollar-Potosi == 2 = = s=7 se ie = 5 99 4 48 4 24 4 30 Chollar-Potosi, including prospecting . - et 6 39 6 93 7 94 Imperial, (Holmes mine). - - - - - 3 63 3 54 4 74 Imperial, (Alta mine) - - - - - 5 27 4 36 4 96 4 73 Imperial, additional cost in sinking new shatt I 34 I 56 2 36 Crown Pomt =. 2 = “S. -f es) 4.p oer ts 8 97 7 50 g 85 9g 80 Tentacle aggre cee eee =a ee Q 22 g 81 8 67 The following statement shows the detailed costs of mining, per ton of ore extracted, in the Gould and Curry mine during two years. Year ending Nov. 30, 1866. | Year ending Nov. 30, 1867. Tons of ore produced - . - - - 62, 425 a 24, 940 Amount. Per ton. Amount. Per ton. Gost of officials 2 - 9. : . . - $13, 254 00 $o 21 $4, 010 00 $o 16 Ixtracting Ores) <9) - aaa = = 193, $22 72 3 10 106, 625 25 4 27% Prospecting and dead work . . - - 131,697 09 211 121,097 60 4 8534 Accessory work = = =< = = = & 113, 846 46 I 82 35,865 87 I 4334 Improvements = <= 2/2 = = 38,502 25 o 62 15,431 S1 62 Total cost of mining . .- . . - 491,122 52 7 86 283,031 53 II 35 Additional general expenses in Virginia ee eae 92 See er 2 13 City and San Francisco. 8 78 13 48 The following is a similar statement, prepared from the reports of the Savage Mining Company, showing the detailed costs, per ton, of production ; to which are added the cost of reduction of the ore, the average yield, and the profit of each ton during three years. Tons of ore produced - Cost of officials - - - - Extractingore - - - - Accessory work - - - Improvements - - -. - Total costs of mining INCIDENTAL, Assaying ore - Assaying bullion Surveying - - - - - Office expenses - - - Exchange - - - - - Horse-keeping - - - - Legal expenses - - - PLAXES ied oS a Sundries - - - - - - Cost of production - - Cost of reduction - - Average yield of all ore Average profit per ton THE COMSTOCK MINES. 153 Prospecting and dead work - reduc Year ending July 1, | Year ending July 1, Year ending Jul 869. 1867. 1868. ka a ead 79) 724 87,342 53954 g g ea in Amount. ca Amount. a Amount. = rz vy vo oy i) my iv) my Oy $23,700 33 | $033 | $24,575 00] $o28|- - - - | $22,123 83|- - -]| $0 4x eee Ee, , Labor -| 153,675 75 | $285 |- - - SE 277 | ?351°t7 93 | 2 7° |) Materials 53,406 61 99 | 3 84 \ Labor - 34,838 00 Ot =e 695154 39 OF 69,475 88 79 |’) Materials 23,394 31 3 z 08 Labor - 79,398 62 r47|- = - 88,836 15 I 25 149,607 57 I 71 ) Materials iouaper ae fe 3d || Labor - 7,105 50 w3/- - - Sanaa a? T 33 49,361 59 57 |) Materials 9,426 00 17 30 Labor - 297,141 70 Sst la = = 471,191 32 6 66 528,837 07 6 05 eae 137,141 78 oe Stas 5,096 50 07 7,548 25 tos) an 31528 19 |- - - 07 15,244 52 22 23,551 93 26|- - == 8,740 82 |}- - - 17 1,807 75 02 2,330 00 ob}--- - T8s0%00 |ha= = 03 31369 64 05 1,837 77 o|--- - 1,157 60 |}- - - 02 7,128 15 Ir 7,532 58 eo9g/--- - 3:254 70|- - - 06 2,062 65 03 2,354 50 O30) o> =. 2,843 15 |- - - 05 21,856 98 3r 7,817 00 09) | Hea She Eee oF 20,937 52 29 40, 342 61 AG | is ee 19,486; 73) i= = = 36 10, 886 49 15 7,768 78 o9}--- - 3,017 19 |- - - 05 559, 58r 52 791 629,920 49 ger{/-- - - 480,361 86 |- - -| 890 974433 23 | 14 04 | 1,162,957 08 | 13 74] - - - - 678,088 52 |- - -| 12 22 1,534,014 75] 2x gs | 1,792,877 57 | 2095 | - - ~ ~ | 11158,45038|- - -| 21 12 ed = = = =| grog |= = = = -| 4084 |= = = =| = = - = al= = =) 34:87 eine Gor erent IG OQ) foam ail) EQ eG) | = ee es [mien Sat mS aS The Hale and Norcross Mining Company’s report for the year ending March, 1867, furnishes the following statement of costs of mining 29,401 tons of ore: Per ton. Manaserall cost. .2ee-:<2ces2-- ee Bey es ne Seen eas SO 31.7 LOIStINe WO WON ares 22k anc mince cen Seewak eta ee tse Pee Oe Byort| Wine MGOSi dee oee ete aee career anew wees nrasee ge Reece ‘ 4 79.0 Improvement cost he Sete seta tataxe valores a ieianeta eens i nieieis deine i= =i Pe ee TNs 65.9 Relative expense, (weighing, sampling, and contingent) .....-.... 92.9 9 08.2 154 MINING INDUSTRY. The following are analytical statements of the disbursements of the same company during two years, showing the sums expended for the several items, the percentage of each, and the amount per ton: Number tons produced- - - - For accounts of previous year. - SribyiCee Te Se ese eee Mine account, including labor and materials employed in the mine. Wirewood! <3. 24. “= as) ee Working ores’ 5. = oa = Realestate. < 2° 2s .<. Se Tases = She, oe ee Freight! 2 °= 2s 2.7 tus Sinking Fair shaft - .- - . In advance to superintendent .- Law expenses and fees - WGK abhelsia\= ee Wee es Me Seen NSSOV SS! agit iat See Gee oy ee Miscellaneous expenses - . ~ Dividend sre: mes ee va Cashonihand =. i a2 «= Year ending March, 1867. Year ending March, 1868. 29, 401 Z 25,432 Sums. Per ton. Percent. Sums. Per ton. Percent. $6,092 68 | $o 21 -44 9, 980 76 0 34 93 $9,000 00 | $0 35 .78 190, 187 36 6 47 13.86 208, 304 92 8 I9 | 18.14 30, 784 gI I 05 2.24 | Included in mjine account. 408, 366 44 13 89 | 29.74 360, 105 63 14 16) 31335 5,727 04 20 .42 584 21 02 708 II, 113 90 8 .8r 12,404 04 49 I.08 10,575 64 36 77 TI 349 02 44 -99 Ir, 560 65 4o 84 212 684 85 8 36] 18.52 6,442 93 22 -47 3,734 25 15 32 33,997 30 I 15 2.47 10,015 83 40 Bisiy 6,266 42 22 -46 10,424 17 | 35 | 76 7,912 06 31 70 8,168 8o a7 .60 12,245 87 48 I.07 490, 000 00 16 66 | 35.69 300, 000 00 II 80 | 26.12 133, 288 99 4 53 9.70 183 93 OI 202 372/077" 00: 46 70 | 100, I, 148,524 61 45 16 | Ioo, The cost of mining labor, per ton of ore extracted, is stated in later reports at 59 01,5, for year ending February, 1869; and at $5 13,5 for year ending February, 1870. The following are analyzed statements of mining costs in the Chollar- Potosi mine: THE COMSTOCK MINES. 155 Statement of Mining Costs, including nothing for Milling, of the Chollar-Potosi mine during the year ending May 31, 1868. , Sinking new shaft, re- ’ Extracting ore. ; ’ Prospecting. pairs, and pumping. Tons of ore produced by company, 70,340. | | Sums. Perton,. Sums. Perton. Sums. Perton. Wit esmeme we oes ene nm 2 $205,255 22 | $2 92 $38, 238 oo ae is $27,024 25 Miscellaneous supplies - - 21,079 QI 30 105397770) | a: fee 5,583 94 Timber and lumber - - - 58,189 70 83 II, 080 25 ae 3,984 82 Firewood - - . - - - 9,248 00 13 3,555 00 aa 2,962 50 Glee © oe ee Se eee 1,513 25 02 1; 730/00: |) = 597 75 Waters. ue Toi m2 s I, 882 50 0214 I, 200 00 awe 620 00 Orevassays © 9s. SS <= 2) os Se 1,035 68 2% 2,391 52 Goals: 2. f23 Ges Wea oe pe 1,080 00 2% 2,227 83 Candles - - - - - - - - - - -} 3,416 92 71% I, 320 55 POnlsandital low ses fce come cee eae oe oa ee ae eee 1,839 34 _ Wood ee et es a, ae | en Ss | 22,675 75 | Water coc, Spc, gt eiGleeGh Sirsa, oan on | es |e 2,590 00 | SS \ 193,159 20 | 44 30 119, 874 95 $2 67 Statement, &c., continued. Sums. Per ton. Extracting ore,as per foregoing - =< - =< - « =». =« = «= = «| $193,159 20) $4 30 iNew, shatt + + | 123,616 | 116, 489 - - > |e as 3,852,631 12 | 610,000 | 982,000 | | | | a Paid for labor per ton of ore extracted. Crottar-Porost—This mine adjoins the Hale and Norcross on the south. The length of the claim belonging to this company is stated at 1,434 feet. The number of shares in the company is 28,000. The present organization is the result of the consolidation of two or more claims, the chief of which were originally known as the Chollar and the Potosi. The Chollar was orig- inally located as a square claim on the surface, measuring about 1,400 feet along the-length of the lode, by about 400 feet in width; the Potosi located a similar claim, of equal length, parallel to and lying east of the Chollar. At that time the structure of the vein, the form and dip of the ore-bodies, and their relations to each other were not at all understood. The body of ore discovered on the Potosi claim was found to be dipping to the west, and by sinking upon it the company passed beyond the boundary, determined by the square surface claim, into the ground of the Chollar. A suit was instituted 176 MINING INDUSTRY. and gained by the latter company to restrain the Potosi from encroaching upon the ground of the Chollar. In process of further developments the ore- bodies took an easterly pitch, when the Chollar, im its turn, began to en- croach upon the Potosi. This gave rise to further litigation, in which a large amount of money was expended, with the final result of a consolidation of interests of the two companies, forming the present Chollar-Potosi. The two companies previous to consolidation found large and valuable bodies of ore in the upper portion of the lode, from which a large amount of bullion was produced. The ground was worked by means of shafts on each claim, and adits driven in from surface, cutting the vein at a depth of 200 or 300 feet. The productive bodies of quartz, however, did not extend in depth below 450 or 500 feet. Since the consolidation of the two companies, the Chollar-Potosi have extracted from these upper levels a large amount of ore, much of it being of alow grade. This work is still in progress, and during 1869 was being carried on with profit. Meantime, while the productive portion of the mine is confined to the upper levels, the company have been steadily engaged in prospecting their ground in depth by means of a large shaft, which descends vertically 913 feet, at which depth the west wall of the lode is encountered, and thence the shaft inclines at an angle of 45°, following nearly the inclination of the vein. Vhe depth attained in the summer of 1869 was 1,240 feet, measured verti- cally. No ore-bodies have yet been developed by this work below the levels reached by the operations of the old mine. The shaft is of the same general character as those already mentioned. The method of timbering has been already shown. ‘The hoisting and pump- ing works that were formerly established at this shaft were provided on an ample scale for extended operations; but the inclosing buildings were de- stroyed by fire in the summer of 1869. The damage was being repaired at the date of the writer’s visit, but the hoisting machinery had not then been replaced. The following tabular statement shows the extent of the company’s operations during three years, according to the data furnished in their pub- lished reports. The ore statements for years previous to May 31, 1866, are THE COMSTOCK MINES. 177 wanting; but the table shows the sum total of the receipts from ore, the assessments and dividends, from the date of organization to May 31, 1869. Statement showing the operations of the Chollar-Potosi Mining Company during three years ending May 31, 1869. y ' J ke n | Po rs) 5 iS) 3 oO ay = eS a a Koo oes Ge e|| Vey eee Ibis ci eho lc a Bog Bue | = ep Suo|2s , ag é 2 cs) n BS | Ean =| Came! S . ares WEROY | ease sd 3 3 g a o 8 63 |] Ges 9 o + 29 gs 4) B=] ey AS. a 8 eH) a, 2 5 5 | a s os Ae a a a ra) way Hy CaN o ie 5 5 s) 8 > 3s a = a & | & iS) <4 4” < fa) _ | | : 2 | > Previous to May 31, 1866 - - - | - - -|- - - -- -- - -| $917,981 56 | $280, 000 . . 2 | n 9 s During year ending May 31, 1867 | 57,799 | 57,799 | $6 39 | $14 97 | $25 73 | 1,348,323 13 | - - - | $70,000 ; ‘ 38) | | During year ending May 31, 1868 | 70,33: | 477,957 693 | 1475 | 24 14 | 1,905,421 49 | 182,000] 350,000 During year ending May 31, 1869 44,900 | 246,867 794] 1315] 23 70 1,185,141 92 - - -| €42,000 | | A | | ay Total - - ------ - | 173,030 | 182, 623 - - - - - - | 5,350, 868 10 | 462,000 | ¢ 462,000 | | | | a. This cost includes dead work and prospecting in new shaft. See pages 155 and 156. &. Including some ore taken out by contractors on tribute. c. Later in same year, 1869, six other dividends, amounting to $52,000, or $9 per share, were paid to stockholders. The Chollar-Potosi is the southernmost of the mines situated on the Virginia group of bonanzas. Beyond it, ina southerly direction, the ground becomes poor and continues so for a distance of 1,000 or 1,500 feet. Within these limits is situated the claim of the Bullion company, the southern neigh- bor of the Chollar-Potosi. This mine has been most persistently explored without any very encouraging result. The claim is 940 feet in length, meas- ured on the course of the lode. A shaft has been sunk upon it, vertically, until reaching the west wall at a depth of about 809 feet, and then inclined with the vein several hundred feet further, so that the whole vertical depth of the explorations is about 1,200 or 1,300 feet. Prospecting drifts have been made at successive levels, developing large bodies of quartz, but gen- erally too poor to pay for extraction. During the several years that it has been worked the product.has been practically nothing; according to the statements of the treasurer of the company it does not exceed 51,000. In 1868 the assessments were $100,000; in 1869 they were $67,500 ; and the total amount of assessments is more than $1,090,000. Operations were still in progress in the summer of 1869; but they have recently been suspended, according to newspaper reports. 23 178 MINING. INDUSTRY. ImpertAL and Emprre.—The next occurrence of rich ore-bodies begins not far south of the Bullion mine, and is known as the Gold Hill group. Within a length of 1,000 feet are situated some 15 or 20 claims, most of them yery short, from which their owners extracted, in early days, a very large amount of bullion. From some claims, not exeeeding 20 or 30 feet in length, one of them being only 10 feet long, a very large monthly revenue was obtained. An accurate record of this production is not in the writer's possession, and probably does not exist. Chief among the mines of this group are the Imperial and Empire, of whose operations a statement will be found further on. Both of these companies, although working very short claims, have been very productive and profitable, having disbursed large divi- dends, without having, until recently, called assessments. The Alpha, Chal- lenge, Confidence, and others of the group, have also been prominent in times past. The productive ore-bodies of these mines, and those of their neighbors belonging to the same group, all occurred within 500 or 600 feet of the sur- face. The richest of them were worked out long ago. During the past two or three years the old ground has been reworked; deposits of ore that were too poor to pay in former times, have been mined, and thus the production has been sustained, though on a much diminished and less profitable scale. The chief hope for the future of all the mines of this group is based on the work of exploration, now being carried on in depth by a vertical shaft, sunk jointly by the Imperial and Empire, but also designed for the develop- ment of the neighboring claims. This shaft, located like the deep shafts of the other large mines, in the eastern country-rock, has reached a depth of over 1,100 feet, and has cut the vein at about that distance from the surface. No important developments of ore have yet been made by this work, but it is still vigorously prosecuted. The shaft is similar in kind to those already described. It has four compartments. It is 28 feet 4 inches long by 5 feet wide, for 600 feet of depth, where the size is contracted to 18 feet of length, divided into three compartments. The machinery for pumping and _ hoisting is liberally provided. There are two hoisting engines, having cylinders 16 inches in diameter and 86 inches stroke. These both drive one shaft, on THE COMSTOCK MINES. 179 which the winding reels are operated by means of clutches and brakes, as already described. The water is removed from the mine by means of vessels, raised and lowered like the cages, and operated by the same machinery. A pumping engine is provided, but the pumps are not yet in place. There are four tubular boilers, 16 feet long and 52 inches in diameter. The whole of this establishment is inclosed in a large building, with which are connected carpenter and smith shops for all necessary work of construc- tion and repair. The total cost of sinking this shaft, and establishing the surface works appertaining to it, and conducting the explorations in connec- tion with the same, amounts already, according to the reports of the two companies, to about $400,000. The following statements present a summary of the operations of the two companies, Imperial and Empire. Statement showing the operations of the Imperial Mining Company from date of their organization to May 31 1869. : a. a. 8 3 3 3 Bp 5 be = oo zi i] hy = wt a = o Oo oS on a q.2 = g & 3 8 = 5% : ° Sie Be ae ae 2 F a vom) Bows al os 8 an o od og r3) no = % £5 £5 Ep tes 5 5 ° as as a ae DB °° g 25 | £8 3 8 2 = So = 2 = a > oF a = = lees as) < ia < a | | (Premousitamiayiars thos smee Moreh yee |is Ben ee ee lle cg $640, 369 43 $50,000 00 | $67, 500 00 During year ending May 31, 1865 . 28, 237 $5 37| $xz 50 $30 26 B54 O30 50: \ are “sz. s 220, 000 00 | During year ending May 31, 1866 - 35, 182 527 Io 00 29 97 I3019;275 92'|'5 28s. = @ 240,000 00 During year ending May 31, 1867 - 40, 878 4 36 g 00 25 93 L060, 0540101]. 92° se 396,000 00 | During year ending May 31, 1868 . 41, 234 4 96 9 66 2I 75 897; z08'02:)=> 42) 3 2. 120, 000 00 During year ending May 31, 1869 . 455172 473 | 7 8x 73 35 603,146 42 100,000 00 24,000 00 | 189,724] - - -|- - - | - - - | 85,074,584 45 | ¢150,000 00 | 1,067,500 00 a. Costs of mining are only approximately stated. They do not include the outlay for new shaft, prospecting,&c. oF a = a a ich oS E 128, 000 330, 455 544, 000 gog, 316 The following table presents a summary of the statements given in this review : Summary of foregoing tables, showing the value of the Ore Products, the amount of Assessments, and Dividends of leading companies working on the Comstock lode. Pera a Tannen Assessments. | Dividends. worked and sold. Ophir...) 2s. = as $5, 240, 000 00 $672, 000 $1,394,400 | To January 1, 1870. Gould and Curry . . 14, 875,935 24 358, 068 3,778,800 | To November 30, 1869. DAVATE! Gs. Sos soe 13, 275, 360 43 188, 000 , 208, 000 To July 1, 1869. Hale and Norcross. - 6 3,852,631 12 610, 000 982,000 | To February 1, 1870. Chollar-Potosi - - - 5,356, 868 Io 462, 000 462,000 | To May 31, 1869. Akeayorssctlh ee ee 5,074,584 45 150, 000 1,067,500 | To May 31, 1869. EMmpitee es) eee) eae 2, 629, 339 94 30, 000 489,600 | To December 1, 1869. Yellow Jacketa. . . 10, 583,470 30 I, 350, 000 1,740,000 | To January 1, 1870. Kentick) ss 62 3, 641,062 00 40, 000 I,142,000 | To November 1, 1869. Crown Point - 3, 861, 931 00 305, 370 858,000 | To May 1, 1869. Belcher = 20 I, 570, 370 00 668, 720 421,200 | To December 31, 1869. Overman. - - 909, 316 00 544, 000 To December 31, 1869. ¢70, 871,138 58 5,378, 158 16, 543, 500 a Partially estimated. ‘Commercial Herald and Market Review. 6 The product of this mine previous to March, 1866, is not included. cThe products of the Mexican mine and of many of the small but very rich claims of Gold Hill are not included here ; for a more complete statement of the bullion product of the lode see pages 189 and 190. 188 MINING INDUSTRY. OurstpE Mines.—There are a number of mines in the Washoe region that, being located on other veins than the Comstock, are generally classed as “outside.” They are on various ledges that have from time to time been dis- covered, partly prospected and developed, and, in most cases, again abandoned or neglected on account of the low grade of ore produced and the high cost of working. Among them, however, are several that have been persistently worked, and of these a still smaller number have established a claim to an im- portant place in the list of successful and profitable mining enterprises. ‘The Occidental is one of the most prominent of this class, located on a large ledge, between one and two miles east of the Comstock, nearly parallel to the last- named vein in trend, and dipping also to the eastward at an angle of about 45°. This vein is a mass of limestone and quartz from 20 to 40 feet wide. The silver-bearing mineral, resembling in most respects that of the Comstock, is associated with the calcareous and silicious gangue, and thus far the lime- stone has been the richer of the two. The pay-seam is from 6 to 12 feet wide, The mine is worked for over 1,200 feet in length and 300 or 400 feet deep. It is opened and developed entirely by tunnels, and a lower tunnel is now in course of being driven, which, when completed, will be 1,600 feet long, cut- ting the lode at a depth of 800 feet. The company own a mill near Dayton, and are now building a new and large one near the mine. The yield of the ore is stated at $12 to 516 per ton. In the summer of 1869 the mine was producing about 25 tons per day. ‘The writer is not able to give any accurate statements concerning the total production of this mine. The company has is paid one dividend of $20,000; and, if the writer be correctly informed, has never levied any assessment. Further north, and probably the same vein under a different name, is the Monte Christo lode, crossing Six-Mile Canon near the Gould and Curry Mill. This lode is developed to a much less extent. The Lady Bryan, one of the most important and best developed of the outside mines, lies further east, probably on a different lode, in the so-called Flowery District. This mine has been worked several years with varying snecess ; once entirely abandoned, the machinery was removed and the prop- sold tor a trifling sum; then revived by cther parties and now working erty sold for a trifling tl | by ether part 1 now working THE COMSTOCK MINES. 189 vigorously again with fair prospects. The lode strikes north 30° east, true, and dips easterly 45° to 55°. The croppings are very large and the vein consists chiefly of quartz. The surface works yielded a large amount of ore of low grade. The underground developments had reached a depth of about 200 feet in October, 1869. A shaft, having three compartments, was in prog- ress. The mine is provided with excellent hoisting and pumping works; and a new 10-stamp mill was built last year close by the shaft. The mill is furnished with four McCone pans and two large settlers. It can crush and amalgamate about 20 tons per day. The rock is said to yield $30 per ton. The assessments of this company amounted to $15,000 in 1866; and in 1868 to $150,000. Accounts of its production are not in the writer's possession. Among other promising mines is the Twin, or, as it is more recently called, the Hope, working ona narrow gold-bearing vein near Silver City. It is said that this vein, although worked on a limited scale, has yielded fair profits to its owners. A new mill, containing stamps that are to be driven by the direct action of steam upon each stamp-stem, is in process of construction. Below Silver City, on the road to Carson, is the Spring Valley district, the scene of much exploration several years ago, and containing some ledges to whose prospective value the railroad may add largely. Butyion Propucr or THE Comsrock.—The total yield of the Com- stock lode from the date of its discovery in 1859, to December 81, 1869, is probably not less than $100,000,000. In 1859 and 1860, little was ex- ported, and that chiefly in the form of rich ores that were sent to Europe. In 1862 and 1863, the bullion production increased rapidly, reaching its maximum rate in 1864 and 1865. The following statement, prepared chiefly from data furnished by the Commercial Herald and Market Review, cf San Francisco, shows the annual production for nine years. As this statement is chiefly based upon the products of prominent mines, whose operations are well known, it is safe to assume that enough more has been obtained from sources not included in this account to swell the total to $100,000,000. 190 MINING INDUSTRY. PRGOs, che gots gi ese octet seat careseee atee ae ee eee $100, 000 10: ee eee TNC ME SY ree ok eOO ES teP 2, 000, 000 PSG Soe cus ce ees eae eee ee 6, 000, 000 186.202) ee eee ee a eee nee 12, 400, 000 Tid (ete eS ee ee eee ee eee 16, 000, 000 TSG Eig acct Saas ee Se ey eee nes 16, 000, 000 THGG bee eae ee eee Fee ciersie Seah 11, 739, 100 SGT Leena ek eee eee ee eee 13, 738, 618 AAS: Oe ce Bcc er oie ee eee ee 8, 479, 769 Hes. te A) SA ene) ok ee ee ee ee 7, 405, 578 93, 863, 065 The following tables, chiefly obtained from the Commercial Herald and Market Review, of San Francisco, show the assessments, products, and divi- dends of leading companies working on the Comstock lode during the last four years. These accounts are based on the operations of each current year. and the figures may therefore appear to differ from some of those already given in foregoing statements, which were based on the operations of each fiscal year of the company concerned: 191 THE COMSTOCK MINES. *poyeunsy v o00'SSr'r gLS'SoFtZL 009‘ F62'r o0S'Srbis 69L'6Ltg ooo! Z9Str oS6' 166° 46 LrogfZ‘€x oSz‘Zoz'z oof'rZ9'r 98 oor'6EL‘rr ozg'€Sr'r o00tagE oootogStr 2 | cootagt oootogf o00'oog ooo'oSr o00'oo€f 16 glz'6zL'x ooo'obe 00006E +6 z€1'L6z'z cootogr "7 > Jayovye AMOI olg's ee = ale ee © Aydinyy pur oy Ay ooo'Sr ogf'1Sr a ames = Sog'ze 000'06 See = at tay he 000'96 D se & = = = o0S'S¢ " * * Bpeadny CIUIIS ooo! Fr BBs =f SPs = ae "7 5 =" Sapis oog'zr Ce rLE'p cot ge ie ce So a cot'g Pes ee 7 es ~ TYII_ payesoisag ooofogz €og‘zor'r Soa us ooo'ter'r gag testa 2s o00'009'r zx oot ZEL‘€ eee ooo'ozE 60 6Lg‘tretr Sars “7 ss + 98Baeg Sgh'gfE o00'gzr Boosie 06S'zS€ o0o0'g lr 2 fe Lr gr€‘z6r ooo'ze SS Has: 00 ES6'Zz o00'goz "7 7 5 UBUAAG oor Soot Ie oooZgr peas 00 gory oog'tgr cause go eLb'drb oog'tgr S ee TUG), ooo'og FEg'gzg ooo'or ooofogt LoLl'6Sz'r wae 000'S0S +6 rbL'obr'z Sse ooo! Lr1r 6£ goStxZs gfe cy " "5 7 = yonjuo3y LeL'€lz ooo'oor ooo'tz oto'tgo o00'oor ooo0'ogE o$ S6toor'r — oo0'9 Zr LE Lgf‘or6 ree S "es Tenadury 000'96 zrg*6zo'zr = 2 35. oot 'z6E o00'coz ooototh St L6z‘Z60'r o00'og oo0'oS gE EFS‘ogr'z Ee ~ SSOIDNION puL o[vTT 00'S E se eons LSS‘6z ooo'sZ = RD: Pee 1S ozg'b19 oootozr ooo'zSz ro rgZ‘tzo'r F) Fos "+ Aung pur pinoy Loz‘Sg ooo'or ooStZ 9gg‘for cootor oSZLi€e zb 66£'gox as 2 Ps CS ae ae a “+ Zend ITH PIeD ooo'tz sone si Be % ooo'gr = ee ooo'z 7 ss = ganbayoxgy *Auvduroy Sut gto'gtr o00'of Bae Ss rLL'€rz Ss ee ooz'6h Lr Log'glz ER cae oot'zé gt 16z'zzb = 5s “UIT pur TY erduy grZ‘Sor ooo'oSr oootogfS ofz‘ggotr 00006 ooo! Foz 96 L£1L‘oz6 ooo'og Ooo FEzg €r rZb er! suo "7 7 Julog UAMoID ooz'zS art yer ope: Sas Be ter hs a 2) ss ee; ayers FUE. 46 ra ieee ee * BIUISILA payeprjosuog 6gg'gz ooc'r€ os gggtorr 009'Sr Piet ari oF 6totzbr ooz'oL ae ae) LZ 1£6'Fo€ 000'6€ “ * * * gatapyuog ooo F6z8 Sgf‘ggf'x aa ees glo'segs oootobr ooo'ozhs gf Sgg'ggg'zs | cootzh BO 00 1SL'ghge ees * * s0}Og-1e]TOYD, 0006 ie eS = enuary o0g'of eles 2 eo gee oO ae "55 BROTOFITES) o0$'Lg Ee ei Be ea ooo'cor ier ae? es SET ooS‘LEr We ae seers ooo'SLr SF es TONNE z1f'grg o0z‘6or por me an oe ooo'for in ee OC: ogg hl wee ot. Gir ps) 24 ozS‘€br ee 10) CIs § 02'S oer we 7 ees ooo fr - UvOHOUYy-dlownyyeg ooo'gr Se 6 doe oog' FE ars ye Seo ae ee See Dey See SE Sats oP eaves eae = eS = 5 9% Tyspomy oootoEg Sse? 2 ee o00'o6s a hae oP oe ae ooo'z 1g See Po 000'g68 2 ee seydry: — A . *syUOUL ? “syuoul 3 F *syuouL . ¥ *syuoUr SpuspIatq | *sjonporg -ssassy SpuepIAIq | ‘sjonporg -ssassy SpuoprAtd syonpolg -ssassy spuapi Ald syonpolg -ssassy “SUIT “699r *gogz *Logr "998r *2po] YI0jSUMOD ay] uo swans Suipvez oy fo ‘6ggr pup ‘gqg1 “LOSI ‘QQ8t eval ay2 Surunp spuopiarg puv ‘spnpotg ‘spuoiussasspy fo syuousnys ADINQUT CHAPTER IV. TREATMENT OF THE COMSTOCK ORES. SECTION I.— GENERAL OUTLINE OF THE PROCESS—CLASSIFICATION OF ORES—CRUSH- ING—GRINDING AND AMALGAMATION—PANS--SETTLERS—RETORTING FURNACE— MELTING FURNACE. SECTION II.—DETAILS OF CRUSHING AND AMALGAMATING MACHINERY—STAMPS FOR WEL CRUSHING—QUANTITY OF WATER USED—PANS: WHEELER’S, GREELEY’S, VARNEY’S, HEPBURN AND PETERSON’S, WHEELER AND RANDALL’S, MCCoNE’s, Founrain’s, HorN’S—SETTLERS OR SEPARATORS—AGITATORS—GENERAL AR- RANGEMENT OF MILLS. SEcTION III.—Costs AND RESULTS OF MILLING OPERATIONS—COSsTS OF LABOR AND MATERIALS—RELATION OF MINES TO MILLS—SAMPLING OF ORES—MILL- ING RESULTS—RELATION OF YIELD TO ASSAY VALUE, SECTION [V.—TREATMENT OF THE RESIDUES—AMALGAMATION OF SLIMES IN PANS— THE O'HARA ROASTING FURNACE—CONCENTRATION OF TAILINGS—TAILING RESERVOIRS—AMALGAMATION OF RAW TAILINGS. SECTION V.—TREATMENT OF FIRST-CLASS ORE—DRYING—CRUSHING—ROASTING— BARREL AMALGAMATION—STETEFELDT’S ROASTING FURNACE. SCE TON. a. GENERAL OUTLINE OF THE PROCESS. CLASSIFICATION OF oRES.—The ores of the Comstock lode consist chiefly of various sulphureted forms of silver, native silver, and gold, finely, almost imperceptibly, disseminated through a gangue of quartz. With these are as- sociated a few other accessory minerals in inconsiderable proportions. Their mineral composition and chemical nature will be more fully discussed in an- other chapter. For metallurgical treatment they formerly were, and to some extent still are, divided into three classes. The basis of this assortment is, of course, ar- 25 194 MINING INDUSTRY. bitrary. It is not the same in all mines, and does not appear to have been the same at all times in individual mines. The chief object of the classification is to separate those ores whose mineral composition and, more especially, whose high value demand a very exact and careful treatment in order to ob- tain the highest possible percentage of their precious contents, from those of lower grade, which must, by reason of their inferior value, be treated by less expensive methods. The first class usually embraces those ores whose assay value exceeds $150, or, in some cases, $100, per ton. The second class, where distinguished at all, is usually designed to include ores whose assay value ranges between $90 and $150 per ton. The third class embraces all workable ore of lower grade than the foregoing, the average assay value varying considerably in different mines. The first-class ores form but a very small proportion of the whole. The tabular statement in the foregoing chapter, showing the ore product, with the actual yield per ton, of some of the principal mines during five years past, al- though not complete in this respect, will serve to indicate the relative propor- tions of the several classes of ore. Thus, during the year ending July 1, 1868, the Savage mine produced, including the amount taken out by contract- ors, 87,341 tons of ore, of which 2774 tons were first-class, having an average assay value of 5449 40 per ton, and an average yield of $359 52. During the same year 4,745 tons of second-class ore were produced, of which the average assay value was, as determined by two different methods of sampling, $124 25 and $142 82 per ton; the average yield being $78 16. In the following year, in a total product of 69,287 tous of ore, only 684 tons were distinguished as first-class, having an average assay value of 5275 47; while no assortment of second-class ore was made in that year. During the year ending July 1, 1868, the average assay value of 78,4324 tons of ore produced by the Savage mine, and denominated as third-class, was, by two different methods of sam- pling, respectively, $52 O1 and $55 11 per ton; the average yield being S37 20. In the following year the average assay value of 55,411 tons of third-class ore reduced was, by the two methods of sampling, $60 29 and 550 78 per ton; the average yield being $34 64. TREATMENT OF THE COMSTOCK ORES. 195 In many of the mines the proportion of the second-class ore is so small, or the character of the ore so uniform, that no such distinction is made, the whole product being worked without assortment. About twenty-five to thirty per cent. of whole value contained in these ores is gold, the remainder is sil- ver. In the bullion produced the relative proportion of the gold is a little higher, as it is more easily saved than the silver. The silver of the first-class ores is intimately combined with sulphur, zine, lead, iron, and other base metals, which render the extraction of the silver dif- ficult. They cannot be profitably treated by the simple methods to which the more docile ores of the second and third classes are subjected, but are crushed dry, roasted with salt in reverberatory furnaces, and then amalgamated in barrels by what is known as the Freiberg process. This will be described with more detail further on. The ores of the second and third classes are treated by one and the same method, known as the pan process; the chief difference, where any exists, in the details of treatment as applied to the two classes, consisting in the duration of time allowed for amalgamation and in the quantity of quick- silver and other chemicals used in the operation. In the following pages a general description of the method of treatment of these two classes of ores will first be given; the machinery employed for crushing, grinding, and amalgamating will then be described in detail ; after which the costs of milling, the yield of the ore and its relation to the assay value, the operations of different mills, the treatment of the “tailings” or resi- dues, and other matters of interest will be discussed. Crusuinc.—The ore to be treated by the ordinary Washoe process? is delivered from the mine to the mill in pieces varying in size from fine particles to those as large as a man can lift. It needs first to be crushed to a fine condition. This operation is performed by stamps or heavy iron pestles that are lifted and allowed to drop in iron mortars into which the ore is thrown. The larger pieces of ore are first broken to a suitable size for feeding the stamps, either by a sledge or a mechanical rock-breaker, Blake’s machine being in general use for this purpose. 1The process of pan amalgamation is commonly known as the ‘* Washoe process,” having been first used in the Washoe district. 196 MINING INDUSTRY. The stamps vary in weight from 500 to 1,000 pounds; they are lifted and drop about 8 or 9 inches, making from seventy to ninety blows per minute; they are arranged in batteries, which consist, each, of one mortar with usually four or five stamps. Wet crushing is always employed for these ores; that is, a stream of water is admitted to the mortar with the ore, and, flowing off} carries with it the pulverized ore as soon as the latter is sufficiently reduced in size to pass through the screens placed in front of the discharging apertures of the mortar. The screens through which the crushed material is discharged from the mortar are either of brass wire-cloth, having 35 or 40 meshes to the lineal inch, or more frequently of Russia sheet-iron, perforated with fine holes. Screens of the latter sort, in general use, are known as Nos. 5 or 6. In the last named the hole has a diameter of 35 of an inch. In former years the amalgamation of the precious metals of the ore with quicksilver was carried on in the mortar, a supply of quicksilver for that pur- pose being introduced with the rock into the mortar. This feature of the proc- ess has, however, now been given up in the mills of the Washoe district. The stuff being discharged from the battery is conveyed in troughs by means of the flowing water to settling tanks, of which there is a series placed in front ofthe batteries. These tanks are usually built of plank, are 3 or 4 feet deep by 5 or 6 or more feet square, and are so arranged as to have communication with each other near the top, so that the stream of water carrying the crushed ore in suspension, having filled one tank may pass into the next, and so on through several, depositing the material and not finally leaving the tanks un- til it has become tolerably clear. The number of tanks must be sufficient to allow of a certain portion being emptied while others are receiving their sup- ply, and the conveying troughs are provided with gates so arranged that the stream can be admitted to one portion of the tanks and shut off from the other at pleasure. The stream, having deposited in these tanks the bulk of the ma- terial, is still charged with slimes, or rock reduced to an impalpably fine con- dition, which is only settled by a slow process. For this purpose the stream is sometimes permitted to pass through other large settling tanks, or to slowly deposit its charge ina pond or dam outside the mill, where such an arrange- TREATMENT OF THE COMSTOCK ORES. 197 ment is possible. These slimes forma variable and in some mills a large per- centage of the whole amount crushed; in some instances, it is stated, more than ten per cent.; and although they have a high assay value they have not until re- cently been worked successfully and with profit. When one or more of the settling tanks in the mill have been filled the stream is diverted from such to others that have been emptied, and the full ones are in their turn cleaned outthe sand or crushed ore being then subjected to the grinding and amalgamating process of the pan. GrinpInc AND AMALGAMATION.—Pans.—The pans employed for this purpose present a great variety in the details of construction. Since the first “common pan,” a very simple form of apparatus, came into use, many inventors have exercised their ingenuity in devising improvements, and at present there are several different patterns, each of which has some special claim for excellence, and finds its advocates among the practical mill-men of the district. A more detailed description of some of these will be found further on. The common features are a round tub, see Plates XXI and XXII, usually of cast-iron, but sometimes with wooden sides, 4 to 6 feet in diameter and about 2 feet deep, having a hollow pillar cast in the center, within which is an upright shaft projecting above the top of the pillar that may be set in revolution by gearing below the pan. To the top of this shaft is attached, by means of a key or feather, a yoke or driver by which the muller or upper grinding surface is set in motion. To the bottom of the pan, on the inside, is fixed a false bottom of iron, cast either in sections, commonly called dies, or in one piece, having a diameter a little less than that of the pan, and with a hole in the center adapted to the central pillar. This serves as the lower grinding surface. The muller, forming the upper grinding surface, is usually a circular plate of iron corresponding in size and form to the false bottom just described, having a diameter nearly equal to that of the pan, and a flat, conical, or conoidal form, according to the shape of the pan-bottom. Its un- der side is furnished with shoes or facings of iron, about an inch thick, that may be removed when worn down and replaced by new. The muller is attached to the driver, which is put on and over the central pillar of the pan and, being connected with the interior upright shaft as above described, is thus caused to 198 MINING INDUSTRY. revolve. There are various appliances for raising or lowering the muller, so that it may rest with its whole weight upon the pan-bottom in order to produce the greatest grinding effect, or be maintained at any desired distance above it when less friction or mere agitation is required. Various devices are also in use for giving proper motion to the pulp,so that, when the muller is in revolution, the ma- terial may be kept constantly in circulation, passing between the grinding sur- faces and coming into contact with the quicksilver. Some pans are cast with a hollow chamber, an inch or two deep in the bottom, for the admission of steam in order to heat the pulp, while others employ only “live steam,” which is delivered directly into the pulp by a pipe for that purpose. The operation of the pan consists in the further reduction or grinding of the stamped rock to a fine pulp and in the extraction of the precious metals by amalgamation with quicksilver. The quantity of ore with which a pan is charged for a single operation varies from 600 or 800 to 4,000 or 5,000 pounds, according to the size of the pan. The ordinary charge of pans, most generally in use at present, is 1,200 to 1,500 pounds. In charging the pan the muller is raised a little from the bottom, so as to revolve freely at first, water is supplied by a hose pipe, and at the same time the sand is thrown into the pan with a shovel. Steam is admitted, either to the steam-chamber in the bottom of the pan or directly into the pulp. In the former case the temperature can hardly be raised as high as in the latter; but, on the other hand, when steam is introduced directly, care is necessary to avoid reducing too much the consistency of the pulp by the water of condensation. The pulp should be sufficiently liquid to be kept in free circulation, but thick enough to carry in suspension, throughout its entire mass, the finely divided globules of quicksilver. In some mills both methods of heating are employed in the same pans, the temperature being first raised with each charge by live steam, and afterward sustained by admitting steam to the chamber only, Some pans are covered with wooden covers to assist in retaining the heat. When properly managed the temperature may be kept at or near 200° Fah- renheit. When, in the use of live steam, the pulp becomes too thin the sup- ply of steam is cut off, the covers removed, and the pulp allowed to thicken by the evaporation of the water. The steam in the chamber may keep the temperature up to the desired point in the meantime. Another advantage of TREATMENT OF THE COMSTOCK ORES. 199 the steam-chamber is that the exhaust-steam from the engine may be used in it, while for use in the pulp it is better and customary to take steam directly from the boilers, because that which comes from the cylinder of the engine is charged with oil and is injurious to amalgamation. The muller is gradually lowered after the commencement of the grinding operation, and is allowed to make about 60 or 70 revolutions per minute. In the course of an hour or two the sand should be reduced to a fine pulpy condition. When this has been accomplished, and by some mill-men at a still earlier stage (even at the beginning) of the operation, a supply of quicksilver is introduced into the pan, the muller slightly raised from the bottom to avoid too great friction, which would act to the disadvantage of the quicksilver, and the action continued for two hours longer, during which the amalgamation is in progress. The quick- silver is supplied by pressing it through canvass, so as to scatter it upon the pulp in a finely divided condition. The quantity varies greatly in different mills, the ordinary supply being about 60 or 70 pounds to a charge of ore con- sisting of 1,200 or 1,500 pounds. In some mills a quantity, varying from 75 to 200 or even 300 pounds, is put into a pan when starting up after a clean-up, and subsequently a regular addition of 50 or 60 pounds made with each charge. To promote amalgamation it is the general custom io add to the charge, either at or soon after the beginning of the grinding, or at the time of supplying the quicksilver, various materials generally described as “chemicals,” and usually consisting, at the present day, of sulphate of copper and salt. Since the first introduction of the pan process a great variety of substances supposed to effect the decomposition of the silver sulphurets and to facilitate amalgama- tion have been suggested by process-vendors, and employed by men possessing little or no knowledge of the science of chemistry. Even tobacco-juice, de- coction of sage-bush, and various other equally absurd ingredients are said to have been used by some operators and believed to be effective reagents in the decomposition of the ore and amalgamation of the silver. The long list of mate- rials once in use has now been reduced, excepting in few places, to sulphate of copper and salt. The quantity used varies from a quarter or half a pound to three or four pounds to each charge of ore; the two substances being employed in very variable proportions in different mills. The action of these, however, 200 MINING INDUSTRY. which is generally supposed to be analogous to that produced by the same re- agents in the Mexican “patio” process, is but imperfectly understood, and their efhiciency, at least in the manner and proportions in which they are at present employed, may well be doubted. ‘This is apparent from the fact that in some mills both sulphate of copper and salt are used, in others only the first is used without the second, and in others only the second without the first, or, if at all, in proportions so minute that its efficient action is incredible; others have dispensed with the use of “chemicals” altogether, and under all these varying circumstances equally good results have been obtained. Some mills, accus- tomed to use both salt and sulphate of copper, have dropped either one or the other, while working continuously on the same kind of ore, without perceiving any difference in the result; and it is the opinion of many intelligent mill-men that neither salt nor sulphate of copper, in the manner and quantity as at present employed, are essential to the efficient working of the ore in pans. This subject will be further discussed on a following page. Two hours having been devoted to the grinding, and two or three more to amalgamation, the pan is discharged and its contents received by a settler or separator, The discharge of the pan is usually aided by a supply of water, which dilutes the pulp and permits it to run freely from the pan into the set- tler. The pan being emptied and partly washed out by the stream of water, is again charged with a fresh quantity of sand and the grinding operation is resumed without delay. Serriers or SePArators.—These, like the pans, differ somewhat in details of construction, but they usually are round tubs of iron or of wood with cast-iron bottoms, resembling the pans in general features, but larger in diameter. A hollow pillar or cone, C, Figs. 1 and 2, Plate XVII, is cast in the center of the bottom, within which is an upright shaft, S. This shaft is caused to revolve by gearing below the pan. To its upper end is attached a yoke or driver, D, that gives revolving motion to arms, A, extending from the center to the cir- cumference of the vessel. The arms carry a number of plows, or stirrers, of various devices, usually terminating in blocks of hard wood, P, that rest lightly on the bottom. No grinding is required in the operation, but a gentle stirring or agitation of the pulp is desired in order to facilitate the settling of the amalgam and the quicksilver. The stirring apparatus, or muller, makes about fifteen revolutions per minute. Plate XVII : 3 | SHPARATOR oe SETTLER | Scale: 24 TREATMENT OF THE COMSTOCK ORES. 201 The settler is usually placed directly in front of the pan and on a lower level, so that the pan is readily discharged into it. In some mills two pans are discharged into one settler, the operation of settling occupying four hours, or the time required by the pan to grind and amalgamate another charge. In other mills the settling is allowed only two hours, and the two pans connected with any one settler are discharged alternately. The consistency of the pulp in the settler is considerably diluted by the water used in discharging the pan and by a further supply, which in many mills is kept up during the settling operation. In other mills, however, the pulp is brought from the pan into the settler with the addition of as little water as possible, and allowed to settle fora time by the gentle agitation of the slowly revolving muller, after which cold water is added in a constant stream. ‘The quantity of water used, affecting the consistency of the pulp, and the speed of the stirring apparatus are important matters in the operation of set- tling or separating. Since the object of the process is to allow the quicksilver and amalgam to separate themselves from the pulp and settle to the bottom of the vessel, itis desirable that the consistency should be such that the lighter particles may be kept in suspension by a gentle movement, while the heavier particles fall to the bottom. If the pulp be too thick the metal will remain suspended; if it be too thin the sand will settle with it. Too rapid or too slow motion may produce results similar to the above-named, because by too violent motion the quicksilver will not be allowed to come to rest on the bot- tom, while if the motion be too slow the coarser sand will not be kept in cir- culation. A discharge hole, near the top of the settler, permits the water carrying the lighter portion of the pulp to run off, and at successive intervals the point of discharge is lowered by withdrawing the plugs from a series of similar holes, h, h, in the side of the settler, one below the other, so that finally the entire mass is drawn off, leaving nothing in the settler but the quicksilver and amalgam. There are various devices for discharging these. Usually, there is a groove or canal in the bottom of the vessel, as shown in Figs. 1 and 2, Plate XVII, leading to a bowl, B, from which the fluid amalgam may be dipped or allowed to run out by withdrawing the plug, p, from the outlet- pipe. 202 MINING INDUSTRY. The quicksilver charged with amalgam is carefully cleaned by washing with water and removing from the surface the associated impurities such as heavy particles of dirt, pyrites, &c. In some cases the cleaning is performed ina small iron pan, resembling the settler in manner of construction but much smaller, in which it is stirred slowly with plenty of clean water, which serves to wash out the impurities and remove them from the pan. When properly cleaned the amalgam is strained through a canvas filter or conical bag, 10 or 12 inches in diameter at the top, and 2 or 8 feet long. (See Fig. 8, Plate XVII.) The quicksilver is drained off and returned to the pans for further use, while the amalgam is thus obtained for the retort. In some mills this straining is not performed after every charge of ore, as is the case in others, but only at stated times, say once in twenty-four hours, or once in three or four days. Under such circumstances a consider- able quantity of quicksilver is kept in the settler, sometimes 200 or 300 pounds. This excess of quicksilver, holding the amalgam in solution, is in a highly fluid condition, and when discharged from the settler by means of the tube and cistern just described, it is returned to the pan for further amal- gamation, its “charged” condition—that is, having silver already in combina- tion—being considered an advantage, as it is thought to be more active than pure metal in the amalgamating process. In some mills, at a stated hour of each day, the quicksilver coming from the settlers is strained and the amal- gam extracted; in others, as the quicksilver thickens or becomes sluggish by the accumulation of amalgam, it is diluted by the addition of fresh quick- silver, and the straining of the amalgam is only made once in several days From time to time, as at the end of the month or other given period, or when any special lot of ore has been finished, of which it is desired to know the exact yield, the pans and settlers must be stopped and cleaned up thoroughly. For this purpose the mullers must be raised, the shoes and dies remoyed from their places, and all the iron work of the pans and settlers care- fully scraped with a knife to remove and collect the hard amalgam which attaches itself to such surfaces. In many cases one-fourth or even a greater proportion of the total product of amalgam is obtained in this way. Rerorting anp Metrine.—-The amalgam, having been strained in the bags and forcibly pressed, in order to expel as much of the fluid quick- i uy é TREATMENT OF THE COMSTOCK ORES. 203 silver as possible, is then subjected to the process of sublimation, by which means the quicksilver is separated from the gold and silver. This is effected in a cast-iron retort. The retorts in use are of various forms, but the most-approved is cylindrical, about 12 inches in diameter inside, and from 3 to 5 feet long; the casting beimg an inch and a half thick. (See Figs. 1 and 2, Plate XVIII.) The open end of the retort, or the end by which the charge is introduced, is cast with a flange or hood into which the door or cover of the retort is fitted. Within the cylindric por- tion of this flange or hood are two inclined lugs, opposite each other. A bar or bale, turning upon a pin in the center of the door, holds it firmly in its place by the ends of the bar being turned under the inclined lugs. When charged, the joint between the door and the bottom of the flange is made tight by means of clay luting. Another method of securing the door is shown in Fig. 9, Plate XVIII. The opposite end of the retort is usually made conoidal in form. In such case the main cylindrical portion, 12 inches in diameter, is 3 feet long, at which point the diameter of the con- oidal neck is gradually diminished to 24 inches at the extreme end of the re- tort, from which the exhaust pipe, 6, the purpose of which is to afford escape to the volatilized quicksilver, turns downward and passes through the condenser, the construction of which is shown in Fig. 8. This is usually arranged on the principle of the Liecbig condenser and consists of a pipe, a, of considerably larger diameter than the exhaust pipe, 6, so that the latter may pass entirely through the former, which, when in use, is kept constantly supplied with cold water by a pipe, d, opening into the bottom, the heated water flowing off at the outlet, e, near the top. The quicksilver condensing in the exhaust- pipe falls into a receiver, placed under the end of the pipe, and which is algo nearly full of water. The end of the exhaust pipe dips below the surface of the water to prevent access of air but not sufficiently to permit the pas- sage of the water into the heated retort under any circumstances. The retort is set in a brick furnace of simple construction, sometimes supported by a brick arch, through which a number of flues permit the pas- sage of the heat from the fire-place below, sometimes resting on cross-bars of iron, the ends of which are fixed in the brick sides of the furnace, as shown in Hig. 1, Plate XVIII. Directly below the retort, extending under its whole 204 MINING INDUSTRY. length, is the fire-place and ash-pit. Above it is an arch, from the top of which the flues, /; lead to the stack. Some retorts are set in such manner that tempo- rary brick-work may be built up in front of the door during the sublimation to prevent the escape of heat. Dampers are so arranged that the heat may be applied more or less vigorously to the front, back, or middle of the retort according to its requirements. The retort is furnished with amalgam trays, illustrated by Fig. 4, Plate XVII, having a semi-circular shape adapted to the bottom of the cylinder. There are usually several of these, and they are of a size convenient for handling when loaded with amalgam. In many mills, however, they are not used, the amalgam being charged directly upon the bottom of the retort. Before intro- ducing the amalgam into the tray or the retort the surface of the latter is covered with a thin wash of clay or slime, such as is produced in stamping, to prevent the metal from adhering to the iron. Whiting, wood ashes, or paper are some- times used for this purpose and recommended as being less likely to choke the pores of the bullion. The amalgam being placed in the retort and the door properly adjusted and luted with clay, the fire is lighted and heat is applied, at first very gently and afterward gradually increased. If heated too strongly at first the surface of the bullion in contact with the retort is lable to fuse and prevent the escape of quicksilver from the central part. The charge for acylinder of the dimensions above described is about 1.200 pounds. The firing usually occupies about eight hours. When quicksilver ceases to vola- tilize, the retort is gradually cooled down and the bullion withdrawn. About one-sixth of the original charge usually remains, or 200 pounds of crude bul- lion from 1,200 pounds of amalgam. This retorted amalgam is broken up, melted, and cast in ingots ready for market. The melting furnace commonly used for this purpose is shown in Figs. 5 and 6 on Plate XVIII. Fig. 5 is a front elevation of a double furnace. The cover of the left-hand furnace is re- moved, showing the size and position of the flue. Fig. 6 is a transverse section on the line A Bin Fig, 5. Fig. 12 shows the tongs for removing the melting pot. Fig. 10 shows the form of ingot mold usually employed. The loss of weight in melting the retorted amalgam, or crude bullion, is between two and three per cent. The ingots, when obtained, are assayed, and their fineness, ex- pressing the proportions of gold and silver contained in thousandths, as well as TREATMENT OF THE COMSTOCK ORES. 205 their coin value, in dollars and cents, are stamped upon them. The value of the ounce of bullion ready for market usually varies between $1 75 and $2; the gold representing about one-third and the silver about two-thirds of the whole amount. The pulp, after passing from the settlers, in which, as before described, the quicksilver and amalgam are separated from it, is variously treated in different mills. Frequently the whole mass is allowed to pass through agi- tators, tubs or vats of various devices, for the purpose of saving some of the quicksilver and amalgam that is unavoidably carried off with it from the settler. In some mills various kinds of concentrators are employed for a similar purpose, and to obtain the heavy undecomposed sulphurets in concen- trated form; in other cases, where there is water sufficient and the lay of the land favorable, blanket-tables are constructed outside the mill, over which the stream of tailings’ is allowed to run, and a portion of their valuable contents caught in blankets; and, at convenient points, dams are constructed for the accumulation of tailings, which, after months of exposure to the influences of the weather, may be again worked over with profit. The ordinary working result obtained by treating the ore as above described in the pan and settler varies between sixty-five and seventy-five per cent. of the assay value, which, by subsequent treatment, as just indicated in the foregoing paragraph, is increased sometimes to eighty-five or ninety per cent., or possibly a little more. ‘This subject, as well as the costs of working and many other interesting details connected with the business, will be con- sidered more minutely further on, after having first described, in detail, some of the various kinds of crushing and grinding machinery employed in the process, of which the main features have just been given. 1 The term “ tailings” is applied to the residue of sand or pulp that leaves the sep- arator or agitator after the principal portion of its valuable contents has been extracted. The term “shines” generally applies to that portion of the ore which is crushed under the stamps to an impalpably fine condition, and which usually passes out of the mill without being deposited in the tanks, where the coarser sands are collected for pan treatment. The difference in the value, mechanical condition, and methods of treatment of “tailings” and ‘“ slimes” makes the distinction between them an important one. That part of the “ tailings” which, by grinding in the pan, has been reduced to a slimy condition, is sometimes called ‘pan slimes,” and thus distinguished from “ battery slimes.” 206 MINING INDUSTRY. SECTION Tf. DETAILS OF MACHINERY EMPLOYED IN CRUSHING AND AMAL- ,AMA TING? The machinery of a mill for the treatment of silver ores by the ‘wet process,” or method just indicated, consists of rock-breakers and stamps for crushing; pans, for grinding and amalgamation; settlers, for the separation of the quicksilver and amalgam from the pulp; agitators, which are supplemen- tary to the settlers, and save escaping quicksilver; various appliances for the concentration of the residue, or ‘‘tailings;” the retort for the sublimation and separation of the quicksilver from the precious metals; besides the motive power and its auxiliary parts. The rock-breaker generally in use is Blake’s. It serves simply to crush the large pieces of rock to fragments of smaller size, not exceeding a few cubic inches, which are then conveniently supplied to the stamps. The machine is well known, not only in mining regions but throughout the country, bemg employed in breaking stone for road-making and other pur- poses. It hardly needs a detailed description here. Sramps.—The stamps consist of a series of heavy pestles of iron, which are lifted to a height varying from 7 to 15 inches, and allowed to fall upon the ore that is to be crushed. ‘They work in a mortar or trough, also of iron, into which a constant supply of ore is introduced, and from which the crushed ma- terial escapes through openings furnished with closely fitting screens, as soon as it is reduced to the desired degree of fineness. The mortar is usually rectan- gular in form, and contains from three to six, commonly five, stamps, forming what, in this country, is called a ‘‘battery.”. The mortars rest on a solid foundation, and are established in a substantial framework of timber. The stamps are lifted by means of revolving cams or arms of iron, keyed to a cam- ' Although the writer has prepared this section almost entirely from his own notes or personal observation, he has made frequent reference to several well-known works, chief among which is KUSTEL’s CONCENTRATION AND CHLORINATION, an excellent treatise on the mechanical preparation of ores. PROFESSOR GAETZSCHMANN’S valu- able work, “Die Aufbereitung,” and RITTINGER’s “ Lehrbuch der Aufbereitungs- Kunde,” are commended to the student as complete and thoroughly scientific discus- sions of the same subject. fa el i TO an AHN | | PE RT LUGs7 Plate XIX Oy £' Foundation Timber or Morter Blocle h Stamp head T Transverse Sill e Shoe C. Battery Posts d Ne GG Te Fimbers t Tappet D Braces | c lam R Rods LS P| A Gamshati Mo Mortar | P. Paller on Camshatt 1. Feedaperture Pp Driving pulley u. Screen hk Driving shat? J. Sereentrame ». Tightener 0. Lugs to secure frame gg Guides w Wedge or key Ee q Battery covers 8 Stamp Stem or lifter yf scale .-33 TREATMENT OF THE COMSTOCK ORES. 207 shaft, which is placed directly in front of the batteries, and which receives its motion from the driving power of the mill. The stamps move vertically between guides that form a part of the battery frame. Fig. 1, on Plate XTX, shows a front elevation, and Fig. 2, a transverse section, on the line A B of Fig. 1, of two five-stamp batteries, the several parts of which are indicated by the table of reference accompanying the drawing. The foundation for the batteries in stamp mills generally preferred in Nevada, as well as in California, consists usually of heavy timbers, standing vertically, placed close together, and firmly connected by means of cross tim- bers and bolts of iron. The timbers are from 6 to 12 feet long, according to the character of the ground and the desired height of discharge for the mor- tar. Sometimes they stand on a horizontal timber, so laid as to serve as the base of two or more batteries, and resting upon the ground, the surface of which has previously been removed and leveled down sufficiently for the whole number of batteries to be placed on a firm bottom. When the founda- tion-timbers are in place, the space about them is packed and stamped as firmly as possible with clay or earth. Where the ground on which the bat- teries are to be built is a hard, compact gravel or a firm, clayey material, the surface is sometimes leveled off so as to admit of laying the transverse sill- timbers, 7, of the battery frame, and a narrow pit is then excavated, only long and wide enough to receive the ends of the mortar-blocks, and several feet deep, into which the posts or blocks are introduced, ina vertical position, their bottom ends resting directly on the ground, without any intervening horizontal timber. The remaining space in the pit may then be compactly filled with clay that is pounded or stamped firmly into its place. he sill- timbers, 7, and the battery posts, C, are securely bolted to the foundation- timbers. The posts, C) are braced by the timbers, D, and the rods, J, and are connected by the tie timbers, G', G’, which also support the guides, g, g’. Morrars.—The mortars are now usually placed directly upon the verti- eal mortar-blocks, without any horizontal piece intervening, and are secured in their place by bolts shown in the figure. They may be constructed of wood and iron, having a solid iron bed-plate, with sides and ends of wood, forming the stamping trough; or they may be made entirely of iron. In the 208 MINING INDUSTRY. former case there is often great difficulty in keeping the mortar tight enough to prevent leakage and consequent waste of ore. The mortar in general use for wet-crushing is an iron box or trough about 4 or 5 feet in length and depth, and 12 inches, inside, in width, and so cast that bottom, sides, and ends are in one piece. A front and end view of one of the most-approved forms is shown in place, in the drawing of a bat- tery of stamps, on Plate XIX. The feed opening, /, is an aperture about 3 or 4 inches wide and nearly as long as the mortar, by means of which the rock is supplied to the stamps. On the opposite side is the discharge open- ing, furnished with a screen, 2, through which the crushed material must pass. This opening is as long as the mortar, or nearly so, and 12 to 18 inches deep, the lower edge being 2 or 3 inches above the top of the die. In some mortars, especially for dry crushing, the discharge is on both sides, in which case the feed-opening is above the screen; but the single discharge is in gen- eral use in the Washoe district. The sereen is attached to a sereen frame, 7, which is secured in grooves cast in each end of the mortar, and by two lugs, 0, cast in front of the dis- charge-opening, being held firmly in place by a wedge driven behind it in the grooves just referred to. Screens are sometimes placed vertically, sometimes inclined, as shown in the figure. The discharge is generally thought to be better in the latter case. Screens are made of fine brass wire-cloth, having from 40 to GO meshes to the lineal inch, or, more generally for wet-crushing, of Russia sheet-iron, perforated by finely punched holes, varying from j5 to 3 of an inch in diam- eter. The wire-cloth or sheet-iron plate is attached to the screen-frame by nails or serews. The punched plate is preferred for wet crushing. The wire- cloth, though affording more discharging surface, wears out faster, and not only is more liable to break, and so permit large particles to pass through, but frequently stretches, giving meshes of irregular size. A piece of canvas is usually hung before the screen for the crushed ore to splash against as it issues from the mortar, falling thence into the trough below. Dres.—The mortar is furnished with dies which are so fixed in the bot- tom as to receive the blow of the stamp and sustain the wear which would, in its absence, fall upon the mortar itself The die is a cylindrical piece of TREATMENT OF THE COMSTOCK ORES. 209 cast iron, corresponding in form to the shoe of the stamp that falls upon it. It is from 4 to 6 inches high. In the bottom of some mortars there ave circular recesses made for the reception of the dies which are caused to fit into them. In others, to prevent the rock from working in under the die and displacing it, the circular recess in the bed-plate is cast with a flange, and the die with a small projection or lug. A groove is also made in the bottom of the mortar, so that the die may be introduced with its lugs dropping into the groove. The die being then turned about 90 degrees, the lugs come under the flanges of the recess and the die consequently held in place. A simpler and the most common form is to cast the cylindrical part of the die on a flat, square base, as shown in Fig. 1, Plate XX. The bottom of the mortar is also made flat and the dies dropped in, resting on their bases, which just fill up the space in the bot- tom of the mortar. The corners of the bases of the dies are beveled off so as to allow the insertion of the point of a pick, by which means they can be taken out when necessary. In addition to the dies, plates of iron, a half-inch thick, are sometimes applied to the sides and ends of the mortar, exposed to constant wear, which, like the dies, can be taken out and renewed when necessary. The top of the mortar is covered by two pieces of plank, cut so as to fit closely, and resting on flanges cast on each end. Semi-circular recesses, cut opposite each other on the adjacent edges of the two pieces of plank, afford a passage for the movement of the stamp-stems. The stamp consists of a stem or lifter ; a head or socket, attached to the lower end of the stem, and furnished with the shoe, a movable part which sustains the force of the blows and the wear of the operation ; and the collar, or tappet, by means of which the revolving cam lifts the stamp for its fall. The stem is a round bar of wrought iron, about three inches in diameter, usually turned in a lathe. Its length is 10 or 12 feet. Its lower end is slightly tapered and corresponds in form to a socket or conical hole in the upper part of the stamp-head. The rest of the stem is usually made round throughout its entire length, the method, now in general use, of attaching tue tappets to the stems not requiring any modification in the form of the latter, as was formerly the case. The stamp-head, illustrated by Fig. 2, Plate XX, is a cylindrical piece 27 210 MINING INDUSTRY. of tough east iron about 8 inches in diameter and 15 inches high. In its upper end is a socket, shown by dotted lines, corresponding with the axis of the cylinder and conical in form, designed to receive the slightly tapermg end of the stem, to the dimensions of which it must be adapted. This conical hole, or socket, is about 7 inches deep. At its bottom is a hole, or key-way, a, passing through the head, at right angles to the cylindrical axis, by which passage a key may be driven in to force the head from the stem when neces- sary. To attach the stamp-head to the stem, the latter is placed in its position between its guides, and the head standing immediately under it. The stem being dropped enters the socket, and a few blows of the hammer drive it in with sufficient force to cause the head to be raised when the stem is lifted. The stem and head, being suffered to drop together a few times, become firmly connected. In the lower end of the head is a similar hole or socket, b, but larger than the upper one, likewise taperimg or conical in form, made to receive the stem or shank of the shoe, which is thus connected with the head in similar manner; a rectangular hole, or passage, c, through the head at the end of this lower socket permits the removal of the shoe in the same way as the stamp-stem is forced out from the upper socket. A stout wrought- iron hoop encircles each end of the stamp-head, being fitted and driven on when hot and allowed to shrink in place. The shoe in common use in these mills is a cylindrical piece of cast iron about 8 inches in diameter and 6 inches high, above which is a shank or stem, the base of which is 4 or 5 inches in diameter, tapering in form and about 5 inches high. It is made of the hardest white iron. It is attached to the head in manner somewhat similar to that just described for connecting the head and the stem, but is wedged on by means of strips of pine wood. ‘These strips which are cut about as long as the stem of the shoe, a quarter of an inch thick and about a half an inch wide, are placed around the stem of the shoe and tied with a piece of twine, as shown in Fig. 8, Plate XX. They must be thick enough to wedge the stem of the shoe firmly in its socket, without allowing the head to come in contact with the body of the shoe. When the shoe is ready to be fixed to the head it is placed in proper position with the stem of the shoe directly under the socket of the head, and the TREATMENT OF THE COMSTOCK ORES. 2 at stamp and head are then allowed to drop upon it. If necessary, a few blows of the hammer must be struck upon the top of the stamp-stem. The whole may then be raised, the shoe keeping its place, and suffered to fall repeatedly until the shoe is firmly established in the socket. During this operation a piece of plank is interposed between the die on the bottom of the mortar and the shoe for the latter to strike upon. Whenever a shoe has been worn out it may be removed from the socket by driving the key into the key-way, c, and forcing it off. Care is required that the shoe does not become so thin as to permit the head to sustain undue wear and so become weakened. Shoes should be removed when worn down to one inch of thickness. The collar, or tappet, is a projecting piece, firmly secured to the upper part of the stem, by means of which the revolving cam may lift the stamp and let it fall upon the substance to be crushed. Tappets vary in form and method of attachment to the stem, but that which seems to combine the greatest number of advantages and to have been most generally adopted in California and Nevada is that which is known as Wheeler's gib-tappet. Fig. 4, on Plate XX, shows an elevation and vertical section of this contrivance. It is a piece of cast iron, cylindrical in form, about 8 inches in height and diameter, hollow at the center so as to receive the stamp-stem. To secure the tappet to the stem there is a gib, g, about 2 inches wide and neatly as long as the tappet, having its inside face curved so as to correspond in form to the circular hole through which the stem passes. ‘The gib being fixed in its place in the tappet and the latter being put upon the stem, it is pressed against the stem by means of two keys, 4, 4, driven into the key-ways, with force sufficient to hold the tappet and stem firmly together and prevent slip- ping between them. This is found to be a very effective method of securing the tappet while permitting it to be fixed at any desired point on the stem, according to the wear of the shoe. The stem is uniform in size and the work of cutting facings, screw-threads, and key-seats on the stem, required by other methods in use elsewhere, is thus avoided. The rotary motion of the stamp, imparted by the friction of the cam against the tappet, is in very general use in Nevada. This is one of the ad- vantages offered by the use of round shoes, stems, and tappets. The revoly- ing cam, meeting the tappet, and raising the stamp, causes it while being Fit? MINING INDUSTRY. lifted to make a partial revolution about its vertical axis, which rotary mo- tion bemg continued during the free fall of the stamp, produces a grinding effect between the shoe and die upon the substance to be crushed. Not only is the effective duty of the stamp at each blow increased in this way, but the shoe wears down much more evenly than when it falls without such rotary motion. Guipes.—The stamp is held vertically in ‘its movement by guides, between which the stem passes. These were formerly made of iron, but such have been almost entirely replaced by wooden ones in Nevada and Cal- ifornia. One set of guides is placed below the tappet, about a foot above the top of the mortar; the other set is placed near the top of the stem, so that six inches or a foot of the latter may project above the guides. They are supported by the cross-timbers, or ties, G, G’, which form a part of the battery frame, connecting the two uprights or posts. They are usually made of pine, though hard wood is preferred, and are from 10 to 16 inches wide. One part of the guide is made in a single piece for the whole battery, bolted to the cross-timber; the other part may be in one piece like the first, or cut into as many pieces as there are stamps in the battery, as in Fig. 5, Plate XX, which are then secured to the corresponding part by bolts.” In each part are cut semi-circular recesses, which, when the two parts are put together so that the recesses correspond, the holes or stemways for the reception of the stamp-stems are formed. When the guides are so worn by friction as to permit too much motion of the stems, they may be dressed down on their adjacent faces, by which means the recesses are reduced to nearly the proper dimensions. Cams.—The cam is a curved arm fixed to a shaft, which is so placed in front of the battery that, by the revolution of the shaft, the cam is brought into contact with the tappet of the stamp-stem, causing the latter to rise to a height determined by the length of the cam, and to fall at the moment of is release from such contact. In Nevada the cams are made of tough cast iron, and are usually “double armed,” that is, having two arms attached to one central hub. Figs. 6 and 7, on Plate XX, show the form of cams most generally in use; in Fig. 7, @ is the hub, 6, 6 are the arms, ¢ is the face, and d, a strengthening rib. | XX Plate figs 23, hig. 6 6 Vid "Y ; 1 Seale & TREATMENT OF THE COMSTOCK ORES. . Pili The proper curve of the face of the cam, in order that it may perform the desired duty with the least friction, is the involute of a circle, the radius of which is equal to the distance between the center of the cam-shaft and the center of the stamp-stem. This produces a line for the face of the cam which meets, better than any other, the various requirements. The bottom of the tappet is constantly perpendicular to the radius of the curve of the cam; the tappet, and with it the stamp, is lifted vertically and uniformly, so that the lift of the stamp is always regularly proportioned to the revolution of the cam-shatt. The cam-curve may be constructed on paper by means of tangents, as shown in Fig. 6, Plate XX. If represents the center of the cam-shaft, and cr the distance from the center of the cam-shaft to the center of the stamp- stem, the circle described about c, with cr asa radius, is the developing circle of the involute. The distance, representing the height to which the stamp is to be lifted, is laid off upon the circumference of this circle, as from the point 1; which distance is subdivided into a convenient number of equal parts, determining, as in Fig. 6, the points 2, 3, 4, * * * * * 13. From each one of these points in the circle a tangent is drawn, on which is laid off a distance equal to the length of are between the point 1 and the point from which the tangent is drawn. All the pots thus determined in the tangent-lines are points in the cam-curve, and may be connected, as shown in the figure, thus producing the line for the face of the cam. In practice the line of curvature is produced by cutting from a thin board a circular piece, the radius of which is equal to the horizontal distance from the center of the cam-shaft to the center of the stamp-stem. Ata given point on the periphery of the circular piece is fixed one end of a thread, which must have the length of the greatest desired lift of the stamp, and to the other end of which is attached a pencil point. The circular piece, with the attached thread wound on the periphery ef the circle, is laid on a smooth board, on which the line is to be traced, and the thread, being constantly stretched to its furthest reach, is unwound until it forms a tangent to the circle at the poimt where the other end is attached. The line described by the pencil point is the desired curve. Some builders slightly modify this curve, giving to the cam-arm a greater 214 MINING INDUSTRY. curvature near each of its ends, in order that the cam, in its revolution, may come in contact with the tappet at the least practicable distance from the cam-shaft, where the concussion is less than ata greater distance, and to diminish the friction between the extreme end of the cam and the face of the tappet. The face of the cam is 2 or 2$ inches wide. Its extreme end is fashioned so as to correspond to the outer edge of the tappet, which is circu- lar. The cam is placed as near the stamp-stem as practicable, without com- ing in contact with it. The cams are caused to revolve by means of the cam- shaft, to which they are secured by one or, sometimes, two keys or wedges. The cam-shaft is a round shaft of iron, which is smoothly tured and finished, having one or two key-seats or grooves, cut in it lengthwise, for the purpose of securing the cams in their places. The shaft rests in boxes, which are usually supported by shoulders cut on the upright posts of the battery frame. Cam-shafts vary in diameter from 4 to 6 or 7 inches, according to the number of cams to be fixed upon them and the weight of the stamps to be raised. In some mills a single cam-shaft is made long enough to carry all the cams for as many batteries as there may be. In Nevada and California, how- ever, short. cam-shafts are in general use, a separate shaft being employed for each battery, or, in many cases, one shaft for two batteries. Separate cam- shafts are preferred, on account of the independence of each battery, so that if one be stopped by any accident to the cams or the stamps, or for repairs of any kind, the operation of the others is uninterrupted. Each shaft, in such case, is driven by its proper pulley, which receives its motion, by means of belting, from a countershaft. In the figures on Plate XIX the pulleys and belting are shown. The cam-shaft is set in motion by applying the tighten- ing pulley to the belt. The number of stamps in each battery is commonly four or five. The latter number seems to be preferred. The order in which they are allowed to drop is not always arranged in the same manner in different mills, but the desired conditions are that the weight of the stamps to be raised may be uni- formly distributed on the cam-shaft, so that the weight of metal lifted may be, as nearly as possible, the same at any moment of the revolution, and that each stamp may fall effectively upon the material to be crushed, and, by the force of its blow, aid in the proper distribution of the stuff among its neigh- TREATMENT OF THE COMSTOCK ORES. 215 boring stamps. If the stamps are allowed to rise and fall in regular succes- sion, from one end of the battery to the other, the material is usually found to accumulate at one end, and the effective duty of all the stamps greatly diminished. The order must therefore be varied. Ina five-stamp battery a common arrangement is to let fall first the middle stamp, then the end stamp on the right, then the second stamp on the left, then the second stamp on the right, and finally the end stamp on the left. The order in which the stamps are to fall being determined, it is carried into effect by fixing the cams on the shaft in such position that each cam, by the revolution of the shaft, will lift its respective stamp at the desired moment. For this purpose the key-seats cut in the hub of the cam must be determined with care; one common key-seat being cut on the cam-shaft, when the desired position of any given cam has been ascertained, the key-seat in the hub is cut to correspond with that of the shaft. When it becomes necessary to hang up a stamp so that the cam may revolve without reaching the tappet, it is supported by a prop or stud, x, which is shown in the drawing on Plate XTX. The lower end of the studs, of which there is one for each stamp, is pivoted on a small shaft fixed across the battery from end to end, resting in boxes, which are secured to the uprights. Each stud is just long enough to support the stamp, when placed under the tappet, at a height which is about an inch above the highest lift given by the cam. ‘To bring the end of the stud into this position, when desired, the work- man lays a smooth stick on the face of the cam as it is rising to the tappet, and holds it there while the stamp is lifted. The stick is as wide as the face of the cam, long enough to be held conveniently, and an inch and a half thick at the end which comes between the cam and tappet. By this means the stamp is raised high enough for the stud to be put in place, which being done, the stamp is supported above the reach of the cam. ‘To set it again in motion the operation is repeated, the stud being withdrawn at the moment when the stick on the face of the cam has lifted the stamp clear of its support. In Nevada the weight of stamps in most general use is between 600 and 700 pounds. They are usually run at about 70 or 80, sometimes 90 or even 100, blows per minute; they drop from 7 to 10 inches, according to their speed, the greater number of blows per minute requiring shorter lift. In 216 MINING INDUSTRY. reducing the quartz of the Comstock lode by wet crushing, discharging through a No. 5 or No. 6 screen, the average duty is about two tons in twenty-four hours. In some mills it is said to reach three tons per day. Much of the effectiveness of the stamps depends on the degree of care devoted to keeping the working parts in good condition and with the regularity with which they are supplied with ore. This is commonly done by hand labor, the rock being shovelled in at such rate as it is crushed and discharged. In some mills, however, automatic feeders are employed, which give satisfaction. These consist of a hopper, filled with ore, from which a trough or chute leads to the feed-opening of the battery, so inclined that the ore will slide down from the hopper to the battery, if the chute, which is hung on a pivot, be agitated. A rod is attached to the chute, and so placed that the tappet of the stamp, when the latter gets so low as to require an additional supply of rock, will strike its upper end, thus giving a shock which causes the ore to move down and fall into the battery. QUANTITY OF WATER USED.—The quantity of water consumed in the bat- teries varies with the character of the ore and the degree of fineness to which it is crushed. Usually, in the mills of the Washoe district, the consumption is between 250 and 300 cubic feet per ton of rock treated, or from one-third to one-half of a cubic foot of water per stamp, per minute; but this includes the water used in the pans which does not pass through the batteries. At the Petaluma mill the supply tank contains 4,400 cubic feet of water, which is sufficient for eight hours’ work of full duty. The mill has 24 stamps, which crush 55 tons of rock per day, discharging at only one side of the mor- tar, through a No. 6 punched screen. The consumption, in this instance, is equal to 240 cubic feet of water per ton of rock, or #4 of a cubic foot ot water per stamp, per minute. ~ Making a due allowance for a portion of the water used in amalgamation, without having passed through the batteries, the quantity actually used in crushing, in this mill, does not exceed one-fourth, or possibly three-tenths, of one cubic foot per stamp, per minute. The method of measurement, in the delivery of water, is by ‘‘miners inches.” A “miners’ inch” is the quantity of water that will pass through an orifice one inch square in the side of the measuring box, under a head, usually, of six inches. The measurement is not uniform throughout the country, as TREATMENT OF THE COMSTOCK ORES. AAI G different heads are used in different places. Generally, however, in Califor- nia the aperture is made two inches deep and as long as need be in order to furnish the requisite number of inches, and the water in the measuring box, which is at one side of the supplying flume, is allowed to attain a height of six inches above the center of the orifice. The quantity of water that will pass through an orifice of one inch square in the side of the box, under a head of six inches, determined by multiplying the area of the orifice by the theoretical velocity \/ 2yh, and taking two-thirds of the product as effective discharge, is .02633 cubic feet per sec- ond, 1.578 cubic feet per minute, and 94.68 cubic feet per hour. The mill just referred to uses five inches of water. Assuming that its measurement is uniformly in accordance with the above conditions, the amount delivered in twenty-four hours is 11,361 cubic feet; equal to about 2064 cubic feet per ton of rock treated. ‘Taking the operation of this mill as a criterion, one inch of water is a supply for five stamps, including the quantity required for amal- gamation as well as for crushing. The mills of Virginia City and Gold Hill, that have no springs or other sources of water of their own, are supplied by the Virginia and Gold Hill Water Company. This company obtain water by means of tunnels driven into the hillside for the purpose, and by purchase from mining companies, whose works furnish considerable quantities. Under ordinary circumstances the supply of water, derived from sources above Virginia City and available for use there, is suflicient to meet all demands at that place; in addition to which there are more sources below the city, in the mines and lower tunnels. In seasons of drought some inconvenience is experienced. Pans.—The common features of the grinding and amalgamating pans have already been described on a foregoing page. There are, however, various kinds of pans which, although resembling each other in general char- acter, present some important differences in the details of construction. These differences have been gradually developed since the first introduction of the common pan, each aiming especially to meet some one or more of the various requirements of an efficient machine. The main objects sought for by inventors have been to produce grinding surfaces of most effective form, securing the greatest uniformity of wear with 28 218 MINING INDUSTRY. economy of power; to obtain the most favorable conditions for amalgamation, depending mainly on the free circulation of the pulp, the wniform and thorough distribution of the quicksilver, and the proper degree of heat; and to combine, with these requirements, simplicity and cheapness in construction, facility in management and repair, large capacity, and economy of time, labor, and materials in the performance of duty. The attempts that have been made to obtain these results have met with varied success, the different devices of any one pan sometimes obtaining a high degree of excellence in certain details at the cost of it in others. Among the differences in characteristic features of pans the most notice- able is that of the bottom and the grinding surfaces, some being flat, and others variously curved; other details, of more or less importance, such as the construction of the muller and the method of attaching it to the driver, the form of the shoes and dies, the means of fixing them in place, of providing for the heating of the pulp and for its circulation during the grinding and amalgamating process, vary considerably in the several patterns. The opinions of practical mill-men are somewhat divided regarding the comparative advantages of the different forms of pan-bottoms. The prevail- ing opinion, however, among those with whom the writer has conversed, seems to be, all things considered, in favor of the flat bottom. While other forms of grinding surfaces may possess superior advantages, theoretically, their greater efficiency, in practice, is often lost by the unequal wear of the surface of the muller, usually resulting from the difficulty of keeping the other parts of the machine, on which the grinding surfaces depend, in perfect order, The various parts of the flat muller are simpler in form, more easily handled, and more conveniently replaced when worn out. While the flat-bottomed muller involves the expenditure of more power in carrying its load of thick pulp, this disadvantage is counterbalanced, in the opinion of some, by the more complete distribution of the quicksilver and the, consequently, more perfect amalgamation. The flat-bottomed pans of Varney and of Wheeler, and that of Hepburn and Peterson with conical bottom, have been widely used during several years past. Some improvements have been added to them lately, and they are still held in high esteem by mill-men. Within the last year or two, other makers ° REFERENCE to Fig. 2. A Pan Run BCantral Cone C Gntral Shalt D Muller E. Driver, f Aperture for altaching shoes to muller h. Step bow g shoes i Dies J Lever for raisiuig muder hk. Rod for moving lever L Proection on Pan Run m Suniar projection on muadles’ n Wings alached to Pan km p. Ou conveyer J coe \ | \ ih i) lu lig lig Lig Plate XX1 Tig 4 Lf \ g \\ : D Se 1 Wheeler and Randalls Laceasior Pan 2 wheelers Amatgamalor 3. Hepburn and Petersons Pan 4 Shoe in Wheelers Pan TREATMENT OF THE COMSTOCK ORES. 219 have introduced new pans, the characteristic features of which are great capacity and simplicity of construction. Such are the large, flat-bottomed pans of McCone, Horn, and Fountain, which, in their mechanical details, seem to combine some of the best results of the experience that has been gained since pan amalgamation was introduced, and, by their enlarged dimensions, to have the capacity for treating, in the same or nearly the same period of time, a charge three or four times as great as that treated by any of the pans formerly in use. In the following pages a few of the pans that have been used, and are still in most favor, will be described briefly but with sufficient detail to indicate their most characteristic differences. Plate XXI presents views of three well-known pans. They show the three different forms of pan-bottoms, the flat, conical, and conocidal. The flat-bottomed pan, Fig. 2, known as Wheeler’s Amalgamator, is, perhaps, in more general use than either of the others, although Hepburn and Peterson’s pan is in great favor among many mill-men. WuerEter’s Pay.—The Wheeler pan of ordinary size is about 4 feet in diameter, at the bottom, and 2 feet, or little more, in depth. The general arrangement of the several parts of the machine may be readily seen by a glance at the drawing. A is the rim of the pan, im the center of which is the hollow cone, B, rising from the bottom, with which it is cast in one piece. Through this cone the vertical shaft, C, passes, which, being driven by the gearing below the pan, gives motion tothe muller, D, by means of the driver, E, which is keyed to the shaft, C. The muller is provided, on its under side, with shoes, g, that form the upper grinding surface. The form of the shoes is shown in Fig. 4, on same Plate. They are attached to the muller by means of two lugs or projections, f, f, which are received in corresponding apertures in the muller-plate and securely wedged with pieces of wood. The lower grinding surface is formed by the dies, 7, which are usually four or eight in number, covering the greater portion of the pan-bottom and secured to it ina manner similar to that by which the shoes are fixed to the muller. There isa radial slot or space between the dies which is commonly filled with hard wood. Below the bottom is a steam-chamber for heating the pulp. The vertical shaft or spindle, C, rests in a step-box, 4, to which oil is conveyed by the pipe, 220 MINING INDUSTRY. p. A vertical pin passes downward through the center of the step-box, in contact with the shaft and resting its lower end on the lever, 7. This lever may be raised or lowered slightly by the hand-wheel, on the rod, #, thus rais- ing the muller from the dies, if desired. The shaft, C, is also furnished with aserew by means of which the muller may be raised up entirely above the rim of the pan for the purpose of cleaning up or of changing the shoes and dies. The hoisting apparatus required in the absence of this screw is thus avoided. In order to impart an upward current or movement to the pulp there are inclined ledges, 7, on the rim of the pan; and smaller ledges, m, on the periphery of the muller, but inclined in the opposite direction. The pan is also provided with wings, or guide-plates, 2, four in number, which serve to direct the moving pulp toward the center. They are fitted into and may be removed, at pleasure, from a T-shaped projection on the pan-rim. The muller is caused to make, usually, about 60 revolutions per minute. It re- quires from two and a half to three horse-power. Its ordinary charge is 800 to 1,000 pounds. In some mills a still larger charge is worked. The capa- city of the pan is sometimes increased by adding a rim of sheet iron so as to increase the height of the side. The treatment of the charge usually requires four hours. The shoes and dies wear out in from three to six weeks, though they are made to last longer in some mills, their duration depending greatly upon the order in which the pan and all its principal work- ing parts are kept. On this condition the economy in the wear of iron and the efhcient operation of this and other pans chiefly depend. Neglect in oil- ing the working parts of the running gear is apt to cause unequal wear, the vertical shaft gets loose and out of line, the grinding surfaces cease to work together eyenly, and the efficiency of the pan is greatly impaired, while the costs of working are very much increased. Mill-men generally prefer a shoe and die of moderate rather than excessive hardness. The former wear out faster, but are thought to grind more efliciently. Such are usually cast of an equal mixture of white and soft iron. Greevey’s Pax.—A pan known as Greeley’s, which is used in some mills and which is highly spoken of, possesses the essential features of Wheeler's, but differs from it in minor details and has larger capacity. In the Petaluma mill, where ten of these pans are employed, the charge of ore consists of 2,200 pounds. TREATMENT OF THE COMSTOCK ORES. PPL The bottom of the pan, like Wheeler's, is flat and has a steam-chamber. The dies are cast in four quadrant-shaped pieces. In the middle of each piece, on the upper side, is a radial groove or canal, leading from the center to the circumference, which permits the free circulation of the material. A similar space is left between the two adjacent edges of the several pieces. The dies are secured to the bottom of the pan by a dovetailed or wedge- shaped projection, 5 or 6 inches long and from 8 to 4 in width, on the under side of each piece, which, fitting into a similar recess in the pan-bottom holds, them fast. The muller is a circular plate, cast separately from the driver, to which, for use in the pan, it is connected by means of four short uprights or legs, that are bolted both to the driver and the muller. The shoes are attached to the muller-plate in a manner similar to that by which the dies are secured to the bottom. On the upper side of each shoe is a projection, wedge-shaped in horizontal section, 5 or 6 inches long and from 3 to 4 wide, which fits into an aperture of corresponding form in the muller-plate, and so placed that the smaller end of the projection follows the larger end in the direction of revolution; so that the motion of the muller tends to fix the shoe more and more firmly in its place. (See Fig. 4, Plate XXII.) The muller, when in place, is raised and lowered, not by a lever below the step-box, as is the case in the Wheeler pan, but by a serew which passes through the hub of the driver and rests with its lower end on the top of the driving shaft. A hand-wheel at the upper end of the screw serves to turn it, raising or lowering the muller, and another hand-wheel, lower down, acts as a jam-nut to keep the muller at the desired height. When the muller is in motion it may be raised or lowered by arresting the last-named wheel. (See Fig. 3, Plate XXII.) To clean the pan up the muller-plate is lifted entirely out by means of a block and tackle. In some mills this is conveniently supported on a truck, which moves on a railway ata suitable height above the pans. By this means the truck can be brought into position above any one of the pans from which it is desired to raise the muller, and the hoisting apparatus thus applied. No guide-plates are used for directing the pulp, the circulation of which, without these contrivances, is very active, the pulp passing from the periphery 222 MINING INDUSTRY. of the pan, at the surface, downward toward the center, producing the sur- face of a hollow cone, through the aperture at the base of the driver and out- ward through the channels and between the surfaces of the shoes and dies, to the circumference, where it rises to repeat the process. The legs or stand- ards of the driver, connecting it with the muller-plate, promote this circula- tion by forcing the pulp to the center and downward between the shoes and dies. The pan is said to require about four horse-power. Varney’s Pay.—This is one of the older flat-bottomed pans, that has long been in great favor with many mill-men. The points of difference be- tween it and Wheeler’s are not of very great importance. It has about the same dimensions and capacity. It has no steam-chamber, but a pipe intro- duces steam directly into the ore, above the muller. The dies, on the pan-bottoms, are arranged nearly like those of the Wheeler. In this pan, and sometimes in others, the radial slots in, and the spaces between, the dies are filled with pieces of hard wood, of which the fiber is fixed vertically. The wooden surface wears slightly in advance of the die, affording a passage for the pulp, and, according to some, increasing the grinding capacity of the pan. The shoes, of which there are twelve, are fastened by bolts to the mul- ler. "Phe circular plate of the muller is separate from the hub or driver, on which it rests, and which has two projections at the base by which motion is imparted to the muller. The hub or driver is keyed to the vertical shaft or spindle, by which means it is set in revolution. Heppurn AnD Prrerson’s Pan.—Fig. 3, on Plate XXI, presents a view of Hepburn and Peterson’s pan. ‘The bottom of this pan has the form of an inverted cone, inclining toward the center, as may be readily seen in the fig- ure. The bottom is covered by four dies of corresponding form, which are secured in a manner similar to that employed in the other pans already described. There is no steam-chamber in the bottom, steam being intro- duced directly. In the center of the pan a hollow pillar rises, through which the driving shaft passes. The form of the muller corresponds with that of the bottom, and at the center has an upright hollow cone, by means of which it is connected with the hub or driver. The under side of the muller is fur- TREATMENT OF THE COMSTOCK ORES. 293 nished with shoes, between which, when attached to the muller, there is a channel or radial passage left for the circulation of the pulp. The muller also contains radial grooves between the shoes, so that, when the latter wear down, the channel may still be large enough to permit an easy movement of the material. The muller is raised or lowered by means of a screw and moyable nut at the top of the hub, the screw resting on the top of the driv- ing shaft, to which the hub is keyed. The circulation of the pulp in this pan. is effected without the use of wings or guides, such as are commonly employed in other pans for this purpose. When the muller is in motion the pulp, passing between the grinding surfaces, from the center to the circum- ference of the pan, descends again by its own weight toward the center, on the upper side of the muller; a movement promcted by the conical shape of the muller-plate. In the use of guide-plates or wings to aid the circulation there is sometimes a difficulty experienced im the tendency of coarse sand to settle and pack firmly, if the pan is stopped for a little while, and giving much trouble in starting again. By thus dispensing with the use of wings some inconvenience is avoided. The charge of the pan is about 1,500 pounds, usually working four hours on a charge. It runs at 60 or 70 revo- lutions per minute. Waueever and Ranpaui’s Pay.—Fig. 1, on Plate XXI, presents a view of a pan known as the Excelsior, devised by Wheeler and Randall. This pan differs from those before described chiefly in the form of the bottom, which is conoidal. The object of this device is to produce surfaces of such form as to insure perfect uniformity of wear and the highest degree of grind- ing effect. Its efficiency, in this respect, is attested by the experience of practical mill-men. It is not, however, so generally used as the ordinary Wheeler or other pans already mentioned. The dies, muller, and shoes have, of course, a form corresponding to that of the pan-bottom. They are secured in place in much the same way as in the Wheeler pan. There are guide-plates to assist in directing the move- ment of the pulp, and there are openings in the muller between the shoes for its free passage between the grinding surfaces. 'The gearing of the pan, step- box, and driving shaft, and means of raising the muller, do not differ materi- ally from the common Wheeler pan. ‘This pan is made of various sizes; the 224 MINING INDUSTRY. hl ed larcest is 44 feet in diameter, and treats 3,000 pounds of ore at a single oO 2 ? ? 5 charge. It weighs 5,000 pounds. Within the past two or three years pans of much larger dimensions, and, consequently, of greater capacity than those formerly used, have been intro- duced in the Washoe district, and have, generally, found great favor among mill-men. Until lately they have been chiefly used in working tailings, to the treatment of which, as well as of low-grade ores, they are especially adapted. It is claimed in their favor that they treat a charge of ore three or four times as large as that of the ordinary pans in the same, or but comparatively little more, time, economizing thereby not only time but labor and power. One large pan requires much less machinery and fewer auxiliary parts, in its ope- ration, than three or four smaller ones, of equal capacity in the aggregate. The attention of the workman is more concentrated, and there is a much snaller loss, proportionately, by wastage of ore, quicksilver, and other mate- rials. While the time allowed for amalgamation is much less in the larger charge than in the smaller one, in proportion to the quantity of ore treated, the results, so far, seem to be nearly or equally as good. These considera- tions are of special importance in the working of low-grade ores, which can only be done profitably on a large scale and at small expense per ton, and in which the loss of a small percentage of the value is comparatively trifling in amount. McConr’s Paxy.—The McCone pan, constructed by Mr. McCone, pro- prietor of the Nevada foundery, at Silver City, is one of this kind. Some of the details of its construction, and the method of setting it up, are shown in the drawings’ on Plate XXII. Figs. 1 and 2 show the pan, as it is mounted on a timber frame-work, and the gearing by which it is set in operation. In Fig. 2a portion of the pan-rim is removed to show the interior. Fig. 5 shows a vertical section and Fig. 4, a plan of the pan. In the latter a portion of the muller-plate is shown and another portion is removed, exposing the shoes and dies below. This pan is 5 feet in diameter and 28 inches deep. It is From drawings recently made and furnished to the writer by Mr. Tyrrell, of the Nevada Foundery. HI Mi GN Kl) HS eZ rr TREATMENT OF THE COMSTOCK ORES. 22 flat-bottomed and made either with or without a steam-chamber. When the latter is desired the false bottom is cast separately, with a rim an inch deep, and is then bolted tothe main pan-bottom, thus forming the chamber. ‘There are no standards or legs for the pan to stand upon, the bottom being a square- cornered plate of iron, projecting beyond the pan-rim, and it may be bolted directly to the timbers on which it is to rest. The bottom, with its central hollow cone, may be cast in one piece with the pan-rim, or, instead of the latter, a simple flange may be cast, corresponding in size with the rim, to which flange the rim, which may then be either a cast piece or made of sheets of iron riveted together, is bolted. An improvement has lately been made to save the wear of the rim or side of the pan and prolong its usefulness, by placing in the bottom of the pan a false rim or circular facing for the pan-side, about nine inches deep. This is cast in segments and made to correspond in form to the rim of the pan. When fixed in place it saves the pan-rim from wear in that part which would otherwise suffer the greatest degree of friction, just as the shoes and dies protect the pan-bottom and muller-plate. When worn thin by the friction of the pulp the plates may be removed and new ones substituted for them. The driving shaft or spindle, c, passes up from below through the central hollow cone, b, but its point of support is usually independent of the pan, resting, in such case, in a step-box, 4, which is fixed on a timber below. Some, however, prefer to have hangers bolted to the bottom of the pan and furnishing the support for the driving shaft, so that, if the foundations of the pan settle, the relative position of the several parts is more readily maintained. The step-box is cast in one piece, with a bearing for the end of the shaft on which the vertical miter-wheel and pulley of the common driving gear are fixed. , The driver or hub, £, which is secured to the vertical shaft, is in two parts, an upper and lower. The upper is fixed to the shaft by two strong feathers or sliding keys, 4. The base of the upper driver is cast with lugs, or projections, which fit into corresponding recesses in the top of the lower driver, by which means the latter is supported and set in motion. Above the upper 29 226 MINING INDUSTRY. driver is a cap-piece, 7, carrying the usual screw and nut arrangement for raising and lowering the muller, the bottom of the screw resting on the up- per end of the vertical shaft. The lower part of the driver has three or four stout lugs, or projections, at its base, which fit into carriers on the circular part of the muller at d, Fig. 4. These carriers are also made to serve as the means of aiding the circulation of the pulp, as they assist in directing the current toward the center when the muler is revolving, For this purpose they are sometimes cast five or six inches high, presenting a curved surface, (not shown in the case illustrated) to the pulp and forcing it toward the cen- ter of the pan. By this means the guide-plates or wings, usually fixed to the side of the pan, but which, to some extent, obstruct the motion of the pulp, are dispensed with. Grooves for attaching guide-plates are, however, cast in the pan-rim, so that those who prefer may use them. The dies and shoes used in this pan resemble, in many respects, those of other pans. There is an inch anda half space between the outer edge of the die and the edge of the pan, and a similar space between the adjacent edges of the dies. The shoes, between which there are similar spaces, and which also have radial channels, or grooves, on their under side, to facilitate circulation, have the same radial width as the dies. The radial width of the muller- plate is a little less than that of the shoe and die, in order to allow a freer inlet and outlet to the pulp. The muller makes from 60 to 80 revolu- tions per minute. The pan takes 4,500 pounds of pulp at an ordinary charge, and sometimes more. It is set up very simply, being bolted to timber supports below; and is put in motion or arrested by the aplication or withdrawal of a tightener to the driving-belt, as shown in Fig. 1. The price of this pan, with its necessary gearing, pulleys, &c., is about $800. Founrain’s Pan—The Fountain pan and the Horn pan, each so called from the name of its inventor, have been in use two or three years. They are much alike, differing only in minor details, and both, in many respects, resem- ble that just described. The first-named has been changed somewhat since its first introduction. In its present form, the body of the pan is 5 feet in diam- eter at the top, and 44 feet at the bottom. The bottom, rim, and central hollow pillar, are cast in one piece. A steam-chamber, when desired, is provided by TREATMENT OF THE COMSTOCK ORES. PDT bolting to the bottom of the pan a circular plate that is cast with a rim an inch deep. The upper edge of the rim is grooved out and a round piece of rubber packing laid in the groove, which, fitting closely against the pan-bot- tom makes a steam-tight joint and allows for the unequal expansion and con- traction of the metal. The dies are attached to the pan-bottom by means of a wedged-shaped projection as in the pan just described. The driver is cast in one long piece; its upper part, which is attached to the driving shaft by means of a key or feather, is cylindrical, and furnished on the inside with a long babbited bearing for the shaft; its lower part consists of three legs or standards, each of which has a square lug or projection at the bottom, which, fitting into a raised clutch on the muller-plate, carries and gives motion to the latter. The space between the legs or standards being open, affords free passage for the circulation of the pulp about the center. In front of each lug on the standards of the driver is an iron plate with a flaring or irregularly concave surface which, when the driver is in motion, tends to force the pulp to the center; while directly in front of this contrivance, that is, in the direc- tion of revolution, a large piece is cut out of the muller-plate, thereby afford- ing free passage to the pulp downward and between the grinding surfaces of the shoes and dies. Wings and guide-plates are thus dispensed with, though the pan-rim is cast with the ordinary means of attaching such plates if desired. As the bottom of the pan is flat, and the muller has the plane-circular form, the wearing eflect on the grinding surfaces is much greater near the circumference than near the center, owing to the difference in radial velocity. It frequently results from this that the shoes and dies of ordinary plane- circular grinding surfaces wear down much more rapidly at the circumference, leaving the metal thicker near the center, and so preducing an uneven bearing of the muller upon the bottom and, consequently, an irregular movement. In the Fountain pan the radial spaces between the shoes and between the dies are made wider, horizontally, near the center than they are uear the circumference, so that the area of grinding surface at the circumference may be more largely in excess of that at the center than it would be if those ? Spaces were of uniform width; thereby obviating, at least in part, the 228 MINING INDUSTRY. inequality of wear. ‘These spaces in some of the Fountain pans, are filled with wood, as already described in pans of other makers. The shoes at their circumferential edge are provided with plows to stir up the quicksilver lying on the pan-bottom. These pans work 8,000 or 4,000 pounds of sand ata single charge. Their average duty, in working tailings, is stated at ten tons per day. SETTLERS oR Suparatrors.—The settlers or separators (see Plate XVII) in which the quicksilver and amalgam are allowed to settle or separate themselves from the pulp, after treatment in the pan, have already been generally described on a foregoing page. ‘They do not present so many important differences in details of construction as the pans do. They are made larger than the pans, usually having a diameter of 7 or 8 feet. They are commonly made now with a flat, sometimes concave, circular, cast-iron bottom, having a hollow cone or pillar at the center and a flange at the circumference, to which the rim, either of wood or sheet-iron, is attached. The central shaft, with its driving gear below, the screw and nut arrange- ment above, for raising and lowering the stirrers, and the yoke or driver fitted to the revolving shaft, are not essentially different from the similar parts of the pans. Hangers are sometimes bolted to the bottom of the settler to carry the step-box of the vertical shaft and support the driving gear; or these may rest on a timber frame independent of the bottom, as shown in the figure on Plate XVII. To the yoke or driver are attached four radial arms reaching to the circumference of the vessel. On each arm are two or sometimes three legs, terminating in a wooden shoe, variously shaped, which touches the bot- tom, These legs are movable radially, so that any one may be fixed at such point between the center and circumference as may be desired, and they are usually arranged at different distances on the several arms, so that in the course of each revolution each part of the surface of the bottom is passed over by one or another of the shoes. The discharge of the separator is usually effected through outlet-holes, already described, and shown in Fig. 1, on Plate XVI. Sometimes, as in a separator constructed by Mr. Fountain, the discharge holes are placed in the central cone of the vessel, in order that it may be where there is the least TREATMENT OF THE COMSTOCK ORES. 229 motion, avoiding thereby the loss of fine particles of amalgam or quick- silver. The method of withdrawing the fluid amalgam or quicksilver from the vessel has already been indicated, and an ordinary contrivance for this purpose is shown in the figures on Plate XVI. Different makers vary this plan in some of the details. In some separators the groove or canal for the collection of the quicksilver is circular, concentric with the pan-bottom, and usually placed midway between the circumference of the bottom and the base of the central cone. The outlet-pipe for the discharge of the quicksilver and amalgam is connected with the bottom of this groove, leading out under the vessel to a point beyond the circumference, where it may terminate ina bowl or may turn upward and be fitted with a vertical pipe in which the outlet may be fixed at any desired height and the quicksilver allowed to discharge itself con- tinuously as fast as it accumulates in the groove or receptacle in the pan-bot- tom. A cock or plug at the lowest point of the discharge-pipe permits the whole of the quicksilver to be withdrawn when desired. Aarrarors —The agitators, see Plate XXII, through which the pulp passes after leaving the separators are, in general, wooden tubs, that vary in size from 6 to 12 feet in diameter and 2 to 6 feet in depth. The main object in letting the stream of pulp pass through them is to retain and collect as much as possible of the quicksilver and amalgam and heavy par- ticles of undecomposed ore that are carried out with the pulp discharged from the separator. A simple stirring apparatus somewhat resembling that of the separator keeps the material in a state of gentle agitation, the revolving shaft carrying four arms to which a number of staves are attached. In some mills there are several agitators, in most cases only one, and by some they are not used at all. The stuff that accumulates on the bottom is shoveled out from time to time, usually at intervals of three or four days and worked over in pans. Beyond these are a number of contrivances for concentrating the most valuable portions of the tailings. Among them are blanket sluices and other variously devised machines, some of which will receive further description in a following section when tailings and sluices will be more particularly noticed. GENERAL ARRANGEMENT OF Mixis.—The general arrangement of the ) 230 MINING INDUSTRY. machinery in a mill, working silver ores by the method described in the fore- going pages, may be illustrated by a drawing on Plate XXUIT, which presents a sectional view of the building and the more important machines employed in it. The batteries of stamps, as many as there may be, are arranged in one straight line. Behind them, that is on the feed side, is the breaking floor, where the rock is prepared by a stone-breaking machine, or, in its absence, by hand. When the slope of the ground permits it, large bins are sometimes constructed above and behind the breaker, into which receiver the wagons or cars bringing the ore from the mine may discharge their contents. As the outlet of the bins is on a higher level than the mouth of the breaker, the rock is delivered to that machine without much handling. Such bins, where prac- ticable, are of great advantage in providing a reserve of ore for the mill when- ever communication with the mine is interrupted for atime. The batteries discharge the crushed ore upon an apron, or, as in the case illustrated, into a trough, or launder, which conveys it to the settling tanks. These stand di- rectly in front of the batteries, though in some mills, for lack of space, they extend along the adjacent side of the building. A platform is usually pro- vided upon which the pulp may be deposited when shoveled out of the tanks. Some mills are so arranged as to use a car, in which the pulp is moved from the tanks to the pans. ‘This is especially necessary when the tanks are more remote from the pans, or when the latter are arranged in a line at a right an- gle to the line of the batteries. Generally the pans are arranged in a straight line, parallel to the line of batteries, as in the case illustrated. The separators stand in front of the pans, arranged in a parallel line, and on a sufficiently lower level to permit the charge of the pan to run into them. Below the separators are the agitators or other similar contrivances for the purpose of preventing the escape of quicksilver or amalgam. ‘The power is usually communicated from the steam-engine or other motor, by gearing or belting to a line-shaft which is placed in front of, and par- allel with, the line of batteries. On this shaft are pulleys, opposite to those of the several cam-shafts, to which they transmit, by belting, the power necessary for the stamps. The same shaft imparts motion, by means of countershafting and belting, to the rock-breaker and to the pans. Forthe latter a line of Al. Ore Floor B. Rock Breaker. C Batters D. Tanks Ee. Fans. Li) Separators. GAAGUAOLs Dine SHale. hiCam Shalt, L Countershalt?, tor Rock Breaker. WeCountershal? tor Pais and Scpararors . i Seale: 7 Ree sage TREATMENT OF THE COMSTOCK ORES. 931 shafting is usually arranged under the row of pans, from which shaft each pan, separator, agitator, or other similar machine may be driven by a separate pul- ley. The power required for each stamp of ordinary or average weight, with due allowance for friction, is about one and a-half horse-power per stamp. The power demanded by the pans is from three to six horse-power, accord- ing to their size and capacity. The expenditure of power per ton of ore crushed, ground, and amalgamated, judging by the relation existing between the power of the engines provided and the work performed by the mills, is between one and a-half and three-horse power, averaging probably about two, but varying according to the capacity of the mill and the economy with which the power is applied. va MINING INDUSTRY. SECTION IIt, COSTS AND RESULTS OF MILLING OPERATIONS. Cost or Lanor anp Marerrats.—The number of men employed in a well-managed mill of twenty-four stamps and ten Greeley or large Wheeler pans, having a total capacity for treatment of about 50 or 55 tons of ore per day of twenty-four hours, is as follows: Two, breaking rock and supplying the feeders, both by day; two feeders supplying the stamps, one by day and one by night; three tankmen discharging the tanks and supplying the pans, each working eight hours; two amalgamators; two helpers; two engineers, one each by diy, and one each by night; one foreman and one mechanic—in all fifteen men. The price of labor varies from $3 50 to $6 per day, averaging, perhaps S450 per day for the several classes employed in the mill. The cost of labor per ton of rock treated, would, however, reach a somewhat higher figure in the course of a year than is indicated by the foregoing list of employés, owing to unavoidable loss of time for repairs or other hinderances, which diminish the actual capacity of the mill. The average cost of labor, per ton of ore, is from $2 to $3. The other chief elements of cost in the operation of a mill are iron, consumed in wear of castings for stamps and pans, averaging about S1 per ton; quicksilver, consumed or lost in the amalgamating process, of which the amount is rarely less than one pound and frequently one pound and a-half per ton, costing about SL; fuel, the cost of which varies from $6 to $16 or 518 per cord, according to the distance of the mill from the source of supply, and varying therefore from $1 to $3 per ton; water, when purchased from the Virginia and Gold Hill Water Company, at about $100 per inch, costing from 30 to 40 cents per ton of rock,' in mills of fair average duty; other materials and incidental expenses making in the aggregate an important item; and finally, transportation of the ore from the mine to the mill, varying from S1 to 4 per ton, which, if not properly an item of milling expense, enters into the account as an offset to cheap fuel or water-power, which can only be had at a considerable distance from the mines. ‘The Petaluma mill uses five inches of water, for which it pays $500 per month, treating 1,650 tons of ore; equal to a cost of thirty cents per ton of ore for water. TREATMENT OF THE COMSTOCK ORES. 233 The foregoing may be illustrated by some of the statements that follow, showing the details of cost in two mills. The first statement concerns one of the best mills in the district, situated between one and two miles from the mine supplying the ore. The transportation of the ore in this instance aver- ages about $1 50 per ton. The mill is driven by steam, and pays $12 per cord for wood. There are twenty stamps and twelve Wheeler pans. The capacity of these is between 35 and 40 tons per day, for days actually worked. During the six months to which the figures apply, 6,019 tons were treated in 1684 days’ work, an average of nearly 35} tons per day; the remaining 154 of the 184 days the mill was idle. The costs were as follows: ral OOr MG MiNi Slee eee od ope ee ee oe OS elas oe De iG iorewood. per: ton, 4 Ol One- Cond. ..2.: 3224054020 oc ua ctu 2 00 Wor-qaielsitver, pen ton, 1, pounds... 2 0 ee cee eee sks 1 15 Morcastings, per ton, 6? pounds....2 2.5.22. 2.se2-4 225204556 60 Forsulphate of copper, per ton, 14 pounds....---.62-.- 202.2 27 UES AOI Spicer Serge pelea eet rele gt mae ete ier rane ale abe ow os ES, 12 Mor hauling aad Sundnies. 2.61 yo shot ace kede teen! Gauls sdeveescwcecaxee es 2 dl AO ta lapel LOMma seh peck eo tete nant tates es occ 9 02 During the six months next ensuing, the cost, per ton, for treating 6,539 tons, was $8 33. The statements just given are drawn from accounts made in the year 1867; but for the mills of the neighborhood referred to the costs of perform- ing the same kind of work have not been much, if at all, diminished since that date. The following statement presents carefully analyzed accounts of milling costs in the Savage mill, one of the two belonging to the Savage Mining Company, and employed in treating ores from the Savage mine. This mill is situated in Washoe Valley, fourteen miles from the mine. Unlike the case previously referred to, this mill has the benetit of cheap wood, costing $6 per cord, and a partially sufficient water-power; advantages obtained at the 30 234 MINING INDUSTRY. cost of long transportation of the ore, involving an expense for that item of not less than $4 per ton, and sometimes more. An additional disadvantage is the liability to long-continued interruption in the work, owing to the im- passable condition of the roads during bad weather, stopping the supply of ore, and diminishing the earnings of the mill, while some of the expenses must of necessity continue. Thus, during the months of January, February, and March, 1868, no ore was received from the mine or crushed; and the total loss of time by the stamps or crushing machinery, owing to this and other causes, was 150 days during the whole year. The pans lost during the same year 118 days. In the following year, the stamps lost 195 days, while the pans lost 180 days. The power is supplied by a 28-foot water-wheel, and an engine of 16- inch cylinder. The capacity of the stream is unknown to the writer, and the proportion of power furnished by the wheel is uncertain; but as about five cords of wood per day were consumed, on the days of actual running, the engine must act an important and indispensable part in the operation of the mill. The mill has sixteen stamps weighing each about 700 pounds, and twelve Wheeler pans. The method of operation corresponds in its essential features with the general description already ‘given. TREATMENT OF THE COMSTOCK ORES. Detailed statement of Milling SAVAGE MINE. Cost for the years ending Fune 30, 1868 and 186g. 2 30 Number of tons reduced- - - - - OMicers and general labor - .- - - Driving power: bole“ oo al ty Se OR AS eo ee AiMoleys! pe Pee ce ee Bia ay eee Sundries, meeca= | see, f= @=. fe = Us Preparing ore for batteries - - . - Batteries : [Sao Cerne Tras. cen ash ose) bee ee ee Ge fe ee DUNOGLICS? = tages ae bots hoe on ee a Amalgamating: [ab OT sas Bie io tear Sp tebe oh a Castings Slee se pk a, en TS Salt ot some eink SS gw ow ath co Sulphate of copper - - - -..-~- Quicksilver 2 cues aac 2 © Repairs: WaDOT er a eewe FS |e a= weet ete Sundries Seen tte ee ee Incidental, 2 s2- 2 725 Sars eases = Total cost forlabor - .- - . . Total cost for material . .- . . Total cost for incidental - . . .~ Haulineore = ae) oe ee) ee eyes Total for hauling and milling - - Received from tailings - .- . - ~ Net costi<7 22) Sree SE 1868. 1869. =P eed < 7,749 6,440 Per ton. Per ton. Per ton. Per ton. 2 Mei oe foie So 60.7 5 So 52 ey = $0 60.6 $o 65.8 ae 86.4 93-4 = 08.2 09.3 D552 I 68.5 Sh, eS 2's 22.4 ca Pan 25 = 3.4% 21 23 See 20.2 21 ane 03.3 O4 H 44.5 48 2 & 71 67.7 ae Wins 61. oes 07 Me st os 17 ir as) 63 go 78 PN 6-hine 220: sew G30 20.1 a st me 50 I2 I 13.6 35.41 a eee 38.9 | - - - 49 == 2 99-3 2 59.6 Syeies 3 59-4 2 92 gg 38.9 49 | 6 97.6 6 97.6 6 00.6 6 00.6 See =. 2 4 28. as 4 06 ees eee Ir 26 ao 10 06.6 a cee ar eee 3 63 aoe T6726 =< - os 7 63 - 8 39 It appears, from the foregoing, that the actual costs of milling in the mill referred to were $6 per ton in 1869, and $6 97 in the year 1868, not includ- ing anything for hauling of the ore. The writer is not in possession of similarly detailed accounts of the costs 236 MINING INDUSTRY. of such work in mills where water-power only is employed, but it is said by man- agers of such mills to be between $5 and $5 50 per ton, not including hauling. The hope for the future is to reduce these costs to a still lower figure ; and it is not improbable that by increasing the capacity of the mills, and using large pans, that low-grade ores, demanding less nicety in treatment than is necessary for those of better quality, may be milled for $4 per ton. Indeed, it is the expressed opinion of some of the most experienced mill-men in the district, that such ores may be treated in steam-mills at the last-named figure, by the aid of the advantages conferred by the new railroad, cheapening trans- portation of both ore and fuel; with the further benefit to be derived from a reasonable reduction in costs of labor. In the account just given of the cost of operations for two years of the Savage mill, it will be observed that the bullion produced from the tailings is subtracted from the total cost of milling, apparently reducing the expense of working by $3 63 per ton in 1868, and $1 67 per ton in 1869. This is, in fact, no reduction of the costs; it is simply an addition to the product that had already been derived from the first treatment of the ore by the regular process. In the case of a custom mill, receiving a fixed price for working ore and returning to the customer a certain percentage of its assay value, pre- viously agreed upon, the tailings become the property of the mill; and what- ever may subsequently be extracted from them, accruing to the mill owner, actually diminishes, by the amount of such product, the expenses of his business, and, so far, the costs of milling per ton. In the present case, while the product of the tailings does not reduce the working costs actually, it does so relatively ; that is, the cost, to the mining company, of working ore in its own mill, as compared with the cost of having it worked in custom mills, is not only lessened by the difference that exists between actual costs and the miller’s price, but still further diminished by whatever value may be obtained from the treatment of the tailings, amounting, in the present instance, as we have just seen, to $3 63 per ton in 1868, and $1 67 per ton in 1869, for every ton of ore worked. This will, perhaps, be more clearly understood when the location of the mills, their relation to the mines, the methods of sapling and determining the assay value of the ores, and the relation of that value to the yield obtained by milling, have been more fully set forth. TREATMENT OF THE COMSTOCK ORES. 237 RELATION or Mines to Miris.—The mills working on the Comstock ores are located at various distances from the mines, some being in the immediate vicinity, while the most remote are from thirteen to fourteen miles away. The several cations or ravines of the Washoe hills, leading down from the croppings of the vein, where the hoisting works of the. mines are situated, to the valley, 1,500 or 1,800 feet below, are all occu- pied by mills, thirty-five or forty in number, that are within a radius of three miles, or at an average distance of one and a half miles from the supply of ore. These are all driven by steam-power. More remote from the mines, but nearer to the sources of fuel, are other mills, some driven by steam, some by water, and some by steam and water combined. On the Carson River, distant from seven to ten miles from Virginia City, are a dozen or more mills, whose position gives them the advantage not only of cheap fuel but also of water-power, either partly or wholly sufficient for their demands. In Washoe Valley, lying west of the Washoe hills, and separating them from the Sierras, are eight or nine mills, some of them likewise enjoying the ad- vantages of a partly sufficient water-power and cheap fuel, but situated ata distance of fourteen miles from the mines, and incurring consequently a great expense in the transportation of the ore. The comparative advantages of these different locations so nearly coun- terbalance each other in a long-continued period of operations that it is per- haps difficult to pronounce decidedly in favor of either, at least under condi- tions existing previous to the completion of the railroad. The first-mentioned class of mills, while paying dearly for their motive power and supply of water for milling purposes, have, on the other hand, the advantage not only of cheaper hauling, but, owing to their proximity to the mines, a steadier supply of ore. Some of the distant mills, especially those that have water sufficient to enable them to dispense with steam altogether for purposes of power, may diminish the actual cost of reduction of the ore sufficiently to more than counterbalance the additional cost of hauling, but they are sometimes liable to loss of time on account of impassable roads or other obstacles that interrupt the constant sup- ply of ore, and a few days of idleness will more than absorb the profits of a mouth’s work. Nearly all the mills of the district are “custom mills;” and the greater 238 MINING INDUSTRY. part of the ore produced from the various mines is worked in such. “ Cus- tom mills” are those that receive the ore from the producer, work it at a fixed price per ton for treatment, and return to the customer a certain percentage of the value of the ore, the latter having been previously determined by assays. This price for working ores during two or three years past has varied between S813 and S15 per ton, including the cost of hauling the ore from the mine to the mill. Quite lately it has been reduced somewhat, though during 1869 the average was but little, if at all, below $13. Since the beginning of the pres- ent year, according to late advices from Virginia City, some of the mills of the district have reduced the price to 59 per ton. Some of the large producing mines also own mills, but seldom of capacity sufficient to meet all their demands. Thus the Savage mine in the year ending July 1, 1868, treated 16,810 tons of ore in its own mills and 67,815 tons in custom mills. The ores are carefully sampled, both before delivery to the mill and after crushing at the mill, as will be explained in more detail below, and a return of sixty-five per cent. of the assay value is required of the mill owner. Falling short of this in bullion, the mill is bound to make good the deficiency, while any excess obtained by so much of the process of treatment as has been already described in this chapter belongs also to the mine or customer. Some mills, as may be seen by the tabular statement further on, make returns as high as seventy per cent. or even more, but, as might naturally be expected, the average return of the mill to the mine does not much exceed the requirement. The residue, or “tailings,” of the ore, after it has passed through the separators, belongs to the mill, and this is in many cases made to yield a good result on reworking. It is, therefore, the interest of the mill owner, when working at a fixed price per ton, to treat as many tons as possible and to return no more bullion in excess of the required standard than may be necessary in order to maintain a good reputation among com- peting mills. Sixty-five per cent., therefore, does not fairly indicate the per- centage of value actually extracted from the ore, and is not a fair criterion by which the efficiency of the process may be judged. 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I s — a : : a : a : | a : *soqdurns *sojdues ‘soqd aru Saly *soqdurts [[It 19, *saydures [[ru 19 *satdurvs uosvAA 19 . -19d—uoly [itu 19q | vost 19g att w d -UITS UOSTA 19g 1 mt d J ° d iad! }-Inq an uf ; aur a “AQuendg goss puv Pate poonpoid uoypng Ries ; J° | -y9d—oa0 ayy ut 19.Aq1s sonqwa Aussv yo ‘yuao rod ‘pjary *uo} tod aro jo onpea Avssy ielelnactatee th pur pjos jo uoyiodorg [:g340 ssv1D-dauIHL] Oggt ‘1 AL 07 ‘ggg ‘I Ayn morf ‘ging ayz uotf dgimp woyr sapgiuvs Cg pew sagiuvs uoSvar Kg potnuapop sv jougpr Lossp ap ypir uous0utos ur ‘ag fo uoympoy fo synsey Myjuozy Jo guomanps TREATMENT OF THE COMSTOCK ORES. 945 Rexiation oF Yretp ro Assay Vatun.—A glance at the columns of the foregoing tables, stating the percentage of the assay value obtained by milling, will show that the yield frequently exceeds sixty-five per cent. of the contained value. This is indeed more notable in the first of the two years referred to, because in the last year the ore of this mine has not only been of lower grade but has carried with it more base mineral, rendering the extraction of the precious metals more difficult, and consequently dimin- ishing the yield obtained. The impression generally existing that only sixty-five per cent. of the value is obtained by pan process and that thirty-five per cent. is lost is erron- eous; for the return of sixty-five per cent. is based on the result of treating the ore in the pan and collecting the amalgam.in the settler; in some mills the additional product of the agitator is returned with that of the pan and settler, while in other mills this is not done, especially if the required stand- ard of sixty-five per cent. has been already reached by pan and settler with- out further addition. Moreover, the return of sixty-five per cent. includes nothing of what is, or may be, obtained from the subsequent treatment of slimes and tailings; and, furthermore, it is to be considered that the ore, as charged to the account of the mill, contains an average of six or seven per cent. of moisture, for which, in the return, no allowance is made ; the sample for assay, by which the return is made, being previously dried, sixty-five per cent. of the dry sample is really equivalent to sixty-nine or seventy per cent. of the wet rock. This may be illustrated by the following data, concerning the operations of the Savage mill, during six months ending December 31, 1867. During that time 5,830 tons were worked. The assay value of this ore was $318,639 80 per mill samples, and $324,206 72 per wagon samples; or S54 65 per ton, by mill samples, and $55 61 per ton, by wagon samples. The total yield obtained was $220,785 17; equal to 69 per cent., by mill samples, and 6875 per cent. by wagon samples. ‘This yield was obtained by the ordinary operation of crushing, amalgamating in the pan, and collecting the amalgam in the settler; this much constituting the process to which all ore is submitted in all mills. It will be observed that the required standard of sixty-five per cent. was already exceeded by this alone, without including 246 MINING INDUSTRY. the product of the tailings or allowing anything for moisture. During the six months to which these figures relate, the product in bullion from the tail- ings was $12,730 71; and if this be added to the yield of the ore originally obtained by the first operation, we have a total product of $233,015 88, equal to 71.87 per cent. instead of 68.1 per cent. by wagon samples ; or 73.12 per cent. instead of 69.2 per cent. by mill samples. Tf, in addi- tion to this, we now allow for seven per cent. of moisture on the ore, not taken into account in the assay sample to which the foregoing percentages are referred, we have an actual return of 77.27 per cent. by wagon samples, and 78.62 per cent. by mill samples. Finally it is to be observed that the product from the tailings above given is not all that is obtained from that source. The amount here stated comes chiefly from the agitator. The stream of tailings passing from the settler, in which the bulk of amalgam is collected, enters the agitator, where much of the amalgam and quicksilver that has escaped the settler has further op- portunity to deposit itself. At intervals of four or five days this vessel is emptied and the accumulations are reworked in an ordinary pan, yielding $18 or $20 per ton. The yield thus obtained is nearly $2,000 per month, and forms nearly, if not quite, all the product represented in the foregoing statement. After leaving the agitator the stream passes on, the tailings still carrying enough value to make them worth further treatment; for which purpose they are, in fact, sold by the mill to second parties, who do a profitable business in working them again; but this last product is not in- cluded in the figures already given. The yield obtained by this final work- ing of tailings is not definitely known to the writer but is generally stated at about $5 50 per ton, which would add about ten per cent. more to the results of the process in the mill, as already shown. Some mills claim to have obtained more than eighty per cent., and even eighty-eight per cent., of the assay value of the ore, by the ordinary methods, without including the product of the tailings or allowing anything for moist- ure. This, if true, is exceptional; but it is not impossible that a certain lot of ore may have contained an unusual proportion of free gold, which, while easily escaping due representation in the assay, would add greatly to the value of the bullion obtained. TREATMENT OF THE COMSTOCK ORES. 247 The following table shows some of the comparative results of a number of different mills, all working on Savage ore at sundry times, between July 1, 1867, and March 1, 1868. The statement is furnished from the records in the office of the Savage Mining Company. The careful manner in which Mr. Bonner, the superintendent of this company, and his assistant officials have collected and preserved in comprehensive form the various results of milling and mining experience is worthy of high praise and extended imita- tion among others similarly engaged. The following table is but one exam- ple among many which their records afford of valuable contributions to useful or interesting statistical knowledge. The percentage of assay value obtained stated in the table, is based only upon the amount taken from the customary process of treatment in pan and separator, without taking into account anything subsequently produced from the agitator or working of tailings, except where the contrary is specially mentioned in the appended notes. MINING INDUSTRY. Comparative statement of Operations of twenty-one different mills treating ore from Savage Mine between Fuly I, 1867, and February 1, 1868. 2 Assay value of | Relative proportions of Yield per Percentage of gold and Fs ore per ton gold and silver in the cent. aS| Relative silver obtained as 8 Amount of Su Shea Ore as: Per ie proportion | P&— = ore in— in the bul- . a 3 Mill Wagon 3 lion of— Mill Wagon Se , e sample. sample. g : & sample. sample. my . f=} (3) 2] a 5 F < g S A Fie : rey es oH 5 : Lu : u : 7m 8 Hf Pla | BL SISISIE] Bl lSelPlel ele £leie = Ss = = S ll det lee |e he Silt lS il/#zilsopl#Iisé8 ls a & a I i o tial oO a tal a i oe) a 1c) a o a No. 1] 5,830! « $54 65 | $55 61 | 29.5 | 70.5 71.5 | $37 86 | 69.2 | 68.0 | 36.3 | 63.7 | 85.3 | 62.5 | 86.5 | 60.7 2| 6,720 | 55 66} 53 35.| 29.7 | 70.3 72.0 | 38 67 | 69.4 | 72.4 | 36.0 | 64.0 | 84.0 | 63.3 | 93.2 | 64.4 3] 5,209 | 1,080 | 124 25 | x42 8x | 22.3 | 77.7 74.1 78 16 | 62.9 | 54.7 | 36.6 | 63.4 |103.0 | 51.3 | 77.1 | 46.8 4] 3,090 | 1,380] 50 22 50 12 | 29.7 | 70.3 70.8 | 32 47 | 64.6 | 64.7 | 37-5 | 62.5 | 81.6 | 57-4 | 83.2 | 57.1 5| 71334 |500] 48 34] 50 94 | 27.2 | 72.8 71.7 | 3295 | 68.1 | 64.6 | 36-3 | 63.7 | 91-0 | 59.6 | 82.8 | 57.5 6] 7,871 | 1,060] 49 24 | 48 68 | 31.5 | 68.5 71.6 | 33 98 | 69.0 | 60.8 | 34.3 | 65.7 | 75.1 | 66.1 | 84.2 | 64.0 7| 4,713 | 1,140] 47 86] 50 27 | 28.0 | 72.0 72.6 | 3497 | 73-0 | 68.7 | 32.8 | 67.2 | 85.5 | 68.2 | 82.8 | 63.4 8 507 | 1,170] 49 79} 55 24 | 30.8 | 69.2 | 27.3 | 72.7] 28 70 | 57.6 | 52-9 | 49.4 | 59.6 | 74.3 | 49.6 | 76.8 | 42.5 g| 1,82t | 1,670} 48 98] 59 74 | 34-4 | 65.6 | 29.4 | 70.6 | 36 29 | 74.0 | 60.7 | 38.7 | 61.3 | 83.2 | 69.2 | 79.6 | 50.2 10 825 | 0,490] 49 69] 52 70 | 32-0 | 68.0 | 28.3 | 71.7] 30 43 | 61.2 | 58.8 | 38.3 | 6z-7 | 73-2 | 55-6 | 79-4 | 50.7 tr 800} - - 47 53 54 44 | 29.2 | 70.8 } 28.4 | 71-6 52:2, 67.7 | 59.2 | 35-2 | 64.9 | 8r.4 | 62.2 259° | 53<7 r2| 2,744 | 1,810] 47 2 53 96 | 27.0 | 73.0 | 28.6 | 71.4 | 33 34 | 70.3 | 61.8 | 37-9 | 62.1 | 98.7 | 60.0 | 83.7 | 53.8 13] 3,618 | 1,180 3.04 | 47 67 | 27.4 | 72.6 | 28.2 | 71.8 | 29 37 | 68.2 | 61.6] 35.7 | 64.3 | 89.0 60.4 | 78.0 | 55.1 14] 1,544 | ,150| 54.37] 46 43 | 30.5 | 69.5 | 28.8 | 71.2 | 32 94 | 60.5 | 70.9 | 36-5 | 63-5 | 72-5 | 55-3 | 90.0 | 63.1 1s| 1,500]0,900] 44 37] 51 14 | 21.1 | 78.9] 29.9 | 70.1 | 34 47 | 77-6 | 67.4 | 41.2 | 58.8 |r51.3 | 57-9 | 92.6 56.6 16 368 | 0,310] 48 45 | 52 56 | 29.3 | 70.7 | 28.0] 72.0] 35 96 | 74.2 | 68.4 | 34-2 | 65-9 | 86.3 | 69.2 83:0: | 62.7 Iz 298 | 1,510] 46 25 52 42 | 28.8 ca (kc ae | 68.7 31 07 | 67.4 2.2 | 40.5 | 59-5 | 94.2 | 56.2 | 76.5 | 5.4 18] 1,116 | 0,700} 48 37 | 52 60 | 28.7 | 71.3 | 28.1 | 72.9 | 27 94 | 57-7 | 53-1 | 37-8 | 62.2 | 76-0 | 50.4 | 72-5 | 45.9 19 250 | 1,920] 4493 | 48 63 | 24.3 | 75-7 | 27-3 | 72 32 30 | 71.9 | 66.4 | 33.0 | 67.0 | 97.3 | 63.7 | 80.0 | 61.3 20 250 | 0,670} 46 24 58 15 | 30.6 | 69.4 | 29.0] 71.0 | 31 40 | 67.9 | 54-0 | 42-5 | 57-5 | 94-2 | 56.3 | 80.8 | 43.3 21 340 56 50 | 53 68 | 28.6 | 71.4 | 28.4 | 71.6 | 36 00 | 63.7 | 65.4 | 36.0 | 63.8 | 80.4 | 57.0 | 82.0 | 58.4 56,656 | 1,640] 56 62 §0:77'} 27:8 | 72.2 |-27.8. 172.2] 38.27'| 67.5, || 63.8 |-96.2 | 63.8 | 87.0.| 50.7 | 82.8 | 56.5. Total assay value, as per mill samples, gold $892,213 60 Bullion produced, gold . $784,680 86 Total assay value, as per mill samples, silver =. 2,315,810 07 Bullion produced, silver. 1,383,744 54 Total . 3,208,023 67 Total . Zi s < 2,168,425 40 Notes on mills referred to in foregoing table. No. 1. Wheeler Pan: Charge of ore 1,000 pounds; salt 5 pounds; sulphate of copper three-fourths of a pound; quicksilver 60 pounds, added after two hours’ grinding. Steam admitted directly. Time in pan, four hours. No. 2. Details as in No. 1. No. 3. This was all second-class ore, consequently less docile. used with each charge, but only a pinch of sulphate of copper. Salt is TREATMENT OF THE COMSTOCK ORES. QAO No. 4. Wheeler Pans: Charge of ore 1,000 pounds; 2 or 3 pounds of salt; 3 or 4 ounces of sulphate of copper; 30 to 50 pounds of quicksilver, put in when the pan is charged. Steam used directly. Time in pan, four hours. No. 5. Chiefly Wheeler Pans: Charge of ore 1,000 pounds; salt 6 pounds to each charge; subsequently the use of salt was abandoned without affecting the result; sulphate of copper 1% pounds; quicksilver 75 pounds, put in after every clean-up, subsequently 35 pounds with each charge; a quantity is also kept in the separators. Steam is used directly. Time in pan, four hours. No. 6. Hepburn Pans: Charge 1,400 pounds; no salt used; sulphate of copper, from 3 ounces to 2 pounds, put in with the charge; quicksilver 30 to 50 pounds, added with the charge. Steam used in chamber and direct. Product of the agitator, also product of reworking slimes, returned to the mine. Time in pan, four hours. No. 7. Wheeler Pans: Charge 1,500 pounds. No salt used. 13 pounds sulphate of copper, added in solution ; quicksilver 60 pounds, put in with the charge. Steam used in the chamber. Time in pan, four hours. Slimes, which in some mills are mixed with the sand to be worked in the pans, are never treated in this mill. The superintendent attributes to this much of the efficiency of his work, experiments having satisfied him of the evil effects of thus mixing slimes with sand. One ton of ore is thought to produce about one hundred and fifty pounds, or from seven to eight per cent. of slime. No. 8. Pans, reconstructed Wakely ; in effect, large Wheeler: Charge 1,500 pounds. No salt used. Sulphate of copper, one pound per ton of ore, added after grinding the charge one hour; quicksilver 75 pounds, added with the copper. Steam used in chamber. Time in pan, four hours, This mill having large tank capacity, the stream of pulp from the batteries has unusu- ally protracted opportunity for settling, and, in effect, the foreman reports that the water runs from the last tank “clear enough to drink.” The final tanks contain the slimes and these are mixed with the coarser sand, in the proportion of one-third of slime and two-thirds coarser sand, to be worked inthe pans. Without attaching undue significance to this note, it is inter- esting to contrast with it the note on No. 7, and to observe that the results of 250 MINING INDUSTRY. these two mills, as given in the table, are among the two extremes of good and bad work. No. 9. Varney Pan: Charge of ore 1,200 to 1,400 pounds; salt, 3 or 4 pounds per ton of ore; sulphate of copper, three-fourths of a pound per ton of ore ; quicksilver 50 pounds, added with each new charge, after the latter has been ground two hours and a half. There is always more or less quicksilver and amalgam remaining in the pan, except just after a clean-up. Steam used direct. ‘Time in pan, four to five hours. In addition to the usual sepa- rator there is a second or supplementary vessel of similar character, the pro- duct of which, though not very important, is returned to the mine. No. 10. Wheeler Pans. No. 12. Hepburn Pans: Use both salt and sulphate of copper. No. 14. Varney Pans: Use both salt and sulphate of copper. No. 15. Old-fashioned common pan or tub. The great excess of gold in the return, as referred to the mill sample assay, is probably to be explained by some fault in the assay of that sample, since the return does not differ widely from the general average of other mills when referred to the wagon sample, in which the proportions of gold and silver are about as usual. Nos. 16 and 21. Use the Knox pan, an older and simpler form than any of those described in detail in this chapter. In judging of the comparative efficiency of various mills or methods by the results obtained, on a large scale, at any of the mills in question, it is important to remember that the assay, which is the only standard to which the results are referred, is not infallible. Notwithstanding all the care exercised by the parties interested aud the great number of samples selected for assay, the result, after all, is only an approximation to the truth. Some portions of a given parcel of ore may contain free gold or segregated particles of rich silver ore, which quite escape due representation in the sampling, or the contrary may occur and the value of the parcel be thus overestimated. Further, the variable amount of moisture in the ore affects the result, since the assay is of the dried sample. Finally, the ores produce, in crushing, very variable quantities of slime, on account, partly, of the character of the gangue, some being more clayey than others, and partly by reason of the varying conditions present im the bat- TREATMENT OF THE COMSTOCK ORES. 251 teries, the weight and speed of the stamps, the size of the screen, &c., affect- ing the proportion of slime produced. These slimes carry with them a cer- tain percentage of the value of the ore, and the relative amount of slimes and coarser sand, produced in the crushing of any given parcel of ore, be- comes an important element in the consideration of the results obtained, whether the former pass out of the mill without treatment or whether they are mixed with the sand and worked in pans; especially if, as many believe, the finely divided condition of the particles composing the slimes is unfavor- able to amalgamation. Without considering the various details of manipulation in the pans, it will be seen from the foregoing that the mechanical elements of the problem are quite as important, if not much more so, than the much discussed and little understood action of the chemical reagents employed in the methods of reduction of Comstock ores. The possible and probable action of these will be further noticed in the following chapter. bo It bo MINING INDUSTRY. SECTION IV. TREATMENT OF SLIMES AND TAILINGS. The treatment of the residue, or that which remains of the ore after it has been subjected to the process already described in this chapter, is a mat- ter of much importance. In the earlier years of operation on the Comstock lode but little attention was paid to the stream of tailings that was constantly flowing from the mills, carrying with it a considerable proportion of the orig- inal value, because it was generally assumed that the first process had ex- tracted from the ore everything that could be obtained with a margin of profit above the costs of milling; but with the gradual improvement in methods of work and the reduction in costs of operation, the attention of mill-men has been generally turned to this subject. Frequent reference has been made, in the course of this chapter, to the character of these residues, the way in which they are produced, and their value as a souree of profit to the mills engaged in reducing the ore. It may be repeated that the term “slimes” applies to that portion of the erushed ore which is reduced by the stamps to an exceedingly fine condition and, flowing from the batteries in the stream of ruming water, does not find sufficient opportunity to deposit itself in the tanks in which the coarser sands are collected, but is carried beyond them, and only settled, after a long time, either in another set of tanks or in large reservoirs. These are properly called “battery slimes,” to distinguish them from the material that may be reduced to a similarly fine condition by the operation of the pan. The term “tailings” is understood especially to apply to that portion of the crushed ore which, after having been subjected to the grinding and amal- gamating process in the pan and settler, flows away from the latter, or from the agitator, and passes on out of the mill, deprived of the greater part of its valuable contents. A part of this material is in a very fine and slimy condi- tion, but the bulk of it may be better described as a fine-grained sand. Leav- ing the mill the stream flows onward, and is usually subjected at once to various methods of concentration, the most common of which is the blanket- table, by which means a portion of the escaping amalgam, quicksilver, and heavier particles of ore may be extracted to be reworked, while the great mass TREATMENT OF THE COMSTOCK ORES. 253 of material is finally collected in dams or reservoirs for still further treatment. Reservoirs for this purpose are placed at convenient points along the courses of the streams, or cahons, on which the mills are usually placed, though on account of the limited space in the narrow valleys they are necessarily small; but at the mouths of the cations, in the level country adjacent to the foot-hills, there are a number of reservoirs of large capacity, in which everything brought down by the streams finds a resting place, and is reserved for work in the tailing mills established there. A few paragraphs will here be devoted to a brief notice of the character of the slimes and the methods by which they are worked, the common means of concentrating tailings, and the disposition of the concentrations; and, finally, the treatment of the unconcentrated or “raw tailings.” Tt has already been shown that the quantity of slimes produced in crush- ing ore’ varies considerably in different mills. In some mills the proportion of slimes is thought to be about two per cent. of the ore crushed by the stamps, while in others it is said to be as high as ten per cent. This is partly due to the difference in the character of the ore or its gangue, and partly to the difference in the conditions under which the crushing takes place. As these slimes carry with them much of the very finely crushed silver ore, their assay value is not only considerably higher than that of common tail- ings, but is often higher than that of the original cre. Especially that portion of the silver-bearing mineral of the ore which exists in the form of rich sulphurets, being soft and readily crushed, is liable to be reduced to an impalpably fine condition, particularly if freed from particles of quartz, that might, if present, preserve it in a coarser form, and escape with it from the battery before being reduced to slime. AMALGAMATION OF Sires iy Pans.—The attempts to work slimes by ordinary methods in pans have not hitherto, or at least until recently, been followed by very satisfactory results. This has been attributed partly to the finely divided and clayey condition of the material itself, the particles of quicksilver and amalgam becoming coated with an adhering film of the slimy substance, preventing amalgamation and involving great mechanical loss of quicksilver; partly, also, to the probable existence of the silver in the form of sulphurets, as just indicated—a combination resembling that of the first-class 254 MINING INDUSTRY. ores, which require to be roasted with salt, chloridizing the silver and prepar- ing it for amalgamation. This roasting process, however, has hitherto been teo expensive to be used profitably in working slimes. Owing to these difh- culties the slimes produced in crushing have not been, at least until lately, a source of much profit. In some mills, as has been already stated, it has been the custom to mix a part of the slimes with the sand of the tanks, or, in other cases, with common tailings, and so work them over in pans; but the data are not sufficient to furnish any reliable estimate of the degree of efh- ciency attained in extracting their valuable contents. In other mills the stream bearing the slimes has been allowed to run off with the common. tail- ings, finding its way to the grand reservoirs at the mouths of the canons, while others have accumulated them in dams, made specially for that purpose, holding them in reserye for a time when they might be turned to some account. Within a year or two past much progress has been made in working these slimes in pans without previous roasting, and several mills of consider- able capacity have been devoted exclusively to this business, purchasing their supply of slimes from neighboring crushing mills, and treating them in such manner as to obtain a fair percentage of their value with considerable profit. The Messrs. Janin and Mr. Tra 8. Parke have mills of this description, in Six-Mile Cafton, not far below the large mill of the Gould and Curry company. The method of treatment employed in working slimes in these mills does not differ much, in mechanical details, from that by which the fresh ores are worked, the most notable feature of the process being the use of inuch larger quantities of chemical reagents than is customary in milling ordinary ore. The reagents themselves do not differ in kind, but the quantity is increased to an extent which makes it possible to believe in their efhcient action. In the Janin mill there are four McCone pans. These each receive 2,500 pounds of slime at each charge.’ The charge of ore for this pan is 4,000 or 5,000 pounds, but as slimes increase greatly in bulk on the addition of water, it will not take more than 2,500 pounds of the dry material. TREATMENT OF THE COMSTOCK ORES. 255 Twelve pounds of the sulphate of copper and thirty-six pounds of salt are put into the pan with each charge, and the whole is worked for two hours before putting in the quicksilver. Little or no grinding is required, as the material is already exceedingly fine; the muller is raised high enough above the bottom to avoid unnecessary friction, but is revolved at about the same speed as in working ore, the main object being to keep up a rapid and pertect circulation of the pulp. After two hours the quicksilver is added, and in large quantity, usually 300 pounds. The charge is then worked for four hours longer, and afterward drawn off into the settler, from which the amalgam is collected in the manner already described, while the residue is allowed to pass through large agitators, before finding its way to the tailing stream, in order to save as much as possible of the escaping amalgam and quicksilver. The quantity of quicksilver employed in this process is so large that the loss of that metal in the operation is proportionally great, especially as it 1s believed that the clayey condition of the slimes greatly facilitates its escape. This loss is stated at about five pounds of quicksilver to the ton of slimes. This item, together with the cost of the chemicals, which, by reason of their liberal use, amounts to a considerable sum, makes the treatment of slimes quite expensive, probably not less than 512 per ton. The supply of slimes is obtained by purchase from the neighboring erush- ing mills, their value being previously determined by assay. This value varies from $25 to $50 per ton, and the purchase price, for some time past, has been from 53 to $5 or more per ton, according to their contents. It is said that the method of working just described extracts upward of sixty, and frequently eighty, per cent. of the assay value. In Mr. Parke’s mill, in the same neighborhood, the method of operation is very similar to that just described. He uses, however, large wooden pans or tubs, having cast-iron bottoms but wooden sides. The tubs have large capacity. The wooden sides of the tub, which are 3 inches thick, are fur- nished on the inside with a lining, also of wood, 1 inch thick, which, when worn down, may be replaced by new pieces without reconstructing the tub. Tn addition to this inner lining it has been found advantageous to attach strips of wood, 2 by 4 inches thick, to the inner circumference of the tub; these strips stand vertically, and about 2 inches apart, producing a rough or corru- 256 MINING INDUSTRY. gated instead of a smooth surface en the inside of the tub. This has been found to assist greatly in the disintegration of the lumps of slime, which, although consisting of the most minute particles, hold together, like clay, with great tenacity when wet, and, in ordinary pans, frequently present a serious obstacle to thorough amalgamation. According to late advices from Virginia City, Mr. Parke has carried this improvement. still further by making this corrugated surface on a rim of cast iron. The corrugations may be on the rim which is east on the pan-bottom for the purpose of attaching the wooden staves of the side, or the rim may be cast separately and placed in the pan. The corrugated surface is 10 inches high and the rim is 38 inches thick. As the wear of a pan-rim is confined chiefly to within 10 inches of the bottom, the provision of this surface, which, like the shoes and dies, may be easily renewed when worn down, without changing the pan, is deemed a great improvement. Roasting or Siimes.—Before the working of slimes raw, or without roasting, had been brought to the degree of efficiency that it has in the hands of the Messrs. Janin, some efforts were made to devise cheap methods of roasting them with salt at a cost that would leave some margin of profit. The usual means of reasting first-class ores is by reverberatory furnaces, which involve a large expense, especially in labor, as the material to be roasted must be constantly stirred and turned, in order to present every particle to the oxidizing and chloridizing agencies. The cost of this method is too great for slimes of ordinary value. For the purpose of effecting a cheaper roasting, a furnace was devised, some time since, the chief object of which is to accomplish the operation with the least possible amount of manual labor, using some mechanical contrivances for stirring the pulp, and partly effecting, by the same means, the continuous supply and discharge of the material. This invention, known as the O'Hara and Thompson Roasting Furnace, sometimes as the Yerrington Furnace, from the name of the proprieter of the patent, consists of a horizontal flue 4 feet wide and 11 inches high in the arch and 80 feet long, built of common brick. At the two sides are three fireplaces, one near the middle on one side, two near the ends en the epposite side. At one end of the furnace is a chimney, but the main flue, just described, instead of opening directly into it, TREATMENT OF THE COMSTOCK ORES. PAST is connected with it by two side flues, that branch off from the main flue about ten feet from the stack, leaving space for a platform between the stack and the end of the main flue, which is open, or only closed by a sheet-iron door. The firing being in progress in the several fireplaces, the heat passes along the main flue and then by the branch flues to the stack. The material to be roasted is put on the platform at the end of the flue near the stack, and is moved, by the mechanical appliances referred to, into the flue and slowly along its whole length, at such speed as may be desired, and, at the same time, subjected to constant stirring and turning. This is effected by means of an endless chain, passing through the flue, and carrying a number of scrapers, Which, as they move along the ine, just rest on the bottom. The chain moves over two pulleys, one at each end of the flue, and is so arranged as to pass, in one direction, in and through the flue, and, in the opposite direction, outside of and above it. At two opposite parts of the chain are two circular pieces of iron, having the form of a ring, with a diam- eter about equal to the width of the flue. To each of these circles are attached the scrapers, six or eight in number. They are shaped something like a plow- share. As they pass through the stuff spread on the flue bottem they move it along and turn the particles with which they come in contact. The scra- pers may be so set on the ring that the entire surface of the flue bottem is covered at some time by one or another of them. According to the angle which the face of the scraper makes with the larger axis of the flue the for- ward movement of the material will be greater or less. By this means, as well as by the speed at which the chain is caused to move, the length of time which a given portion of the matevial shall eccupy in passing through the flue may be determined. The rings, carrying the scrapers, are jointed or hinged so as to pass over the pulleys on which the chain moves. At each end of the flue is a sheet-iron door, the lower part of which is hinged so that the rings may pass. There are also slots cut in the hinged parts for the passage of the chain. This furnace, although devised several years since and affording then satisfactory results with experimental trials, has not yet come into general use. Some furnaces of this kind, but differing in some details of construction, were 33 258 MINING INDUSTRY. built, in 1868, at the Rising Star mine, in Idaho, but, owing to the stopping of the mine, were not long in operation. Tn the first furnace of the kind, built at the Merrimac mill, on the Car- son River, experiments, on a large scale, showed that slimes could be roasted at a cost varying from $5 to $7 50 per ton, according to the price of fuel, and chloridized to such a degree that from seventy-five to eighty per cent. of the assay value-could be extracted, after the roasting, by working in pans. The treatment of the roasted material, in pans, should not cost more than $4 or $5 per ton. Another furnace, known as the ‘“Stetefeldt,” designed for the cheaper roasting and chloridizing of ores, will be described further on. Concentration oF Tattrnas.—Tailings, in the Washoe district, have generally been found more profitable than slimes. It has been already said that the stream of water, carrying the tailigs out of the mill, is usually passed over blanket-tables, in order to save all that can possibly be obtained in that way. The blanket-table, the most common means of concentration, is a long shallow trough, about 20 inches wide, with sides only an inch or two high, and of indefinite length, according to the supply of tailings, water, the char- acter of the ground, and other conditions. A number of these tables are usually established side by side, sometimes only two, three, or four together, sometimes as many as fifteen or twenty. They are inclined gently, usually having a fall of six or twelve inches in twelve feet of length. They are covered with coarse blankets, made especially for the purpose, in strips about two feet wide, and cut in such lengths, usually ten or fifteen feet, as may be deemed convenient for removal and washing. As the stream of tailings runs over the blankets the heavier portions of the ore, sulphurets, &c., and particles of amalgam, are retained in the blankets, while the poorer sand is washed away. The quantity of water must be carefully adapted to the purpose, suth- cient to prevent the accumulation of sand and not enough to carry away the heavier particles. The operation is usually assisted by a man who, with a broom, sweeps the surface of the table lightly, aiding the even distribution of the material and exposing the particles more thoroughly to the action of the TREATMENT OF THE COMSTOCK ORES. 259 water. ‘The blankets are taken up from time to time and washed out in a tub of water, usually once in twelve hours. While the blankets of one table are being washed the stream is turned so as to run over the neighboring tables. The concentrations washed from the blankets are collected and worked in pans. They usually yield from $18 or $20 to $30 per ton. In each of the principal cations or ravines in which the mills are situ- ated, below Virginia City, are continuous series of blanket-tables, making in the aggregate several miles. Some of the tables are owned by mills, dis- charging tailings into the cation, but generally they belong to other parties, who agree with the mill-owner for the use of the tailings. According to the report of the Surveyor General, Mr. Marlette, there were in 1866 over 2,200 feet of blanket-sluices in Six-Mile Catton. Their cost is estimated at about $1 per foot, including blankets. At the Santiago mill, on the Carson River, there are sixteen tables, side by side, 100 feet long. They belong to the mill, which crushes 50 tons of ore daily. The tailings pass over the tables, yielding about five tons daily of concentrations, which produce about $20 per ton. Two men are necessary to attend to them. Of the sixteen tables eight were designed for use in the night, leaving the biankets to be washed in the day-time when the stream passed over the other eight; but when the washing is performed day and night, eight tables are suthcient for the quantity of ore above mentioned. At the Brunswick mill, also on the Carson, the amount of ore crushed, and the quantity and value of the concentrations were in about the same proportions as above given. ‘The profit accruing from this source to the mill reduces con- siderably the original cost of crushing and amalgamating. The following are the results of working some concentrated tailings, from the Atchison mill. The assays, on which the original value of the tail- ings is predicated, were made of samples selected from the heap. In the sey- eral months included in the report, the proportion of the number of assays to the number of tons worked was not always the same. In the best lot there was one assay for about 10 or 12 tons of the concentrated tailings. MINING INDUSTRY. re a ee SY November, 1866. December, 1866. January, 1867. Tons worked . 120 148 314 Gold. Silver. Total. Gold. Silver. Total. Gold. Silver. Total. Assay value per ton . | $11 85 | $49 59 $61 44 | Sze 73 $53 92 $66 65 $10 54 $42 77 $53 31 Yield per ton ese | 6 40 23 12 29 52 575 19 59 25 34 4 36 12 88 17 24 Proportion of gold and silver— 19-3 | 80.7 100.0 Ig. 80.9 00.0 | 20.0 80.0 100.0 in assay value of tailings. Proportion of gold and silver 21.7 | 78.3 100.0 22.7 77*3 100.0 25.3 74°7 poeta) in bullion. : Percentage of gold and silver BLO: 46.6 45.2 B08 41.3 30+2 extracted. { | Yield per cent. of assay value 48 38 32-4 i Various other contrivances for concentration have been introduced into the district, but none, so far, have come into general use. Among other noticeable machines for this purpose is Hunter's concen- trator, which has been used for several years in California, and which the in- ventor sought, about a year ago, to apply successfully to Comstock tailings This is a percussion table of small size, being about 30 inches long by 24 wide, so suspended in a frame-work as to admit any desired inclination and the shght movement imparted by the percussion. The bottom of the table is slightly inclined from each end toward the middle. The tailing end is usually placed about an inch lower than the head. The material is supplied by a distributing launder about 8 inches from the head and, close by it, nearer the head, is a launder supplying clean water, which, like the material to be concentrated, is fed through a series of holes, so as to distribute it evenly across the table. The percussion is applied at the lower end of the table, at the rate of 200 to 240 shocks per minute. Its effect is such that the denser particles are sent toward the head in resistance to the stream of water, while the lighter particles yield to the force of the water and are car- ried down to the lower end and discharged. The separation therefore takes place at the point of supply, the heavier particles moving in one direction and being discharged at the head, the lighter sand moving with the water to the lower end and discharging there. A revolving scraper, just touching the sur: TREATMENT OF THE COMSTOCK ORES. 261 face of the material, assists the discharge of the waste-sand after its separa- tion from the heavier portion. The inclination given to the table, the speed of the percussion movement, and the quantity of water used, determine the degree of concentration. The capacity of the table is stated at 2 or 25 tons in 24 hours. Very little power is required and one man can attend to many tables. Tare Reservorrs.—The tailings coming down the cations from the mills above, after having passed over the blanket-tables, or having been sub- jected to other methods of concentration, are finally allowed to accumulate in reservoirs. Some of these, of small capacity, are placed along the course of the streams, but the principal deposits of that sort are on the level land adjacent to the mouths of the canons. Thus at Dayton, where Gold Hill Canon opens upon the plain, there are two or three reservoirs, the aggregate contents of which probably amount, at present, to 400,000 tons. ‘This quan- tity is daily increased by what is brought down by the stream from mills above. Further down the river, near the mouth of Six-Mile Cation, and receiving everything brought down from the mills on that water-course, is another known as the Carson reservoir, containing not less than 200,000 tons of tailings. In Six-Mile Cation, two miles above its mouth, is a smaller reservoir, formerly estimated to contain 100,000 tons, but of which a large portion was swept away, some time since, by freshets. The quality of the tailings in these dams varies considerably, depending on several conditions, among others, the proportion of slimes that may be mixed with the sands. Thus assays of the slimy and richer parts may show a value of 525 or 530 per ton, while the coarse sands vary in yalue from $4 orS5 to $12 or 515 per ton, according to the original character of the ore and the degree of eth- ciency with which its valuable contents have been extracted. The contents of some of the smaller reservoirs about Dayton are said to have an average value of 516 to $18 per ton, though the larger reservoirs are probably less rich, a number of assays giving results varying from 89 to $138 per ton. The Carson reservoir has been tested by many assays, varying be- tween $7 50 and $25, averaging about 513 per ton. AMALGAMATION oF Raw Tartincs.—There are now a number of estab- 262 MINING INDUSTRY. lishments in the district engaged entirely in working over the tailings of the crushing mills. Some of the smaller ones are situated in the cations or in the immediate vicinity of the mills which furnish their supply, but the most important are placed near the large reservoirs just described and draw from them the material for their work. The largest of all the mills thus engaged is that of Mr. Birdsall, at Dayton. This mill was formerly a crushing mill, provided with 30 stamps and 20 Wheeler pans. It has lately been refitted and devoted to the working of tailings. The stamps, of course, are useless for this purpose. A number of large Horn pans have been added to the machinery of the mill, making 30 or 35 pans in all, with capacity for work- ing between 250 and 300 tons of tailings per day. The mill has an excel- lent water-power, derived from the Carson River, ample for all its needs. As it is conveniently placed with reference to the supply of material, it should be able to do its work very economically. It is said that the business of this mill is exceedingly profitable, but the writer is not in possession of definite information concerning the yield of the tailings or the costs of work- ing them. In the neighborhood of the Birdsall mill, also at Dayton, and engaged in working tailings from one or more of the reservoirs there, is the mill of Messrs. Janin and Baldwin. This mill has five McCone pans, with a capa- city of about 50 tons per day. It is driven by steam, an engine of 12-inch cylinder doing the required work. Each pan works a charge of 4,000 or 5,000 pounds; and four or five charges per day, making a full duty of 10 tons per pan for each 24 hours. Sulphate of copper and salt are supplied to the pans with each charge ; the former reagent in quantities varying from 3 to 6 pounds per ton of tail- ings, and the latter largely in excess, from 20 to 80 pounds per ton. The pans are covered, and supplied with steam, keeping up a high temperature. The yield obtained is thought to be about sixty per cent. of the assay value, which is said to average $16 or $18 per ton. From the accounts of this mill, furnished by the kindness of Mr. Baldwin, it appears that during five months, ending October 31, 1869, the quantity worked was 6,732 tons; of which the average yield was $9 75 per ton. The total expense of the mill during these TREATMENT OF THE COMSTOCK ORES. 2638 five months, covering not only the costs of working, but both ordinary and ex- traordinary repairs, amounted to $43,672 79, or $6 48 per ton. The mill, however, was refitted during this time and several new pans were purchased to replace others that were worn out. The current costs of operation appear, from the accounts of these five months referred to, to be about as follows : Per ton. layer ooo eee Ne are ele PA ts N $1 40 Oieeii ver, ani sete ete nce an ey ote meee ee a ee pe ame nee 95 Et eee etal ee eee merce Wiel Ghetto dete means 68 Sulphate of copper..----------------++ 22sec e sence test eee eee cece: 65 Thr see geet ere cee eee eh ets Sanaa iewaces 1-20 Wastes. .-cmees Bia en Coe seen eee aha ve ae ekwse eS eee een raes 12 5 00 To this may be added some incidental expenses, not very large under or- dinary circumstances. In the month of October, when the mill worked 1,556 tons, the whole expense per ton was $5 60. The tailings worked in this mill are rather richer than the average material of taht sort, and are there- fore treated with a larger quantity of chemical reagents, making for these items a large cost. Wood is also expensive in the neighborhood of this mill, costing not less than $10 per cord, and often more. Tailings of lower grade, requiring less outlay for chemicals, worked in less time, especially if in mills of greater capacity, may be treated for proportionately less money. In Avery’s tailing mills, in Washoe Valley, where wood is obtained at $6 per cord, the cost pe- ton is said to be $3 50. In Janin & Baldwin’s mill there are seventeen men employed, comprising one foreman, five amalgamators, (three by day and two by night,) two engineers, one wood-passer, three teamsters, (bringing tail- ings from the reservoir,) and five shovelers, (loading teams and turning the tailings over to dry.) 264 MINING INDUSTRY. SECTION V. TREATMENT OF FIRST-CLASS ORB. The treatment of the first-class ores was briefly referred to in the first part of this chapter. The combinations in which the gold and silver exist in these unfit them for profitable treatment im the simple grinding and amalga- mating process which has been described in the foregoing pages. They require a chloridizing roasting, after which they are amalgamated in barrels. The quantity of high-grade ore now preduced in the district is so small that the single establishment of Mr. J. H. Dall, in Washoe Valley, has much more than sufhcient capacity for its treatment. It has already been shown that during the twelve months ending July 1, 1868, the Savage mine, which was then the chief source of high-grade ore, produced but 2773 tons of so-called first-class ore; and in the following year only 684 tons. The establishment referred to, which is built in connection with a wet-crushing and pan-amalgamating mill, has twenty stamps for dry crushing, eight reverberatory roasting furnaces, and twelve barrels, capable of treating some three or four hundred tons per month. The method of treatment to which the ore is subjected consists of dry- ing, crushing by stamps without the use ef water, roasting with salt, amalga- mation in revolving barrels, and the separation of the gold and silver from the quicksilver by the usual method of retorting. These principal features of the process will be briefly described. The drying kiln consists of a series of flues, covered by a cast- Dryine. iron floor, on which the ore, already reduced to a size suitable for stamping, is spread. The surface for the reception of the ore is about 8 feet wide by 12 feet long. The iron is cast in sections or plates, 8 feet long by 3 feet wide, with a strengthening rib on the under side. The base of the kiln is brickwork, and the flues are about 8 inches deep. They are covered by the iron plates. At one end of the kiln is a fireplace, and at the other a stack, so that the heat passes from one end to the other under the iron cover or floor, on which the ore is spread to a depth of 4 or 5 inches. The ore is constantly raked and turned until quite dry. When the kiln is conveniently placed, as in some similar establishments TREATMENT OF THE COMSTOCK ORES. 265 in Eastern Nevada, the heat from the roasting furnaces, on its way to the stack, passes through the flues, saving a special firing. In the present in- stance there are three kilns, able to dry about twenty-five tons per day, consuming in all about a half cord of wood in twenty-four hours, and requiring one man’s attention to keep up fires and rake over the ore. Crusninc.—For crushing the rock, after drying, there are twenty stamps, arranged in batteries of four, weighing about 600 pounds each, dropping 8 or 9 inches about 65 times per minute. The foundations and battery-frame are not essentially different from those im wet-crushing batteries. The mortars differ from the high ones used for wet-crushing, consisting of a bed-piece with sides and ends that are only high enough to provide the means of bolting the iron casting to the wood-work of the battery-frame, attaching the screen- frames, &c. The dies are flat, circular pieces of cast iron, that fit into recesses in the bottom of the mortar. Each die has two lugs or projections on its periphery, which, being dropped into a groove in the bottom of the mortar, may then be revolved 90 degrees, under a flange or lip with which the recess is cast. Molten lead is then poured in to hold the dies firmly. When it is desired to remove them, quicksilver is poured into the battery, dissolving the lead and loosening the dies. By retorting the quicksilver, both metals are recovered. The discharge is at both sides and ends. Screens of brass wire-cloth are used, having 40 meshes to the lineal inch, or 1,600 holes to the square inch. The stamps crush from a half ton to one ton per head per day of twenty-four hours. The batteries are inclosed by housings or closely fitted boxes, which serve as receivers for the crushed material. The casings are provided with doors, by means of which the workmen can enter and remove the crushed ore by shovelling it into barrows. Roastinc.—The fine ore is then roasted with salt in reverberatory furnaces. These are built of common red brick. Figs. 1 and 2, on Plate XXIV, show the method of their construction.' Fig. 1 is a horizontal section through the line, A B,on Fig. 2. In the drawings, # is the hearth; D, the 1From drawings furnished by Mr. J. B. Hiskey. 34 266 MINING INDUSTRY. stirring door; d, the discharge door; G, the grate; C, the bridge; F, the flues; P, the ashpit; J, the hopper. The charge consists of 1,000 pounds of ore, which is mixed with six per cent. of salt, the latter being added to the charge in the hopper by which the furnace is supplied. The charge is heated very gently at first, the temperature being gradually raised, until at the end it is subjected to a high heat. Usually six hours are required for the roast- ing. The charge is constantly stirred, and once or twice during the opera- tion it is turned; that is, the portion of the charge remote from the bridge is caused to exchange place with that which is near. The operation effected by thus roasting with salt consists, very briefly expressed, first, in the oxidation of the metallic compounds, converting the sulphurets, in which form the silver chiefly exists in the ore, to sulphates; and the subsequent decomposition of these combinations by the salt, with the formation of the chlorides of the metals. Sometimes an addition of limestone is made to the charge, for the purpose of decomposing the chlorides of cop- per, zinc, &c., thus preventing, to some extent, their subsequent amalgama- tion in the barrel, and obtaining bullion of a purer quality. Each furnace, roasting four charges of 1,000 pounds each, or two tons, in twenty-four hours, consumes one cord of wood. ‘Two stirrers are employed on each twelve-hour shift, making four men in twenty-four hours. One man is required to receive and attend to the ore on the cooling floor, after its dis- charge. The same man can attend to more than one furnace. The roasted ore is passed again through a screen, having 1,600 holes to the square inch, in order to remove from it any lumps that may have formed by caking in the furnace, or coarse particles that, may have escaped the bat- tery-sereen. It is then elevated to a large hopper, placed above the amalga- mating barrels, to which latter it is thence supplied by means of smaller hoppers, one of which is suspended over each barrel. Barret, AMALGAMATION. The barrels are 4 or 5 feet in length and diameter. They are usually made of soft pine. Figs. 3 and 4, on Plate XXIV, show a vertical section and end view of an amalgamating barrel, formerly used at the Gould and Curry mill. The ends of the barrel are made of plank, nicely fitted together and joined with a tongue of hard wood. 'The ne bee ad HHH ag _ Plate XXIV TREATMENT OF THE COMSTOCK ORES. 267 staves of the barrels are sometimes made of six-inch stuff, without lining ; sometimes, as shown in the figure, the staves are 2 or 3 inches thick, with an interior lining of blocks 4 or 5 inches square, and 3 or 4 inches thick, and so placed in the barrel that the wear is on the end of the grain. This lining can be removed when worn out. The staves of the barrels are bound with iron hoops, the ends of which are drawn together as shown in Fig. 5. he ends of the barrel are strengthened by a four-armed flange of cast iron. The bar- rels are caused to revolve by cog-gearing, the teeth being put on in segments, around the end of the barrel; or by belting, or, as at Austin, by friction-gear. The barrel, of which a section is shown in Fig. 3, shows a contrivance for admitting steam to the pulp through the trunnion. This arrangement, not very common, consists of a steam-pipe, p, Fig. 6, which enters the trunnion and fits smoothly against the end of another pipe, g, that passes through the -end of the barrel and admits the steam to the interior. The interior pipe, q, revolves with the trunnion, while the exterior pipe, p, is fixed and remains without motion. The trunnion, 7) is keyed to the flange already referred to. The barrels are charged with about 2,000 pounds of ore, mixed with water enough to make a moderately thick paste. Before adding quicksilver, the charge is revolved for two or three hours in the barrel with several hun- dred pounds of scrap-iron. The object of this is to effect a partial reduction of the chlorides present, which would otherwise be performed at the expense of the quicksilver. The chloride of silver is partly reduced by the metallic iron, and is subsequently amalgamated by the quicksilver. The same is true of the lead and copper. Quicksilver is added according to the richness of the ore, usually varying from 250 to 500 or more pounds. The barrel is run two hours, at twelve or fifteen revolutions per minute, and then examined that the consistency of the paste may be ascertained. If the latter is too thin, the quicksilver settles on the bottom. 'This condition is remedied by the addition of more roasted ore; while if too thick for the most favorable distribution of the quicksilver, more water is added. The barrel is then allowed to revolve again for fourteen hours, making fifteen revolutions per minute. The whole time occupied from the charging to the discharging of the barrel is eighteen or twenty hours. When the amalgamation is complete, the paste is thinned by 268 MINING INDUSTRY. the addition of water, and the quicksilver and amalgam are thus allowed to collect on the bottom of the barrel. Below the barrels is a large bopper or funnel-shaped contrivance, sloping down from the four sides to a common center. When a barrel is to be dis- charged, a small plug in the side is loosened while turned upward, and when ‘he harrel is revelved, so that the plug is downward, it is drawn out by hand. The quicksilver and amalgam are discharged into the hopper or funnel just deseribed, and are allowed to run from the barrel until the pulp begins to fol- low, when the plug is replaced. When all the barrels, ready for that purpose, are discharged, the amalgam in the hopper is carefully collected and washed, and afterward cleaned in a common pan like those in use in other mills for similar purposes. The straining of the quicksilver and retorting of the amal- gam is performed in manner similar to that already described. After the hopper below the barrels has been cleaned of all the quicksil- ver discharged into it, the residue is permitted to flow from the barrels and to run down into a large agitator, eight or ten feet deep, and twelve or fifteen feet in diameter, in which stirring-arms are revolving in manner similar to that already described in the foregoing. By this means, the unseparated quicksil- yer and amalgam are allowed to settle, and the concentrations of this vessel are worked over in pans in the common way, while the mass of tailings, pass- ing from the settler, are subjected to further methods of concentration and subsequent treatment. The actual costs, in detail, of the treatment of ore by this method, or the actual percentage of value obtained from the ore, are not definitely known o the writer. 1e former probably vary between $20 and $30 per ac- to tl t The f probably vary between 520 and $30 per ton, ac cording to the richness of the ore, the amount of salt, quicksilver, and other material consumed, and other conditions! The only mill now employed in the reduction of high-grade ores produced by the Comstock charges the pro- ducer $40 or $45 per ton for treatment and guarantees the return of eighty per cent. of the assay value of the ore. The supply of ore is so limited, and the establishment consequently unoccupied for sucha proportion of the time, 1 Wood costs, per cord, $5; common labor, per day, $3; salt, per pound, 3 cents; quicksilver, per pound, 60 cents. TREATMENT OF THE COMSTOCK ORES. 269 that the actual costs are probably considerably greater than they would be if the mill were constantly working up to its full capacity. In effect, the mill purchases the ore of the mine for eighty per cent. of its value, less $40 or 545 per ton, the stipulated price for working, making its return in cash or bullion without any statement of the yield actually obtained. The following is a statement concerning the first-class ore produced by the Savage mine during the year ending July 1, 1868, and treated at this mill: Tons. Quantity of ore délivered trom: the ming. -<-2.5-22-:2---2-2~--- 222-2: 277950 Less moisture, amounting to 679; per cent., leaving..--.-.------------ 258209, Assay value of the ore, per ton—gold.-.-.-...-----.-+--------- $123 66 Assay value of the ore, per ton—silver .......--------------- 325 74 $449 40 roportionioL sold in the ore; per cent,» 22. tec. oe oes 2785 Proportion of silver in the ore, per cent.....-----.-.--.---------+---- 1225 Mo tails aSSaiys VAMC —P Ol arp oa ess lel ea ele etareep = ie aie 834, 317 08 Motal assay; vallG—SUVELe = 22 02 cca 2 ame teresa me aia = 90, 402 43 === $124,719 51 Return of bullion, equal to 80 per cent.....----.--------4---+2+-+-5--- 99, 775 59 Open vON seca eee eee oo ae ctte ee eine eieetre ea ee siete ers io eicsers sak 359 52 Price paid for working, per ton........-------.---+----+-2---- +--+: 41 87 Sinilar statement for year ending July 1, 1869. Tons. Quantity of ore delivered from the mine.....-.----.-----------.------ 68420, Less moisture, amounting to 5,% per cent......---------------+++-+--+-- 64555 Assay value of the ore, per ton—gold.....---.----- .---++---- $73 69 Assay value of the ore, per ton—silver.......-.-.------------- 201 78 $275 47 Proportion in the ore of gold, per cent.....----------+---+--++--+-+---- 26.7 Proportion in the ore of silver, per cent. .--.-------.----+-----+--++--- 73.3 Total assay value of the ore—gold..-.....--...---..-------- $5,026 36 Total assay value of the ore—silver......------ ------+------ 13, 763 72 SS $18, 790 08 Return of bullion, equal to 80 per cent....-...--------+--++-+--++-++-+- 15,028 33 Or per ton - 2 2222-22. see se oe esse ere rs ee ee cen ene ee ee tee eee sta 220 32 Price paid for working, per ton.--.-------.-------++++--++ ee eee eee: 3 12 270) MINING INDUSTRY. Srereretp?’s Furnace.—The most expensive item in the cost of work- ing first-class ores by the method just described is the roasting and chlorid- izing operation. ‘This alone is generally estimated at $15 per ton of ore, though it is sometimes less. Any efficient method of obtaining the same results at a less cost is greatly to be desired, since there are many mining districts, not only in Nevada, but throughout our silver-producing regions, the development of which is hindered by the want of cheaper metallurgical processes. Within the past year a new furnace, devised and introduced by Mr. C. A. Stetefeldt, of Austin, has been put in operation near Virginia, and, judging by the experience thus far obtained, it promises results that will be of great importance to our silver mining districts. It is reported that one of these furnaces is about to be built for the Manhattan Company, in Austin, a region where, as will be shown further on, cheap roasting is very much to be desired. A brief description of the Stetefeldt furnace is given in the following para- graphs. This is designed as a desulphurizing and chloridizing furnace. Its oper- ation consists essentially in allowing the very finely pulverized ore, mixed with salt, to fall against a current of hot air that rises in a shaft, during which fall the fine particles of sulphureted metals are decomposed, forming metallic oxides, sulphurous and sulphuric acid. The latter attacking the salt, chlorine is liberated, which combines with the oxides of the metals, or acts upon the still undecomposed particles of sulphuret, thus producing the metallic chlorides. The chemical action is in most respects the same as that which takes place in the reverberatory roasting furnace, but as the ore falls in a finely divided condition, or shower of particles, each atom is exposed more freely to the op- eration of the heat and the oxidizing and chloridizing agents; their effect is more rapid and complete while the amount of manual labor required is very much less than in the reverberatory. The furnace was invented several years since and an experimental one was built at the mine of the Twin River Com- pany, in Ophir Canon, Nevada; but although affording results that were in most respects satisfactory, it was not then brought into continued use. During the past year another, designed for regular and permanent operation, was built at Reno, near Virginia, and employed in roasting ores brought from TREATMENT OF THE COMSTOCK ORES. PTA | Humboldt County. This furnace consists of a shaft something over 20 feet high and from 3 to 4 feet square. At the base of the shaft, on two opposite sides, are fire-places from each of which a short flue leads to the main shaft. At the top of the shaft is the feeding machinery, which supplies the finely pulverized ore in a continuous stream. Just below the top of the shaft is a flue through which the gases escape, and leading from the furnace to a series of dust chambers, in which the heated current may deposit that portion of the fine material which it carried upward with it. An auxiliary fireplace in this flue serves to sustain the heat and prolong the oxidizing and chloridizing operation. A discharge door is at the bottom of the main shaft, whence the bulk of the material that has been acted upon is withdrawn; and similar doors are placed at convenient points along the main flue and in the dust chambers. The main stack, for the final escape of the gases, is at the end of the dust cham- bers and is about 40 feet high. In the regular operation of the furnace the ore is mixed with salt on the drying floor and then crushed under stamps. ‘The screens used in the crushing battery are No. 40. It is then raised by an elevator to the top of the furnace and deposited in the hopper of the feeding machine, whence it is sup- plied continuously to the furnace. The heat in the shaft is maintained as uniformly as possible, and at a sufficiently high degree to keep the ore, which accumulates at the bottom, red hot. From time to time this ore is discharged through the doors at the base of the shaft and in the flue, or canal, leading to the dust chamber. It is claimed by Mr. Stetefeldt, as a result of actual experience at Reno, that this furnace performs a more efficient chloridizing roasting, with far less cost for labor, fuel, and salt than is the case with the reverberatory furnaces. It is said that about ninety per cent. of the silver contained in the ore is chlo- ridized. One Stetefeldt furnace, operated by 8 men, accomplishes the treat- ment of 20 tons of ore, which would require 10 reverberatory furnaces and the labor of 86 men. ‘The fuel thus far used in the furnace at Reno averages about two cords per day, and may roast at that rate of consumption the same quantity of ore which would require the consumption of ten cords in a rever- batory furnace. The salt used in the Stetefeldt furnace varies from three to six per cent., according to the richness of the ore, while in the reverbera- AEG! MINING INDUSTRY. tory furnaces about twice that quantity is expended; the principal cause of difference being that in the shaft-furnace the salt is more thoroughly utilized, every particle accomplishing its purpose. It is also claimed by Mr. Stetefeldt that the bullion produced from ore roasted in this furnace is of a higher quality than where the reverberatory is employed, owing to the decomposition of the chlorides of the base metals. These chlorides are formed in the shaft-furnace but are again decomposed in the presence of steam derived from the burning fuel, thus forming hydrochloric acid and the oxides of the metals. The roasted pulp accordingly contains much less of the chloridized base metal than it would if the ore were roasted in a reverberatory. In this respect it is held that the furnace is admirably adapted to the treatment of base ores. The cost of roasting per ton, thus far, at Reno, is said by Mr. Stetefeldt to be between $6 and $7, which may be reduced by projected improvements and by working the furnace at full capacity. CHAPTER V. CHEMISTRY OF THE WASHOE PROCESS. BY ARNOLD HAGUE. MINERALOGICAL CHARACTER OF THE ORE—CHEMICAL ACTION OF MERCURY AND OTHER REAGENTS—PAN EXPERIMENTS—CHEMISTRY OF THE PROCESS. The adaptation of the amalgamation process to the reduction of argentifer- ous ores depends to such an extent upon their character that in considering its application to Washoe it is necessary, as far as possible, to understand the true nature of the varied mineral ingredients that constitute the ore of the Com- stock vein. A large number of mineral species have been found in the vein during the course of its development; very many of them, however, are extremely rare, while others only have been observed near the surface, or within very limited areas. A discussion of its mineralogical features will be found in another chap- ter; it is only desirable here to consider such minerals as are everywhere scattered through the body of quartz, and are present in sufficient quantities to materially affect the question of the amalgamation of the associated goldand sil- ver. ‘The average ore as it comes from the mines presents to the eye a mass of nearly white, brittle, crumbling quartz, ranging insize from fine dust to pieces that weigh several pounds; occurring with it are small fragments of wall-rock and clay, that impart a somewhat grayish tinge. An inspection of the ore piles at the different mines and mills generally shows the presence of iron and copper pyrites. Except in first-class ore, which is always roasted before being sent to the amalgamating pan, it requires a somewhat closer examination to detect well-detined specimens of other minerals, so finely are they disseminated through the entire mass. A more careful search, however, will generally de- 30 274 MINING INDUSTRY. velop the presence of blende, galena, and argentite; more rarely, polybasite and stephanite. Samples of finely crushed ores were subjected to a microscopical exami- nation. The following minerals were observed: quartz, small cubes and par- ticles of iron and copper pyrites, flakes of blende, and thin pieces of a dark lead-gray mineral, which were determined to be argentite. In order to determine the chemical and mineralogical composition of the ore more accurately, samples of carefully chosen first and third-class rock were subjected to a thorough analysis. The first-class came from the Savage mine, and was taken from a lot of ore that had been crushed at Dall’s mill. Its assay value was 5489 22. The third-class ore came from the Kentuck mine; it was obtained at the mill from the troughs immediately after leaving the bat- teries, in the same manner as the mill samples are ordinarily taken. The ma- terial used was selected from 300 or 400 pounds of crushed rock, collected at intervals during a day’s run of twenty-four hours. Its assay value was $43 74. The results of both analyses were as follows: No. 1, Savage ore; No. 2, Kentuck ore: — No. 1 No. 2 3) 6b: a en a ee eee ene oe 83.95 91.49 Alumina) . -. 2 = #9 2 25s) = =/ = 1.25 1.%3 Protoxide:0f irGm). fa.) Fars Se, pe eee ee 36 02 HUI DOIN etOf SILVEr ee | cen ye: Oe. een eae 1.08 ee” Subsulphide of copper - - - = + = +=: - .30 41 Golde 2) oe a ee 02 .0017 Bisulphide of, iron “2 92 29-2 2 >= Ss = 2 = 1.80 52 Moisture. = 4" Ep 8? 2 on ee) eee 239 +59 Too. 38 99.48 "The writer is indebted to Mr. William G. Mixter for the analysis of the sample from the Savage mine. CHEMISTRY OF THE WASHOE PROCESS. 275 No arsenic or antimony was detected in either case, not even after sub- jecting considerable quantities to Marsh’s test. It is, therefore, inferred that stephanite and polybasite were both absent. It was found impossible to sep- arate the native silver, if any was present, from that existing as argentite; of the former none was observed, but the latter could be recognized under a glass: it is, therefore, all calculated as sulphide of silver. The sulphur ob- tained has been combined with the zine as blende, with lead as galena, with silver as argentite, with copper as subsulphide, and the remainder with iron as bisulphide. The iron still remaining has been estimated as protoxide. It was found impossible to separate the metallic iron, coming from the stamps of the batteries, from the sesquioxide of iron, occurring in the rock and clay material of the vein. The substances found in both analyses are the same, with the ex- ception of there being no manganese in the sample from the Kentuck mine, the differences being only the variable proportions of the same minerals. If in the two analyses we reject the gangue and such matter as can have no other influence upon the extraction of the precious metals than a physical one, by affecting the mechanical conditions in the grinding of the ore, or the consist- ency of the pulp, and consider only those ingredients that may influence the chemical conditions during the operation in the pan, we have the following: Nos 'r; No. 2, Protoxide.of iron = 2°29. = = =) 2 2 = = 1.95 .83 Bisnlphide.of iron) | 4 sees = es) 2 I.80 -92 Subsulphide of coppers =) 29s 2.) 2 = 2 = = +30 41 pulplde:of 7inces-) ee cece c = eee nee I.75 703 MUlpbIdesOn lead. mememnnnee Wes, eM co you (ac .36 .02 SUlpMidetof isilyer cuscueet sts ems s, =) 1.08 ape} Golden a st ras, sue =o Wx, 0's .02 .OO17 7.26 2.4317 CuemicaL Action or Mercury AND OTHER Reacents.—The ore of the Comstock vein may be regarded as composed of the following: Gangue, quartz. 276 MINING INDUSTRY. Metal-bearing minerals of common occurrence: blende, galena, argentite, silver, gold, iron pyrites, copper pyrites. Minerals of much more rare occurrence: stephanite, polybasite. The following experiments were undertaken to ascertain, as far as possi- ble, the action upon the minerals of the Comstock ores, just enumerated, of mercury, and such chemical agents as are employed in the amalgamation pro- cess, or may be formed during the operation in the pan. Mercury and native silver, when rubbed together, unite easily. Mercury and chloride of silver, the latter prepared in the wet way, when brought in contact, form amalgam and chloride of mercury. Mercury and argentite: The mineral was first pulverized and mixed with a little fine sand, the metal added, and the mass allowed to stand for some time; occasionally rubbed together in a mortar. Amalgamation ensued; it was, however, imperfect, much of the mineral being unacted upor. Mercury with stephanite and polybasite, under the same conditions as the last experiment, gave similar results; the decomposition, however, appeared to be more complete, probably owing to the more tnely divided state of these minerals than the more sectile argentite. The above experiments with native silver, chloride of silver, argentite, and polybasite, were repeated with mercury containing a small quantity of copper-amalgam in solution. In the case of the two former there was the same action as when the pure metal was used; with the two latter the decom- position was more perfect and satisfactory. Chloride of silver, argentite, and stephanite were each subjected to the action of mercury and fine metallic iron, with a constant application of heat. The energy displayed by the mereury was much more marked than when employed separately. In the case of the chloride, the decomposition was quite rapid, and the surface of the metal remained bright and clean. Chloride of copper and pulverized argentite were allowed to stand together for ten days, in the cold, with an occasional application of heat, at the end of which time, a small quantity of chloride of silver was formed. A trace of sulphuric acid was found in the filtrate. Two grammes of the pulverized mineral were also treated with a mod- erately concentrated solution of chloride of copper placed in a bottle, with a CHEMISTRY OF THE WASHOE PROCESS. TEE tightly-fitting stopper, to prevent access of air. It was exposed for twenty- four hours to a temperature of 90° centigrade. Sulphuric acid and sub- chloride of copper were found in the solution. Chloride of silver was pre- cipitated. After removing the soluble salts, by washing, the chloride of sil- ver was dissolved out, by digesting it with ammonia. The residue gave, by assay, .099 grammes of silver. ‘T'wo grammes of the mineral produced .1705 of pure metal; showing that, under the most favorable conditions, but little over one-half of the silver was chloridized. The application of heat greatly facilitated the decomposition. Polybasite, after being subjected to the chloride of copper solution, at the ordinary temperature of air, also yielded a small quantity of the chlorid- ized silver. Argentite was exposed to the same treatment, with sub-chloride of cop- per, as in the last experiments. In the cold, decomposition ensued after stand- ing several days. The residue from two grammes of the mineral, subjected to the action of heat at 90° centigrade, without access of air, gave 1655 of a gramme of silver, showing that only .006 had been chloridized. Galena, in a pulyerized condition, was digested with a strong mixture of salt and sulphate of copper, and after standing three or four weeks, at the ordinary temperature, was filtered. The residue exhibited, besides the unde- composed mineral, a light green oxychloride of copper, and a large quantity of sulphate of lead incrusting the galena. Blende was also subjected toa similar treatment. The solution wag found to contain a considerable quantity of oxide of zine, and but little cop- per. The residual blende was coated with the same oxychloride of copper already noted in the case of the galena. Two grammes of the powdered mineral were placed in a flask, a solu- tion of five grammes of salt and seven of sulphate of copper added, and ex- posed for two days to a temperature of 90° centigrade. After remaining three days longer in the cold the amount of oxide of zinc found to have been dissolved was .2785 of a gramme. The same experiment was repeated with the addition of one gramme of iron filings. The latter rapidly disap- peared; metallic copper was precipitated, but was redissolved, probably by the chloride of copper present, the sub-chloride being produced. Later, Zhe MINING INDUSTRY. the iron was thrown down as a basic salt. The oxide of zinc estimated in the solution was .3250 of a gramme. Iron and copper pyrites are but slightly altered by the copper solutions. In practical operations at the mill they are found in the tailings without showing any appreciable signs of having been attacked. It will be observed in the above experiments that the argentiferous sul- phurets were always more or less chloridized by the action of the copper salts. In order to indicate more clearly the relative amount of decomposition produced by the two chlorides of copper, the results are here brought together as follows: Two grammes of argentite gave .1705 grammes of silver. After treating two grammes of the mineral with chloride of copper, the residue gave .099 grammes of silver; after treating two grammes of the mineral with sub-chloride, the residue gave .1653 grammes of silver: showing that in the former 58.0 per cent., and in the latter, 2.9 per cent. was chloridized. No sulphide of copper was detected in any of the residues examined ; sulphu- ric acid, however, was found in the filtrate in several instances. Pan Eixprerments.—With a view to determine, if possible, some of the problems involved in the action of mercury, common salt, and sulphate of copper, employed in the decomposition of the Comstock ores by the Washoe process, the experiments’ described in the following pages were undertaken upon two lots of ore, whose composition was well known. It was necessary, in order to make the investigations of any practical value, that the material should be treated in such a manner as to imitate as closely as possible the operations carried out on a large scale at the mills, and at the same time to be able to repeat precisely the same conditions as often as desired, and to know the exact results of each trial. Of the ores used, one was a lot of first-class rock from the Savage mine, such as is ordinarily sent, on account of its high value and large amount of base metals, to Dall’s Mill, for reduction by the barrel-process, as described in a These experiments were conducted at the Sheftield Laboratory of Yale College. The assistance of Mr. Ellsworth Daggett was obtained, aud to his experience in the mechanical details of milling operations, much of the credit in carrying out the work is due, CHEMISTRY OF THE WASHOE PROCESS. 279 previous chapter. The second lot consisted of several hundred pounds of third-class ore from the Kentuck mine, presented, for the purposes of the work, by the Kentuck Mining Company. This low-grade ore was selected as being well adapted for pan amalgamation; easily reduced, containing but little base metal, and the rock from which it was taken yielding very favorable results at the mill. Both ores were carefully and thoroughly sampled, and passed through a fine sieve in order that they might be well mixed. Repeated assays were made until they had as uniform a composition as it was possible to obtain. After which, to prevent any settling of the heavier particles, both lots were put up in bags, in quantities of 10 and 15 pounds each; from sey- eral of these parcels assays were made, and the results found to agree. The Savage ore assayed, gold, $134 35; silver, $354 87; total, $489 22 per ton. The Kentuck ore assayed, gold, 510 85; silver, $32 89; total, $43 74 per ton. The results of the chemical analyses of both samples are given above. A small amalgamating pan, such as is used in California for the purpose of experimenting upon new ores, was procured. It was made by Mr. Wheeler as a test pan, and in all its essential features was similar to thela rger ones of his manufacture, employed in milling operations. It was 18 inches in diam- eter, and capable of working 20 pounds at a charge. A wooden tub, 3 feet in diameter, 18 inches deep, and provided with four wooden arms, connected with and revolved by an upright shaft in the center, served to keep the pulp in constant motion, and answered all the requirements of a settler or an agi- tator. A room with steam power was secured and a mill upon a small scale set up, which supplied all the necessary conditions of a larger establish- ment. The manner of conducting the operations was the same in every case; the ore was first placed in the pan, the muller set in motion, water added to bring the pulp to the proper consistency, and steam admitted to a chamber below. As soon as the pulp was thoroughly heated, the salt, sulphate of copper, or such other chemical agents as were employed, after being carefully weighed, were thrown in. The mercury was immediately added, in a fine condition, being strained through buckskin. Care was always taken to maintain the pulp at the proper degree of consistency, and to preserve a constant heat, which was 2SO MINING INDUSTRY. frequently tested by means of a thermometer plunged into the pan. A tem- perature of 185° Fahr. was found to act most advantageously. The pan worked well; the grinding action was perfectly satisfactory; the ore being kept in a constant and rapid circulation, and the mercury finely disseminated through the entire mass. The muller made 118 revolutions per minute. The operation concluded, the pulp was drawn off into the settler, the pan thoroughly washed out, or “cleaned up,” and every particle of amalgam re- moved. An additional quantity of mercury was placed in the settler, and water poured in until it was about half full. The stirrers made 80 revolutions per minute. The pulp was withdrawn at the end of four hours. The water, and the very lightest material, was allowed to escape, but the great bulk of sand and mercury was collected together in buckets and separated by hand, to avoid all loss. In washing, the tailings were made to fall upon a slightly inclined table, or trough, so that, if by any accident, mercury went over it could be easily recovered. The quicksilver after being washed free from sand was strained through buckskin, and the amalgam collected for retorting. The difference in weight between the mercury used in the pan and settler and that which remained at the conclusion of a charge, alter adding the amount retained in the bullion, was, in most cases, scarcely appreciable. Owing to the well-known property of mercury to retain asmall portion of silver in solution, which the ordinary pressure used in separating the builion fails to recover, the precaution was taken to have it all previously primed or charged before adding it to the pan, This was accomplished by allowing the mercury and metallic silver to stand in contact for some time, and then straining off the amalgam formed. The amalgam obtained from each experiment was weighed and put sep- arately in small sheet-iron cups. The number of each charge being stamped plainly on the iron, several of them were then placed together, on the bottom of a small cast-iron retort, and the mercury distilled over. After the retort had cooled down the remaining bullion was taken out and accurately weighed. Careful assays of each lot were made, and always conducted with proofs, and the metals separated by nitric acid in the usual way. CHEMISTRY OF THE WASHOE PROCESS. oil From the amount and fineness of the bullion the actual value of the gold and silver obtained from each charge is determined. For the purposes of comparison it was considered desirable to maintain, as far as practicable, the same conditions in each trial; for this reason, there is very little variety in the treatment with chemical agents, or the duration of the operations. The relative amounts of salt and sulphate of copper em- ployed have in every case been the same; one-half the quantity by weight of the latter to that of the former. A large excess of mercury and reagents were used in order to point out any marked differences in the results, and at the same time to obtain the greatest possible yield of the precious metals, without regard to the purity of the bullion, or the practical advantage of the method. The results are given in the accompanying tables; they are recorded pre- cisely as they occurred, although there are in some instances apparent errors. 36 MINING INDUSTRY. 282 ae Rc a M1907 2 Ps mc a ee oe Se Te10L, alba sos oe ot ss ss ss so gaqs ‘spunod Sr jo ad1vyo rod onjva Avssy 6g cf ae ee a a ‘+ + qoapis ‘u0} 19d onyva Arssy Sr-goog- - *- 7 + 7 + 7 + + + prod ‘spunod $x jo adivyo sod onjva Avssy Soorg a SF Pe ea A > + + pros tuoy rod onpva Avssy $68 LE:€6 | gb+16 | go°66 | tg oF | 60 cf | SLor | Egrof | LSrez | gorgo | 2626 | z*906 “Ez £S0°9 S+of b ie a ie eel qt $x fz L6°€g | ogtog | oz'SL | EL g€ | LS gz | org SS-le | €br1z | zxr*go | g'f16 | g'L6g “ox 09'S “LE ¥ E long oa Sx ce Go:ZL | rg°6L | tg'gg | eZ CF | Sz gz | LbL 6z'Sz | 69°6x | og'So | L*bSx | o-zSx | Lee Soz'1€ S*€or b 12 1on9 7 Sx ie 6o'gL | throd | Gxror | or FE | 2x Fs | gGoxr | agSe | gf'dxr | taego | auth | gigrh | tecr 000'OL 00g "92 Ss tg z ¥ Sr r4 LS-zg | SS*€g | to°6L | cx of | gh Le | tog ir'lz | zg'oz | 690 | 2Sg6 | ofg6 | zrze og1'S 000'6z S + = 3 = * : or 61 06 Sg | Zo-tg | gS*6g | gS ZE | Sg de | cL 6 61'gz | 6g-oz | of Lo | g*t16 | o°66g | g*Sx go's oot 1 i ¥ eile) = Sr gt Sgf£g | #r°6g | €grZo | gg gE | cf Ge | of Z rS'Ze | 66-12 | z&*So | 0°616 | gtto6 | atx £s9"s 00S ££ S b to*n9 > Sr dr lo'gL | terzg | EFSq | Sx FE | So Ze | or £ zg'Sz | Gz'ou | E€*So | otohL | z-LzL | grat Szl°9 00° 9f S + or € Sr or S6'tg | gziZg | Ggtgé | gx ZE | 09 gz | OS g gg'Ze | St-1z | Ehtgo | g'fo6 | zZgg | o'ox ofg'sS oot €€ S + Bae Me Sr Sr gor16 | Sgra €9-9g | #6 GE | #S of | of 6 96'6e | 16:zz | Sorlo | g*$96 | b:Zb6 | agr ofg'S o0g*zE $ + % oqu Sr br 00°63 | gore zL‘6L | €6 g€ | gz of | Sog oz'6z | rZ-zz | 6F:90 | #°S46 | 2*SS6 | coz ofZ:S 0090 $ + BE ¥% Sx £1 EL-zg | 26-€g | tr'6L | gr g& | 09 Ze | gS g title | oLtoz | tego | 9'€66 | E26 | z'oz Sgo°S 005 "of s nA 8 K% Sx zr ot'gg | fe'9g | £9°tG | zo gE | gE gz | gz or | £6'gz | derxz | gg*do | 2266 | b-2l6 | g'te Slo-S o0S Zz if + x poe as Sr 11 €g°g6 | z6°z Legit | €2 Ev | oF CF | Lo zr | shee z6-ce S*60 | g*966 | 9'g96 | age Lol'S 00S ‘Le S b So hy rs Sz or 1S*Sg_ | thgZ 6901 | ob LE | og Sz | og rr | Sorge | SE+6r £-g0 | 969 | orolg | g'fe L96°9 oS€°6E S + m1 € Sr 6 zSg_ | 96'gZ €-hor | gz LE | 246 Se | re 11 | g6'Ze | ghe6xr | ghego | acrZ | b6gg | g'ae 11g’9 oS€*6E i t oq £ Sr 8 go'rL | gt €L | ghtog | og z& | lo te | t2g og'tz | So‘gr | SS*go | #°966 | g*1L6 | gttz o6b b ob te s + 8 % Sr L 6S+0g €-6L | LS*tg | Sz SE | goose | £x 6 th-gz | gS'6r | gg'go | *Sg6 | g*096 | ote go6'b Szl‘gz $s + eaten na Sr 9 II‘0g S93 | €grog | to SE | th gz | 0g 9 gz'ge | €€-1z | S6'bo | g*1g6 | $296 | ahx zze-S oSL:Sz MS) ¥ = s+ Spe 5 EL EL €:SL | €S+z zezé | SS gz | olS So'z€ | SS+9z £:So | 2646 | or996 | a‘Er £z9"9 ooc' LE s 9 % I oz bi SotrS | 6th | tere | €€ cz | og tx | ELL €€+ez | og'tz | EL*Lo | #:266 | g*096 | g°1 gtore of6"€s S 9 ee BOF 0% € 6b cl | ig€L | cr'6o | 2 1€ | rete | os Z rLZ"1€ | rz-he Slo | g'196 | c'oh6 | bere tiz'9 org ff } id a4 I of z or'1Z | ch+zZ | Gorlg | or 1€9]| zg Ezg | ge 4g | or-x€ | zgrEs | gzrLo | g'Lg6 | b-oF6 | arrz £Lo"9 oSg"1£ s + % I re I *syuaa | *szrtap | *8779D sameuevey | ‘ammnvddy |'scnozz| “QT "20 ‘soT Ki ae a 4 B a 8 Ps 9 3 wm 1°?) 8 ae) is > 5 z 2 S z =I S = 2. = a 2 ~ B | Ze | ‘4addoo = 3 g a & ee BE F ie Fs § oa Ss 5 ir SHOTS, || CORRALEREY, | 2p & & | jo oyydins : z = 9 5 : : Hot 5 8 2 S| Lam beter “wor AG tite state 3 _ 3 . POAvs "]199 19g a9 fawecssoda. poyovszxa anqea penyoy uoljnq jo ssousutyy jo WS AL speormoyo § suo ynquay uogn spusuiuadxa fo synsoy aya Sumroys 29R7, 283 CHEMISTRY OF THE WASHOE PROCESS. ‘ato asvany uogn syusuisaduag fo synsay ay, Sumroys age wilgf& - 5 5 8 5 8 tm ee ee ee ee ee ee mor cz 6gh Rr gehare PCC gern a Ch wigs * * 7 7 7 7 5 5 + + + aQAqTIS ‘spunod Sz jo a81vy9 19d ontea Avssy Lg $S€ Ets ihe eT a * + q9aqts ‘uo, tad ontva Avssy ro'romg@ * ss 7 tt tt tts) ppos ‘spunod Sr jo as1eyo sod onyea Avssy SG Eres P77 sehes “5 = 7 + ss 5 pjos ‘uo 19d onpea Atssy r ge'ih | gl*€€ | zx1g | 00 zoz | gg Grr | zx zg | ro‘zror | #6°6S | gotrbh | g*bL6 | g*hE6 ‘ob oSh:Sr “Lg Ss + z hd or zr SorgE | bo*Sz | z6oZ | Gr ogz | 16.06 | gz S6 | 1r°€6 | obeSh | toLb | a°LL6 | g*416 | 96S oS6'1r "zg b € jTo*ng a or It LS:oh | e&*Ze | og'SL | cS g6r | $6 96 | gS ror | 92°66 | Lh-gh | GLoS | z-LL6 | g°416 | 9°65 6€L+cr trlo + tes jon ie or or Seth | #L-€€ | 6€-2£ | 00 Lrz | $2 Grr | gc L6 | oS-gor | £g-6S | Egrgh | t-ofZ | $-6c6 | -Zh | x£S-Sx Se t € { é ros Ono | | 34 or 6 gr'ZE | zovSz | gf-69 |) c6xgr |] g gg | zx £6 | 96°06 tbh | oS'oh | g°S46 | g°S16 ‘og 6L9°1r 0S *t9 $ € { ve bons or 8 Se tr1S | og*hh | ZS*g9 | to oSz | 00 gSr | to c6 | eS-Lgr | OSsgrx | zo'6g | ogg6 | F156 | go‘ bE of0'of *Igr s + lo*0 see Ba Z LhxS | €€-bh | gztol | tg 1Sz | bh LSx | ob #6 | OG'ggr | or'grr | og'od | g°Sg6 | 0086 | g'SE 0S6'6z S-bgr S ag re \ase) ot ig aw 9 og'z LE-6x | to'lg | cS 651 | tg gg | gg 06 | So°6xx ! gt-xS | Lr-gg | #°266 | O° fE6 | tbo of6°Sr "98 S + ca I Sr s St‘oh | gg*Ze | Sx-€Z | th g6r | ot g6 | gz g6 | PE-Ltr | Eg:EL | 1L*EL | 07996 | orgz6 | o-gS ozr*6r og "Sir 9 ha aise ss Pe Sr A So:Zb | rr-LE | oSSL | ox €€z j z£ r€x | bh ror | Lg*blr | og'g6 | Lo-gl | 0166 | gSt6 | H°Sb 061 Sz o00°SEr Ss + z r Sr € ons ir'rh | gb-rg | ob SSe | 26 Shr | gh Gor | 29-161 | Sb-Gor | zxr-zg | o°£66 | g'gt6 | bth ozg' Lz oSZ*691 ) i; ca V4 She z g6°gE | ZL-0€ | zbe19 | zg o61g) or gorg} 2S zgh | ob:cbr | Lo-1g | 6g-19 | c*066 | o'St6 | z-Sh of9 "0% oSZ:tor s + Pei es alee Sr I *syuap | *sguap | *squaa *a2emevAay | ‘amps |'sinozy| *sgT "20 *Z "SOT at 2 ro?) 4 ea be) ie be] 2 2 |) eet e ees emer m lec se, | ae eT ie ee. ade tee be & a a & S = g = F. & ii Ane eit ae & 2 | jo oyeydins . 2 5 Pe; . . aa) i=] @ e ig mt A }° . fe} asl 5 “u0} g = | :paavs "yua0 19 : x ! “uor —] 3 *syeorms G ie Poars "Judd 19g Srisgeea oe pa}IeIyXa onjvA [enjoy uoi][nq Jo ssouduT JO WSO AL TeormsyS) ¢ 284 MINING INDUSTRY. Notes accompanying the experiments upon the Kentuck ore. Nos. 1 to 20. Fifteen pounds of mercury added to the settler. Nos. 21 to 23. Ten pounds of mercury added to the settler. No. 3. No reason is known for the low yield both of gold and silver; the amalgam looked well, and the fineness was very high. Nos. 8, 9, 10. These charges gave a higher gold return than any of the assays of the ore. No sufhcient explanation can be assigned for the fact. The assays of the bullion were carefully repeated with the same results. Charge No. 10 shows the greatest difference between the assay and the yield, in which case it is less than fourteen mills’ worth of gold in excess of the amount as- sumed from the assay to be present. This excess may probably be accounted for by errors in the manipulation that the ore was subjected to during the treatment in the pan and settler. It is possible that the mercury when strained yielded a trifle more gold than usual. The fact is worthy of mention that all the charges that show an excess of gold, with the exception of No. 20, follow each other consecutively. Nos. 17, 18. The sub-chloride of copper was added in a solution of salt. The quantity of copper was equivalent to the amount contained in one ounce of the sulphate of that metal. No, 25. The quantity of copper corresponded to two ounces of the sul- phate of the metal. Notes accompanying the Experiments upon the Savage ore. Nos, 1 to 7. Fifteen pounds of mercury added to the settler. Nos. 8 to 12. Ten pounds of mercury added to the settler. No. 4. The pan by mistake ran six hours instead of five. No. 5. No cause could be assigned for the low return of bullion. Nos. 6, 7. The solution of sub-chloride of copper was the same as em- ployed with Nos. 17 and 18 of the Kentuck ore. Nos. 11, 12. The solution of sub-chloride of copper was the same as employed with No. 23 of the Kentuck ore. It must be admitted that the results obtained in the above experiments are not, in all respects, satisfactory, nor do they point out conclusively the ac- tion and value of salt and sulphate of copper in the decomposition of the ar- CHEMISTRY OF THE WASHOE PROCESS. 285 gentiferous ores by the Washoe process. They throw some light, however, upon several important points. In considering the results, as shown in the tables, the most marked fea- ture is the difference in the yield of the gold and silver bullion extracted from the two ores relative to their assay value. There is, with but one exception, in every trial of the Kentuck rock a higher yield than the requirements of the mines demand of the mills, and, in most cases, it is very much larger than is usually returned under the most favorable circumstances, in practical operation. This is probably owing, in a great measure, to the large amount of mercury employed in proportion to the quantity of ore. The Kentuck also gave as favorable results where mercury alone was used as when chemical agents were added. This proves very decidedly the ability of quicksilver aided by heat and iron to decompose the purer and easily reducible argentiferous minerals. With the Savage ore it may be observed that the yield is in all cases not only very much below that from the Kentuck, but lower than the average re- turns from the mills upon ores that are not first subjected to a roasting pro- cess. This is undoubtedly due to the large percentage of blende and galena present, with which the precious metals are in combination. The use of chem- ical agents shows a decided improvement in the production of bullion from such ores as contain large quantities of base metals. The application of salt and sulphate of copper did not increase the loss of mercury, although in many charges large quantities were present in the pulp. In the experiments con- ducted, with every possible precaution to repeat the precise conditions of a charge, using the same quantities of salt, sulphate of copper, and mercury, the results differ as widely as in those cases where the amount of chemical agents employed are much less, or entirely abandoned. The cause of these great dif- ferences in the yield of bullion must be sought elsewhere than in the varying amounts of the chemical agents used, however important they may be, in cer- tain cases, in aiding and assisting decomposition. A favorable yield undoubt- edly depends more upon the native condition of the mercury than anything that is usually added to the pulp. Charges 8, 9, 10, 11, of the Savage table, ran only four hours, which may 286 MINING INDUSTRY. in some degree account for the low yield. Charge 12 ran five hours with a somewhat higher result. It should be stated that the mercury of charges 11 and 12 appeared to contain a small amount of lead, which may have rendered it partially inactive. Charges 21, 22, and 23, of the Kentuck table, were discharged at the end of four hours, without any marked decrease in the production of bullion. It seems probable that in the case of the latter the minerals are all easily reduced, and the amalgama- tion is practically accomplished in the allotted space of time. In the case of the Savage ore the base metals are but slightly attacked by the mercury, and require more time for any chemical changes before amalgamation can take place. There is considerable resemblance between Nos. 3 and 4 of the Savage table, with a large excess of salt and sulphate of copper, and Nos. 6 and 7 with a solution of the sub-chloride of copper. The reason may be found in the fact that in the former the chloride of copper formed would be quickly reduced by the iron to the state of the sub-chloride, and similar condi- tions produced as in the case of the latter. Cuemistry or THE Procrss.—The action and value of common salt and sulphate of copper in the amalgamation of argentiferous ores, by what is known as the patio process, has always been a somewhat disputed question. Numerous theories have been advanced by metallurgists of long practical experience in Mexico, to account for the reduction of the sulphide of silver by the methods adopted in that country. The two which have obtained the most prominence, and which chemists have received with most favor, differ very widely in the manner the decomposition is supposed to be accomplished. The most plausible theory, and the one now generally adopted, is that of Sonnenschmidt. He claims that the salt and sulphate of copper react upon each other, and produce sulphate of soda, which is neutral in its action, and chloride of copper. ‘This latter salt then acts upon the argentiferous sulphide, and yields chloride of silver, sub-chloride of copper, and free sulphur. The sub-chloride reduces a second portion of the sulphide of silver, and causes the formation of an additional amount of the silver chloride, and sub-sulphide of copper. The silver salt is then attacked by the mercury; calomel, or sub- chloride of mercury, is produced, while metallic silver is set free, which com- bines with a second portion of the mercury, as amalgam. CHEMISTRY OF THE WASHOE PROCESS. 287 The following chemical equations show the reactions : 2 NaCl + CuOSO; = NaOSO; + CuCl _ QCuCl + AgS = AgCl + Cu,Cl + § Cu,Cl + AgS = AgCl + Cu, 8 Ag(l + Hg = AgHg + Hg,Cl. Bowring, an English metallurgist, on the other hand, denies that any of sulphide of silver is chloridized, and asserts that before amalgamation takes place, metallic silver is first produced. He claims that chloride of copper, in contact with mercury, forms the sub-chloride of both metals. The sub-chloride of copper, in contact with the oxygen of air,is converted into an oxychloride, which, in turn, acts upon the sulphide of silver, and liberates the metal in a free state, by oxidizing the combined sulphur. These reactions are expressed as follows : 2 CuCl + 2 Hg = CuCl + Hg,Cl CuCl + O = CuCl CuO 3 (CuCl CuO) + AgS = Ag+ SO; + 3 Cu,Cl. Although oxychloride of copper may possibly be found at times, there does not appear to be any decided evidence that such is the case in practical operations, or that it decomposes the sulphide of silver, while the experiments already recorded show conclusively that both the chlorides of copper, under favorable circumstances, do chloridize the argentiferous sulphurets. The experiments, however, would seem to indicate that the action of the chloride of copper was much more intense than that of the sub-chloride. The application and modification of the amalgamation process, as prac- ticed in Washoe, has occasioned among experienced mill-men great doubt as to the beneficial results derived from the use of any chemical agents, at pres- ent mixed with the ore. This doubt is occasioned, or at least strengthened, by the growing custom of late years of decreasing the quantity of salt and sulphate of copper added to the charge, without apparently diminishing the product of bullion. Many amalgamators now abstain from the use of both reagents; others adda small quantity of the sulphate of copper, but no salt ; in a few instances, the custom is to throw in only a little of the latter, while in many mills the rule is to employ a small amount of both substances, owing to a slight prejudice against the abandonment of “chemicals” altogether. The action exerted by these two reagents in the pan would appear 288 MINING INDUSTRY. clearly to indicate that the benefits derived from their use are partly to aid in converting the sulphide into chloride of silver, as in the patio, and partly to decompose such minerals as are but slightly attacked by the mer- eury. In the Washoe process, howeyer, the large quantity of iron present must tend greatly to produce sub-chloride of copper almost as soon as the chemical agents are thrown into the pulp. Notwithstanding the importance of common salt and sulphate of copper in the patio, and, under certain conditions in the pan, their value must be considered as only secondary in the decomposition of a large proportion of the Comstock ores. The advantages derived from their use are shown to be exerted chiefly upon such minerals as blende and galena, which are but slightly attacked by the mercury. But the amounts employed are in most cases too small to effect, any very favorable results. On the other hand, if a sufficiently large proportion of the reagents are consumed in the pulp, in order to produce the beneficial returns, it is always at the expense of pre- serving the necessary purity of the mercury. The quantity of salt deemed necessary by mill-men varies from one quarter of a pound up to seven or eight pounds per ton; scarcely any two establishments have the same rule. Its action upon the ore, without sulphate of copper, in producing any marked results may well be doubted. The consumption of the sulphate of copper also depends upon the ideas of the amalgamators, but the amounts do not differ so widely as in the case of the chloride of sodium. It ranges from one quarter of a pound to three pounds per ton. The addition of the sulphate, without salt, is of late years a common prac- tice. ‘The opinion among those who work their ore in this way is that it gives a little better yield than when mercury alone is employed, particularly where the ore indicates the presence of galena in any considerable amount, in which case it is said to quicken the mercury and render it more energetic. Continued experience appears to determine this fact with a considerable degree of certainty. In working ores containing only a small percentage of lead the quicksilver very soon becomes dull and inactive, or, as it is techni- cally termed, it sickens, and the yield from the pan is consequently low. Lead is one of the most deleterious metals in destroying the amalgamating energy CHEMISTRY OF THE WASHOE PROCESS. 289 of mercury, and at the same time is very rapidly absorbed when the two metals are brought into contact. Sulphate of copper possesses, to a certain extent, the property of expelling lead from mercury, copper being amalgamated and sul- phate of lead formed at the expense of the sulphuric acid of the copper salt. If a concentrated solution of sulphate of copper be allowed to stand upon lead-amalgam the action takes place quite rapidly, mercury containing lead act- ing much more energetically upon the copper solution than when perfectly pure. This salt, however, does not appear, under any circumstances, to possess the power of completely driving out the lead. Another advantage derived from the addition of a small quantity of the sulphate of copper is that mercury, under certain conditions, when exposed to the solution, forms a minute amount of copper-amalgam, which causes the metal to act with a somewhat greater intensity in the decomposition of the sil- ver sulphide than when perfectly pure. Tron, as a reducing agent, in the pan process, probably plays an important part in bringing about the favorable results obtained. ‘This may occur in three ways: First. It aids, in a great measure, the decomposition of the chloride ot silver. Secondly. It reduces the calomel formed during the operation; the chlorine, combining with the iron, goes into solution, and the heavy metal is liberated. In this way it not only prevents a chemical loss of mercury but also serves to keep the surface of that metal bright and clean, which otherwise might be coated with a thin film of sub-chloride, which would greatly destroy its activity. Thirdly. It undoubtedly assists directly in the amalgamation, where the two metals are brought into close contact with the easily reducible sulphurets. The successful and continued operations in Washoe, without the aid of any other chemical agents, sufficiently prove this statement. The experiments already cited in treating argentite and iron filings with mercury confirm the fact. Humboldt, in speaking of the amalgamation problem in Mexico, draws attention to this point and remarks upon the rapidity with which amalgama- tion was secured when the two metals were triturated together with argentite. This action of iron is obtained not only from the constant agitation maintained, which brings the pulp and metal in contact with the sides and bottom of the ‘ 2 o 290) MINING INDUSTRY. pan, but also from the amount of iron disseminated, in a fine condition, through the ore, produced by the wear of the stamps, shoes, and dies. This consumption of metal from the batteries and pans varies very much in the different mills, depending partly upon the details of construction and erinding effects of the pans and partly upon the hardness of the castings em- ployed. The following figures from two mills serve to show the quantity of iron reaching the pulp from this source, per ton of ore worked. The quantity of ore treated is sufficiently large to afford a very fair estimate of the metal con- sumed: Loss of iron in batteries.| Loss of iron in pans. Tons of ore worked. Total. | (Pounds per ton of ore.) | (Pounds per ton of ore.) T4, 000 ray, I om No} ss ie) H ie) b fe) 12, 236 ee i The fine iron coming to the ore in this way is very considerable in pro- portion to the other minerals present. If ten pounds per ton are added from this source it is equal to one-half of one per cent. In the Nentuck ore, of which an analysis has been given, there is, including the iron from the bat- teries, less than two and one-half per cent. of ore-bearing minerals present. Mercury and iron, under the proper conditions, undoubtedly are the principal agents in the extraction of the precious metals by the Washoe method. The results depend, however, in a great measure, upon the mechanical treatments employed to reduce the ore to an exceedingly fine state of division, and to maintain, with the proper degree of consistency, a constant agitation of the en- tire mass; the essential conditions of the amalgamation being that the mer- eury should be thoroughly incorporated in the pulp, and every particle of the reducible minerals brought in direct contact and triturated with the metal, in the manner so well accomplished by the friction and grinding action of the pan. The mercury should also at all times retain a bright, clean surface, free from any film of metallic salts, such as sub-chloride of mercury or sulphate of lead, and any coating of oil or grease. The slightest tarnish appears to retard very greatly the activity of the metal. The iron seems to act as an electro-chemi- cal agent; the immediate contact of the two metals, aided by heat and tric- CHEMISTRY OF THE WASHOE PROCESS. 291 tion, causing a local electric current, which renders the amalgamating energy of the mercury much more intense. Mercury, when perfectly pure, does not apparently possess to so great an extent the power of taking up other metals, or of decomposing mineral com- binations, as when it holds a minute quantity of some foreign metal in solution. The experience among amalgamators in Mexico is that the yield of gold is in- creased by the presence of silver; also, that the latter metal is extracted with greater facility if a considerable proportion of the amalgam is already present. This opinion is held by most mill-men in Washoe. It is stated by some writers upon the question that silver is absorbed with increased activity when copper is employed, and as the former is amal- gamated the latter will be expelled. Both iron and copper cause the forma- tion of copper-amalgam. On the other hand sulphate of copper exhibits a tendency to drive out lead. Karsten mentions the property of this salt to purify the mercury from both zine and antimony. Any one who has witnessed the intensity which sodium-amalgam exerts cannot fail to have been impressed with the rapidity with which it attacks gold, silver, and silver compounds ; yet its application in Washoe in practical operations did not give such results as would warrant its general introduction in the process. Although the presence of a small quantity of several metallic bodies en- hances the amalgamating energy of the mercury, yet a slight excess “sickens” it; that is, it loses its fluidity and becomes dull and inactive. The peculiar phenomena attending the mercury, by which both electro-positive and electro- negative metals are absorbed, and the effects which they produce in increasing or neutralizing its action, are very little understood. The loss in quicksilver during the operation arises from two sources ; the one mechanical, the other chemical. The former depends largely upon the manner in which the final washing from the pulp is conducted; the separa- tion being more or less perfect according to the skill and care with which it is executed. A considerable quantity of the metal, however, is so cut up and ground to such a fine state of division that it is impossible to save it. The chemical loss is occasioned by the formation of the chlorides of mercury, which escape with the tailings. 292 MINING INDUSTRY. In the patio the chemical loss is frequently very considerable; the amounts of common salt and magistral employed are large, while, at the same time, there is no reducing agent present to act upon the calomel formed, as is the case in the pan. In the patio the loss is said to increase in proportion to the richness of the ore in the sulphurets of silver, owing to the fact that for every atom of chloride of silver reduced by the mercury a corresponding atom of the latter metal is consumed as sub-chloride. In the Washoe process the chemical loss would seem to be small in pro- portion to the entire consumption. This is probably due to the beneficial ef- fects of the iron, which combines with the chlorine of the calomel, setting the quicksilver free. The more the metal is ground the more it must be cut up, and the greater the difficulty in recovering it. Now, if the consumption of iron is assumed to measure the grinding effect exerted by the pan, the relation between the loss of mercury and that of iron should be, in a certain degree, proportional. The following table, compiled from the results of several mills, furnishes some interesting details in regard to the loss of mercury : Part 1 shows that the loss of mercury is independent of the consump- tion of chemical agents, Part 2 shows that the loss of mercury is, in some measure, dependent upon the consumption of the iron of the pan. | | nee 2. Pounds per ton of ore. Pounds per ton of ore. Tons of ore. | Sulphate of Sulphuric Salt. 7 Mercury. Iron. Mercury. copper. acid. | 5,400 « 0.33 0.18 1.54 9.42 1.54 | 8, 605 1.74 0.31 1.39 9-79 1.38 | Q 4, 713 | 0:23 | 1.52 - 1.34 9.39 1738 35, 000 9.00 | 3.00 1.33 7-50 1.33 7,523 | 1.38 79 Tata 1.00 CHEMISTRY OF THE WASHOE PROCESS. ho 93 The following is the result of an analysis of some artificial crystals of Washoe amalgam: LWA ee eee eee ee eee Oe A ge aE ey 75.04 SLi eae ee ee ee ea, rer ee eae et ee Ae e eee kM 24.18 Co ee ee eee ie Pe aN ATT, They have the composition very closely of three atoms of mercury to one of silver. From the foregoing considerations of the principal features of the Washoe process it appears— That the ore consists chiefly of native gold, native silver, and argen- tiferous sulphurets, associated with varying proportions of blende and galena. That the action of chloride of sodium and sulphate of copper in the pan produces chloride of copper. That the presence of metallic iron necessarily causes the formation of the sub-chloride of copper. That both the chlorides of copper assist in the reduction of the ore by chloridizing the sulphurets of silver, and in decomposing the sulphurets of lead and zine. That sulphate of copper enhances the amalgamating energy of mercury, by causing the formation of a small quantity of copper-amalgam. It also tends to expel the lead. That notwithstanding the importance of chemical agents, as above indi- cated, the quantities added to the pulp in the ordinary practice of Washoe mills are too small to effect any very beneficial results. That mercury and iron, aided by heat and friction, are the principal agents in the extraction of the precious metals by the Washoe process. That the essential conditions in the amalgamation of the gold and silver are that the mercury be kept perfectly bright and pure, in order to produce a direct contact of that metal with the iron and sulphide of silver. That the consumption of mercury in the Washoe process may be con- sidered chiefly a mechanical, and, only to a limited extent, a chemical, loss. CHAPTER VI. CENTRAL AND EASTERN NEVADA. SECTION L—MINING AND MILLING IN WESTERN NEVADA—MONTEZUMA MINE AND FURNACES—UNIONVILLE AND VICINITY—GOLD RUN—BATTLE MOUNTAIN. SEcTION II.—GkEOLOGY OF THE TOYABE RANGE; BY S. F. EMMONS. Secrion III.—MINING AND MILLING AT REESE RIVER—AUSTIN AND VICINITY—TWin RIVER—PHILADELPHIA DISTRICT—CORTEZ DISTRICT—MINERAL HILL. SECTION IV.—GEOLOGY OF THE WHITE PINE DISTRICT; BY ARNOLD HAGUE. SECTION V.—MINING AND MILLING AT WHITE PINE. SECTION VIL—EGAN CANON DISTRICT; BY 8. F. EMMONS. Si COTTON 1. MINING AND MILLING IN WESTERN NEVADA. The discovery and early development of the Comstock lode in 1859 and 1860 gave a fresh impulse to the spirit of exploration throughout Nevada, and this was soon followed by the announcement of new silver-producing regions. In 1861 the mining districts, first opened in Humboldt County, about 150 miles northeast of Virginia City, attracted great attention, and a year later the Reese River discoveries succeeded these, creating still greater excitement. From these points, as centers, small exploring parties radiated in almost every direction, and each succeeding year witnessed the discovery of one or more new mining districts. Since that time nearly every mountain range in the State has undergone either much or little examination at the hands of the prospector. Regions, until lately, almost totally unknown have become familiar, while others that were so remote from the business centers of the Pacific coast as to be practically inaccessible for industrial pursuits have now been brought into comparatively easy communication with either coast by the completion of the Pacific railroad; and although the day for new and impor- 296 MINING INDUSTRY. tant discoveries of mineral wealth has by no means passed, as the late devel- opments af White Pine and in Southern Nevada plainly show, a fair idea of the general features and resources of the State has been obtained. Many of the newly discovered districts that were at first deemed most important have since proved to be bitter disappointments ; others, though found to contain many productive veins and deposits of great value, must await cheaper labor and materials in order to be worked profitably ; but a sufficient number have been successfully developed to establish the fact that the State possesses in its mineral veins the broad and substantial basis of a permanent mining industry. It will not be attempted in this chapter to give a description of all the mining districts that have been organized in the State and sufficiently devel- oped to make them well worthy of attention. The late. reports of J. Ross Browne, esq., United States Commissioner of Mining Statistics, and his suc- cessor, R. W. Raymond, esq., cover much of the ground and furnish in their descriptions a great deal of information concerning many of them. The writer prefers to confine himself to some account of the more important and most developed localities to which he was able to give his personal attention, and even in so doing, to endeavor, by describing typical mines, the extent and method of their development, and the processes employed for the treatment of their ores, to convey a general idea of the condition of the mining industry, rather than to make especial mention of every mine or mining district that might be considered worthy of it. The main features of the topography and geology of the State have been already briefly referred to in a foregoing chapter; in which, also, the position of the principal mining regions and their relations to each other have been somewhat noticed. In this chapter the several districts described will be taken up in nearly the order in which they might be visited by one crossing the State from west to east. The western part of the State, north of the Washoe region, contains some mining districts that have attracted attention from time to time, but which, so far as development er the production of valuable metals are con- cerned, have not yet attained much importavce. An example of this class is ve a, aCe ca s ae. the Peavyine district, about 30 miles northwest from V irginia City, and seven CENTRAL AND EASTERN NEVADA. 297 or eight in the same direction from Reno, on the railroad, in which some veins of copper ore have been opened in metamorphic rocks, and prospected to a depth of 40 or 50 feet. The surface ore consists chietly of oxides and carbonates, with some sulphurets of copper. It is slightly argentiferous. The region has been lying neglected for several years, but its proximity to the railroad may make it an available source ef copper should future explora- tion encourage further development. Montezuma Mine.—Passing over these localities, that are yet of minor importance, we come to the Trinity Mountains, which have been the scene of some extensive and interesting mining and metallurgical operations. This range of mountains is on the west bank ef the Humboldt River, which here runs in a southerly direction. The principal mine is the Montezuma, the owners of which have expended a large sum of money in the development of their property, and in the construction of metallurgical works for the treat- ment of their ores. These operations were chiefly conducted under the direction of Mr. A. W. Nason, to whom the writer is indebted for much of the information here given concerning them. The Montezuma ledge, chiefly owned and for some time worked by the Trinity and Sacramento Mining Company, is situated in the eastern foot- hills of the Trinity range. The mine is about three miles west, a little north- erly, from Oreana, a station on the Central Pacific Railroad, 262 miles from Sacramento, and the location of the company’s smelting works. The ledge is in a low hill, the ridge of which is nearly parallel to the trend of the main range and separated from it by a shallow longitudinal valley, having nearly a north-northeasterly and south-southwesterly course. The course of the ledge crosses the trend of the hill diagonally, being north 88° east, true. It dips to the northward with an inclination of 40 or 45 degrees. The inclosing rock of the vein may be generally described as porphyry, though it is probably closely related to, if not identical with, the granitic rocks that occur higher up in the range. This granite is overlaid by limestones and slates, which sedimentary beds are found also not very remote from the Montezuma. The vein was discovered by means of an outcrop of the ore on the western slope of the hill referred to, and a pit or excavation was sunk on 38 298 MINING INDUSTRY. the vein at that point, from which a considerable quantity of good ore was taken. At the date of the writer’s visit it had been explored by a cut along the course of the vein from west to east, partly open and partly in tunnel, having a continuous length of about 170 feet, and being about 30 feet below the surface at its deepest part; while below the level of the cut, and starting from it, a shaft had been sunk, measuring on the plane of the vein 120 feet in depth. Beyond the cut, along the course of the lode, are several other disconnected pits extending the general explorations of the vein over a length of 500 or 600 feet. The total length of the company’s claim is 2,000 feet. The outcrop of the vein, as exposed in the long cut, had a width in places of 20 feet, averaging, perhaps, from the surface to the level of the cut, about 10 feet. Below the cut, in the shaft, the average width was about 6 feet be- tween the walls. Along the cut the ore is said to have formed a solid mass, almost entirely filling the space between the two walls; and the sections ex- posed at the time referred to accorded with that statement, the vein being filled with ore, variable in quality but almost entirely free from gangue, and nearly all fit to send to the furnace without assortment. The cut at that time was not deep enough to give a clear exhibition of either wall, unaltered by surface influences. The hanging wall is covered by an accumulation of loose earth and soil several feet in thickness, and below this the wall-rock itself is de- composed and doubtless considerably changed from its original character. Between the wall-rock and the vein on the hanging side is a seam of soft white clay, eight inches or a foot in thickness. On the foot-wall below the vein there is a soft, white, brecciated mass, clayey in character, but penetrating the country-rock, as if the mass of the latter in the neighborhood of the vein had been thoroughly changed. Further south, on the surface, are found deposits of ore and vein-material, indicating the existence of seams or branches of the vein in the foot-wall. In the shaft, which is 120 feet deep, measured from the level of the eut on the inclination of the vein, the walls are well defined. The vein is about six feet wide. For 60 feet of the depth aboye named the shaft passed through ore, filling the vein from wall to wall. Below that point the walls of the vein continued as above, but the inclosed material was found to consist chiefly of gangue with little or no ore. Developments up to that period indicated that CENTRAL AND EASTERN NEVADA. ; 299 the shaft had passed through the lower limit of the ore-chimney. At the point where the vein ceased to be ore-bearing in the shaft, a drift was subse- quently run westward some 80 or 100 feet, which was reported as being in good ore for the whole distance. The ore is of a peculiar character. It consists chiefly of the oxides of lead and antimony, carrying a small percentage of silver, averaging, by assay, about $80 per ton. The ore, as it now exists, is evidently the result of decomposition or alteration of other and more familiar forms of silver-bearing, antimonial ores. It is sometimes hard, massive, and com- pact in character, while the larger proportion is friable, showing a fibrous structure, apparently the form of its pre-existing condition. The harder variety is usually next the hanging wall and needs blasting, while the other kind, lying on the foot-wall, may be removed without the aid of powder. The former is said to be the richer. An analysis of a piece of this ore, made by Mr. William G. Mixter, assistant at the Shefheld Laboratory, Yale College, gave the following results: FAW arg na (0) cS (6 Mate} 0) Pele Perera sare ere er fae ee 51.94. G\xide Of lead’. I Osa cee canines cere ce carceree bas meee castes 40.89 PIVOT, GA Deere ne Meee rene rence 2 hats els «ars dimamcracesmenemes 2383 esd UmGm Om Ol WOM, MG pena sat wcows days eal aedeer. sn kek Caae's adenine’ 60 Insoluble residue-...-- Sse tree ae nee ae eee ee ae eae 1.66 WiHLE eee ee eee op eae eee eee BER ede tiagthel crc cieyavine Sieisislers Stes: 4.58 100.00 The above composition, together with the physical characteristics of the ore, identify it with bindheimite, a mineral described by Dana, occurring in Cornwall, Siberia, and other localities, and derived from the mineral jamesonite by decomposition. A few fragments of undecomposed mineral, strongly resembling jamesonite, were found by the writer in the ore at Oreana. Thus far the extraction of the ore has beena simple process of quarrying in the open cut, and has been done very cheaply. It is said to cost not more than $2 or $2.50 per ton for extraction; mining, and hauling to the furnace, costing, in the 300 MINING INDUSTRY. aggregate, $4 or $4.50 per ton. Little or no expense for timber has been in- curred and no hoisting machinery employed so far. The mine is quite dry, as is the surrounding country, all the water required for domestic purposes being brought from the river, three miles away. This is but little, as five men at the mine were able to supply the furnace, of 12 or 15 tons capacity, with ore, and the teams employed in hauling ore were accustomed to carry back sufficient water on their return trips. The superintendent of the works, Mr. Nason, estimated the supply of ore in the mine at 10,000 tons, the estimate being based on the length of lode exposed at the surface and the average depth assumed from that in the shalt. At the date of the writer’s visit the ascertained facts concerning the continuance in depth of the ore-body were not sufficient to place this estimate beyond question, but the developments thus far made indicated the existence of a large supply. In the neighborhood of the Montezuma, within the district known as Arabia, are a number of other ledges carrying ore like that just described, but lower in value and less in quantity. The locations made on these ledges are numerous, and considerable work has been done on some of them, showing that they occur in series parallel to each other but quite small individually, many seeming to pinch out altogether in depth. Their general course is dif- ferent from that of the Montezuma, being north and south, or nearly so. The ledge that has been most developed and seems to premise most favorably, next to the Montezuma, is the Jersey, which hasa northerly course, and if both veins are continuous, should intersect the Montezuma at no great distance from the workings on the latter. It has been traced for several hundred feet on the surface and explored by inclines to the depth of 100 feet. Tts ore has not thus far been as rich as that of the Montezuma, but it is believed that it can be worked with profit, especially with the increased advantages se- cured by the Pacific railroad, which passes within two or three miles of the property. Montezuma Furnaces —The Trinity and Sacramento Company prose- cuted their mining and metallurgical operations very vigorously during two or three years previous to the autumn of 1868. The mine was openedas already de- seribed, and a large amount of money was expended in providing smelting works CENTRAL AND EASTERN NEVADA. SO for the reduction of the ore and extraction of silver. This establishment had hardly been completed and entered upon the regular performance of its work to the full extent of its capacity, when the company, already deeply involved in litigation, became embarrassed financially and their work was suspended ;! although it appears from the accounts of the mine that, up to the time re- ferred to, the average yield of the ore was largely in excess of the costs of mining and smelting. The method of treatment of the ores, at the time when the work was in active progress and before the completion of the Pacific railroad, presents some novelties, and is worthy of a somewhat detailed description, notwith- standing the fact that a portion of it is no longer in use. In the early history of the enterprise a ten-stamp mill, furnished with three grinding and amalgamating pans, was provided with the intention of treating the ores by the ordinary Washoe method; but as this was soon found to be quite unsuited to the character of the ore it was abandoned, and furnaces for smelting and refining were constructed.. This process consisted of smelting the ore in a shaft-furnace, by which means crude metal was obtained, amount- ing to 45 or 50 per cent. of the charge of ore, and consisting of lead, antimony, and silver; the last named being contained to the value of $160 or $200 to the ton of metal. The metal was then subjected to treatment in a calcining, or sublimation, furnace, by which means the antimony was removed, and the lead consequently enriched by concentration, until it contained from $300 to $400 per ton in silver. From this lead the silver was then extracted by cupellation in an English cupel-furnace. Among the products of the sublimation-furnace was an alloy of lead and antimony, marketable in San Francisco at a remunerative price for the production of type-metal. The accompanying plates, illustrating the construction of the furnaces and their general arrangement, were prepared from drawings made by Mr. Sydney Tuttle, assistant superintendent of the works, and kindly placed at the disposal of the writer. The shaft-furnace, employed for the smelting of the crude ore, is shown by Figs. 1, 2, 8, and 4, on Plate XXV. Figs. 1 and 2 show a front and side 1 According to newspaper reports the mine and smelting furnaces were again in operation in August, 1570. BOY MINING INDUSTRY. elevation; Fig. 3 a horizontal section through A B; and Fig. 4, a vertical section through CD of Fig. 1. The total height of the furnace is about 40 feet. The hearth is built of stone, cut from trachytic rock that occurs a few miles south of the works. The shaft is of common brick with a lining of fire- brick from the hearth up to the throat. In the drawings, £ is the hearth, or sole; F, the sump, or receiver, into which the metal runs on being tapped from the furnace; ¢, tuyeres; g, blast- pipes; 4, pipes to supply water to the tuyeres; Z, lining of the furnace; JL throat; JV, floor for feeding ore; S, stack. The capacity of one of these furnaces is from 12 to 13 tons per day of twenty-four hours. The ore being broken into small pieces is spread upon the charging floor and mixed with flux. This sometimes consists of limestone, but generally of slag, or both together. Litharge, the product of the cupelling furnace, is also sometimes used with fresh ore. The ore for the charge, being mixed with about 25 per cent. of flux, is supplied to the furnace with a sufficient quantity of charcoal, that averages about 15 bushels to the ton of ore. About 100 pounds of the mixed charge and coal is fed to the furnace at once, the sup- ply beimg continuously kept up as the operation of smelting proceeds. The blast is supplied by a fan-blower which is driven by the steam-engine for- merly provided for operating the stamping and grinding machinery in the old mill. When the furnace is in regular operation the slag is discharged contin- uously, while the metal is tapped off, at intervals of an hour or two, into an iron receiver, whence it is dipped out and cast in pigs or ingots of convenient size for further handling. The yield of metal, consisting of lead, antimony, and silver, is from 45 to 50 per cent. of the ore smelted; one furnace smelting 12 tons of ore in a day, supplying consequently about 5 tons of crude metal. The ore, originally con- taining S80 per ton in silver, yields metal which contains from $150 to $200 per ton. The slags are constantly examined. Usually they are quite poor, but if found to contain an available percentage of metal are broken up and returned to the furnace with a fresh charge of ore. ate . . a? al . , Phe consumption of chareoal in this smelting process is usually about 15 Plate XXV Fig. W. CENTRAL AND BASTERN NEVADA. B03 bushels to the ton, but sometimes exceeds that quantity. It is made from the nut-pine, and is brought chiefly from what is locally known as the Kast Hum- boldt Range, 28 or 30 miles distant from the works. It costs, on an average, 50 cents per bushel. Its quality is considered to be excellent. There are limited supplies of the nut-pine nearer to the works, furnishing small quantities of charcoal, but in the more remote range, above mentioned, the supply is rep- resented as quite sufficient for a long time, at the present rate of consumption. There are two blast-furnaces, like that just described, one of them being held in reserve for any emergency by which the other may be disabled. One fur- nace in steady operation could fully supply the refining furnaces that were in use at the time of the writer’s visit. The refining or calcining furnace for the sublimation of the antimony contained in the erude metal, and the consequent improvement of the lead, consists at these works of a bath, or cast-iron pan, about 13 feet long by 5 feet 8 inches wide and 8 inches deep, the metal being an inch thick. The pan is set in brick-work, the construction of which is shown by an elevation, a plan, and transverse sections on Plate XXV, Figures 5, 6, 7, and 8. Fig. 5 isa side elevation; Fig. 6, a horizontal section through E F of Fig 5; Figs. 7 and 8, transverse sections through A B and C D of Fig. 5. The pan rests on a substantial foundation and is inclosed by side-walls, of common bricks, about 10 inches high, over which an arch is turned, as shown in the section. A narrow space is left between the pan and the inclos- ing masonry to allow for expansion. At one end of the structure is a fire- place and ash-pit; the flame passes over a bridge, which separates the fire- place from the pan, and thus over the surface of the metal contained in the pan, toward the stack at the opposite end. There is a horizontal channel passing through the bridge, behind the pan, opening at the sides of the fur- nace and communicating by vertical passages with the interior, by which means air may be admitted to the charge. Doors are provided in the side of the furnace for the purpose of skimming off a crust, or scum, consisting of lead and antimony, that collects on the surface while the operation of calcin- ing is in progress. The charge is also introduced through these doors. There is a tap near the end of the pan on one side, for the purpose of draw- 304 MINING INDUSTRY. ing off the refined metal. At the base of the stack is a chamber for the col- lection of the oxidized antimony that may condense in the stack and fall to the bottom. The whole structure is firmly bound together by irons and bolts, as shown in the drawings. In the figures, Gis the fireplace; H, the ash pit; I, the bridge; J, the air-channel through the bridge; A, the pan; JZ, the spout; J/, the openings for putting in and working the charge; JV, the doors; O, the chamber at base of stack for the accumulation of the oxidized antimony. To set this furnace im operation the metal may be first melted and intro- duced in a fused state to the pan; or, what is more common, the pan is heated to redness and the pigs of crude metal are laid upon the pan-bottom, when melting ensues. The fire may be quite moderate, the only fuel used in this case being sage brush. The antimony is oxidized and passes wp the stack, a part to escape, a part condensing in the chimney. The charge of the pan at the outset is some six or eight tons, but as the molten metal, diminishes in bulk by the sublimation of the antimony, new bars are added to keep up the supply. A scum collects on the surface of the molten metal which is removed by scrapers from time to time. This consists chiefly of lead and antimony with very little silver. While this refining process was still practiced at the works, these skimmings were collected, re-melted, and cast in bars, to be sold in San Francisco for type-metal, Babbitt-metal and other purposes. The alloy consisted of 71 per cent. of antimony with 29 per cent. of lead and was worth 8 cents per pound. The lead in the pan is gradually enriched by this methed of concen- tration, and assays are taken from time to time, usually at intervals of twelve hours, for the purpose of watching the progress of the operation. When the value of the lead has been brought up to about $350 or $400 per ton, it is drawn off in molds and then subjected to treatment in the cupel-furnace. The following series of assays, taken during the progress of one run of metal shows the gradual improvement of the lead: March 10, raw metal-at time of charge, value per ton...-..-..-.-..------- $209 68 10, twelve hours later, value, per ton, of contents of bath........-.--. 214 04 IGL3 53, See ees ees CLOn Pe eae ee See dO2e3ene eee eee G0: setsssesecess 219 44 ale seen a oa eee (Osun yee eeoee Ot. ae (Geese nea .. 238 93 CENTRAL AND EASTERN NEVADA. 305 March 12, twelve honrs later, value, per ton, of contents of bath.......---- $248 68 ee eee Sse 0 Ca ee ee ee OG ares oc (Oss asackekeece < 255 60 d I Perens ets Caer Oe acess a aetes (Omer eee CLO eg ee ey ee 263 36 De steeds chs cis end CO senses eters ee dO sekae eee tenc (literate 273 12 pe eee ee (Os .ceseeesent as OS... 2 wos esas: QOf SE eee eee 279 94. I Uae ee Ree COs eects ete CO geste corpse rea COS eee teins me 282 76 0 Peer pene ee CLOPEEi sce ete CLO? Sere eee oe ore (LOM serene ae 287 58 LO ccnsde ces eek COP Se e265 <2 etc (OZ ae eee e one doef etfs stetee5 292 56 i Gieioe ae ee eee OOssepererssieevs ais (LO Sieic ecaiee ais-asoceues OOteeeeaceea sae 297 22 UG siccareistesa crocs aise CLO Seater ae Oe ee oe CL Oe eens era 302 31 a Ly ea A Rae eer ete C0gseeccoss see (LO 2 eee aS 2 Oster eve ais 2 he 311 68 iL fiemiewak eee, sane (ho reer eee C0 mece acum = ci Oh aeccie eaieieeiece 321 82 LS ye cers eS O02 Se cate ee dOsecee. eee nose Ores eee ae 336 44 LS Phen ae as cane ees (OS eee eee cnc GO2ee erates aoe dOite os. 2eree eee 346 40 EL aera eee O23 ee eee 0 Co eee dO sein seks 346 40 d He ear tee eee CO Qmerrtte sees CLO Seta ea eea era (0 Ko een ee soe 3o1 08 Eee Rear es tae Ow as ee eae ae 0 hs eee rae QOcewasSeese ace 355 96 0 Pee ae ean QO ssmasecene ome Oe eee a erase CT Rape etna Sey eee 365 70 0 fay Se a a WOsseeeee se ccen Omer see rene (LO Merete es opts 375 20 7 Cee ae eae COeteceece ccs. = M02. ot sccceecnee COs ae ts ease a 378 40 Deg eee tee COneweker so 2cces (Ot2e erotics OSPR Soe cece a 385 22 Total quantity of crude metal charged 20.8 tons. Value.........-....--.-- 4,584 89 Total quantity of refined metal tapped 11.9 tons. Value.............-...-. 4,541 12 Loss by sublimation and skimmings, 42.78 per cent. of total weight of crude metal. Loss in silver 0.97 per cent. of total value of silver contained in the metal. The calcining furnace in which the foregoing run was made was 10 feet long by 5 feet wide. The capacity of those subsequently introduced, and such as have been described in these pages, is said to be equal to the treat- ment of two tons of crude metal per day, yielding at the rate of about one ton of rich lead for twenty-four hours. There are four of these furnaces at the works. The pans were cast in San Francisco and brought over to Nevada at a large cost for freight. Much trouble was at first experienced owing to leaks in the pans, by defective casting, involving great expense and loss of time in taking them out for repairs, but they were ultimately brought into a very efficient condition. The cost of calcination is stated at $8 per ton of ore. 306 MINING INDUSTRY. The eupelling furnace is of the kind commonly used in England. Figs. 9, 10, and 11 on Plate XXV show the method of its construction. Fig. 9 is a side elevation; Fig. 10, a horizontal section on the line A B of Fig. 9; and Fig. 11 is a vertical section on the line CD of Fig. 10. Fis the fire- place; G, the ash-pit; H, the bridge; J, the test-ring or hearth; J, the tuyere; k, k, supporting and adjusting screws for the test-ring; LZ, the flue leading to the stack, 17; NV, a melting pot or pan in which the metal may be prepared for the hearth. The hearth consists of bone-earth, prepared from the bones of cattle, which lie in profusion along the track of the old emigrant road, furnishing an abundant supply. The bones are burned and then pulverized in the stamp mill; and being moistened with water that contains a little alkali, leached from wood ashes, the mass is beaten compactly into the test-ring. This is oval in form, being 4 feet long by 3 feet wide. It is a rim of iron, 7 or 8 inches deep, having bars across the bottom to sustain the hearth of bone- earth. The latter being prepared in the rim it is very carefully dried, and the ring is then introduced into the cupel-chamber, supported upon screws, by means of which it may be elevated or lowered, or inclined in one direc- tion or another. When properly adjusted, it is heated, very gently at first, in order to avoid cracking. The heat from the fireplace, passes over the bridge into the cupel-chamber and thence by the flues to the stack. When the hearth is well heated the lead is placed upon it and a blast of air is introduced by means ofa fan-blower and tuyere. This acting upon the surface of the lead, the metal is oxidized, and the resulting litharge is allowed to run off through gutters made for its passage, in the surface of the hearth, mto vessels placed below for its reception. As the lead is gradually oxidized, fresh supplies of metal are introduced, either in the form of pigs, or in a molten state, the pan, N, being provided for the purpose of fusing the metal, if desired. By this means the metal on the hearth is constantly enriched; and when the button of accumulated silver has become as large as may be desirable, the addi- tion of lead is discontinued and the oxidation carried on until the lead is nearly all removed, leaving a mass of silver, of a high degree of fineness, upon the hearth. The litharge produced by this operation contains some CENTRAL AND EASTERN NEVADA. 307 silver. The richer portion is returned to the shaft-furnace and mixed with the charge of fresh ore. The cost of cupellation is stated at $5 per ton of ore. It is stated as a result of a long-continued operation that from 90 to 95 per cent. of the assay value of the ore was extracted by the method of treat- ment above described. The general cost of the reduction of the ore, at the date of the writer's visit to the works, is given in the following statement. These expenses have been somewhat reduced since that time by the completion of the Central Pa- cific railroad, and consequent cheapening of supplies and labor. It may also be observed, in this connection, that the increased facilities of transportation from Oreana to San Francisco, secured by the completion of the railroad, in- duced the manager of the works to dispense with the refining process at Oreana some time before the total suspension of operations. The ore was smelted in the shaft-furnace, as already described, for the production of crude metal, which was then shipped without refinement to San Francisco, where it was subjected to methods of separation or sold for export. Expenses of Smelting Furnace per day. Two smelters and two helpers ..--..---------+++eeeeee terete $16 00 Mv DT Gak CLS ae ee ieee ee ere ee dois enero) el ene ee 7 50 A Phectoy iYalel ence aceeees Re Seo Rec oe ie ee etre es eee rare eae 8 00 Two engineers.------+-+-+--- eee eee eee ee eee tere nett rete tert eens 8 00 Fuel for engine—furnished on contract---.-.------+++++++++2++++-- 16 00 Chinaman—general laborer.-.-.----------+--+++++++++eeeeeeee reese 2 00 General expense -----.-----+ 2-22-22 eee ec eee eceee eee e eect re eee ces 2 00 Smelting 13 tons per day, costing.----------+++++-+++++++++ s-e+- 59250 Cost of smelting, as given above, per ton..---------------+++++++-- 4.57 Sharcoal, 18 bushels per ton, at 50 cents per bushel.-.----.---- 9 00 Estimated repairs per ton..---.--------+----+eee ee eee eee eee ees 50 Mining and hauling per ton-.-..-- -------------++++sreee eter testes 4 50 Superintendence and general account per ton..-.-----+--+++++++++- 3 00 21 57 308 MINING INDUSTRY. To this was at that time added For calcining, per ton of ore.---..--..--- ++ +e eee eee tere eee eee eee 8 OO For cupelling, per ton of ore...--..--.---++-++ +++ err errr eter eee 5 00 Making total cost of treatment, per ton of ore..-..---.------- d4 57 The average yield in silver alone, without taking into account the base metals, was then about 370 per ton of ore. The foregoig statement, showing a cost of 521 57 per ton for reduc- tion of the ore without refining the product, is the result of experience in 1867, since which time important abatements have been made; but accept- ing that as an estimate for the present, we have as the cost of a ton of crude metal, $44, since the result of smelting more than 1,800 tons of ore shows a product of 983 pounds of metal per ton, or 49 per cent. Adding $30 per ton, freight to San Francisco, to the cost of production, we have S74 as the cost of laying down a ton of the metal at the market; against which we have the value of base metal, per ton.---.--21-2+-.-4--s2e. 05-5 cue S100 00 Silver—say 100 ounces, at $1.-....-..------- hepato stra ca toes 100 00 Making a total of..----.--.----.---.+--+--+---- wet ceee se ec cece 200 00 UNIONVILLE AND victnrty.—Northeast from Oreana, 28 miles distant by way of the trayeled roads, is Unionville, the county town of Humboldt County, and the central point of an important mining district. The town is now acces- sible by wagon road from the station of the Central Pacific railroad known as Mill City, 296 miles from Sacramento. Unionville is 21 miles by stage road south of the station referred to. It is situated in one of the canons of the east- ern slope of what is locally termed the West Humboldt range of mountains. This range, rising in the south near the “sink,” or basin, of the Humboldt River, extends northerly to the “big bend” of that river, which there, cutting through a break in the range, makes a sharp turn in its westward course, and flows to the south, having the range of mountains referred to on the left, or east, bank and the Trinity mountains on the right, or west, bank. The higher points of the range reach an altitude of 5,000 or 6,000 feet above the river at its base, and over 10,000 feet above the level of the sea. Many of CENTRAL AND EASTERN NEVADA. 309 its cations are well watered and its slopes bear a moderate supply of nut-pine and cedar, suitable for fuel. The mining region, of which Unionyille is now the center, was the scene of great activity in the years first succeeding the advent of prospectors and miners into this part of the State. The discovery of silver-bearing lodes in these mountains was made not long after the earlier developments of the Comstock lode, and for a season was the oecasion of great excitement. The range, for many miles of its length, was visited by explorers, who have left abundant evidence of their industry in innumerable prospecting holes that dot all the hillsides. Many mining districts were formed, thousands of locations made, towns built, and large amounts of money expended; and when the extravagant hopes of speculators or their victims met with the disappointment that was inevitable, nearly the entire population, only excepting a few who were determined to persevere and a few more who, for want of means to get away with, were forced to remain, deserted the country. The depressed condition of the mining interests of the region, that naturally followed this revulsion of feeling, prevailed until the approach of the Pacific railroad gave a fresh impulse to those districts lying within its influence, when the influx of men into the country, the easy communication with the markets, and the cheapening of supplies brought about a more hopeful state of affairs. In the neighborhood of Unionville some degree of mining activity has been kept up from the outset, and it is there that the industry of the West Humboldt range is now chiefly centered; while, within a year or two, other districts in the same range, and in the ranges further east, have been attracting increased attention, and are growing steadily in importance. For a more detailed description than will be given here of the several mining districts in this range and in Humboldt County generally, the reader is referred to the report of R. W. Raymond, esq., United States Commissioner of Mining Statistics, who has noticed the more important localities at consid- erable length. The writer will confine himself here to a few notes concern- ing some of the points that came under his personal observation. The general geological structure of the West Humboldt range will be more particularly described in another volume of this report. The rocks are chiefly metamorphic, consisting of highly siliceous porphyry or quartzite, 310 MINING INDUSTRY. broken through in central portions by granite, and flanked by massive beds of fossiliferous limestone, slates, and calcareous shales. These stratified or bedded rocks have a course generally east of north and west of south, dip- ping northwesterly at the northern, and southeasterly at the southern end of the range, the geological axis of upheaval not coinciding with the trend of the range. Veins of ore-bearing quartz oecur in all of the metamorphic rocks, having variable course and dip, but those that have thus far appeared most important have been found in the limestones or bedded calcareous rocks, conformable with them in strike and dip. The oldest mining district in the county was organized in 1860, on the west slope of this range, under the name of Humboldt District, a little north of Star Peak, the highest point in the range, and but a few miles from where the Pacific railroad now passes. It was actively prospected for a time, when, owing to general discouragements, all work was suspended, and, at the time of the writer’s visit, nothing was in progress there. The eastern slope, on the opposite side of the range, has been the scene of much more enterprise in the development of the so-called Buena Vista, Star, and other districts. The first of these derives its name from Buena Vista canon, in which the town of Unionville is located. This canon, which, with its several branches in the higher portion of the range, is several miles in length, has been exten- sively prospected. Many veins have been opened, with more or less devel- opment, some of them, no doubt, having little or no value, others producing very good ore and possessing favorable indications of permanency. The most of them, however, the good as well as the bad, have suffered from the general depression, and, since 1865, have been awaiting the return of confidence and capital to proceed with their development. The principal vein of this neighborhood, and the one on which mining operations have been prosecuted with the least interruption, is that Known as the Manitiwoe and Arizona. The ground held under these claims has been persistently worked by Messrs. Fall and Temple, and, within a year or two past, their perseverance has been rewarded by very successful results. A portion of the property has been sold to the Silver Mining Company, and has also been developed to a considerable extent under the manage- ment of Mr. Samuel Stewart. These two companies work their ground at CENTRAL AND EASTERN NEVADA. a ie present through one tunnel, and, in effect, as one and the same mine. The ledge, as it appears from the work already done upon it, is a seam or vein of quartz, from one to four feet thick, and sometimes thicker, inclosed in beds of calcareous shales or slates, that here form the crest of a ndge, which consists mainly of quartzite or porphyritic rock. The vein crops out along the hillside, and is apparently conformable with the bedding of the strata, which, in general, strike northeasterly or east of north, dipping flatly to the southeast; but the strike and dip of the rocks, at the point where the mine is opened, are very irregular, owing to disturbances or movements to which they have been subjected. Indeed the principal mining development of the ledge, visible in September, 1869, has been made near what appears to be the axis of a small synclinal fold in the beds, in which folding the vein or ledge takes part. One of the companies was then working on one side of the fold, its ore-bearing seam apparently striking north 380° west, true, and dipping south 30° west, at an angle of but few degrees near the surface, but increasing greatly in depth; while the other party was at work on the oppo- site side, where the strike of the seam was north 15° west, true, dipping easterly, or north 75° east, at an angle of 35°; that is, the ledge, in the two places referred to, showed two varying dips, in two nearly opposite and approaching directions. The casings of the vein, or ore-bearing stratum, are, for the greater part, very distinct, and are usually accompanied by a “gouge” or selvage of clay. The filling of the vein is chiefly quartz, carrying, distributed through it, par- ticles or bunches of rich mineral, consisting of black sulphuret of silver, argentiferous lead and copper ores, some chloride of silver, and native silver. Some of the ore is very rich, averaging by assay 5400 or $500 per ton; the greater part of it has an assay value of $60 or $70 per ton. The average assay value of all the ore produced is stated at about 5100 per ton. The workings of the two companies extend oyer several hundred feet along the outcrop of the vein, and have penetrated the hill by tunnels over 400 feet in length. Each company was working vigorously in the autumn of 1869, when the mine was visited by the writer. About 45 or 50 men were employed altogether, being nearly equally divided between the two compa- nies. Each company was then producing between 300 and 400 tons of ore * ole MINING INDUSTRY. per month. This product is divided, by assortment, into two classes. The first consists of rich mineral, of which the average assay value is about $500 per ton. This is put up in sacks and shipped to San Francisco, where it is worked by some of the local metallurgical establishments, or sold for export to England. In either case the realized product amounts to about 80 per cent. of the assay value. The second-class ore, having an average assay value of about S60 or $70 per ton, is worked in mills, near the mine, by crushing under stamps and amalgamation in pans. The proportion of first-class to second-class ore is said to be about one ton in twelve or fourteen. Thus, in the month of Sep- tember, in which the average relation of the two classes is said to be fairly represented, the Silver Mining Company produced 800 tons of second-class, or crushing ore, and shipped to San Francisco 25 tons of first-class ore. There are three mills in the neighborhood working on the ores pro- duced from these mines. Two of them belong to Messrs. Fall and Tem- “ple, or the company represented by them; the other, to the Silver Mining Company. They are situated near the mouth of Buena Vista Canon, in the foot-hills of the range, just below the town of Unionville, and a mile and a half or two miles from the mine. One of Fall and Temple’s mills was built several years ago, and was in process of reconstruction when visited. It has a partly sufficient water-power; when rebuilt it will have ample steam- power, and be supplied with ten stamps ef 650 pounds weight, two large Wheeler and Randall Excelsior pans, and one smaller Wheeler pan; besides the usual accompanying settlers, agitators, Kc. The new mill of Fall and Temple has ten stamps of 750 pounds weight, six pans, (four Varney and two Wheeler,) and three settlers, or separators. This mill is driven by steam. The Silver Mining Company’s mill has five stamps of 650 pounds weight, two Wheeler and Randall Excelsior pans, one Horn pan, and two settlers, or separators. The stamps in this mill crush about 10 tons of ore per day, working the pulp in the Wheeler and Randall pans, and reserving the Horn pan for the treatment of tailings. The ores in all these mills are worked in similar manner, the process generally resembling that in use at Washoe. They are crushed wet and amalgamated in pans without roasting. The ores, however, are not so docile CENTRAL AND EASTERN NEVADA. 313 as those of the Comstock lode, and the method is consequently not so well adapted to their proper treatment. The yield from the first crushing and amalgamation is not believed to exceed 50 or, sometimes, 40 per cent. of the assay value; but the tailings are worked over, after standing a while, and a fair proportion of their value is extracted by a simple repetition of the pan process. The yield obtained from the raw ores during the past year has usually varied between $25 and 535 per ton; while the tailings, by rework- ing, yield from $20 to $30, and are even treated repeatedly with profitable results. The steam-mills here use sage brush as fuel during the summer, and find it cheaper than cordwood. The latter costs 512 per cord in this neigh- borhood. Chinese labor is employed in the mills in every department of the work, excepting in driving the engines. ‘The Chinamen give great satisfac- tion. Detailed statements of the costs of mining and milling are not in posses- sion of the writer. It is stated, however, that the product of the second-class ore by the first crushing and amalgamation is sufficient to pay all the costs of operation, leaving the first-class ore and tailings as profit. The Silver Mining Company, according to the statement of its manager, made a profit of 312,000 in the month of September, 1869. This latter company had been in producing condition but four or five months. Up to the 1st of October, 1869, the value of its bullion shipments, produced from second-class ores, amounted to $51,483 27; while the first-class ore shipped up to that date had given a net return of $27,352. The shipments of first-class ore by Fall and Temple from April 1 to October, 1869, amounted to 89 tons, having an average assay value of $450, coin, and yielding a net return of 75 per cent. The bullion shipments derived from second-class ore amounted to about $150,000 in fourteen months, ending October 1, 1869. The two companies whose operations haye just been referred to have of late been the most productive in the county of Humboldt. In the summer of 1869 there was but little work in progress in the immediate vicinity of Unionville, except that which was connected with their mines and mills. There was, however, some activity in prospecting or developing other veins. 40 314 MINING INDUSTRY. Just above the town of Unionville, on the north side of the cation, the Na- tional Mining Company was at work upon a lode bearing the same name, which has been opened along the surface for a considerable length and pros- pected to a depth of about 100 feet. The vein is said to yield a rich gold- bearing quartz. A small mill of four stamps was in process of construction, and nearly ready for operation in September, but had not, when visited, begun to crush rock. Trials of the quartz from this vein, made in other mills, promised successful results. Further up the canon the Seminole Tunnel Company was engaged in driving an adit into the mountain, with the view of cutting a series of ledges that had been opened on the surface, with some indications of value. West of Unionville, on the opposite or western slope of the range, there has been a large amount of prospecting work done in the various canons, most of which was followed by discouraging results at the time of its per- formance, but which may yet be turned to good account under the increased advantages secured by the railroad. One enterprise of importance is the’ Alpha mine, in Panther, or Butte, Canon. The ledge on which this mine is located has been in course of development for several years, though the force employed in the work was very small, at least until lately. It is now owned by the Nevada Land and Mining Company, and is being more vigorously worked. It is easily accessible from the railroad, by which means the higher grade ore is now shipped to Reno and roasted by the Stetefeldt furnace, and subsequently amalgamated in pans. ‘The writer is not in possession of defi- nite information concerning the average value of the ore or the extent of the operations of the present company. Srar Districr.—Directly north of Unionyille, also on the eastern slope of the range, is the Star district, once the scene of very lively prospecting and busy enterprise, that was soon followed by utter abandonment of the region. Star Canon has been explored from its mouth to the crest of the range, and many series of promising veins have been discovered. Among them is the celebrated Sheba mine, which made good its promise, it is said, to the extent of over $125,000, a single pocket or bonanza having yielded $75,000; but its visible resources having been exhausted without meeting the expectations of its speculative owners the work was suspended and has long been lying idle. CENTRAL AND EASTERN NEVADA. 315 The rocks of the range cut through by this canon consist of quartzite, limestone, shales, and slates, dipping with considerable uniformity to the westward, striking north and south or north a little easterly. Most of the important veins, though not without exceptions, conform with the country- rocks in course and dip. Such is the case with the Sheba vein just referred to, a deposit which les between a black rock of slaty structure as a hanging wall, and a bluish, probably calcareous, bed below. In places the ore-bear- ing ground has a great width, it is said 150 feet; but as the mine was inac- cessible to the writer, there was no opportunity to verify the statement. The same vein on the south side of the canon is known as the De Soto. On this property the vein has been explored by tunnel for a length of about 600 feet, and to a depth, at the inner end, of 300 feet below the sur- face. In general, the lode varies from two or three to five feet in width. The hanging wall is well defined, smooth, and regular, generally underlaid by a foot or more of soft, clayey material, taleose in appearance. The filling ‘of the vein or ore-deposit is chiefly made up of bluish limestone, somewhat argillaceous in appearance, very fragmentary in character, having all the seams and interstices filled up by quartz. These quartz-seams are sometimes large and continuous for considerable distances. The ore is associated with this quartz, and consists chiefly of rich silver minerals, antimonial sulphurets, fahlerz, &c. Galena and zincblende are associated with the ores. The assay value of the assorted ore is very high. The ore occurs in bodies, chimneys or bonanzas, and the vein contains long interyals of barren ground. This feature partly explains the history of the Sheba, the mine having been very productive while in bonanza, which, being exhausted, the patience of the stockholders was not sufficient to search persistently for more. The De Soto was first opened in 1861, since which time a considerable amount of work has been done upon it, but with long intervals of quiet. In the summer of 1867 five men were employed there, and the results of their labor were deemed very encouraging; but the work was soon after suspended, and, so far as the writer of this is informed, still remains so. Star City, a town of considerable size and importance in the earlier days of its career, is situated in the neighborhood of these mines. It possesses ¢ number of large buildings, stores, post office, express and telegraph stations. 316 MINING INDUSTRY. One of its hotels is said to have cost $40,000. For the last few years the town has been almost entirely deserted. A mill of ten stamps and four reverberatory furnaces for roasting the ore was built long ago at the mouth of the canon, but has lately been taken down and removed to Unionville, a por- tion of its material being used in reconstructing My. Fall’s mill. The next range of mountains occurring east of that in which Unionville is situated contains several districts, some of which have been extensively prospected, although not very persistently developed. The principal point of operations has been im the neighborhood of Dun Glen, a small town or mining camp seven miles from Mill City, and about 25 miles from Unionville. The most notable mine in this locality is the Tallulah, working on two or three veins, and producing ore that is reported as very rich. Other compa- nies have also made developments that were regarded as very encouraging; but mining operations, during the last two or three years, have not been very actively prosecuted. In the summer of 1869 there were but few men at work in this region, though, later in the year, a mill, situated at Dun Glen and belonging to a New York company, rested work, and a more vigorous development of the district was looked for. Gotp Run.—The Gold Run District les upon the east side of the Gol- conda Mountains, the next range east of that last referred to. The center of operations is about 12 miles from the Pacific railroad. Its point of commu- nication with that road—a station Known as Goleonda—is 341 miles from Sacramento. This region was visited, im 1868, by Mr. Arnold Hague, from whose notes the following brief statement is obtained. The principal mines appear to be located upon one vein, occurring in a metamorphic, siliceous slate, which here forms the foot-hills of the mountain range. The vein strikes due north and south, and is said to have been traced for a distance of more than three miles, extending southerly from the Gol- conda mine to the Jefferson mine, where it is apparently divided, one branch striking southwest and the other southeast. The vein, in that part which is most developed, dips to the west at an angle of 50° degrees from the hori- zon. It is six or seven feet wide. At the time referred to the vein in the Golconda mine had been explored to the depth of 50 feet, and drifted upon, at that level, about 120 feet. So far as developed the vem appears to main- CENTRAL AND EASTERN NEVADA. oly tain uniformity in course, dip, and width, and in the character of its ore. The walls are well defined, and both foot and hanging walls are the same metamorphic slate. The ore is very much decomposed, and consists chiefly of oxidized products, containing a good deal of “base metal.” The silver occurs in the form of sulphuret. The vein rock is cut by seams of soft, white, clayey material, which carries finely disseminated silver sulphurets. The Golconda mine is one mile and a half north of the small town of Cumberland. A force of thirteen men was employed in this mine in the summer of 1868. The company have a mill situated seven and a half miles north of the mine, which is furnished with eight stamps, five Varney pans, and eight Knox pans, used as settlers. The mill was then working about 10 tons per day, of which the average yield was 535 per ton. The other mines had been less developed than the Golconda. The more prominent of these were the Cumberland, Register, and Jefferson. The last named, at the south end of the vein, near the “split,” has an incline, sunk to a depth of 65 feet on the vein. The mill assay of eight tons of ore from this claim gave $48 per ton. Barrie Mountaiw Disrrict.—This district, about 30 miles further east, is one that is rapidly growing in importance. It is south of the Humboldt River and near the railroad. The station of the same name, by which the mines of this region are made accessible from the road, is 879 miles from Sacramento. The district is about 12 miles long, in a north and south direc- tion, by something less in width. It lies on the west side of Reese River Valley, and in the eastern foot-hills of the Battle Mountain range. The river bed here is dry during a portion of the year. The mountain streams, in the neighborhood of the mines, furnish water enough for mining, milling, and domestic purposes, and, in some cases, for driving power. There is a fair supply of wood and timber, suitable for fuel and for use in the mines, in por- tions of the district and in the adjacent country. The principal mine in the neighborhood is the Little Giant, chiefly owned and worked by Mr. G. W. Fox. It is eight miles from the railroad station. The vein, on which this mine is opened, was first prospected in 1867, and was developed by a small force until May, 1868, when the work was prosecuted with greater vigor. During the following summer a five- = t 5 \= 318 MINING INDUSTRY. stamp mill was erected, which, in the autumn, began to crush ore, affording very satisfactory results to the owners of the mine. The vein is inclosed in quartzite. It crops out and is opened upon or near the summit of Little Giant Hill. Its course is north 55° west, true, dipping to the southwest at an angle of 55°. It is from one to three feet wide, averaging about two feet. The gangue is chiefly quartz; this, when clear, is white and hard; but it is usually intimately mixed with the ore, which, being decomposed, imparts to the whole mass a dull yellow color and a soft, crumbly texture. The ores near the surface are, apparently, much oxidized, the products of the decomposition of other sulphureted combina- tions of silver, associated, doubtless, with lead, antimony, and other base metals. In depth the ore is less changed, showing sulphureted and antimo- nial forms of silver-bearing minerals, which make their metallurgical treat- ment more difficult. On the western slope the vem has been opened on the surface, 300 or 400 feet below the crest of the hill, and thence upward it has been stripped along its outcrop entirely across the summit of the hill and down on the east- ern slope at frequent intervals. The length of Mr. Fox’s claim is 1,400 feet, of which some 400 feet have been developed by means of three tunnels or adits. The upper tunnel, 130 feet long, is driven in on the vein from a point about 60 feet below the top of the hill; the second, 60 feet lower, measured on the incline of the vein, is about 100 feet long, and the third, 150 feet lower, is 250 feet long. All of these tunnels have shown a good yein, regu- lar in course and dip, and generally productive of good ore. Some of the ground has been stoped out, though by far the greater portion opened by this work was still available for future operations when visited in September, 1869. A portion of the ore produced, especially from the upper levels, was of a docile character, easily worked by pan amalgamation, although leaving rich tailings; while the other portion, less affected by the oxidizing influences of the surface, remained unworked, and ready for shipment or treatment by some other process. There were on hand, at the time above referred to, about 100 tons of ore of this class, of which the assay value varied between S100 and $1,000 per ton, averaging about $300. The ore selected for mill- ing is said to yield, on the average, 5150 per ton, sometimes reaching a much CENTRAL AND EASTERN NEVADA. 319 higher figure. The tailings assay about $50 per ton. The mill, which is placed near the mouth of the canon, a mile and a half below the mine, con- tains five stamps, each weighing 700 pounds, capable of crushing about 10 tons per day in the aggregate. There are two Wheeler pans, working on freshly crushed ore, and one Horn pan, working on tailings. Ten men are employed in the mine, and eight in the mill. Labor costs $4 per day. The product of the mine, up to July 1, 1869, according to the returns of the county assessor, which include nothing for first-class ore awaiting treatment, nor anything derived from the working of tailmgs, amounted to nearly $70,000. The Little Giant vein has been traced, in both directions, beyond the claim of Mr. Fox, and there are locations made upon it by other parties, none of which, however, have yet been extensively developed. There are, also, other veins in the immediate vicinity, which have been somewhat prospected, with encouraging results, having, it is said, much similarity, in general fea- tures, to the one just described. The southern part of the district, about eight miles from the Little Giant, has lately been the scene of active operations, chiefly in the develop- ment of copper-bearing ores, but also in the discovery and prospecting of veins that are rich in silver, and generally resemble the Little Giant in the character of their ores. The veins of copper have been known several years, but have only of late been regarded as very valuable. The copper occurs in the form of black and red oxide, with which is associated some native metal. It is found in ledges that are from two to six feet wide, and show strong indi- cations of permanency. The ore assays very high in metal, and is said to yield 40 per cent. in large quantities. Shipments of ore were made during the autumn to San Francisco, where it was purchased for export to England. The property is reported to have been sold lately at a large price; and, according to newspaper report, is now undergoing vigorous development with very satisfactory results. At Duck Creek a vein has been opened, resembling, in many respects, the Little Giant. Trials of the ore had been made at Fox’s Mill, with en- couraging results, and development of the property was in progress at the time of the writer’s visit. 320 MINING INDUSTRY. SHOT LON TI. GEOLOGY OF THE TOYABE RANGE. BY §S. F. EMMONS. GENERAL Freatures.—The name Toyabe, which signifies in the Indian language ‘‘mountains,” has been appropriately applied to this great range, whose sharp, serrated ridge rises several thousand feet above the neigh- boring ranges which rib the surface of the great Nevada plateau. The view from its summits extends over more than four degrees of longitude, and is limited only by the White Pine and East Humboldt Mountains on the east and the Sierra Nevadas on the west, whose forms and outlines can be traced with the utmost distinctness in the dry, thin air of these elevated regions. Snow rests upon its higher points until late in the summer, and, with the yerdure which accompanies it, forms a most pleasing contrast to the somber hues that prevail over the mountains of this arid region. Rising nearly 6,000 feet above the broad valleys which border it on either side, its height is rendered still more imposing by its limited lateral extent, its average width from foot to foot being scarcely eight miles in a horizontal line; contrasted with the steep slopes of its sides, the valleys, although very considerably inclined toward their center, seem almost level ground. The present geological sketch and accompanying map, the result of four weeks’ explorations, cover an extent of nearly 60 miles in the direction of the range, including thus its most characteristic portion as an independent and isolated ridge, embracing as well those parts in which any important mining developments have been made. Beyond the limits of the map it spreads out laterally, developing a system of cross-ridges, which, connecting it with the neighboring ranges, form respectively the northern limit of Smoky Valley, which borders it on the east, and the southern water-shed of Reese River Valley, which drains its western slopes. This portion of the range has a trend of about north 23° east, and, in general outline, forms a high single ridge, characterized by a short, steep declivity on the east, and a longer and more gentle slope to the west; but a CENTRAL AND EASTERN NEVADA. BA closer examination of its topography discloses a double ridge system, which prevails through the greater part of its extent, giving rise to a series of inte- rior longitudinal basins; hence the line of the main water-shed is extremely sinuous, although that of north 23° east would pass through all the principal summits of the range. To the north the range consists of two low and some- what broken diverging ridges, inclosing between them the Park basin, which opens out further north into the large meridional depression called Grass Valley. These ridges rise gradually to the south, preserving a certain paral- lelism, though broken through at various points by the waters of the high, narrow valleys which they inclose, until they reach their culminating points, respectively, in Bunker Hill and Big Creek Peaks. In this extent, although the eastern ridge is generally over a thousand feet higher than the western, the greater part of their surface is drained into Smoky Valley through Park Creek, Birch Creek, and Kingston Creek, which break through the eastern ridge, while only Big Creek flows to the west. For a few miles south of Big Creek Peak, the western ridge forms the main divide of the range, which bends round the head of Kingston Creek, but to the south of it forms a continuation of the main eastern ridge. Tor a distance of 25 miles south, the range con- sists of a single and, in general direction, straight ridge, with steep, craggy slopes to the east, and long, smooth western spurs. By the bend in this ridge to the westward at Summit Canon, the western summit again becomes the main divide, its continuation to the north being indicated by the widen- ing of the spurs toward the west, which inclose the small basins at the heads of Cross’s and Washington Cafons. This ridge grows higher toward the south, till in the sharp peak of Mount Poston it forms the highest crest of the range. ‘The eastern ridge, meanwhile, finds its continuation in the shoulders of the eastern spurs, which, rising into high peaks at the Twin Rivers, iclose the large interior basins of these canons, around whose head the main divide makes another bend to the eastward. These numerous mountain valleys afford most excellent summer grazing ground, their slopes being covered with bunch grass, which remains green and nutritious long after that of the plains is parched and worthless; they form, moreover, nat- ural inclosures, where cattle can be left comparatively unwatched, without danger of their straying. 41 322 MINING INDUSTRY. nd The steep, sheltered sides of many of the canons of the range support a growth of pinon and juniper trees, with some yellow pine, fir, and mountain mahogany, which, though somewhat sparse, is abundant compared to the average mountain range of this region, and sufficient to afford several years’ supply of mining timber and fuel to mines that are likely to be opened. The agricultural resources of the range are not sufficient to support its present limited population, being principally confined to the more hardy vegetables, which have been successfully cultivated in some of the larger canons; fair crops of grain have, however, been raised on the bottom lands at the mouths of Big Creek and Kingston Canons, and along the boy- ders of Reese River and of the Smoky Valley Flat, when the supply of water has been sufficient and the slope of the ground suitable for irrigation. The valleys which border the range on the east and west are broad, plain-like depressions, from six to twelve miles wide, their sides sloping up toward the foot-hills of the mountains, which are from 600 to 1,200 feet above their lowest point. Their surface is covered by a scanty growth of sage brush, which, in their lower and more moist portions, is replaced by a coarse wire or swamp grass. That on the west is traversed by the Reese River, which flows northward into the Humboldt, of which it is the longest affuent; but, although opposite Austin it is a considerable stream, with an average fall of 25 feet in the mile, it seldom reaches that river, owing to the great evaporating power of the atmosphere. Smoky Valley, on the east, is both deeper and wider than Reese River Valley, and forms an independent basin; the waters flowing into it from this range all drain toward a large mud or alkali flat, opposite Park Canon, which is about 18 miles long by 6 miles wide; a low divide, opposite the Hot Springs, forms the southern limit of this basin, though the valley extends over a hundred miles further south without any considerable change of level. Such alkali flats as this form a very characteristic feature in the scenery of the great plateau; partially covered by water from the melting of the snows in spring and early summer, its surface, destitute of ali vegetation, is left, by the eyaporation of these waters, incrusted with a thin, white coating of min- eral salts. At its northern extremity is the so-called salt marsh, where these incrustations are so considerable that large quantities of the salts (here con- CENTRAL AND EASTERN NEVADA. 323 taining from 50 to 60 per cent. of chloride of sodium) are collected for use in the reduction works in the vicinity. It is probable that saline springs exist under this portion of the flat, as the salts which have been removed are con- stantly replaced by fresh incrustations. The hot springs in the southern portion of the valley do not differ essentially from others in the State, which are of frequent occurrence in the vicinity of large masses of volcanic rocks. They are a group of circular- shaped pools, from one to thirty feet in diameter, in a slight elevation, formed by the deposit from their waters, on the edge of the wash from the hills; they vary in temperature from that of the air to the boiling point; their supply of water but little more than compensates for the evaporation of the air, and streams run from them but for a short distance. The most interesting of the group is one shaped like a bowl, about three feet in diam- eter and as many deep, from the center of which the steam issues with such force as to throw up the water in a little jet, a foot or more above the surface of the pool. These springs are used both for bathing and cooking purposes; their mineral character has not yet been determined. Rocxs.—The rocks of this range may be divided into three general classes: the sedimentary formations, the ancient eruptive rocks or granites, and the recent eruptive or voleanic rocks. These three classes represent in age the three geological periods—Paleozoic, Secondary, and Tertiary. Sedimentary rocks.—On the accompanying map the colors of the car- boniferous formation have been provisorily assigned to all the sedimentary rocks of this range, inasmuch as the only fossil remains as yet discovered here belong to that period. Limestone—The limestone bodies consist of a compact, dark-blue rock, in general, probably somewhat metamorphosed, fine-grained to granular, and frequently intersected by small seams of white crystalline calespar. The only characteristic and well-defined fossil found by the writer in the some- what limited time of his researches is the Fusi/ina cylindrica, which is gen- erally assigned to the lower carboniferous limestone; besides this were a float fragment of siliceous limestone, containing Syringopora, and some molds of shells too much metamorphosed to be recognized. These limestones are found on the flanks of the range, resting conformably on the slates. 324. MINING INDUSTRY. Slates-—In the slates are comprised the more highly metamorphosed beds, which include fissile limestone shales, more or less siliceous clay-slates, and, loeally, schistose and somewhat crystalline rocks, resembling mica and hornblende schists, and, in one instance, a marbleized limestone. As these rocks form a gradation into the limestone, their line of division cannot always be definitely located. These beds have been so much disturbed and con- torted, and their character so frequently changed by local metamorphism, that it has been impossible for the writer to form a satisfactory estimate of their thickness; probably 7,000 feet would cover that of the slates and lime- stones combined. Quartzites—The quartzite series, found only in the southern portion of the range, form beds of compact white quartz rock, colored reddish-brown on the weathered surface, between which are intercalated thin beds of white granular limestone. These are found underlying the slates, with no appa- rent nonconformity; they represent a thickness of several thousand feet, and may belong to the Devonian series; this point will probably be elucidated by the future work of this survey, when the character and thickness of the strata which make up the carboniferous and lower formations in this region will be definitely determined. Granites—TVhe only considerable bodies of the older eruptive rocks in the range are the granites, which form intrusive masses, upon which rest the sedimentary rocks. They vary in texture and composition, to a certain degree, in the different bodies, but are generally characterized by a large proportion of quartz and an almost entire absence of hornblende; the pro- portion of mica entering into their composition is generally small, and, in one body, replaced by chlorite, forming a protogine-granite. A series of syenite and greenstone dikes, often so fine-grained and com- pact that their composition could not be determined, which occur with remarkable frequency and regularity along the eastern slopes of the range, cutting through the granite as well as the various sedimentary formations, may be considered to forma second phase of the granitic eruption; these dikes, though from 20 to 50 feet wide, were too small to be represented on the map. A body of dioritic rock, occurring at the Twin Rivers, supposed to be CENTRAL AND BASTERN NEVADA. 325 the product of a later metamorphism, has also been left undesignated by any distinctive color. Volcanic rocks—These rocks are not known to occur earlier than the tertiary period; those found in this range may be referred to the two varie- ties, propylite, the earliest of the volcanic series, and rhyolite, generally con- sidered to be among the most recent, though here it has directly succeeded the propylite. Both of these rocks have played an exceptionally important part in the structure of this range, since they usually occupy orographically subordinate position. Propylite—Both hornblendic and quartzose varieties of propylite are found in each of the two localities of this rock in the range, but, compared with other bodies in the State, they are very rich in silica. Rhyolite—This rock, usually noted for its great variety of texture and color, though it occurs here in exceptionally large masses, is of comparatively uniform texture; it is generally of the crystalline or granitic variety, the occurrence of the porphyritic, hyaline, and earthy texture being of subordi- nate importance. The quaternary formations are represented by the extensive accumula- tions of detrital material, which cover the sloping sides of the adjoining val- leys, varying from a coarse gravel, inclosing occasional large rock fragments, to a fine, almost impalpable, silt. The gravel benches of the park basin may be referred to the same period. StructuRE or THE Rance—The geological formation of this range, presenting as it does the result of upheavals, metamorphisms, and eruptions, extending over long geological periods, affords the type of a most compli- cated mountain structure, of which the present report can only claim to give the general outlines. In its original elevation, as represented on the map by the stratified rocks and granites, may be traced the result of the action of forces of con- traction or compression, acting in two directions, laterally, or at right angles to the general line of elevation, and longitudinally, or parallel to that line. The lateral, or main forces of upheaval, have produced anticlinal and syncli- nal folds, whose axes would have the general direction of the range. The effect of the longitudinal compressions has been a disturbance of these eondi- tions, causing a deviation from the general direction, and a crumpling and 326 MINING INDUSTRY. general dislocation of the strata, in those parts where the fractures produced by the first-named forces have not been filled by the intrusion of granite jodies, thus offering a greater resistance to the disturbing forces. By reference to the map, Atlas-Plate 13, it will be seen that there are five principal bodies of granite—two northern, those of Austin and Geneva; two southern, the eastern and western Ophir Canon bodies, and a long intermediate or central body. The Geneva and central and eastern Ophir Canon bodies seem to belong to one line of upheaval, while the Austin and western Ophir Canon bodies represent independent lines of elevation. The central mass of sedimentary rocks, comprising the double ridge system of Globe, Bunker Hill, and Big Creek Peaks, included between the Geneva and central bodies of granite, forms a general anticlinal fold, whose ends overlap respectively the extremities of those bodies; here the effect of the longitudinal compression is most distinctly seen, since the axis of the fold has an extreme variation in direction from about north 35° east, on the northern end, to north 20° west on the southern, with an intermediate re-en- tering angle to the east. On the north the appearance of the Austin granite seems to have been accompanied by an upheaval of the metamorphic slates of Telegraph Peak to the north, and of the slates and limestones to the south, forming a partial synclinal with the western member of the main anticlinal fold where it rests on the Geneya body of granite. The position of the stratified rocks in the portion of the range south of Kingston Cation seems to be mainly due to their upheaval in the line of the granite bodies, which form two generally parallel lines of elevation, repre- sented by the central and western Ophir Canon bodies. The elevation of the central granite body represents in the main a mono- clinal uplift, though isolated bodies of metamorphic rock occur on the eastern flanks of this body, whose relations have not been accurately determined. By the continuation of this line of upheaval to the south, in the eastern Ophir Cation bedy, which is a metamorphic granite, a synclinal fold in the strata is formed between this and the western granite; the western uplift probably extends for some distance north of this body to the limestone on the flanks of the monoclinal. Plate XXVI Toyabe Sections. | Nes, | M' Prometheus Park Mts | = — E.18°S Globe Peak Big Greek Peake st Juan NP 4. | ee 4 eS ” 5 73 ‘ ‘ a ee Z oa 4 ™ vs as 3 Bh SS avY SVM a ; San (ae LE Cus +A Ts —— oye - > EDFS. HORIZONTAL SCALE: /irch - /'2 miles VERTICAL SCALE: /inch = 6000 fect Belmont Section. | | | Mighbridge Hud a RO a Alene) aN NOON oN > : ee: C J c + ANNAN Se SRO = = Cee atte Laks ba Ba aa AS ANB ADS PRELANNOO MEAS SCALE: VERTICAL and HORIZONTAL: /cnch ~ 2000 feet QUARTZITE SHALES. LIMESTONE CRANITE RHYOLITE QUATERNARY CENTRAL AND EASTERN NEVADA. BAT To subsequent metamorphic or eruptive action is probably due the form- ation of the numerous veins and dikes which intersect the original formations. The intensity of metamorphic action has increased toward the south, as seen in the metamorphic granite at Ophir Canon, and the partially crystalline slates, which, at the Twin River, are replaced by metamorphic diorites. There are also evidences of later dynamic action, whose extent cannot be determined. In the voleanic period the appearance of the propylite bodies of the Point of Rocks was accompanied by considerable disturbance of the adjoming rocks, which now seem to rest upon it, and to be somewhat altered at the contact; this action was apparently more extensive to the south than to the north of this body. The southern eruption of propylite seems to form a con- tinuation of the western Ophir Canon body of granite to the south, covering the present bed of the Twin River basins, and to have been accompanied by extensive metamorphic action on the rocks to the east of it. The rhyolite eruptions have not in general been accompanied by any considerable disturbance or alteration of the adjoining rocks. Those of Mount Poston, and the peaks above the Hot Springs, have overflowed the propylite and, probably, the slates of the western slopes of the range; it is not certainly known whether the San Juan rhyolite is part of this flow or an independent eruption; the indications of a lateral fold in the strata here would favor the latter supposition. The rhyolites at the mouths of Big Creek and Kingston are small isolated outflows, which have apparently had no action upon the adjoining rocks. The Mount Prometheus rhyolite has breken through granite, overflowing its flanks and those of the slates which rest upon it. The sections given on Plate XXVI, which present approximate pro- files of the range at different points, will serve to illustrate the idea intended to be conveyed in the above description. No. 1, on a line drawn through Monnt Prometheus, east 13° south, shows the relations of the granite and rhyolite bodies at that point. No. 2, on a line drawn through Globe and Big Creek Peaks, east 6° south, shows the main anticlinal fold, though it cannot serve for an accurate representation of the thickness of the strata, since their strikes vary so much that it is impossible to choose a line which shall cut them at right angles. MINING INDUSTRY. bo os) No. 3, on a line drawn through San Juan, east 27° south, shows a section of the central granite body, the slates and quartzite resting upon it, and the rhyolite on their flanks. No. 4, on a line, north 24° south, drawn through the northern spur of Ophir Canon, shows the two granite bodies, the synclinal fold in the slates, and the rhyolite flow from Prometheus which covers the western slopes. To what extent the present configuration of the range is due to glacial action is not easy to determine, since the decomposable nature of some of the rocks, and the position of the strata of others, are not adapted to preserve the traces of such action. From the fact, however, of glacier polishings having been found on the face of a spur, at the mouth of Santa Fé Cation, in such a position as to ne- cessitate the supposition of the existence of a glacier in that canon, whose lower extremity, covering the end of this spur, extended out into Smoky Valley, it may be inferred that the basin-shaped heads of most of the large canons were formerly filled by glaciers, which, flowing over the inclosing ridges at their lowest points, by their abrasion, followed the course of the present cations; the subsequent action of water having cut the narrow gorges which now exist in their lower portions. The great accumulations of debris at the mouths of the larger canons, whose slope is frequently more than 6°, through which the waters have cut channels from 50 to 100 feet deep, and of more than double the width, favor this supposition, while the narrowness and steepness of the range, and the probable existence of lakes which filled the adjoining valleys, might account for the absence of any well-defined moraines. The Austin body of granite, which is particularly interesting as being the principal ore-bearing body of the range, forms the core of the main ridge of the Toyabe, which is here comparatively low, for five miles south of Tele- graph Pass. It is exposed mainly on the western slope of this ridge, where it is worn into the rounded spurs and open, shallow ravines, characteristic of an easily decomposed granite. This is a normal granite, consisting of quartz, feldspar, and mica; the feldspar of two varieties, a semi-translucent orthoclase, and an opaque white variety, probably oligoclase; the mica a dark magne- sian variety; hornblende is found as an accessory ingredient, sometimes con- CENTRAL AND EASTERN NEVADA. 329 centrated in bands or bunches. It forms the southern foot-hills of Telegraph Peak, underlying the metamorphic rocks, which are dark-blue siliceous lime- stone-shales, dipping to the north and east at alow angle. At Telegraph Pass it is exposed on the eastern slope of the ridge, where it is traversed by a dike, about 15 feet wide, of white granulitic rock, containing sparse crys- tals of mica, and black crystalline grains, probably of tourmaline, concentrated in bunches throughout the mass; this dike has a northwest strike, which.is the direction of the principal veins of this neighborhood. Granite forms the crest of the ridge, as far south as Mount Prometheus. This peak is chiefly conspicuous as forming the summit of Lander Hill, the spur in which have been found the richest veins of the district; its summit, and the flat-topped ridge at the head of Marshall’s Canon, are formed of rhyolite, which covers the eastern slopes of the ridge, and forms the head of the Park basin; while, on the main ridge south of Marshall’s Caton, are found the dark metamor- phic slates of Telegraph Peak, dipping southeast at a low angle with a north- east strike, and separating the granite, on which they rest, from the rhyolite, which forms the saddle connecting this ridge with the hills north of Geneva. The rhyolite of Mount Prometheus is not a very characteristic variety, inasmuch as it contains but little free quartz, while that of the Marshall’s Cation ridge is very like a trachyte, or, in some respects, an older porphyry; but their mode of occurrence, geological relations, and certain mineralogical characteristics favor the assignment to them of a rhyolitic rather than a trachytic origin, while their resemblance to the older porphyries is confined to the compact matrix of a limited local occurrence. The mass of Prometheus and its eastern slopes are composed of a brown- ish-purple vesicular rock, in which a microcrystalline feldspathic paste incloses crystals of glassy feldspar, magnesian mica in large quantities, and occasional grains of smoky quartz; largely disseminated throughout the mass, and lining the cavities, which are frequently as much as an inch in diameter, are spher- ulitic concretions of feldspar, whose occurrence is generally considered to be characteristic of rhyolitie rocks. On the western crest of Prometheus, to- ward the main granite body, this rock passes into a black pearlite, in which the spherulitic structure is still found, though not so prominently developed as in the former, nor with the same concentric structure. The vitreous paste 42 350 MINING INDUSTRY. incloses erystals of white sanidin feldspar and black mica, but apparently no free quartz; it has a dark, glazed, weathered surface, and frequently a columnar structure, forming small pentagonal and hexagonal prisms. The line of contact of this rock with the granite, which has a north and south direction, is marked by a depression in the crest of the ridge west of Prometheus, and a ravine on either side, showing that the granite was decomposed, and hence more deeply eroded on this line; and the pearlitic texture would seem to be due to the reciprocal action of the granite on the rhyolite body. The main rhyolite of Prometheus is also very easily decomposed by atmospheric agents; hence, in the low saddle of the main ridge above Austin and in various depressions of the eastern spurs, it has been eroded off, and the underlying granite laid bare; here the granite is found to be so thoroughly decomposed on the sur- face that it crumbles into fine quartz sand at the touch, the feldspar having been kaolinized, and the mica only leaving its traces in stains of iron oxide through the mass. In several places on the eastern slopes, however, the granite is found in large rounded blocks, in a comparatively wndecomposed state; these may not have been entirely covered by the flow of rhyolite, or their outer decomposed surfaces may have been entirely worn away by the action of erosion, and the undecomposed kernel left as now found. South of the pass above Austin extends a flat-topped ridge, having a gentle slope to the eastward, which is formed of a reddish-brown porphyritic rhyolite; its compact, homogencous, feldspathic matrix incloses small crystals of sanidin feldspar, with no free quartz as far as can be seen by a simple loupe; in the valley to the east this rock is found, having a lighter drab-colored ima- trix, inclosing, in addition to the feldspar, crystals of black mica. Still further south, on the divide which connects this ridge with the hills north of Geneva, and in a line due south from Prometheus, eccur similar rocks, and in the same relative position as on that peak; they are, however, more compact, and have not the spherulites which are found in those rocks. Still another variety of texture is found on the eastern limits of the body; as these, however, are, ina great’ measure, covered by the debris of the Park basin, they are not so clearly defined as the western limits. On the northern slopes of the hills, north of Geneva and near the Overland Stage read, is found a brick-red rhyolite, having an earthy homogeneous texture, probably the CENTRAL AND EASTERN NEVADA. Bol result of solfataric action. At the foot of a northeastern spur of Prometheus, on the western edge of the basin, is found another partially decomposed vari- ety, of white color, having small crystals of quartz disseminated through the feldspathic matrix. The line of fissure of this rhyolite eruption, as has been seen, is about north and south; the southern portion of the body, or that which occurs in the slates, has a different character from the rock of Prometheus, which has broken through the granite, and is, by the occurrence of granite on the pass above Austin, isolated from the rest. There is no evidence to show that these rocks are cotemporaneous or the reverse, since they are not found in contact on the surface; whatever the origin of the more southern rocks, how- ever, the summit of Prometheus evidently marks the vent through which the rocks, composing its slopes, haye come to the surface. The most productive veins in the district occur on the south slope of Lander Hill, the granite spur, which extends to the westward from Mount Pro- metheus; of those most extensively explored the majority have a northwest strike, and dip at a low angle into the hill to the northeast. In these veins has been found a system of fractures or faulting, in a north and south direc- tion, occurring with such regularity and persistence as to suggest the idea that the surface of the spur has experienced a general downward movement to the westward, or, what seems more probable, that the interior core of the spur has been uplifted in the opposite direction, possibly at the time of the rhyolitic eruption of Mount Prometheus, the line of movement being generally parallel to this fissure. In the upper part of Marshall’s Cafion, forming a dike in the granite, is a dark-green, fine-grained rock, impregnated with iron pyrites, which re- sembles a syenite, though its grain is too close to determine with accuracy its mineralogical composition. To the south the granite body gradually grows nar- rower, and in Ely’s Canon, the fourth south from Austin, is no longer seen. Here are limestone-shales, generally dipping south and east, though their strikes seem to vary a good deal. In the next cation south is the commencement of a body of blue limestone, which extends south as far as Big Creek, and seems to be the least altered of any in the range. In it were found a few indistinct molds of fossils, but it is generally rather granular and crossed by small Bia : MINING INDUSTRY. seams of ealespar and quartz; the lime made from it ina limekiln, a few miles north of Big Creek, is said to be of very poor quality. The general strike of the body is north 35° east with a dip of 40° to the west, though the northern end apparently partakes of the construction of the slates resting on the Aus- tin granite. An immense seam or dike of quartz is found near the summit of the ridge, above the limekiln, having a strike parallel to the general direc- tion of the ridge, and corresponding in position to a quartzite dike near the head of Ely’s Canon. The occurrence of such dikes with a probable con- tinuity for a long distance is one of the peculiar features in the geology of the range. Directly east of Austin, forming the eastern water-shed of the Park Basin, is a group of conical granite hills, having three principal peaks rising about 1,800 feet above the neighboring valley, called the Park Mountaims. Their entire mass appears to be of granite, which is in the main a compact, close- grained variety, in which the feldspars predominate ; these are of two varieties, a flesh-colored orthoclase and a greenish-white, probably oligoclase, besides which the granite contains quartz anda magnesia mica, with some small green erystals, probably hornblende. A narrow dike is observable on the slope toward Park Creek, having a northwest trend, corresponding to that on the east of Telegraph Pass; the rock of this dike is a white granulite, containing no mica, and the feldspar seeming partially kaolinized. On the north of the group the waters of the Park Basin have broken through the granite body in a narrow gorge, in which the rock has been very much decomposed by atmospheric agents, causing considerable accumulations of granite sands in the ravines. The granite extends into the hills north of this ravine for a short distance, and is sueceeded by siliceous metamorphic slates which rest upon it, dipping to the northward. The extensive flows of rhyolite which form the table-topped ridges to the north and east, beyond the limits of the map, probably extend to the flanks of these slates. Of the group of hills next south, lying to the north of Geneva, the highest point, which rises about 8,000 feet above the valley, is of dark meta- morphie slates similar to those of Telegraph Peak, succeeded to the north by various fissile slates, whose debris form smooth slopes to the north and west. These slates have a general strike somewhat east of north, and are traversed CENTRAL AND EASTERN NEVADA. eben by several quartz veins, and some dikes of a light-colored breccia mat- ter, having a northwest direction; the latter may have the same origin as the rhyolite, which forms the saddle connecting these hills with the Western or Austin ridge. On the eastern slopes the granite forms more jagged spurs, which are covered with a considerable growth of juniper, while the extreme eastern foot-hills are so covered with debris that the underlying rocks are not apparent. Geneva, or Birch Creek, Cation presents a fine sec- tion of this body of granite; it is a narrow gorge, worn by the action of the water, in a generally straight course, though zigzagging in detail owing to the unequal resistance offered by different parts of the granite to the action of erosion; the walls rise very steeply on either side from 1,000 to 2,000 feet. The western part of the body is a very interesting variety of the so-called giant granite, composed of a mass of large crystals of orthoclase from one to two inches long, and rounded grains of quartz filling up the interstices of, and frequently inclosed within, these crystals; the mica, which is of the white potash variety, occurs in thin sheets between the crystals of feldspar. The general body of the granite is a white mass of quartz and feldspar, in which large crystals of orthoclase are porphyritically imbedded ; small crystals of green magnesia mica and a little white potash mica are generally distributed throughout the rock. As exposed in the Commercial Company’s tunnel, however, the mica is replaced by a light green mineral resembling chlorite. This tunnel has been cut over 800 feet into the granite spur to the south from near the mouth of the cafion, for the purpose of reaching the Big Smoky vein, which crops out about two hundred feet above it on the ridge of the spur, of which it has the general direction. The workings on this vein disclose a large irregular body of quartz and calespar from 15 to 20 feet thick, stained by graphite ; it would seem to be at the contact of the slates and granite, since these rocks are cut in alternate bands by the tunnel which reaches it from the south. A noticeable feature of the granite exposed in this gorge is the regular bedding of the mass, amounting almost to a stratification, having a gentle dip to the westward ; it may be estimated that a thickness of over 8,000 feet of granite is exposed here. About half-way up the cafion the granite is traversed by a dike about 25 feet thick of close-grained greenstone, having a northeast and southwest strike, a5 MINING INDUSTRY. and a dip of about 30° to the northwest. Above the granite the gorge spreads out into an open longitudinal valley, in whose bottom are exposed the upturned edges of the metamorphic strata, which rest on the granite. South of Geneya Cafion commences the main high ridge of the Toyabe Range, which rises suddenly in Geneva Peak to a height of 5,400 feet above the valley. The granite forms only the northern point of this ridge, extending along under its eastern edge, while the summit is formed of slates resting upon it. Geneva Peak consists of limestone shales, striking a little east of north and dipping south at a low angle. From here south as far as Bunker Hill, the main crest of the range is a high sharp ridge of various ar- gillaceous and limestone shales, whose dip changes to the eastward a short, distance south of Geneva Peak. The western slopes toward the interior yal- leys are generally quite abrupt, though owing to the fragile character of the rocks they are so covered with debris and soil that the details of structure are not very apparent. On the eastern foot-hills the slates come in south of Geneva Cafion, having a northeast strike, and dip to the east and south, resting on the granite, and extending higher up into the range as one goes south; these are overtopped by a body of limestone, which first makes its appearance at Tar Creek, and is found in varying thickness along the eastern flanks of the range as far as Kingston. This limestone is a dark-blue, semi-crystallme mass, more or less metamorphosed throughout, and in many places assuming a foliated structure, so that it is difficult to determine the line of division between it and the slates. While the main ridge forms the eastern edge of the general anticlinal fold, there seems to have been a lateral fold between Globe Cafion and Santa Fé, and the strata are found to be much contorted and disturbed in this region. Near the mouth of Globe Cafion the limestone strata have a quite regular dip of 40° to the east, on the north side, striking north and south, those on the south side being irregular and much contorted, while still further south in Santa Fé they are tilted up at a generally steeper angle and have various strikes. On the eastern slope of Globe Peak, which attains the already very considerable height of 11,237 feet above sea level, are a succession of fissile slates of various green and purple shades, including a variety of quartzose mica-schist, containing, however, but a small proportion of mica, which un- CENTRAL AND EASTERN NEVADA. 300 derlie and are conformable with the limestones that form the eastern ex- tremity of the slope. Both slates and limestones are traversed by numerous veins of quartz, some of which show good bodies of galena; these veins have a north and south strike generally conformable with the stratification. On the lower face of the foot-hills, just north of the mouth of Santa Fé Caiion, are the remarkable glacier polishings already mentioned. A thin seam of gray quartz, striking north 15° east, with a dip of 59° east, here forms the face of the spur; its somewhat undulating surface has, on the salient parts, over a tolerably continuous extent of several hundred feet, received a mirror- like polish, equal to the finest produced by artificial means, so that when the sun’s rays strike upon it at the proper angle their reflection is visible as a bright point from a distance of many miles. The lines of striation, which are only visible on a close examination, are parallel to the line of greatest inclina- tion. The surrounding rock, which is a somewhat metamorphosed and slaty limestone, has not been of sufficient hardness to retain any other traces of glaciers, though it is evident that to this agency must be attributed these pol- ishings. Their position is indeed singular, at the foot of such a steep slope, and entirely on the outside of the cafion basin; the head of this cafion, which extends up to the northeastern crest of Bunker Hill, must have been filled by a glacier, whose lower end overlapped this spur, which closes up, in a meas- ure, the mouth of the cafion, and the descending mass of ice and gravel has worn away the less resisting rocks, while this sheet of quartz received its present high polish. As far as known this is the only instance of such ice polishings in the range, though, as elsewhere remarked, the shape of the inte- rior valleys seems to indicate that they were once filled by glaciers. In the limestones of Santa Fé Cafion were found the /usédinae already mentioned. Near the mouth of the cafion is a dike of dark green, fine-grained syenite, consisting of hornblende and white feldspar, the former occasionally in colum- nar crystals; no quartz or mica are found in this rock. Bunker Hill, the second highest peak in the range, (11,735 feet,) holds a central position, geologically as well as topographically ; its neighborhood, after the Twin River region, has been the scene of the most varied upheavals and metamorphisms, and the strike of its rocks forms the greatest angle with the general direction of the range. Its mass consists of the various slate series 336 MINING INDUSTRY. which form the main ridge to the north—here, in general, more highly meta- morphosed—having a dip of about 45° to the eastward, and a strike of north 20° west, flanked on the east by the limestone body, which only extends to the northern edge of the cafion mouth. Kingston Caiion is another of the characteristic gorges of the range, worn, in this case, through slaty rocks; its sides, except near the mouth, are less precipitous than those of Geneva Cafion, and yet sufficiently grand when one considers that looking up a lateral ravine, from the mining hamlet of Bunker Hill, one can see the southern summit of the peak of the same name, rising over 5,000 feet, in a horizontal distance of 10,000 feet. 'The general course of the cafion is at an oblique angle with the formation, which gives the appearance of a greater thickness to the rocks than they really have. = 2g > + [+ + | + JaAoT WMoY}RjJ-0% Jopun 9zUIM 1 ‘ON Suyyutg oS £L1'1g Sein ae ioe ol Se +6 og | > 18 ae Le | ies eS > + [+ +] + Joao, WoYyeJ-Or Jopun 9ZzUIM I “ON SuLyUIS ol +6 Siri is Ac cals ma Fe ret ae oe 8 ees ror feos} sos + 5 + asap Wpe wor yrys me Suisiey 6£ gor'tg | - - - = om €$ 66h] - - Biss es Clan | irs sorte -fs * 8 2 * 2 © © =areys SUTpOUL Janus oo 161 a ae By tx ao 69 +1 a =e SS €r > + fe os] + + + [asap ype wor ySaA JNOssoIO Sud LE gto aera oh = 5 TX Qer |= ned a fe |- -]- -| + * Jaaat worjry-of yeys Jo yynos Sunjuq €x 966'r poe ee = Ms £698 | - - ine zl to [- =] +] + + Joao, moyiry-0€ ‘Yyeys Jo YOU Sung oS 12h te = oo er eh <> = sie coe fx J- + ]- +] + yaaa, moyyy-o2 ‘yeys Jo yNos Buyud g6 €or‘or 7 ean and as 6S 62 | - - = 2 g we} - -|- +] ° + Joaay Wonyry-o2 yeys Jo YOU Sug gr sere == ec aus of tg] - - > ae = 9 6cr|}- -|- +] + * [aaa woyyeys-or ‘Yvys jo WOU Sunsiqg 00 gle 2 as oS oo gh | > - ae on = eae 0, sort ss ss ss yng uado ur Sunsrg oS 121 he mas as cor [°° a es rei gor | x ‘ot ss + = ayeys UL opis UMOp Surserg SL ggz a mois Pace 2668 {° ° 52s ie aera + + + [QAO] WOYIVJ-0¢ UE Opis UMOP Suysvig Lg S€x sy ac ee et: Ba ca oar ae Aga es + + = [QAd] WOYTYJ-Or Ul Opis UMOp Suysrig oc: Grr =e a Ses S22, 47° as aia a |e + + + + + [QAd, [pL Ul opis UAOp Suysrig “PAI 1g tzg'St 2s 28 a ef gf | - - eid ie Zr gob | woyyy-02 ‘azura r°ONT YINOS pur YOU Surdoyg LL gzl'r Gag pase amar gr z oe ae 7 3 69 ur | > - Jado, Woyy-02 ‘Ywys Jo YOU Surdojg 9S L6bz 288 = 3 7s 4g #9 |- ° St ae gor | gt + + AAT WOY}LJ-02 ‘Yeys Jo yNos Surdojg dr Lz i a ee L649: yc? = 2 oe aang gor | €& > JaAOT WOT IWJ-oF ‘9ZUIM FON YINOS Surdoj}g €p SSo >i uns wee go 6L | - - 9 aa Llr | or + yoAd] WoYy-or ‘azuIa I ‘ON YOU Burdojg zz b6z'eG | - - ae a gs SES - - =9< oa 6cxr | 26 + + + [QAd] WOYyL-O1 “Yeys Jo you Suidojzg MY FT eT CATT NRT 2807 | Ste GS at n Ey *SOZUTAA *syeys a g “SOZULAA| “SYLYS 5 g E 5 3 3 wa a. 2, 2, oe 13 |e | Fl & & Es g ne =» | & E 2. *SuLyuIS & z. S *SIOUIUL JO 1Oqu'T “Suryuis Jo ys09 m oe a & A a S *y00} od 9}vyY “yuNS yo} “ON iu 3 388 "Logi ‘1€ 4aguavg Suipus pak ayf sof yson Suauay fo puameznjy CENTRAL AND EASTERN NEVADA. 389 HS TO MON CRG OMI secs sara. ciate ayaa crete apart serait eee acd 2.2 $53, 835 39 Mining captains and timbermen................---.------ 6, 868 53 Wheelers, trammers, and sorters under ground, and landers 12, 401 60 Ost Of raising; oreand: Water's: .. 2222. 43505222 eens eee 9,658 24 Cost of sharpening drills, picks, &c........-...-..-------- 10, 493 05 PAO therm leare lcs rma ive yiOr ene eetere stat erate eet eo 1,316 27 Wan pentGiaw Onl ter rteteeteteretetctentelctsie ass ef ecto ee ae ios 53 , 222 49 Timbers, lagging, lumber, and other materials.........---- 9,187 56 Pump-pipe and rods, labor and repairs.-..-.-.......-.---- 1,526 88 Assorting and hauling ore. Labor in assorting 3,8374 tons ore...........----. Eocaenae 5, 954 INROADS CC Reames SGA ane cee On aacee Aa aSee a aee eee ee 41 PLANS odes DONS OG; LO Usk ecte ete oe sea eee cree 477 Cost of repairs to cars and wagons................------- 38 Reduction cost, as per following statements of current costs AMCUTOD AIT SESS eye here icky cece e eccieusye cisoie sic De eek ee Bullion charges. PUSTiETS JO OTe cai O10 theta ete ter ate a teteoteratire isthe fe tayoteaie fosiaeinise aioe 3, 209 Charges on sales to Austin bankers ..........-----.-.-..-- 10, 232 Melting, assaying, and United States tax ..............--. 5, 308 General expense. Expense of agents, clerk, and superintendence........-.-- 11, 068 Other general expenses, exchange, insurance, State taxes, and incidentals -.... aie sisisleieiictie = oe ei tiameccem oe ><. cise 23, 231 $106,310 OL 3l 09 6, 511 15 155,999 74 — 18,750 26 76 61 34, 300 37 321, 871 53 390 MINING INDUSTRY. Statement of Reduction Cost for Ordinary expenses of reduction, $136,043 77. Expenses for repairs, $19,955 97. Or, $s 19 per ton of ore. Total expenses, $155,999 74. Or, $40 55 per ton of ore. avi ne Or, $35 36 per ton of ore. esc gee gor err re r= 4 ie Fa Bes : = Ss S s a 5 a » £9 5 iehhet a g 5 4 = |§ae . a4 | 8 5g Aa Qo yg oO = us! a nas hep ey es = &g gg = et | 3 aa }/ss | 3° 1867. a Ue Rs e cae & ee 29 ‘eo 5 eres is Hed 5 x g | 8% a ee 3 n a Oy 08 bol we Gy > 3 is 3 te w & & he og 3S ws & ° °o Peace rs ° 0% ~~ oo ~ ~ a ico ke » Pe Pa ~ uw n n no ne n n n n fe) 3° fe) fo) ow & 0 ° fo) fo} [o) oO 1S) oO is} Oo 1e) 1S) Oo iS) January. - 8422 09 | $613 00] $332 00] $270 00 $918 00 2,928 50 | $403 00 | $216 50 c February 400 60 536 00 220 00 255 00 681 00 2,648 50 230 00 140 00 = March 403 36 635 00 246 00 282 50 847 00 1722 50 429 00 252 50 & April 418 38 652 00 270 00 295 00 667 00 2,483 00 399 50 274 00 May - 396 16 646 00 214 00 232 50 663 00 1932 00 343 75 155 00 June . 413 06 661 00 204 00 237 50 603 00 1,667 00 400 50 139 00 July... 396 50 623 00 170 00 195 00 563 00 9772 90 285 00 253 50 August . < 5 396 83 636 00 I2I 00 306 25 649 00 2,353 00 317 50 297 25 September . 428 92 508 25 II2 00 227 50 426 00 9742 00 271 25 288 00 A October . 418 16 589 25 128 00 315 00 505 00 2,257 00 292 50 275 25 | $60 00 November. . 422.79 | 58337 | 13100} 297 00 957 00 3,086 00 | 30000} 272 25 | 100 00 December . 433 28 559 37 107 90 253 75 779 08 2,342 25 297 50 274 25 222 00 4,955 22 | 7,242 24 | 2,255 00 | 3,167 00 8,254 00 | 27,632 75 | 3,963 50 | 2,837 50 | 382 00 —_ REPAIRS. ' woo ! = Bp = S ng no EB Me mS . 9 & oun eS og 24 2 os 1867. as a gos ww 8 S 3 ag $8 at wa Reg, colt ae) 0: Bs oO ro) oS 2 » Wo 2 & wo =| =ie-| aa aog si ial oo: O Rss ° =] 13) ie) a a January . . Ay ee era eee $802 14 $1,144 52 $1,946 66 3r February es a ais" aden fe Sai ER eS 692 10 I,I17 02 1,809 12 24 March = 2) 2 A a ees oes sae 460 87 2,522 17 2,983 04 2634 April . . . Pe ae eee ere é 560 25 958 02 1,518 27 30 Mianvieg ay cet os See ae ee oe 355 39 805 80 I,16I 19 3r DUT een aire ree tat Agee hes 204 06 412 39 616 45 “30 July. = < see wie 3 és 221 77 8rr 43 1,033 20 3r August . . yy Ges PL hy Sa 530 16 816 68 1,346 84 3r September cmenas my 1k 9S) Lee 418 28 325 65 743 93 22 October . . eso = ee 491 54 2,380 84 2,872 38 aos November . - Pa = = 558 42 1,066 55 1,624 97 30 December - 7 e : 949 52 14350 49 2,299 92 27 6,244 50 13,711 47 19,955 97 33834 a. 10 tons and 1,406 pounds additional CENTRAL AND EASTERN NEVADA. 391 the year ending December 31, 1867. : b : , 3. 2 3 woop. | : ra a ao 8 q u a) r= Sa 2. E 68 a das a re les to Say eo ; a] as A: | fad bp Engine. Furnaces. a3 i} as: a Spo 4 “a is) = 2) on 4 a a a a 5 we 2 5 3 3 og S ces a Cords. Cost. Cords. Cost. a a ag g ae | s 1o) 1S) 1S) oO 1e) a 15734 | $2,377 03 215% | $2,473 49 | $2,042 02 $704 69 $172 50 $x48 35 $576 99 | $14,598 16 16414 2,340 94 168 1,628 87 1,539 30 621 73 198 20 120 30 383 17 11,943 61 18756 2,508 45 1798 2,090 45 1,344 00 569 84 126 00 127 80 4oo 48 13,049 88 15758 1,603 51 169% 1,677 63 1,158 50 27 48 165 45 89 00 418 98 10,999 43 18674 r,or4 28 14074 1545 72 847 00 339 84 100 95 3I 30 297 95 9,663 55 182 1,826 17 14634 15494 05 764 74 317 52 132 12 40 42 305 02 9,205 10 375 1,874 4 145 1,435 5° 878 50 364 19 147 05 69 75 349 37 91367 59 20454 2,163 I0 17538 1,682 37 I,130 50 333 02 137 85 88 09 447 84 11,057 60 16738 1,704 55 135 1,303 00 1,053 00 228 67 99 43 66 98 284 73 8,743 28 190) 2116: 37 16178 1,585 70 1,430 18 28t 77 175 62 Io4 58 621 19 II,155 57 21714 2,260 16 22634 2,093 Sr 2,203 44 512 78 113 48 I52 Q1 615 10 I4,IOI 09 24776 2,608 87 18234 1,699 13 2,155 70 See 126 75 176 68 566 50 12,587 03 223878 353357 57 2,046 20,709 72 16,546 88 4,701 53 1,695 40 1,214 16 5257 42 136,471 89 i i I ro tons 1,406 pounds worked for Buckeye Mining Company in October, at$jo . . . - - . . . 428 12 136,043 77 RESULTS. 2 A 38 Z Z 225 25 8 g a" 3 Oo 2 Sees 86 2 : 5 , 2 303 2 5 23 r Sm en Se 3 ae ‘wD 28 gBa8 us ieaiies ie bane) o8: bongs Eh elie 6 3 3 g S88 Sete g ees Rs 3 a ey sod at uid 4 ou & u § wu oO wy oY 6 Mons oS Gy es) op ea of os eoago o 2 SI 2) of £438 a 2 4 28 og & 2 as S| yo 53 8 0 g 8g 3 Bs 3 uw BS i i} 5 ppd 5 I 53% m6 rs FO a Aa < A a a a 404 85. 0. 766 42 417 2.60 1.99 37814 85.6 0.92 36634 35414 2.23 2.18 384 OBR 0.941 384 390 2.065 2.14 327 63.35 0.861 332 351 2-55 -.05 242 50. 0.781 242 236 1.28 1.72 212% 46.35 0.764 24g 21814 teze 1.46 253 47-55 0.858 251 249 1.43 1-73 317 46.77 1.09 323 325 1.57 1.84 238 42.2. 1.28 234 226 1.385 m2973 276 55645 1,02 278 27814 iy5t 1.78 45834 Sr. 943 46014 46014 2.115 2.03 347 72 890 330 34134 1.39 1.8 3183734 61.6 0.922 3184334 3184738 1.72 1.88 worked for Buckeye Mining Company. Number of ounces of bullion produced, 445,37214. Value of product, $427,227 69. Average value of ore per ton, $111 o4. 392 MINING INDUSTRY. During the period to which the foregoing statements apply the praduction..of bullion amounted: tos 2.2.2: 2--s eee ces $427, 227 67 From which deducting the costs at mine, as elréad 7 ShOWlse.2 Stoo eeeeeoee ae eee $321, 871 51 Expenses in New York $7,140 60, currency, equal in:gold. at $140 tO. <2 ..22 sane 3.0% 5,100 00 SS bt Showing a profit on the year’s work of.......-.-..-.----.-+--- 100, 256 16 The total product of the mine from the date of organization to the time ot its suspension of work in the summer of 1868 is shown by the company’s books to be about $700,000. Notwithstanding this large production, the greater portion of which was obtained at a fair profit above the actual running expenses, the company has suffered great pecuniary embarrassment, and, late in 1868, became bankrupt. This last step appears to have been due more to the lack of a proper understanding or of harmonious co-operation in the man- agement of the company’s affairs than to any unfavorable developments of the mine; although, just at that time, the amount of ore in sight was less than usual. The rich ground opened for stoping had been exhausted, and further work was necessary in order to reach the deposits believed to be accessible. The chief cause of the embarrassment, it is said, was the large outlay made at the beginning of operations, in costly surface improvements, involving not only all the money advanced by the stockholders, but all the profits of the mine beside. ‘The mill alone cost $183,000. Meantime the mine was never opened sufficiently in advance of the demands of the mill, so that the latter was often employed to only a part of its full capacity, thereby enhancing the costs of treatment; and it was deemed necessary in the summer of 1868 to close the mill until the mine could be more extensively opened, and ground thus prepared for more economical operations. The production ef bullion being thus suspended, a call upon the stockholders for further capital became necessary; but owing to the existing discouragement on their part or to a lack of a proper appreciation of the true condition of affairs, the assessments were not paid and the company became embarrassed. ‘The property was attached CENTRAL AND EASTERN NEVADA. le and all mining operations were suspended. ‘The amount of indebtedness was comparatively small, not exceeding the actual value of the supplies and material on hand and ayailable for use; saying nothing of the mill, hoisting machinery and improvements that had cost about $250,000. In the summer of 1869 the property of the company was sold by the assignee, and was purchased by a new organization known as the “Cambridge Silver Mining Company.” The new owners employed a small force in thé autumn of last year in draining the mine and extending the explorations; but this work was shortly after sus- pended without obtaining definite results. PHILADELPHIA OR SiitveR Beyp Disrrict.—This district is situated in the range of mountains next east of the Toyabe, and is about 85 or 90 miles south from Austin. The following votes on the geology of the region are furnished by Mr. 8. F. Emmons. Grotocy.—The range of mountains parallel to the Toyabe, which forms the eastern border of Smoky Valley, is called the Smoky Valley Range. At the point where the overland stage-road crosses it, at its northern end, it is composed of rhyolite; from here south to Charlotte’s Pass, which is about opposite Ophir Canon, it is a low, flat-topped ridge, whose form and general appearance would suggest a predominance of volcanic rocks in its formation. At Charlotte’s Pass, through which runs the stage-road from Austin to Belmont, the entire mass of the range is rhyolite and rhyolitic breccia. Out of the ravine, on the western side of this pass, rises a conical peak of reddish-white porphyritic rhyolite, which has a remarkably regular columnar structure. The upper part of the ridge is of rhyolitic breccia, cut of which this long ravine has been gullied; while on the eastern slope are strata of rhyolite, dipping east at an angle of 30°, of highly colored varieties—white, purple, yellow, brick-red, and reddish-brown, South of Charlotte’s Pass extends a group of high, smooth- topped peaks, whose summits carry snow until the middle of the summer. These are probably composed of limestone and metamorphic slates; on their eastern flanks, however, are several outcrops of rhyolite. The southern point of this group, some 30 miles south of Charlotte’s Pass, is the Granite Moun- tain, from which runs out the spur or ridge to the southeast, where the mines of this district are situated. This ridge separates Monitor Valley on the north 50 394 MINING INDUSTRY. from Ralston Valley on the south, being at its highest point not more than a thousand feet above these valleys. The town of Belmont, which is 30? miles in a straight line, south 51° east, from the mouth of Ophir Cajfion, is situated in a ravine on the southern slope of this ridge, at an elevation of 7,393 feet above sea-level. The Granite Mountain is a triple-pointed peak, having an elevation of between 9,000 and 10,000 feet; its mass is, as its name indicates, of granite, whose weathered surfaces are somewhat rounded by the action of the atmosphere, but not de- composed to as great an extent as that in the immediate vicinity of Belmont. From it extends down to the southeast, toward Belmont, a long, continuous spur of granite, on whose northern side are metamorphic slates dipping to the northeast; at the line of contact are nodular shales having a bronze color and a curiously wavy or rippled surface, as if rounded pebbles were crushed in between the layers. Beyond this belt of slates are limestone strata, conform- ing with it in dip and strike; the line of contact between the slates and lime- stone can be traced for miles down the ravine on the north of this spur. To the south of the spur, on its slope toward Ralston Valley, and west from Bel- mont, is a very picturesque little tract of country, still well wooded, as are most of the hills around Belmont, where the granite, here easily decomposed by the atmospheric agents, has been worn into various curious shapes—castellated peaks and table-topped mounds; columns consisting of blocks standing one upon the other, originally square, but now so rounded that they seem boulders piled up by man’s hand, and in imminent danger of falling off In all these ravines are small springs and rivulets, around which are small extents of green grass. Belmont itself is built over the line of contact between the granite and the slates; the foot-hills below it and the crest and southern slope of the ridge to the south are all of granite, a coarse-grained, easily decomposed rock, con- taining large twin crystals of orthoclase, which remain after the surrounding mass has crumbled away. In this granite are frequent dikes of white fine- grained granulitie rock, composed mostly of quartz and feldspar. ‘To the east of Belmont, quartzite is the contact rock next the granite on the north, beyond which are metamorphic slates, while the foot-hills of the Smoky Valley Range, still further north, are composed of strata of blue limestone, in which were CENTRAL AND EASTERN NEVADA. 395 found no fossils; they are probably of the same age with the 'Toyabe lime- stone. To the cast of Belmont, and beyond a hill of granite which rises imme- diately above it, is Highbridge Hill, in which are the principal veins of the district. This hill is composed of quartzites and slates, and in the ravine which separates it from the main granite ridge south is the line of contact between the quartzite and granite. In this hill are two series of veins, the one in the quartzites, the other in the slates, both generally conformable in dip and strike with the formation; having a strike north 15° west and a dip of about 45° to the north and east. The former includes the El Dorado, Atlanta, Galvin, Arizona, and other ledges, which extend from the southwest extremity of the hill up over its main crest. ‘The second series includes the famous Highbridge and ‘Transylvania veins, which occur low down on the northeast slope of the hill. These two are probably part of the same ledge, though the connection between them has not yet been traced, and the existence of a fault would prob- ably be necessary to explain the relatively lower position of the latter. This belt of slates and quartzites seems to contain the most of the veins of the district, though none have been developed to any extent outside of Highbridge Hill. In the limestone a few miles northwest of Belmont is the Silver Champion, which has produced some rich ore, and various other undeveloped ledges. Along the northern slope of the granite ridge south of Highbridge are some small veins, on the contact line with the granite. This body of granite seems to be cut off by a break in the ridge some five miles southwest of Belmont, while the slates extend further on in the ridge which connects with the Moni- tor Range. The vein southwest from here extends over a wide extent of coun- try, whose hills are mostly low, table-shaped, volcanic ridges, which give it a very desolate and forbidding aspect. The large mill of the Combination Company is situated just east from Belmont and north from Highbridge Hill. Near this the white quartzite crops out very distinctly, and beyond it are the limestones; out of these rise, just north of the mill, on the very edge of the yalley plain, three peculiar-looking hills, composed of a grayish volcanic pearlite, very much decomposed, which are probably of rhyolitie origin, as this is the only voleanic rock found in this range. It occurs in the eastern foot-hills of the Smoky Valley Mountains, about 396 MINING INDUSTRY. five miles north of Belmont. The section No. 5 on Plate XXVI gives a pro- file of Highbridge Hill and the granite hill southwest of it, on a true scale. The section is made on a line north 58° east. The quartzites exposed here are probably the product of a local metamorphism, and do not seem to corre- spond to the quartzites of Summit Cajon in the Toyabe Range. Mintvea DeveLopMENts IN PaitapeLtpHiA Disrricr.—The town of Bel- mont is the center of a mining region of considerable importance, situated 85 or 90 miles from Austin, in a south-southeasterly direction. It is in the “Smoky Range” of mountains, next east of the Toyabe, separated from the latter by Smoky Valley. The district of most importance, judging by devel- opments thus far made, is called the “ Philadelphia,” or, sometimes, the ‘Sil- ver Bend.” It is in this district that the town of Belmont is located; and the first important discoveries of silver-bearing lodes, in this vicinity, were made near the site of that town in 1865. A small spur of the main range branches off here to the southeast, and it is on the eastern slope of this spur that the principal mining developments have been made. The best developed and most promising veins are inclosed within a belt of metamorphic rocks, resting op granite, which here forms the central portion of the range. These meta- morphic rocks, where in contact with the granite, are frequently highly al- tered, and may come under the general name of quartzite; while, a little more remote from the granite, further to the eastward, and overlying the quartzite, is a belt of slates, striking nearly north and south, or north a little westerly, and dipping to the eastward, from 80° to 50°. This belt of slate is probably not less than a half or three-fourths of a mile in width, measured from west to east, and is the outcropping rock of the hillside, from its contact with the quartzite or granite down to where the slope merges into the plain of Monitor Valley. The ledge, or vein, on which the largest amount of work has been expended, and by reason of which the district has become widely known, is the Highbridge or Transylvania. It is inclosed within the slates, conforma- bly with them, having a course north 15° west, true, and dipping to the east- ward generally, at an angle of about 30°, but sometimes much steeper, espe- cially where the ground has been much disturbed, as in the Belmont and Combination mines, where the dip varies between 60° and 90°. The out- crop has been traced, for a distance of many hundred feet, along the side of CENTRAL AND EASTERN NEVADA. 397 the hill, and, perhaps, 200 or 300 feet above the level of the valley. On this vein are located the mines of the Combination Gold and Silver Minmg Com- pany, Belmont Silver Mining Company, the Elmore—a short claim—and the Silver Bend Company. The mines located by these several companies were not at first generally believed to be on one and the same ledge, and a differ- ence of opinion still exists among interested parties, but the developments show pretty clearly that the ledge is one that has been faulted on the Bel- ~ mont property, the southern extension of it having been thrown to the east- ward about 150 feet. The Belmont claim is, therefore, in two parts, the northern claim being on the so-called Highbridge, unquestionably the contin- uation of the vein claimed by its northern neighbor—the Combination Com- pany; while the southern portion, a little further east, but having similar course, is located on what is termed the Transylvania, which is, without doubt, identical with the vein of the Elmore and the Silver Bend, further south. The indications, both on the surface and underground, so far as opened, point clearly to the conclusion that these locations are all on one vein, known as the Highbridge, north of the fault or break, and as the Tran- sylvania south of that point. Compination.—The northernmost claim, on which any important work has been done, is that of the Combination, which is said to be 5,000 feet in length, although their explorations have been chiefly made within 400 or 500 feet of their south boundary, while the ground proved by actual developments to be productive was, at the date of the writer’s visit, in the extreme southern portion of the claim, not exceeding 225 feet in length. The surface workings yielded largely in “chloride” ores, and the vein along the croppings, which was split into two or three branches, has been extensively wrought. In depth the vein has been opened from below by means of a tunnel driven in from the eastward, through the country-rock, located about 150 feet from the south boundary, 244 feet in length, and cutting the vein at 70 feet below the sur- face. Where cut by this tunnel the vein was poor, but a drift to the south about 30 feet encountered a good body of ore. From the end of the ecross- cut a winze was sunk, which also, at a depth of GO feet, encountered the same body, which continued from this point down to the water level, 160 feet below surface. A vertical shaft, located east of the croppings on the surface, 398 MINING INDUSTRY. has also been sunk, with the intention of cutting the vein in depth. At 90 feet depth it reached the water level, and at that point a cross-cut was driven to the vein, which was reached in 246 feet and cut at 160 feet below the croppings, about 236 feet north of the south boundary. This was the lowest point reached at the date referred to, as no efficient means were provided for the drainage of the mine. The developments made by the works thus far prosecuted, show a well-defined vein, varying in width from a mere seam to 8 or 12 feet, and sometimes more, (in one place nearly 30) filled with hard, white quartz, which carries the silver-bearing mineral, distributed through it in bunches or disseminated particles, rarely arranged in banded form, as in the Reese River veins, or in large masses, free from gangue. The pay-ground usually forms a belt near the hanging wall, not often, though sometimes, filling the whole space between the walls of the vein. The occurrence of ore also appears to be in chimneys, or distinct ore-bodies, leaving other portions of the vein small and barren. Thus, in the Combination, as shown in the section, the ore, so far as devyel- oped, occurs in one body, measuring, on the first level, about 100 feet hori- zoutally, and, on the second, 140. ‘The inclination of this body is to the north, dipping at about 45°. Its shorter axis, at right angles to its dip, appears, from the descriptions given, to have been about 60 feet, and its width varying from 2 to 12 feet, sometimes fillmg the whole space between walls. The principal silver mineral is stetefeldtite, an argentiferous ore of antimony, with which is combined sulphur, lead, copper, and iron. The ore produced from the mine up to the middle of 1868 appears from the available records to have an average yalue of about S80 per ton. It is divided into two classes, of which the first assays about 590, and the second about $35 to $40. This will be given with more detail further on. The pay-ground known to exist in this mine had been nearly worked out, from the surface to the water level, early in the summer of 1868, and the future product depended on the discovery of new bodies of ore above that level, or in openings to be made at greater depths. For this latter purpose the vertical shaft, already referred to, had been begun and provided with hoisting and pumping works, consisting of an engine, 16 inches diameter of cylinder, with three winding reels driven by friction- CENTRAL AND EASTERN NEVADA. 399 gear. The shaft is sunk in three compartments, each five feet square, two for hoisting rock and one for water. This machinery, however, had not at that time been made available, having been set up in winter and rendered useless for a time by the settling of the foundations. The work was unfortunately standing idle in consequence. The bottom of the mine was looking well, however, and its further development was to be proceeded with as soon as the machinery could be properly established. The company have a large mill of 40 stamps, arranged for the treatment of both first and second-class ores, by the dry and the wet, or Washoe, process, of which some descriptive notes will be given in a following paragraph. Breitmont.—Next south of the Combination is the Belmont Company’s claim, covering 850 feet. Immediately adjoining the claim of the Combination they had some excellent ground, which yielded from the croppings and near the surface a large amount of ‘ chloride” ores, producing, it is said, over $110,000. About 90 feet from the line a vertical shaft was sunk on the crop- pings 180 feet, which was standing idle when visited. The vein becomes small and pinched at no great distance from the line, and is soon lost in ground that has evidently suffered much disturbance. It is here that the fault, already re- ferred to, occurs, the continuation of the vein appearing about 150 feet further east as the Transylvania. On this portion of the property a shaft has been sunk, about 400 feet from the south line, to a depth of 170 feet, and the vein opened by levels driven to the northward until reaching the fault, which, in the upper level, is 130 feet from the shaft, and, in the lower level, little more than 50 feet. The vein is 7 or 8 feet wide, and, near the shaft, is very reg- ular and well defined. The ground between the shaft and the fault was found quite productive in places, and much of it was stoped out. It is said by those in charge to have yielded 2,000 tons, worth, on the average, 550 per ton. The work was idle in the summer of 1868, partly because no greater depth could well be reached without hoisting and pumping machinery, of which there was no provision, and partly because the property was then under offer for sale in England. Sitver Beyp.—Next south of the Belmont is a short claim, 150 feet in length, known as the Elmore ground, on which some work has been done; 400 MINING INDUSTRY. beyond that is the Silver Bend, claiming 2,000 feet, and on which some 600 or 700 feet have been opened at a depth of about 70 feet. The ledge on this property presents the characteristic features shown in the neighboring mines. It varies from a few inches to 8 or 10 feet in width, carrying a belt, or seam, generally near the hanging wall, in which the ore is well distributed. At the bottom of the north incline the vein is 8 feet wide, filled with quartz. The pay-seam here is two feet wide. Further south the ledge pinches to a mere seam as it passes the ravine, where a vertical shaft, 30 feet deep, located east of the croppings, connects the work with the surface, and affords ventilation. Further south the ledge widens out again, varying from 1 to 4 feet, and showing productive ground. These openings have afforded, without any stoping, between 150 and 200 tons of ore, of which 100 tons have been worked, yielding over $100 per ton, while the appearance of the remain- der indicated a still higher product. Ten tons were being worked about the time that the writer was there, of which the pulp assay was $190. This mine is one of much promise. It is owned by an eastern company that has sus- pended active operations for a time, but will probably proceed with its devel- opment when other conditions are favorable. + South of the Silver Bend Company’s claim the outcrop of the ledge turns westward, partly due to the flat dip of the vein and the slope of the surface ; partly, perhaps, to a change of the course of the lode. Some other locations have been made on what is claimed as a separate ledge, though believed by many, in the absence of actual proof, to be the same ledge as that of the Sil- ver Bend. Such are the Mountain Queen and, further south, the Quintara. About 1,000 or perhaps 1,500 feet west of the vein above described is a succession of mines, in the earlier stages of development, which, for aught that so far appears to the contrary, are on one vein, though further developments may show them to be on several distinct veins. These are the El Dorado South, the El Dorado North, Atlanta, Arizona, and some other claims. The ledge on which they are located appears to be parallel to the Highbridge-Transyl- vania, but nearer the junction of the quartzites and slates with the underlying granite. The El Dorado South is the southern claim, and the most developed of all. At their works the ledge crops out plainly, showing a belt of quartz CENTRAL AND EASTERN NEVADA. 401 from 2 to 6 feet thick, and sometimes thicker, dipping eastward at 30°, or 40° on the south end of the openings, and steeper on the north end. The inclosing rock at the El Dorado is a hard quartzite, mixed in places with bands or belts of slate. Further north, as at the Arizona, the inclosing rocks are more slaty in structure and general character. The general course of this ledge is north 15° to 20° west, true; and the various claims above named, regarding them as on one vein, cover several thousand feet. The El Dorado South own 2,000 feet, and have extracted from surface workings near the croppings a large amount of “chloride ores,” yielding from $150 to $300 per ton, and even more. This work is said to have been the source of great profit to the owners. In depth the vein had not been extensively wrought. A shaft, or incline, had been sunk 130 feet, showing a large vein of quartz, carrying a good deal of ore; but at the time referred to, operations were confined to the surface-diggings, which were very rich in chloride of silver. Adjoining this claim on the north is the El Dorado North, which has less development, but very good prospects. The Atlanta, the Arizona, and some others have opened this vein still further north. The Arizona was at work in June, 1868, and was producing some excellent ore from within 50 or 60 feet of the surface. The developments were not extensive, but were deemed very encouraging. The principal mining developments of this region are centered in the locality of the veins described in the foregoing paragraphs. There are, how- eyer, in addition to these, many locations of promise, some in the immediate vicinity, others within a few miles, chiefly along the slate belt, some of which will probably become important. The Spanish district, seven miles north and west of the region just described, is very well spoken of, but was not visited by the writer. Comprnation AND Betmont Mitis.—There are two mills in the vicinity of Belmont; one belonging to the Combination Company, the other to the Belmont Company. The former is a large, handsomely-built establishment, not far from the mine. It was completed early in 1868, at a cost of not less than $225,000. The methods of treatment, both wet and dry, are the same, in all essential features, as those already described elsewhere. A few notes ol 402 MINING INDUSTRY. concerning the capacity and working of the mill are given here. It has 40 stamps, of about 800 pounds weight, dropping about 9 inches, 70 times per minute. -shaped groove. ‘The ends of the spool-staves have a corresponding form so that they may fit into the grooves of the flanges. These latter are attached to the spool- shaft, 4, by a feather, on which they may be moved toward or from the spool. In the former case the flanges, pressing against the ends of the spool, impart to it the motion of the shaft, winding the rope and raising a load from the mine; while in the latter case, the pressure being relieved, the spool is free, and may be reversed for lowering the skip, or may be held firmly by means of the brake-band, g. The flanges are pressed against the spool by means of two rods, h, h. The ends of the spool-shaft are bored out so that the rods may be placed in the position shown in the drawing, and pressed, when desired, against pieces of iron, 7, 7, which are long enough to bear evenly against the euds of the flange-hubs, fF, F. These pieces of iron are about 15 inch thick and pass through slots cut in the shaft, which is 7 inches in diameter ; they are kept in place by pins at 7. By a system of levers, not shown in the drawing, the attendant may, by a single movement, press the rods h, /, against the flanges, thus setting the spool in motion, or, with equal facility, relieve the pressure, reversing the motion of the spool, or holding it firmly by means of the brake, g. It will be seen in Fig. 1 that the spool-shatt is furnished with a spur- ——_ = SSS | Shops Ore Room Tramway to Stamprall Scale, 2 kig./. GROUND PLAN : Or NORTH STAR HOISTING WORKS. Fig.2. Section of Frictional Winding Drum Lig. JS. SAF Dumping Ship. GOLD MINING IN COLORADO. 529 wheel, A, which is driven by a pinion, %, and may be constantly in motion, whether the spool be in revolution or not; by means of gearing LZ, Za line shaft, 7, transmits power to the spool NV, which is operated in manner similar to that just described. ‘The pinion 0, and spur-wheel O, are provided for driving the pump, which is not yet placed in the shaft. All the minor appurtenances of the works, such as water-supply, force-pumps, wood-yard, and sheds, and similar conveniences, are quite complete, and the establishment is unsurpassed in Colorado as regards method of arrangement and fitness for its purpose. The mill in the building adjoining the west shaft-house contains 22 stamps, weighing 550 pounds each, and has a crushing capacity of about 20 tons per day. The average yield of tie stamp-rock has been already shown to be about $15 50, coin, per ton. The mine was producing regularly in 1868, but all its yield and more has been absorbed in the costs of the work already described, which is said to have involved the expenditure of more than $100,000. In 1869 the company became much embarrassed financially, and its regular operations were interfered with, although some work was still in progress. GarpNer Lopr.—The Gardner lode is nearly parallel to the Ilinois and between 300 and 400 feet further north, its outcrop being further down the slope of Quartz Hill, toward Nevada Gulch. Its course is north 85° east, true. Its dip is 75° tothe south, and both course and dip, so far as observed by the writer, are very regular. The lode was discovered and partly opened as early as 1860, and has been worked, with some intervals of interruption, from that time to the present. It has been claimed and somewhat developed for a length of over 800 feet, but the most important operations on the vein are in the Clark-Gardner mine,a claim of 200 feet in length. The adjoin- ing claims, both east and west, have been worked to varying depths, not exceeding 200 feet, and have yielded some handsome returns, and as they are partly owned and controlled by the same people who own the Clark-Gardner, there is some hope of a consolidation of interest that will bring at least 800 feet under one management. ‘This is much to be desired for the interest of all owners, as under the present conditions the costs of equipment, opening of ground, and administration of such short claims are so great as to absorb a large share of the proceeds. 67 530 MINING INDUSTRY. The lode, as shown in the Clark-Gardner mine, is a large and regular vein. Its width is seldom less than 3 feet and often 10 or 12. Its walls are smooth and well defined, standing firmly, and involving but comparatively little expense in timbering. The ore, as in the veins already described, is a mixture of iron and cop- per pyrites, carrying, however, a considerable proportion of galena and zinc- blende. The valuable mineral appears to be more widely diffused throughout the general filling of the vein than generally observed elsewhere; for while there is usually a compact seam of pyritous ore, it is almost always narrow, and the proportion of high-grade ore, worthy of selection for smelting, is very small. During several months of 1868 not more than 20 tons of first-class ore had been selected from 1,500 or 1,600 tons of ore produced, equal to one in about 80. To compensate for this there is a good degree of uniformity existing in the quality of the milling ore, and occurring, as it does, in a comparatively wide vein, it can be extracted cheaply. The main filling of the vein is a siliceous and feldspathic mixture, but where the vein is wide there is frequently what appears to be an inclosed mass or “horse” of country-rock, granitic in character, though carrying an impregnation of pyrites through it. In the Clark-Gerdner mine one-half or two-thirds of all the vein-matter broken is sent to the stamping mill, and yields, on an average, about 6 ounces of crude bullion, or $100 coin per cord, equal to $12 or $14, coin, per ton. The proportion of first-class ore of the Clark-Gardner mine has already been shown to be small. The sale of this quality to the Smelting Works amounted, in eight months of 1868, to 38 tons, averaging 32 ounces of fine gold and 114 ounces of fine silver to the ton. The Clark-Gardner mine, 200 feet in length, is opened by two shafts, the westernmost having reached a depth of about 360 feet. The ground near the surface was generally unproductive, but at the depth of 80 or 100 feet a good body of pay-ore was encountered, and the mine below that, excepting some poor spots, has been mostly worked out to a depth of 300 feet. The costs of working the ground are comparatively light. Drifting costs from 35 to $10 per foot; sinking, 8 feet by 5, costs $20 per foot; stoping, from $12 to S22 per ruming fathom. Much of the ground in the lode can be picked Vee down, and comparatively little powder is required. Two men have broken a GOLD MINING IN COLORADO. 531 fathom of ground in one day. Eight men have supplied the stamping mill with not less than 20 tons of ore per day for two months. The ground is comparatively dry and the costs of timbering are light. The mine is provided with hoisting machinery consisting of a small portable engine that drives a simple winding apparatus by belting, in the common way. The shaft-house is a large stone building, originally designed to contain a stamping mill that is not yet set up. The power provided is sufficient for both hoisting and stamp- ing on a small basis of operations. Burroucus Lopr.—The Burroughs lode is about 400 feet north of the Gardner. Its outcrop is further down the slope of the hill and about 100 to 150 feet above the bed of the Nevada Gulch. Its course is almost exactly parallel to that of the Gardner, being, where observed by the writer, north 85° east, true. Its dip is nearly vertical, or slightly to the south, its average incli- nation in the Ophir mine being 85°. It is one of the earliest discovered and most developed lodes in the Territory, the main shaft of the Ophir mine having reached, in the summer of 1869, a depth of 630 feet. It is opened for a con- tinuous length of more than 2,000 feet, and worked along that distance to depths varying from 200 to 500 or 600 feet. Unfortunately, it has the practical dis- advantage, in common with many other valuable lodes of Colorado, of being subdivided into many different claims, the greater number of which are too short to make independent mines and only serve as obstacles to a consolidated and comprehensive management. One company, the First National, although owning more than 600 feet of the lode, hold it in three or four disconnected portions, between which several other claims intervene, a condition that must greatly increase the cost of operations, if not presenting an effectual barrier to systematic development. The following list shows the claims on that part of the lode that is dis- tinctly traced and opened by mining work, beginning on the east and proceed- ing toward the west end. The length of each claim is given and the depth attained by their work at the time when the accompanying section was pre- pared in 1868, since which little or no important change has been made: 532 MINING INDUSTRY. Name of claim. Length. -Depth reached. Wai Cushiiiaits sas , ees pee see: pe ee 267 300 Burroughs Gold Mining Company - - - - - - - 155 220 LAG OSE 7.7 en tet eee ete ae ee eee 50 a17s Burroughs! 4.9/2.8) 282. => 2a 2 eee Se 100 60 Coloradoge es an ee eee nee ene eee ee eee 200 305 GonleGi. oye) stints) ase ey cc eee fee eee a ae 20 30 (0.0) a1 ese geen Ta Sah al 2 462 560 Birst Nationale 7 Reem ge eee poe ee eee 183 265 Gold sill ayes erp ee eee 70 128 Baltimore and Colorado - - - - - - - - = - 4o 200 Ouartz Hil 2 ea ee Spe Sea ee 99 240 Goldy Ta) eae Bouse es ie ee ee Seog a 20 Pirst National <<< 2. = «2 « 292 Gs = 5 233% 230 AJ lfot O21 0Y sae er Sa S. Ses Sea epee cee 6674 30 AMATGWiy Ds tees: > Ba eas Gee, (7 fe wee go 98 Birst National: 9-9 325 (ask eens sia a ee Wc 100 60 First National, (one-half interest) - - - - - . . | 200 a Cut by tunnel. The section of the lode on Plate XXX, chiefly prepared from one made in 1868 by Mr. A. Buddee, mining engineer, and supplemented by later data in 1869, shows something of the development of these claims. Ophir Mine-—The Ophir is the deepest and most extensively worked of all the mines on the lode. It is situated centrally, as regards the developed portions of the vein, and may properly serve to illustrate the general features of the latter. ‘The Burroughs vein, as shown in the Ophir, resembles in most respects the lodes that have already been described. The country-rock is the same half-gneissic, half- granitic rock already observed. The walls are usually well defined, smooth, and regular, sometimes carrying a thin gouge of clay, sometimes having the seam of ore resting directly upon it without anything intervening. ‘The vein, however, is not wide as compared with other leading veins, varying from 8 or 10 inches to 3 or 4 feet, seldom exceeding the latter. The vein-matter and the ore, consisting usually of a solid seam of the latter from a few inches to more than a foot in thickness, and associated with a belt of siliceous and feldspathic material highly charged with pyrites, pre- sent the same general features in mode of occurrence and distribution that GOLD MINING IN COLORADO. 535 have been already noted in connection with the other lodes, but the pyritous ore is more exclusively iron rather than copper pyrites; in fact, the small proportion of the latter, at least in the Ophir, is very marked, and the iron pyrites is not only gold-bearing but the Ophir ore carries more silver than is generally associated with the ores of the district similar to these in other respects, the average assay of the first-class ores sold at the Smelting Works showing about 6 ounces of fine gold and 12 ounces of fine silver to the ton. The ground is generally hard, requiring the aid of powder for its removal. Very little of it can be picked down. ‘The mine is opened by means of two shafts, one at 125 feet from the eastern boundary of the property, the other about 60 feet further west. Both of these shafts have reached a depth of about 600 feet. The upper part of the mine was not worked by the present owners and little or nothing is known now of the distribution of ore in the ground taken out; a considerable portion of the mine was poor and is left standing, but nearly all above the 467-foot level is regarded as exhausted of its valuable contents. The earlier owners worked out what they found with- out much attempt at regular methods, and the first level driven as a prepara- tion for back-stoping was carried forward by the present management at a depth of 467 feet. Sixty feet below that another level was driven nearly the entire length of the property and stoping carried on above it, while the east shaft was sunk with the view of opening another level below in advance of the needs of the mill. The two shafts are well timbered up and the eastern one is divided into two compartments, one of which is devoted to hoisting, the other to the pump and ladder-way. The pump, which is in two lifts, the lower one being at 467 feet deep, has 8-inch plungers, but the column is a 6-inch pipe, chosen of this diameter to save freight. The water is raised from the bottom to the pump- cistern in buckets; the quantity is comparatively slight; although this mine is the deepest on the lode, the pump seldom runs more than two hours per day. Hoisting is done in both shafts by iron buckets that are operated in the manner already described as common in the Territory, by means of belting and a friction-brake. The engine for driving the pump and operating the winding apparatus is at the east shaft, and has a 9-inch cylinder. There is 534 MINING INDUSTRY. one 14-foot boiler to supply steam. From the main engine-shaft the power is transmitted by a belt to a line-shaft, 60 or 70 feet long, by means of which both winding spools are driven and from which another belt communicates power to the pumping gear. The rock, when brought from the mine to the surface, is first assorted, selecting the first-class ore for smelting, and separating the waste-rock, that is thrown away, from the low-grade ore, that is sent to the stamps. The company have a 24-stamp mill, which is situated in the valley di- rectly below the shaft-house, so that a gravity tram-road, a few hundred feet in length, is laid on the hill-side, by which means the ore is conducted in cars from the shaft-house to the mill, the descending loaded car bringing the light one up by its greater weight. The 24 stamps, weighing about 500 pounds each, have an average capacity of 16 to 18 tons per day. The yield of the rock, which will be stated with more detail in a following paragraph, is about six ounces of crude bullion to the cord, equal to $13 or $14, in coin, per ton. In addition to this is the product derived from the tailings, which, as may be seen further on, is considerable. The treatment of tailings will be more fully described after discussing more particularly the general features of the milling process. - The superintendent of this mine, Colonel George E. Randolph, deserves much credit for the systematic and careful method of account-keeping intro- duced by him. The data furnished here from his books, concerning the ope- rations of the company, are especially valuable, because so little attention is generally paid in Colorado to acquiring and preserving the statistics of costs in the various departments of mining and milling; or to recording such results, obtained from month to month in the progress of the work, as may enable one to form an intelligent judgment of the future by an accurate knowledge of the past. Colonel Randolph took charge of the work in April, 1868. The following statement shows the number of fathoms stoped, the quantity and class of the ore produced, and the costs of mining and milling the same, dur- ing the succeeding five months: GOLD MINING IN COLORADO. 535 Tons of ore mined. Se | =| Fathoms a a Fa ira a 3 Month, aa ae e 8 § stoped. oe ° 2 ae ist class. | 2d class. i) a 8 g ial oO oO al April at Ss., Gade, we 4613 8 366 = $12 06 TE a Os 61 15 430 180 16 80 | $4 62 | S2r 42 JUNE ch cE es 713% 6 586 296 12 10 4 26 16 36 July - - - - -- - 821 4%4 594 379 TI 42° | 2 85 14 27 August. - - - - - 53 12 416 455 1379 | 3 65 17 44 The fluctuation in the cost of both mining and milling is due to a variety of circumstances, such as the variable amount expended on ordinary repairs in any given month, and the quantity of rock produced or milled during that month. Thus, in the months of July and August, the costs of milling were less than in the foregoing, because the expenditures for repairs were not so great during those months while the capacity was enlarged by increasing the speed of the stamps and the number of days of running, thus diminishing somewhat the costs per ton. The first-class ore, sold at the Smelting Works, netted the mine, in the month of May, $93; in July, $98; and in August, $104 per ton, in currency. The yield of the stamp-rock, including that treated in the company’s mill and in custom mills, was, in May, $24 50; in June, $15; in July, $12; and in Au- gust, 519 per ton, in currency. The total receipts from ores and sale of tail- ings, and expenditures of all sorts, during the four months referred to, were as follows: Month. Receipts. Expenditures, May S02 es tht & = 2 $16, 491 $II, 731 12 Ahi: A 5 ae a4 os 8, 766 10, 306 48 July Ser ee oe 8, 310 9, 883 36 AUMPUSE = Say Sp ae). 12, 000 8,798 62 Total for four months 2 = 45, 567 40, 719 58 I$ $$ 536 MINING INDUSTRY. The proportion of first-class, or smelting, ore to the second-class, or stamp- rock, appears from the accounts to be about one in fifty. Thus we have in— Aig) 2 oes nana de os aes Boece 8 im374 orlin 46 1 2 eee eee wee ee eee 15 “im445 . or tin 73 UNG cx: einaah oes Pee 6 i592. ordain 9% Oly se5e5: 34 aide cca geomneae gee 4.5 im 598.5 or lin 133 (AU eUptccohyea teat ere eeu 12 in 428 orlin§ 3852 Or, for the five months........- 45.5 in 2,437.5 or lin 53.6 This statement shows that the great bulk of the ore produced by the class of veins represented by the Burroughs is of the low-grade, or stamping rock. The proportion of the two classes above given differs considerably from the general estimate of those who do not keep careful accounts, but, so far as the data furnished by this mine and others, where the relative quantities of the two classes of ore are accurately noted, afford any basis for judgment, the proportion of first-class to second-class ore is very small. The relation existing between the amount of ground mined and the quan- tity of stamp-rock produced is indicated by the following figures: Month. Fathoms of ground Tons of stamp Tons per fathom. stoped. rock produced. April 46.5 366 7.87 May 61. 430 8.15 June 2 71.66 586 8.17 July 5 es ee ee = 82.8 | 594 vee iy | Gree os Sak 4 ee 53% 416 7.83 Or an average of = = = = 7.60 The fathom paid for in stoping is the running or superficial fathom; that is, six feet measured on the length and the dip of the vein, but varying in width according to the thickness of the vein. Estimating the average width of the stope at little more than three feet, the weight of the solid fathom GOLD MINING IN COLORADO. Wd would be ten tons, from which, as we have just seen, seven and six-tenths tons of stamp rock are obtained, or about three-fourths of the ground broken. According to this, a fathom of stoping ground produces a cord of stamp-rock, which yields, on an average, six ounces of crude bullion, worth about $100 in coin. The price paid for stoping varies very much, according to the character of the ground. It is sometimes as low as 525, and sometimes more than $50 per fathom. Drifting costs from $12 to 520 per foot. Sinking the shaft, 7 feet wide by 14 feet long, at the date of the writer's visit in 1868, cost 552 50 per foot, the miners furnishing their own supplies. The foregoing notes concerning the operations of this mine were obtained in the latter part of 1868. Shortly thereafter the company became embar- rassed_ financially, and, when visited in 1869, but little work was in progress. A few miners were at work on their own account. First National—There are several claims on the Burroughs that have been worked to considerable depths, but, during the past year or two, their de- velopment has not been very vigorously prosecuted. The Gilpin was steadily worked for along time, but, in the summer of 1869, little or nothing was in progress on that claim. The First National Company, owning several discon- nected claims on the lode, resumed active operations, in 1869, on that which adjoins the Ophir on the west, and have since been steadily engaged in its de- velopment. Their shaft, on this claim, has reached a depth of nearly 500 feet. Stoping has been in progress, during the past winter, between the 400-foot and 470-foot levels, furnishing ores that yield an average of 510 50, coin, per ton. A careful system of account keeping has been inaugurated in this mine, and the following statements, setting forth some of the results of their operations, will be found interesting, as throwing light on the relations existing between cost of production and yield of the ore. It will be seen that the former exceeds the latter, and the experience of this mine is one illustration of the disadvan- tage under which a short claim is worked on a vein like the Burroughs, a fair representative of the Colorado gold-bearing lodes. The vein is narrow, the average value of the ore is low, and the pay is not uniformly distributed. A vein of this character needs all the advantages that may be derived from eco- nomical and systematic methods of work. Here, however, is a claim, 183 feet in length, working through a shaft nearly 500 feet deep, the cost of sinking 68 538 MINING INDUSTRY. which is 10 per cent. of all the expenses of the company. As the mine has no connection with its neighbors, the shaft can only aid in the develop- ment of a small part of the ground for which it would be sufficient if the claim were longer. The cost of hoisting works, the consumption of fuel, labor of the engineers and some other men, the cost of superintendence and other management of the company’s affairs, are nearly or quite as much as they would be if the production of the mine were ten-fold greater. Thus the costs per ton are much increased, and ore, rich enough to afford a profit under fa- vorable circumstances, is produced at a loss under existing conditions. This is true of many of the mines in Colorado. Some of the best lodes, apparently possessing all the necessary qualities for profitable working, under one comprehensive and economical management, are divided into a multitude of short claims, worked independently of each other, at great expense, and losing their possible profits for the lack of consolidation. The following statement shows the operations of the mine, in detail, for five weeks, from October 9 to November 13, 1869: ie M : og ¢ ] 3 2 ne a6 3 a n & a 2S o oO ° tw 3 a= oth Pe a Vien ne! eee) 4 d : * J Be o 3 39 AN A. 8 Week ending— Q a aire) — a 2 ey o & es wo aon =) ny a 3 = Po 5 a Of Dis: fs fo) nd & a A P= a 3) “3 acs co) a z eS a = 8 a Bose 3S = 2 Q oe 5 Ones ° = a o) a 2 fH 6) fH a October 16 . 87 | $6 96 $1 71 $8 68 56 $5 38 $14 06 | $16 43 23:0 72 601% Oey I 80 II 97 72 5 38 17 35 10 29 30 eae ni77 wale ze76 1 82 9 59 74° 5 38 T4 97 12 OL November 6 .- 67 8 68 0 35 9 03 76 5 38 I4 41 II 79 13 117% 497 I 93 6 go - 4 45 II 35 All expenses are included in the foregoing; among special costs is in- cluded the sinking of the shaft. The following is a summary of operations from October 9, 1869, to Jan- uary 1, 1870, including the foregoing: Number of tons of stamp-rock raised and milled.-.............-.--. 850 Average assay value in coin—gold, $25 13; silver, $1 94—total.... $27 07 Number tons smelters’ ore raised and sold, (1 in 65,)....-..-..----- eB 2 GOLD MINING IN COLORADO. 539 Average assay value in coin—gold, $131 21; silver, 516 22—total.. 5147 43 Ufotal, (Ons 1aisd sate v2baes S2ectwn cree ee cee eee gn ceo ch op ee ese 863. 27 Average assay value, Coin --...-------------+2eeee seer etter rece eee $28 92 Average yield, per ton, of milling ore, in currency.------------+---- 12 68 Average yield, per ton, of smelting ore, in currency.-.--.----------- 11007 Average yield, per ton, of all ore, in currency...---.------.-.--+-+-- aS leg Average cost, per ton, for ordinary expenses of mining and milling, 13 59 Average cost, per ton, for special expenses----.--------------------- 2 08 Toial ayerave cost, per ton; N-CUITency.< <2 22 oO 5 OG Sera ere=! a < < a Bop tale eee an eee BObtal te ee vee: oe 404 4.78 8.00 6.37 Keottail, 2) <2 oe a 2, es | Black Bawk. «. . 9%. or eas 7.00 7.80 WoOpta ee ese cel CL TUSthee Bama Gog oP 65 5.10 7.50 2.50 ob tallege pete oie OCUSENGerHeL = aa oe) fe 2 II.00 15.00 10.50 Bobtail Meee arene |MOLerlIng= 2. = Eee 2 146 5.82 6.65 5.70 Hiskes hie) ee ey come) sei] poterlings ay N2> Jase 12 5.00 7.00 9.30 Gresoty = 3 1= = — -| Narragansett. © -- : 18 2.25 7.00 9.00 Gregory - - - - - -| Gregory Consolidated - 8 4.25 10.00 3.50 Gresory me a a es = |) BIISSS. eo eS 136 5.25 10.50 Gregory - - - - - -| Smith & Parmelee - - 28 3.46 I2.00 lsbiieceiehinaisc < E. AY 66)) Sa = 9S olay ee eee 12 3.25 10.00 2.00 BOTLOUs See wey Saat wre | eO)DUIieet es ee 230 4.85 10.00 Burroughs! =2-) 4 2) =) Gilpmie =) 2 5 % = 178 4.25 8.50 Burroughs - - . - -| First National 20 3575 g.00 Gardner <5 2) cel 2 | Clarkes 2.205 2-3 38 3.84 11.26 MMOS eee teeta, ote een EINOTU Star eo pie, oe 5 Be25 I5.50 Galittormae= = woae) eee |otalkersi sys 5 =. 5 42 2.89 18.00 Coaleya meee ene nay Bt | OOaley = ania? Sues ois) =A 205.00 ViclOMNen a MA See ila, ema ey nes ah 31 ae 270.00 PriZee eee en ect] te Si Rie Se! cae 95 2.00 25.00 The works of the Boston and Colorado Smelting Company were built during the summer of 1867, and begun smelting operations in February, 1868, Since that time their capacity has been largely increased, and, during the past year, was quite equal to, if not a little in excess of, the supply of ore. They 74 586 MINING INDUSTRY. are managed by skillful and experienced men, and, it is said, have been profit- ably conducted. The establishment has been and is of great advantage to the district, affording, as it does, the best and almost the only suitable method of treatment that has yet been introduced for the first-class ores. The first shipment of matt was made from these works in June, 1868. A complete statement of the shipments since that time is not in the writer’s hands, but from available data may be estimated at about 25 tons of matt per month, containing, on the average, 40 ounces of fine gold, 200 ounces of fine silver, and 40 per cent. or 800 pounds of metallic copper, per ton. This is equal to 1,009 ounces of gold, 5,000 ounces of silver, and 20,000 pounds of copper, per month. The gross value of these metals, thus shipped, is about $30,000, coin, per month, or $570,000 from date of beginning to January 1, 1870. Cuiorimation Works.—These works were established in this district in 1868, by Mr, Cash, a gentleman who had already had a considerable expe- rience at Grass Valley, in California, in the treatment of auriferous pyrites by the chlorination process. It is the purpose of this process to extract the gold by first converting it from the form in which it exists in the ore into that of the soluble chloride, obtaining this in an aqueous solution, and then precipi- tating the gold, in the metallic state, by the sulphate of iron. This process has been successfully employed in Europe during many years, and was intro- duced in California about ten years ago, where it has given great satisfaction. It was brought to Colorado by Mr. Cash with the purpose of treating tailings, but owing to various hinderances had not entered upon regular operations at the date of the writer’s visit in 1869. One cause of this delay is said to be the low value of the material to be treated, the tailings having been formerly supposed to be much richer than now appears to be the case. It is now reported that the establishment will be provided with some suitable crushing machinery and be employed in the treatment of first-class ores. The works consist of one reverberatory furnace in which the ores are subjected to a chloridizing roasting; four large chlorination vats, or tubs, in which the roasted material is subjected to the action of the chlorine gas; the necessary apparatus for generating chlorine; two precipitation tubs, in which the gold is thrown down by sulphate of iron; anda small melting furnace, for running the metallic GOLD MINING IN COLORADO. 587 gold into ingots. The present capacity of the works is about three tons per day. For a full description of the chlorination process, the reader is referred to Guido Kiistel’s “Concentration and Chlorination.” The California Reduction Works, another establishment designed for the working of high-grade ores, especially those rich in silver, are situated near Black Hawk. They have not been in constant or regular operation during the past year or two. The process employed is that of chloridizing roasting, per- formed in a Briickner cylinder, and subsequent amalgamation in barrels. This is essentially the same as that which is in use at Georgetown, and noticed with more detail in the next chapter. Propuction or Giipix Counry.—The total value of the bullion produced in Gilpin County during the past two years may be very nearly ascertained by adding to the aggregate shipments of the three banks of Central City the value of the matt shipped from the Boston and Colorado Smelting Works. Nearly all the bullion produced in the county is shipped in one or the other of these two forms; the crude bullion, obtained in the stamping-mills, being either sold to the bankers or shipped through them; while the value of the first-class ore is represented in the matt. The amount that leaves this part of the country in private hands, or by other means than those just indicated, is thought to be insignificant by those who are very competent te judge. A record of the bank shipments, during the period referred to, has been very carefully kept by Mr. Frank C. Young, cashier in the banking-house of Warren Hussey & Co. The following is Mr. Young’s statement, showing the coin value of the aggregate shipments of the three banks at Central City during the years 1868 and 1869: 588 MINING INDUSTRY. Month. 1868. 1869, Jariany? seve) genase ee aera) eo oe ee ee $80, 000 $77, 000 Febtuary: =. = is a8 2 en = G2 0-0 = =o Ne 95, 600 85, 800 Maren. 2. G6. a ar @ Gee So st Je Ee ee. 75, 000 IOI, 700 April: 2. SS) Sei ag cs 4: 2) tates I a 79, 000 108, 000 May ee es, oe! Pte Mer te oat Se Get ee pes gs 104, 000 I16, 000 sJULTIGS tees ates ee eee ete 106, 000 147, 000 July. cc Si ter ve SS Ser SS Gases: Ei Se IOI, 000 I24, 000 Aupusts.-% 2. «25° Ss 3a %eisen 8 tage Ss 113, 700 IOI, 500 September. 2 mw: 3° 3. = haa = =P => eae 85, 000 122, 000 ,@ fo} <0} 91-5 cae Co ie a a Bre ce 3 113, 000 II0, 000 November< <= < « .« = = = =» = = = “js I14, 500 120, 500 December « © < 6 6 See i = = = = 108, 200 106, 500 I, 175, 000 I, 380, 000 Currency value - - - - - - - - - -| $1,648,550 $1, 835, 975 Total coin value of gold shipments from the banks during two Years. ---.------- 22+ eee ee eee A RE Hair Sone ge Pome rn Pe ptr The gross coin value of the gold, silver, and copper contained in the matt shipped from the Boston and Colorado Smelting Works, during the same period, may be estimated as follows, in accordance with a statement on a foregoing page: O70) (0 Dekeet Aenean aS IaeS, seis ee ne enema ener cee ren $390, 000 Silvereeeeeee ese Se ae Fe aoe eee a yee ee 123, 000 Copper... catekencinaad thytaestuce Seu pecereer me Reames: - 971,000 Total coin value produced and shipped in 1868 and 1869.. $2, 555, 000 570, 000 3, 125, 000 The above statement makes no allowance for undervaluation of bankers’ shipments, amounting to five or ten per cent. In the estimate of the total bullion production of the Territory, given on a foregoing page, this element is taken into account. CHAPTER X. SILVER MINING IN COLORADO. SECTION I.—GEORGETOWN SILVER-BEARING VEINS—TERRIBLE, BROWN, U. 8. COIN, : SHERMAN MOUNTAIN, BAKER MINE, EQUATOR, ARGENTINE, TUNNELS, SEcTION IL—TREATMENT OF THE ORES—SMELTING WORKS—AMALGAMATION WORKS—CONCENTRATION—PRODUCTION. SECTION IiI.—SNAKE RIVER MINES. oa ON. I GEORGETOWN MINES. The most productive silver-mining district in Colorado, at the present day, is that of which Georgetown is the center. Indications of its mineral wealth were discovered in 1859, but the developments then made were not very extensive. During several years following the district was prospected by a few parties, but it was not until about 1866 or 1867 that the mining enterprise of the region began to assume the importance which it now possesses. About that time new and valuable discoveries were made which gave a fresh incen- tive to exploration; many veins of more or less value were opened and pros- pected, a few of which have already proved to be productive and profitable mines, while many others, though less extensively worked, have afforded encouraging results. Metallurgical works of various sorts have since been erected, and are now steadily employed in the treatment of the ores; a town containing 1,500 or 2,000 inhabitants has been established and provided with good hotels, postal, telegraphic, and express offices, churches, schools, and other essentials of civilization; the mines are being persistently developed, and the value and importance of the region appear to be steadily, if not rapidly, increasing. 590 MINING INDUSTRY. The district is located in the elevated portion of the mountain range, on the southern and upper tributaries of South Clear Creek. George- town is situated at the confluence of two beautiful mountain streams, which, descending from the crest of the range, through deep and sharply- eut ravines, to their point of junction, unite there to form the South Branch of South Clear Creek, which flows thence in a northerly and easterly direc- tion, about four miles, where it joins the main stream known as South Clear Creek, at a point about four miles below the town of Empire. Thence the stream flows on in an easterly direction, fifteen miles, to its junction with North Clear Creek, a point still in the elevated mountain region, and twelve or fourteen miles from the foot-hills. Thence, as Clear Creek, and by this time a respectable mountain river, it flows on, emerging from the foot-hills at Golden City and emptying into the South Platte, a few miles below Denver. The country about Georgetown is of an exceedingly rugged, mountain- ous character. The town itself is over 8,000 feet above the sea. The valley, from the fork of the stream, where Georgetown is situated, to its junction with South Clear Creek, is narrow and deeply cut. Near the town it is from 500 to 1,000 feet wide from the base of the hills, on one side, to that on the opposite side, and its comparatively level bed affords a favorable site for settle- ment. The mountains rise very abruptly, almost precipitously in places, to the height of 1,200 or 1,500 feet above the stream. Although very rocky, their sides are partly covered by timber. Ascending either fork of the stream, above the town, the observer finds a narrow valley, on either side of which the mountains rise steeply 1,500 or 2,000 feet high, cut here and there by sharp lateral ravines. Between the forks of the stream, Burrell Mountain rises directly behind and south of the town; the crest of the spur, of which this mountain forms the end, turns to the westward, ascending toward the summit of the main range, its successive peaks or higher points beyond Burrell Mountain being locally known as Leavenworth, Pendleton, and McClellan Mountains. On the north side of the right-hand fork, which has an east and west course for three or four miles above the town, is Sherman or Republican Mountain, and beyond that, further west, and sepa- rated from it by a narrow ravine, is Brown Mountain. ° Below the town the mountains are locally termed, on the left hand or SILVER MINING IN COLORADO. 591 west side of the stream, Democrat, Columbia or Colfax, and Douglass Moun- tains, the latter being at the confluence of the south branch with South Clear Creek. On the opposite or eastern side of the valley, a half-mile below the town, is Griffith and Summit Mountains. In all these hills, and in others adjacent, whose names have not been mentioned, the work of exploration has been carried on, and, in some cases, attended with very important results. Tue Verns.—The veins of the Georgetown district are highly argen- tiferous, but they contain little or no gold. Some of them are reported to be slightly gold-bearing, but so far as the writer's observation extends, the typical veins of the region have no gold whatever. The country-rock is generally granite and gneiss, presenting many lithological and mineralogical varieties. The prevailing character is, perhaps, gneissic, but many varieties of structure and mineral composition occur in close proximity to each other, and sudden and frequent transitions from one form to another may be observed throughout the district. The veins, generally, are not very wide. Like the gold-bearing lodes of Gilpin County, they present among themselves a striking similarity in course and dip; and, further, the prevailing direction is very nearly the same as that of the veins about Central City. With rare exceptions, the course of veins, observed by the writer in this district, is between due east and west, on one hand, and north 55° east on the other. The last named course, itself some- what exceptional, is that of the Equator, one of the most prominent lodes of the district. The Terrible, another of the most distinguished veins, strikes north 77° east, while the majority of veins, less developed than those first named, have a course of due east and west. In this statement the true course is spoken of, allowing about 15° easterly variation in the magnetic course. The veins dip generally at a high angle, in many cases vertically. Like those of Gilpin County, they are regular, well-defined fissures, and are not faulted. Their other natural features, the character of the gangue and ore, and the mode of occurrence and value of the silver-bearing and other associated min- erals, will be more fully shown in the following description of some of the best developed and most important examples. Terriste—The Terrible mine is located on Brown Mountain. This mountain is one of those on the north side of the right-hand fork of the 592 MINING INDUSTRY. stream above Georgetown, and is three miles distant from the town. The hillside rises very steeply from the bed of the valley. The lode on which the mine is located bears the same name; it crops out on the southern slope of the hill, several hundred, perhaps a thousand, feet above the stream at the base. It is said to be clearly traced for 2,000 or 3,000 feet along the hill-side, but it was discovered and has been chietiy developed in the immediate neigh- borhood and on the west side of the ravine that divides Brown Mountain from Sherman Mountain. On Plate XXXV will be found a longitudinal section of the mine, which represents the extent of the work that had been accomplished at the end of August, 1869. The following are some of the results that appear from these developments. The course of the lode is 62° east of magnetic north, or about 77° east of true north, coinciding nearly with the trend of the hill. Its dip is vertical to the depth of 80 feet, where it inclines slightly to the north at an angle of 75° from the horizon. The width of the vein is from 1 to 5 feet. The country-rock, where observed by the writer, is a close-grained granite, con- taining reddish feldspar anda fine black mica. The walls are very well defined; they frequently show polished and striated surfaces and are usually separated from the main filling of the fissure by selvages of clay an inch or two in thickness. The filling of the vein consists usually of an ore-seam which is from 2 to 14 inches thick, averaging about 8 inches, and with this is associated a gangue rock of somewhat varied character. The gangue, appa- rently most intimately associated with the ore, is a mixture of quartz and feldspar, the latter being sometimes in coarse particles. Sometimes this material is taleose and finely laminated. Gangue of this character almost always, if not invariably, accompanies the ore, frequently occupying the space between the several seams of pay-mineral. In other parts of the vein, and often closely associated with the foregoing, the vein-rock appears to be com- posed of quartz, feldspar, and mica, presenting the appearance of true granite. These two kinds of gangue rock sometimes occur separately, sometimes together; in the latter case there is usually a marked difference in their appearance, hardness, color, and mineral composition, which suggests that they are of different age or origin. Plate XXXV Legis: a Gangue rack, GJaartxose and felspathte matler 6. Linchlende with sante gilena and rich silver minerals © Vern matter, mired Cas” Oats” wrth streaks of ore d. Seams of clay and blende. tf. Clay selvage on wall. e. Chietly gatena with g Country grantte. Z oO. Scale: Fe = Fig. 2. aGanguwe rock Mbp SKK SCD 3 Chielly pyrites with some pe" 2 ey fatlerx and blende c. Coarse grained galena. — a Galena, blerde, pyrites Weck WQ.| Ni we’ a containing guare fragments s Dividing seam of clay. and some stlyver ores @ e Vewer gangue rock, —_ pad = —7 pad i % ae g8 NK ss gS Bb as Me ar Wh Ws \\ TWN ented As = g Guntry granite. Ys Scale: so. ZS KKK iJ i Iv Seale: 1200 SILVER MINING IN COLORADO. 593 The ore consists chiefly of galena and zincblende with some iron and copper pyrites; with these are associated some rich silver minerals, compris- ing stephanite, silver glance, fahlerz, some native silver, and, occasionally, ruby silver. The galena is thought to be quite rich in silver, which may also be true of the zincblende, but the great value of the ore is probably due to the abundant occurrence of true silver minerals. The gangue mineral most fre- quently found with those just named is crystallized quartz, with which are associated fluor spar, heavy spar, and others in small proportions. The ore-seam, where seen by the writer, was generally compact, occur- ring sometimes on the south wall and sometimes on the north wall of the vein. Occasionally, however, it is split up, forming a number of parallel seams. A narrow selvage of clay divides it from the wall of the vein, and sometimes from the accompanying belt of gangue rock. The minerals com- posing the seam are often crystallized, and vugs, or cavities with crystalline linings, are frequently met with. Fig. 2, on Plate XXXYV, represents a transverse section of this vein at a point observed and sketched by Professor Schirmer, an educated mining engineer, formerly residing at Georgetown and connected with the Terrible mine. The alternating seams of ore and accompanying gangue are clearly shown. According to the view of Mr. Schirmer, who has had occasion to study closely the formation of this vein, the middle mass of gangue rock, e, is of later origin than the other material on either side, having intruded itself into the vein, widening the fissure, and producing the slickensides, or polished surfaces, that may be observed on the planes of contact between it and the older rock, a. This view is also supported by the occurrence, in the supposed newer rock, of imbedded fragments of quartz several inches thick. Fig. 3, on same Plate, is a somewhat similar section, taken in the Brown lode, a vein ocewrring near the Terrible; but in this case the differ- ences between the masses of gangue rock are less clearly distinguished. The value of the ore may be best shown by the following statement. The developments made in the mine comprise the sinking of the main shaft, 185 feet deep; the driving of the three levels shown in the section, the upper one being 810 feet in length, and the stoping, which is also indicated. The whole extent of ground stoped, at the time referred to, was 60 or 70 fathoms. Ass fv 594 MINING INDUSTRY. From this work were produced’ 98 tons of ore that yielded $560, coin, per ton; 29 tons shipped, or ready for shipment, to Newark, having an average assay value of S642, coin, per ton, but from which the returns of actual yield had not been received; 68 tons of second-class ore, of which 48 tons, worked, yielded $210, coin, per ton; besides which, it is said, there are from 1,200 to 1,600 tons of third-class ore on hand, consisting of inferior quality of vein- matter mixed with small particles of rich ore, broken in the mine and on the assorting floor, the whole of which is estimated to contain, by assay, $80 to $100 per ton. This material must be concentrated before treatment. This mine was discovered in the winter of 1866-67, and has been devel- oped gradually by a small force on a careful and economical basis. The ori- ginal outlay of capital is said to have been small, and the profits of the work considerable, but the writer has no direct information on that point. The costs of mining cannot be very closely estimated from the available data. Sinking costs 540, currency, per foot; drifting, $20 per foot; stoping, 540 per fathom. The mine is provided, at the mouth of the shaft, with a small engine for hoisting and pumping. ‘The pump is small and the water abundant, and, for this reason, the work, in the lower part of the mine, was suspended during the summer of 1869, awaiting the completion of a tunnel, then being driven in from the hill-side. The steep slope of the hill affords great advantages for attacking the lode by tunnels, and this is now being done. An adit, about 350 feet long, strikes the vein at a depth of 260 feet, dispensing with the necessity, for some time to come, of raising either rock or water. The out- crop of the vein being several hundred or a thousand feet above the valley, it may be worked by this means to a very considerable depth. The tunnel referred to is 62 feet wide by 72 feet high. It passes through very hard granite. It is driven with the aid of the Burleigh drill, which gives great satisfaction, performing its work at half the cost of hand labor, according to the estimate of the owners of the mine. ‘The whole working cost of driv- ing this tunnel had been, at the time referred to, about $40 per foot. Several other tunnels are being driven in this district, some of which employ the Bur- leigh drill, and will be noticed further on. The following are a few notes ‘ According to statement furnished by Mr. I’. A. Clark, one of the owners and manager of the mine. SILVER MINING IN COLORADO. 595 concerning the experience in this kind of work, in the tunnel just referred to, at the Terrible mine. The air compressor of two cylinders, each 12 inches diameter and 16 inches long, only one of which is required for the present work, is set up at the mouth of the tunnel, and driven by an engine of 12 inches diameter. It is capable of running two drills, but only one is used. The drill is worked under a pressure of air of 35 to 40 pounds; strikes 300 blows per minute; the drill is 14 inch steel, with 1} inch bit; the progress of the drill in the hole averages 2 inches per minute; each drill, on the average, drives 30 inches before needing to be sharpened; the machine is managed, at the heading of the tunnel, by two men on each shift, who drill from six to eight holes per shift, including the time required for charging and firing, the latter being done by electricity, and for removing the broken rock; the force required at the tunnel. comprises six men, four of whom are drillmen and two engineers, be- sides the smith, at the mine, who sharpens the drills. Labor costs 54 50 to 35 per day, for shift of twelve hours. ‘The average progress of the tunnel is 12 feet per day of twenty-four hours. It is reported that the property of the Terrible mine has been recently sold in England for $500,000. Browy.—Brown Mountain, oa which the lode just described is located, has been extensively prospected, and a number of valuable veins have been opened. Among these the John Brown, U. 8. Coin, Lilly, Roe, Mammoth, and others have been developed considerably, and have produced some very rich ore. The John Brown lode crops out on the hill-side, 800 or 400 feet above the Terrible. It has a nearly parallel course, north 75° east, and dips almost ver- tically, but slightly inclined to the south. The width of the vein is variable. Where both walls are clearly defined they appear to be from two to five feet apart; but the south wall is often difficult to distinguish, and as the filling of the vein is, to a large extent, granitic, or like the country-rock, it is not always easy to define their position. Where cross-cut in one or two places the vein is thought to be from 15 to 24 feet wide. The ore of this vein resem- bles that of the Terrible in most respects, but is characterized by the occur- rence of much more zincblende. This is the predominating mineral, and is said to be argentiferous. With it is also mixed cousiderable galena, rich in silver, and a small proportion of pyrites, with true silver minerals. ‘These are 596 MINING INDUSTRY. stephanite, pyrargyrite, proustite, polybasite, fahlerz. antimonial silver, and na- tive silver. The rich silver minerals seem to be less abundantly distributed in the Brown than in the ores of the Terrible, though some lots of selected ore have proved to be very rich. The ore is sometimes concentrated in one compact seam, lying upon one wall, or is sometimes divided into several branches. The width of the seam may be from 2 to 10 or 12 inches. Fig. 3, on Plate XX XV, shows a cross section of this vein, observed by the writer, not far below the surface. The north wall is well defined, carry- ing seams of rich ore; the south wall is not so clearly identified, the left hand side being limited by the side of the drift, and the true character of the ad- joining rock remaining undetermined. The mass of gangue rock here is a mixture of quartz and feldspar, much broken up, traversed by clefts and joints and colored by oxide of iron. The several seams of ore appear to unite at a point not far below that where the section was taken. The mine has been opened by a tunnel, 180 feet long, through the coun- try-rock, at a right angle to the vein, which it strikes at 160 feet below the surface. From this point of intersection a drift has been made, about 180 feet on the vein. A tunnel or adit, starting from a point about 100 feet higher than the drift just mentioned, has been driven in on the vein from its outcrop in the neighboring ravine, about 250 feet in length, and connected by winzes with the drift below. In connection with all this work considerable stoping has been done. The company owning this mine have expended a large sum of money in the development of the property, chiefly, however, in the construction of met- allurgical works and other appurtenances. As the mine is worked by tunnels, no hoisting machinery has been required, but a large and costly crushing mill and smelting furnaces have been built at the base of the hill, just below the mine. These works consist of 20 stamps, a Blake’s rock breaker, some concentrating appliances, a roasting furnace, lead-smelting furnace, and cupelling furnace. Some details of the various methods of treatment applied to the ores of the district will be found further on. It will suffice to say here that the first-class ore is crushed without concentration, while the bulk of the mine product is reduced by stamps, concentrated in a round buddle, and the richer portion ob- tained for roasting and smelting. The ore of this lode is rather too poor in SILVER MINING IN COLORADO. 597 lead for smelting alone, and that metal is usually supplied by purchasing ga- lena elsewhere, which is then mixed with the material to be treated. Accord- ing to Mr. Watson, superintendent of the mine, the greater part of the product of the mine is low-grade ore, requiring concentration. During the summer of 1869 there were 191 tons of mineral smelted at these works. The greater part of this was obtained by concentrating ores that, in the raw state, had an average value of 20 to 30 ounces of silver per ton. According to the average rate of concentration, six tons of raw ore furnish one ton of mineral. This being mixed with the first-class ore, the whole is subjected to the roasting and smelting process. ‘The average assay value of the smelted mineral, during the period referred to, was 200 ounces of fine silver per ton, of which an average of 90 per cent. was obtained by metallurgical treatment. From this it appears that the product of the works, during the summer of 1869, was be- tween $40,000 and $50,000... The ore furnishing this yield came partly from the Brown and partly from the U. 8. Coin lode. The latter is said to pro- duce much richer ores than the Brown. As the hill-side on which the mine is situated is too steep to admit easily of the construction of a wagon-road, the mine has been provided with a sus- pension tramway, the upper end of which is at the mouth of the tunnel and the lower end at the base of the hill. This contrivance consists of two wire ropes, each 1} inches in diameter, stretched side by side, 6 or 8 feet apart, elevated above the ground and supported at intervals of 200 or 300 feet. The ends of the ropes are securely anchored in the ground. The average inclination of the ropes, from the upper to the lower end of the tramway, is about 20°. Each rope serves as a separate track for the passage of a car, which is attached to a framework of iron; the latter hanging upon the rope, on which it rests by means of two sheaves or wheels, which, turning freely, permit the movement of the car along the rope. The two cars are so arranged that one descends, carrying a load of ore, and, by its weight, draws up the other car, which may also carry a light load of supplies or material for the mine. A small wire rope, a half inch in diam- eter, connects the two cars, passing around a drum at the upper end of the According to statements made by Mr. Watson, superintendent, and Mr. Cheever, assistant. 598 MINING INDUSTRY. tramway, which drum is controlled by a brake. The car is capable of con- taining about 1,000 pounds of ore. ‘The details of construction, showing the method of supporting the cables in such way that the cars may pass, the form of the framework to which the car is attached, and the arrangement of the sheaves cannot be very intelligibly explained without drawings, which are not in the writer’s possession. It is said to work satisfactorily. Comw.—The U. 8. Coin lode has been developed by the same company. It crops out a little higher up the hill and is opened further west than the Brown mine. . Its course is nearly due east and west, the dip being almost vertical. The ore, in its mode of occurrence and general character, is like that of the Terrible and Brown lodes in most respects, but is usually concentrated in a narrow seam of rich mineral. Ruby silver is said to occur frequently. Small lots of ore from this lode have yielded very high returns. Lrtty anp Ror.—The Lilly and the J. J. Roe, though different locations, are thought to be on one and the same vein. This is still higher up the hill than the last-named. Its course, where observed, is north 55° east, true, dipping to the south at an angle of 80° from the horizon. This lode has also produced rich ores, similar, in general character, to those just described. In 1868 two tons of selected ore yielded $400, coin, per ton. The lower grade ore, treated at the amalgamation works in Georgetown, yielded about 5150, coin, per ton, for a lot of 44 tons. The developments on this lode have been considerable as compared with other lodes in the neighborhood, but have not yet reached great depth. When seen by the writer the deepest point attained was not more than 100 feet. The vein had been stripped along the surface but not drifted upon very extensively in depth. SuermMan Mounrary.—Sherman Mountain, as it is called by some, or Republican Mountain, by others, is next east of Brown Mountain, from which itis divided by a narrow gorge or ravine. This hill has also been exten- sively prospected and many lodes have been opened, though only a few have been developed to a depth exceeding 100 feet. They are generally of the same type as those just described. Prominent among them are the Cashier, Mendota, Snowdritt, Robert Emmet, Bush, Huntington, and others. The first-named is thought to be an extension of the Terrible, though its identity could not be established from observations made at the time these notes were SILVER MINING IN COLORADO. 599 taken. A shaft has been sunk on this vein to the depth of 62 feet, showing an ore-seam 8 or 10 inches wide. The ore at this depth is chiefly zincblende, but carrying the other minerals already mentioned as characteristic of the lodes on Brown Mountain. Some of the ore has a high assay value, but not much has been worked. The course of the vein is north 80° east, true, dipping almost vertically. Baxer.—The mountain slopes, bordering the right hand fork of the stream above Georgetown, have been explored, more or less, along their entire length Three or four miles above Brown Mountain, and about seven miles from Georgetown, Kelso or Quail Creek enters the main fork from the south side. At this junction is situated the mill of the Baker Mining Company, a large and costly establishment. The mine of the same company is located four miles from that point, on the eastern slope of Kelso Mountain, near the head- waters of the stream. It is not far below the crest of the range, having, it is said, an altitude of over 11,000 feet, and being in the immediate neighbor- hood of Gray’s Peak, which has an elevation of about 14,300 feet. The mine is probably more extensively opened than any in the Georgetown dis- trict, though, thus far, the vein has not been very productive. The general strike of the lode is about north 80° east, true, dipping northerly at an angle of 55° to 60° from the horizon. The width is variable, generally about 3 feet, but sometimes expanding to 15 feet, or more. The inclosing rock is granite or gneiss. The walls, particularly the south wall, are good and well defined. The vein-matter is generally a mixture of quartz and feldspar. It is usually soft and separated from the walls by a seam of clay. In some parts of the vein the filling is chiefly siliceous, and sometimes becomes a hard flinty substance, without showing much ore. The ore-seam is not continuous. So far as developed, when visited by the writer, the pay-mineral occurs in dis- connected bunches, or pockets, and not very abundantly. The ore consists chiefly of galena, zincblende, and silver sulphurets. The associated gangue is mainly quartz, but in the lower levels an abundance of fluor spar is a char- acteristic occurrence. The mine has been opened by three tunnels or adits. The upper one, known as the Discovery tunnel, was, in the autumn of 1869, about 200 feet long, driven in upon the vein, having started at the outcrop ; the two lower tunnels are partly in the country-rock and partly on the vein, 600 MINING INDUSTRY. the middle tunnel being about 200 feet, and the third, or lowest, being over 400 feet in length. These adits are connected by winzes. The amount of stoping that had been done, at the date referred to, was comparatively small. From these openings small lots of selected ore had been obtained that had yielded from $200 to $300 per ton. The lower grade, or common ore, yielded from $50 to $100 per ton. Up to the date referred to no very large amount had been worked, as the company’s mill had not then commenced operations. The total product of the ores treated is said to have amounted, at that time, to about $6,000; besides which about 200 tons of common ore were awaiting treatment in the company’s mill. The construction of this establishment was begun early in 1868, but owing to changes of plan and other hinderances it was still unfinished in the autumn of 1869. The pro- cess at first selected was that of smelting with lead and subsequent cupella- tion, for which method the furnaces were built ; but as the ore proved to con- tain a lower percentage of lead than is requisite, this was discarded and the chloridizing-roasting, with barrel amalgamation, was adopted. Some details of this method will be given further on. The mill consists of crushing machinery, which comprises one Dodge crusher and two Ball pulverizers ; three of Briickner’s revolving cylinders for chloridizing-roasting; six barrels for amalgamation ; a retorting furnace, and other appurtenances necessary for the business, including two excellent steam-engines, the cylinders of which are 14 inches by 30, geared together to drive all the machinery. Two large boilers supply steam. The left-hand fork of the stream above Georgetown has been as actively explored, at least for a portion of its length, as the right-hand fork. The course of this stream, from its head-waters to its confluence with the other fork at Georgetown, is generally from the southwest to the northeast. The principal mining developments have been made in the hills which rise between the two streams. Of these hills, that which is known as Leavenworth Moun- tain has, thus far, been the scene of the most active operations. Equatror.—The Equator mine, on a lode of the same name, is, at present, the most prominent mining enterprise in this neighborhood ; the Winnebago, on the same lode, and the Argentine, McClellan, Gilpin, and others, in the vicinity, ave of growing importance. The Marshall tunnel is also in this hill, SILVER MINING EN COLORADO. 601 driven in from the mountain side and penetrating the country-rock at a right angle to the general course of the veins, and at such a level as to intersect them at considerable depths. The Equator lode, located high up the hili-side above the bed of the stream, was discovered in July, 1866. Its course, coinciding nearly with the trend of the hill, is about north 50° or 55° east. The dip is nearly vertical, inclining a little to the north. The north wall is well defined, smooth and regular in course; but the south wall is less clearly marked, making it some- times difficult to determine the width of the vein. In some places where cross-cut it is said to be 15 feet wide, but the average width, as shown in the greater part of the work, is 4 feet. The filling of the vein is of soft material, consisting chiefly of quartz and feldspar; but it sometimes passes into a harder rock, more granitic in appearance. The ore is galena, zincblende of several varieties, considerable fahlerz, with some ruby silver and native sil- ver. Some of the selected ore is very rich, several tons possessing an average assay value of $1,000 per ton; while the lower grade, which is treated by the amalgamation process, has an assay value of $150, coin, per ton. The extent of development im this mine may be seen by a reference to Fig. 4 on Plate XXXV, which shows the amount of work performed previous to Sep- tember, 1869. The depth attained is little over 200 feet. The mine has been quite recently provided with hoisting machinery, consisting of an engine, the cylinder of which is 10 inches in diameter by 16 inches stroke. This drives a winding apparatus, of the kind described in the foregoing chapter, consisting of a spool moved by a belt. The work of mining is comparatively cheap. Drifting costs 57 to $8 per foot; sinking the shaft $30 to $35 per foot. Stoping has been done by the day at $3 50 to $4 per diem. The total production of this mine from the beginning of operations to the end of August, 1869, is about 570,000, coin, or nearly $100,000 in currency, making allowance for the average premium, during that period, on coin value. 70 602 MINING INDUSTRY. ~ This product has been derived about as follows: = rs oo a Sie B = a=] a xa lo} een) go 2 2 a? aU 6 = 3 Gos eis oS ca Date. 3 Class. oe mS a s O90 aS ide So tM = to © o By n Gow g fo} & a o ev Oo a = 5 > eet 1s = a eee 4 $191 36 SNOW GIEEIOAG sete et een ee ae gee ara ee Be 60 80 to 190 00 Vefaqtrhdopqylalakei= ee A Re ee Ae ees go 150 00 Werriblelode}see. = 97 ee eA agai gis 8 ee Re Bee Fall and Temple, cited.... 310,312,313 | PRCA OE At ORIG een ee Fall River, Colorado. --.-..-=.25-: 479 OES Es see ae istane ag Je 205 PQYOSttES Soe ee weenie scotia 3 415 ene oe ee ee ee ae Faults in Lander Hill veins. ....... 354 eet nee Per a a Field, claim on Bobtail lode. ...... 505 het nas ore.3206 Fire in the Yellow Jacket mine.... 184 eae First-class ore, treatment of at ee a BOIES: aires SE te eet eee _ 964 Furnaces of Montezuma mine..... 300 First-class ore, statement concern- ue para rue ole CC en en eae 269 ees gt ans First-class ore, treatment of in Col- Seg a 306 ni NR eee ee 579 treatment of Colorado First-class ere, gold ores of Colo- gold ioe wuss 581 TAC O.cWOG) PAUL TON: seme «mai oSt See beat ous First National mine on Burroughs dea Pores tie GOonee _ lode: Colorado S225 35. ke oe 532, 537 HOD Seen tee 607 Tirst National mine, statistical state- ment concerning ....--..------- 538 Gabb, W., cited.....-.....---- 461, 463 First National mine, experiments to Gaetzschmann, Professor, cited.... 206 ascertain the percentage yield of Gardner, James T., cited..-.-..-- = Alay ORG eeGaacses cs Sees at yt AOR on. 560 Gardner lode, Colorado........ 524, 529 Fiske lode, Colorado....-- 495, 502, 505 Garrison min 6222-2 ee ee = eee 406 Flack lode, Colorado......---- 524,541 Genesee mine....-.----+-+---+--- 429 TH G2: ec eydenot shea ee 540 Geneva Peak.......--..-+------- 334 WWatS:cie Wie (PING ose eosn et 412, 425 | altitude of-- 22.2.2 2 347 OCCUITENCE OL OLE ON. -.2-- =. 419 Georgetown .---..-----. ya MCSE Sera ve 479 Plorida& Mine..-22.2...2.-2. 361, 569, 570 TOTES O Lecsets = eect eee 5389 Fossils from Green River Coal Basin = +409 dressing works. ....-- G14 Foundation for stamping batteries 207 bullion product of.... 616 Hyoyranyeanhayca Cp Nery ee eee 219,226 | Gib-tappet, Wheeler’s..-...------- 211 Fox, G. W., cited......-.---+- 317,318 | Gilliganlode.........-- al on 448 INDEX. 635 Pago. Gilpin County, Colorado..... ieee 493 lode@s: Of 2 .ceeeeaa= 486 bullion product of Gilpin lode, Colorado............- 546 near Georgetown, Col- OLAMO Soe).