^J5S>— ■ ^K— €^ ,. JALIFORNIA STATE MINING BUREAU. I i A. S. COOPER, State Mineralogist. ULLETIN No. 18. San Francisco, October, 1900. } TH E lother Lode Region of California. By W. H. STORMS, E.M. '^:? Published uuder the Directioii of HENRY T. CtACtE, Governor of the State of California. ^m J. JOHNSTON, / .\ SS'^Sl SACRAMENTO: SUPERINTENDENT STATE PRINTING. ± V 1 1900, i — ^s~^<$^: TnTRTnrr TiMTArn-pcTTV nv rAT.FFnRNTA! i I ^S^Rbh The May Rock, Mariposa County. Croppings of the Eagle-Shawmut Mine, Tuolumne County. CALIFORNIA STATE MINING BUREAU. A. S. COOPER, State Mineralogist. P » BULLETIN No. 18. San Francisco, October, 1900. THE Mother Lode Region of California. By W. H. STORMS, E.M. Published under the Directiou of HENRY T. GAGE, Governor of the State of California. A J. JOHNSTON SACRAMENTO: , : : : : superintendent state printing. 1900. UNIVERSITY OF CALIFORNIA CONTENTS. LETTER OF TRANSMITTAL ------- 3 INTRODUCTORY - -------- 5- r> GENERAL GEOLOGY OF THE GOLD BELT - - - - 7- u The Schists and Metamokphic Rocks - - - - -8-13 The Alteration of Other Massive Rocks - - - . i3_ 14 SEVERAL DIVISIONS OF THE GOLD BELT - - - - -14-26 The Central Gold Belt ------- i5_ iq Classification and Description of Rocks ----- 16- 18 The Dolomitic Vein -------- 19- 21 The East Lode - - - - - - - - -21-26 METHODS OP MINING - - - 26-35 Timbering - - - - - - - - - -29-31 Filling ---------- 31- 32 Drainage - - - - - - - - - -32-33 Comparison of Steam and Cornish Pumps - . . . 33. 35 The Diamond Drill -------- 35 THE COST OF MINING - - - - ' - - - - 35-39 Detailed Cost of Mining at Mahoney Mine - - . - 36 Detailed Cost of Milling at Mahoney Mill - - - 37 Detailed Cost of Mining and Milling at Gwin Mine - - 38 MINING MACHINERY - - - 39-40 MINE BELL SIGNALS - 40-42 California Code of Signals ------ 40- 42 THE MINES OP AMADOR COUNTY 43-87 THE MINES OP EL DORADO COUNTY - - - - - 88-89 THE MINES OF CALAVERAS COUNTY ------ 100-127 THE MINES OP TUOLUMNE COUNTY - . . - - 128-141 THE MINES OP MARIPOSA COUNTY - 142-147 THE MINES OP MADERA COUNTY ------ 148-150 LIST OF ILLUSTRATIONS. Fig. . P^«^- 1. Diagrams illustrating the transition from jointing to schistose structure in Greenstones ---------- 10 2. Method of working veins in swelling ground - - - - - 29 3. Separator at the Zeila slimes plant - - - - - - 47 4. Zeila canvas plant, Jackson -------- 48 5. Canvas table, Zeila Mill -------- 48 6. Hydraulic ejector at Zeila slimes plant .-_--- 49 7. Pointed box at Zeila slimes plant ------- 50 8. Plan of Groom distributor -------- 51 9. Manner of placing machine-drill holes, Kennedy shaft - - - 54 10. Sketch showing strike of formation at Kennedy shaft - - - - 55 11. Horizontal section showing timbers in Kennedy vertical shaft - - 56 12. Vertical section showing method of timbering of Kennedy shaft - - 57 13. Vertical geological section of Argonaut-Kennedy vein - . . 59 14. Sketch showing strike of formation at new Oneida shaft - - - - .60 15. Station at 1900-foot level of Oneida Mine . - . _ - 61 16. Station at 2000-foot level of Oneida Mine ------ 62 17. Geological sketch, Wildman Mine ------- 65 18. Fault, 900-foot level of the Mahoney Mine ------ 66 19. Sketch of vein in Wildman Mine ------- 67 20. Slaty cleavage in folded strata at Sutter Creek - - - - - 67 21. Sketch showing strike of formation at vertical shaft, Wildman Mine - 68 22. Section of guides and divider in Wildman shaft - - - - - 69 23. Method of timbering in Wildman shaft ------ 69 24. Screen frame, Wildman Mill .--_---- 70 25. Old style of screen frame at Wildman Mill ----- 71 26. Cross-section of Lincoln Mine, Sutter Creek - - - - - 73 27. Corrugated chuck-block. Keystone Mill ------ 79 28. Method of timbering, Gwin Mine - - - - - - - 101 29. Screen frame and chuck-block at Gwin Mill ----- 103 30. Geological section of Sheep Ranch Mine - - - - - - 105 31. Geological cross-section near San Andreas, Calaveras County - - 106 32. Mill screen, Lightner Mill, Angels ------- no 33. Chuck-block, Lightner Mill 110 34. Chlorination vat, Utica Reduction Works, Angels ----- nc 35. Fault in Pine Tree Mine, Mariposa County ----- 145 36. Cross-section Rex Mine, Madera County - - - - - - 148 37. Horizontal section. Rex Mine, Madera County - - - - 149 May Rock, Mariposa County .-._-- Frontispiece Croppings of the Eagle-Shawraut Mine, Tuolumne County - - Frontispiece Oneida ]Mine, Amador County -------- 61 Central Eureka Mine, Amador County - - - . - - - 61 Mahoney Mine, Amador County -------- 65 Timbering in caving ground, Mahoney Mine, Amador County - - - 65 Lincoln Mine, Amador County -------- 73 Bunker Hill Mine, Amador County ------- 73 North shaft and mill, Utica Mine, Calaveras County - - - - - 113 Keystone Mine and Mill, Amador County ------ 113 Croppings of the Mariposa Vein, Mariposa County - -. - - - 145 Croppings of the Louisa Mine, Mariposa County - - - - - 145 LETTER OF TRANSMITTAL. San Francisco, Cal., September 30, 1900. To His Excellency Henry T. Gage, Governor of the State of California; The Honorable The Board of Trustees of the California State Mining Bureau; and Hon. A. S. Cooper, State Mineralogist. Gentlemen: I have the honor to submit herewith the report of my investigation of the mines of the Gold Belt in El Dorado, Amador, Calaveras, Tuolumne, and Mariposa Counties during the spring and summer of 1900. I regret that the necessity of visiting some of the northern counties of the State during June and July made it impossible to complete the work during the season, but, as it is a field of active operation, the coming year will find development further advanced, and at that time the investigation may be continued with more satisfactory results than would have been obtained had the work been done the past season. Very few other than operating mines were visited, and of these the description in this bulletin is limited to the most important ones, the others appearing in a general report which shortly follows this bulletin. I find among the more progressive superintendents and mine managers a disposition to experiment with a view to improving mining methods and to decreasing the expense of treating ore, and as a result we find not a few innovations which in most cases will be adopted in general practice, with such further improvements as additional experience may suggest. It affords me great pleasure to state that the mine owners, managers, and superintendents, almost without exception, spared neither time nor trouble in affording every facility for investigation of the mines under their direction, which made the task not only light, but pleasant. I am, yours respectfully, W. H. STORMS. THE MOTHER LODE REGION OF CALIFORNIA. By W. H. storms, E.M. 4 The California Gold Belt has furnished a most interesting field for geological research ever since its discovery in 1849. It has received the attention of many geologists, and a great deal has already been pub- lished concerning it. Among the most noted and valuable of these con- tributions to our knowledge of the Gold Belt are the early writings of Dr. Rossiter "W. Raymond and Ross E. Browne, and more recently those of H. W. Fairbanks and Ross Browne, and the exhaustive maps and reports of the United States Geological Survey. The various reports of the State Mining Bureau have also furnished a large amount of valuable technical and statistical information on the subject. In consideration of the very large amount of descriptive matter already published concerning the mines of the Gold Belt, or Mother Lode, it was with the feeling that the subject was worn somewhat thread- bare that the writer undertook the re-investigation of this important mining field in January, 1900. Since the publication of the Xlllth report of the State Mineralogist in 1896, no publication has been issued by the State regarding the progress of work in the counties along the Gold Belt, though this period has been one of unusual activity and progress and also of innovation in these mines. Old methods have in many cases given place to more modern ideas, and still more radical changes may be anticipated in the near future. An era of deep mining has commenced which can only be carried to the greatest success by the adoption of modern mining methods and improved machinery, together with a closer attention to the economical treatment of the ores. Already it has been shown that mines which were worked in former years under disadvantages and at an expense considerably above that now necessary to accomplish given results, after years of idleness, upon being reopened and equipped with modern machinery, can again be made to yield a handsome profit, where formerly some of them were worked at a loss. This has been made possible by the reduced cost of labor in later years; by the superior efficiency of nitro powders over the black blast- 6 CALIFORNIA STATE MINING BUREAU. ing powders used formerly in all mining operations in this State; by- better and cheaper mining supplies of all kinds; and in no small degree, by improved hoisting, pumping, and milling machinery, and to some extent also by improved mining methods. There is little doubt that the marked mechanical success attending very deep mining elsewhere, notably in the Lake Superior copper mines and in the gold mines of South Africa, has proven a great incentive to the miners of California to emulate, in a measure at least, these splen- did efforts, and we now find large vertical shafts being sunk to a depth far exceeding anything heretofore attempted in California mines. There are mines in Amador and Nevada Counties now operating to a depth of 2500 feet or more through old inclined shafts, usually sunk to conform to the dip of the vein, or approximating it, and there are numer- ous mines in several mining counties where inclined shafts are down 1500 to 2000 feet. The managers of these properties realize the impor- tance of having shafts sunk at a uniform angle — whether vertical or inclined — thoroughly equipped and provided with the best hoisting machinery in order to reduce the cost of mining to a minimum, for in nearly all of the large mines it is known that there are immense bodies of low-grade ore, too poor to pay when worked by old methods, but which would afford a good profit if mined by modern methods and with well- equipped shafts and machinery of proper construction. This matter will be more fully discussed under the title of " Methods of Mining." The introduction of extensive slimes plants, and the successful opera- tion of the cyanide process in its various forms, have also contributed in a measure to increased financial success, and electric plants have also been installed at several points for the distribution of power to mines along the Gold Belt. These installations are said to be success- ful financially as well as mechanically. Transmission of power through the medium of compressed air, though not an innovation, is more exten- sively employed than formerly. THE MOTHER LODE REGION — GENERAL GEOLOGY. GENERAL GEOLOGY OF THE GOLD BELT. Owing to the extremely complicated structural geology of the Cali- fornia Gold Belt, positive assertions as to the relative age of the intru- sive rocks which so commonly occur throughout its length are generally unsafe, but in a general way it may be stated that, upon rocks of an uncertain but very great age, possibly Archaean, there was laid down in Palaeozoic time a deep series of sediments consisting of mud, sand, finely comminuted calcareous fragments, calcareous ooze, etc. Follow- ing this there was evidently a long period of volcanic activity, during which there was accumulated a vast quantity of basic rocks, chiefly diorite and diabase, and basic tuffs and breccias. These rocks are mineralogically closely allied to the andesites, and are called the old andesites by the United States Geological Survey. The underlying formations, together with the tuffs, were consolidated into rock; the mud being transformed into shale, and by further process of meta- morphism, into slate, the sand becoming quartzite, and the calcareous material, limestone. There were evidently successive periods of elevation and subsidence also, resulting in the formation of extensive beds of conglomerate along the shore lines. During the Jurassic age there was deposited upon these older formations a stratum of fragmentary material consisting of fine silt and sand, forming eventually thick beds of shale and sandstone. During a portion of this period volcanic activity was again pro- nounced, particularly about the close of the period, during which there was again accumulated a large amount of diabase tuffs and breccias. In some localities the mud deposits and the tuffs are found interbedded, showing that the volcanic outbursts were intermittent. In some cases a sandstone is found wholly made up of diabase material, and this is probably the result of the disintegration of some previously erupted material, which was carried down from an elevated ridge and deposited in the bed of the sea. These sediments have subsequently been uplifted, folded, crushed, and faulted. The dynamic forces were still at work, and large dike-like masses of diabase, diorite, serpentine, and other intrusive rocks were thrust from below into the complex of older rocks. The Palaeozoic rocks, owing to their large development in Calaveras County, have been named the Calaveras formation, and the later deposits of Jurassic age have been called the Mariposa beds (as this formation is most extensively exposed in Mariposa County), and it is in more or less close association with these beds that the so-called Mother Lode of California occurs. Lying to the eastward of the above described formations is found a broad expanse of intrusive rock, which, owing to its peculiar mineral- 8 CALIFORNIA STATE MINING BUREAU. ogical character, has been named grano-diorite. At numerous points along the contact of the grano-diorite with the formations heretofore mentioned there is found abundant evidence that the grano-diorite was intruded later than the greenstones, and it is also later than the Mari- posa beds. There is some reason to believe that the grano-diorite is as late as the Cretaceous. The Mariposa beds appear generally to occupy a position along the trough of a synclinal fold, the Calaveras formation being found both to the eastward and westward of the Mariposa beds. The occurrence of the diabase tuffs and the intrusion of great masses of basic dike rock (diabase and diorite) have rendered the positions of the Mariposa beds and the Calaveras formation very irregular and often extremely puz- zling, as the distribution of the tuffs, breccias, and intruded dikes is most erratic. It is more than probable that a cross-section taken every half, or even every quarter mile along the Gold Belt, would show an entirely different structural condition. The Schists and Metamorphic Rocks. — The tremendous compressive stress to which these rocks have been subjected since their uplift, has resulted in the formation of a series of highly crystalline metamorphic rocks — the mud being altered into slates, the sandstones changed to quartzite, and not infrequently the limestones are found altered to marble. The greenstones have likewise been changed over broad areas. The pressure and movement accompanying it have resulted in many cases in a complete obliteration of the original character of the normal rocks, and in place of the crystalline granular greenstones we find schists and slates (the amphibolite schist of the United States Geolog- ical Survey). Throughout the entire length of the Gold Belt are found greenstones of greatly varying texture (chiefly diabase), which have suffered little or no alteration. These masses of greenstone are from a few feet to several hundred feet in width, and it seems not improbable that they were mostly intru- ded since the formation of the schists. In some instances this is posi- tively known to be the case, as they are found cutting the schists in strike and dip. In some of the gold mines these greenstone dikes may also be clearly seen to be more recent than the inclosing rocks, and occasionally they are found intersecting the quartz veins. Instances may be observed, however, where only portions of certain massive formations are schistose, and this can only be attributed to the local effect of the dynamic forces similar in character to those which produced the original metamorphism of the older formations. The gen- eral features of the schistose greenstones (both massive and tufaceous) occurring in California are so similar physically to those of the Mar- quette and Menominee regions of Michigan that there seems no room to THE MOTHER LODE REGION — GENERAL GEOLOGY. 9 doubt that in each case similar causes operated to produce like effects. The Michigan region has been studied with great care by several of the best geologists of America. Those interesting rocks and the manner of their formation have been fully described by G. H. Williams, and a few extracts are taken from his excellent contribution to this important subject, the dynamic metamorphism of eruptive rocks,* for the reason that they apply so perfectly to the conditions found in California along the Gold Belt, and I have not the slightest doubt that greenstone schists, wherever found, whether as the result of the alteration of massive green- stone tuffs or of fragmental rocks (sandstones), derived from the degra- dation of older greenstones, are the direct result of the causes ascribed by Mr. Williams as having produced the schists of the Michigan region. In referring to the value of the microscope in the study of metamor- phism of rocks, Mr. Williams says: The most important problems presented by an unaltered massive or igneous rock relate to (1) its chemical composition, and (2) to the conditions under which it was formed. The composition expresses itself in a general way, in the nature of the com- ponent minerals, while physical conditions attendant upon the formation of the rock may be traced in its structure. Each of these has therefore been, in turn, the particular object aimed at during the first two periods of petrographical research. But if petrography were able to solve satisfactorily all the problems presented by the unaltered maSsive rocks, it would even then be prepared only to commence its most difficult and most important mission. Rocks are in reality far from being dead, inert, stationary masses, which they appear to the ordinary observer. The fascinating study of chemical geology, especially when aided by the microscope, shows them to be in a state of almost constant change. It is true that some of the oldest rocks seem to have suffered hardly any alteration since they were first formed, but most of them are ever- active laboratories where old products are being pulled to pieces and new ones built up. The tracing-out of such changes is an important aim of petrography in its present stage. In the study of the structural geology of the California Gold Belt, it was found necessary to employ the microscope, and the conclusions reached in this study are identical with those submitted by Mr. Williams. Upon his study in the Michigan area, continuing, he says: There are two distinct kinds of alterations which take place in a solid rock mass, dependent, of course, on the nature of the changed physical conditions. These are: (1) Metamorphism ; or the passage, under circumstances of high temperature or pressure, or both, of less crystalline into more crystalline compounds ; or the change of minerals into others not less crystalline or insoluble than themselves. (2) Decomposition or weathering ; the passage, under ordinary atmospheric condi- tions, of crystalline rock constituents into compounds less crystalline and more soluble than themselves. This is accomplished generally by hydration or carbonization. Both of these processes are frequently seen to have gone on in succession in the same rock mass, the latter more or less completely effacing the effects of the former. While distinct, both processes agree in being atomic and molecular rearrangements in a solid mass, necessitated by some change in external conditions. The differences in these conditions, however, produce widely different results ; and all of these again are essentially different from those produced by the solidification of a liquid magma. The student of the crystalline rocks can distinguish, in a general way, four classes of * Bulletin No. 62, United States Geological Survey. "The Greenstone Schist area of the Menominee and Marquette regions of Michigan." 10 CALIFORNIA STATE MINING BUREAU. constituent minerals, and this is true in spite of the fact that the same species niay be represented in two or more of these classes : (1) Original minerals of the acid rocks, formed by the solidification of a magma in a state of aqueo-igneous fusion or by the aid of mineralizers ; e. g., quartz, orthoclase, mica, zircon, etc. \MMMMMll \\mmiW^'^^'^^ m wlm M\i\\i ■ 1 Wm wmmm 1 1 DiAGtf\Ai^s 'illusiratii9§-|1=)e-rrahsi+-ioi7 h'oir) joil^fing tbschistose sti'uctures in the gre en stones. Fig. 1. (2) Original minerals of the basic rocks, formed from a state of dry fusion ; e. g., plagioclase, augite, olivine, etc. (3) Metamorphic minerals, formed as above explained, from originals; e. g., horn- blende, albite, biotite, zoisite, garnet, staurolite, andalusite, etc. (4) Decomposition minerals; e. g., chlorite, quartz, carbonates, hydroxides, etc. * * THE MOTHER LODE REGION — GENERAL GEOLOGY. 11 Rocks may be altered by simple pressure, but the accumulated strains which are generated within tliem are relieved and adjusted by overcoming the force of cohesion along certain planes. Here there will be a shearing motion of greater or less extent, and a consequent crushing of the rock. The rent is soon healed by the crystallization of new compounds which cement the crushed fragments, and in this way a schistose band, of width varying with the intensity of the force, may be developed in the midst of an otherwise solid and massive rock ; or a number of such bands may be formed parallel to one another and together imparting to the rock the appearance of a foliated or even a banded schist. Conclusive proof of this process might be difficult to discover without the aid of a microscope, but this instrument is happily able to afford sufficient evidence to overcome all doubt. * * * The first step toward the formation of a schistose structure in Twin Falls green- stones (and this is hardly ever absent) is the division of the massive rock by two systems of joints, which stand about perpendicular to the surface and intersect at a varying but acute angle. These joint systems divide the mass into diamond-shaped or rhomboidal prisms, the cross-sections of which are well displayed upon the frequent smoothly glaciated surfaces of the rock. The appearance of such a siirface is diagram- matically represented in Fig. 1. As we approach the schistose band in the massive rock these interlacing rhombs become lengthened out more and more by an approximation to parallelism between the two systems of joint planes. These elongated prisms finally become very much extended lenses, which interlock and produce a well-developed, wavy, or even parallel schistose structure. The almost slaty rocks thus produced, especially as seen at Lower Twin Falls, have a tendency to break, not so much along a definite plane, as parallel to a line — i. e., the direction, normal to the surface, parallel to which the original joint planes ran. It is difficult to obtain well-shaped hand-specimens of these rocks, but narrow rhombic prisms of almost any angle are easily procured. There is an almost equal tendency to cleave along any plane which is parallel to the longest axis of these prisms. If the prisms due to the original joint planes were subjected to a lateral pressure which developed in them a cleavage that successively approached more and more nearly to the long axis as the prism was lengthened, this peculiar tendency to separate along a line rather than along a plane is precisely the structure which we might suppose would result. The strike of these schistose bands follows the direction which bisects the acute angle of the rhombic prisms. This is for the most part from S. 70° to 80° E. ; agreeing with the prevailing strike of all the rocks in this system. There are, however, many exceptions where these schistose bands, even where near together, follow different directions ; for instance, I observed in the massive though jointed rock on the Michigan side of Upper Twin Falls, two schistose chloritic bands quite near together, one having a strike N. 180° E., and the other S. 73° E., while the dip of each was nearly vertical. Such cases are easily explicable on the supposition that these bands were produced by mechanical agencies, but it is quite impossible to reconcile them with the supposition that these bands are in any way the result of sedimentation. It is not infrequently noticed that there is a local development of schistose structure of massive rocks in the immediate neighborhood of fissures and veins. A typical instance of this character may be observed on Wood's Creek, a few hundred feet below the pumping-station, near the Bonanza Mine at Sonora, in Tuolumne County. Here a quartz vein, about twelve inches in width, traverses a hard, dark-green diorite. The walls on either side are altered for a width of three to five feet, being soft talcose or chloritic schist near the vein, and passing over by transition to the normal diorite. These occurrences are not at all uncommon, though often of local character. 12 CALIFORNIA STATE MINING BUREAU. In Amador and Calaveras Counties, and also to some extent in El Dorado County, I found peculiar banded schists, which have attracted the attention of many geologists. Similar banded schists occur in the Michigan area, above referred to, of which Mr. Williams speaks as follows: The banded greenstone schists which form the prevailing rock over the northern por- tion of the Marquette area, have been regarded by all geologists who have ever studied them, as originally sedimentary deposits, and repeated examination of them in the field seems incapable of leading to any other conclusion. They are everywhere stratified witn the greatest regularity in bands of lighter and darker shades of green. This structure is to be most advantageously seen in the woods just north of Marquette and near Lighthouse Point. Here glaciated areas of considerable extent often show a finely ribboned appearance, looking as though the sharp parallel lines had been drawn with a ruler. The alternation in the composition of the layers is so frequent and so constant) and their parallelism to the east and west strike of all the rocks in this neighborhood is so exact, that no hypothesis of their originally massive character will satisfactorily account for the observed facts. * * * On tlie other hand, their chemical as well as their mineralogical composition renders it impossible to separate them from the massive and highly altered greenstones (uralite diabases, etc.), with whicli they are most intimately associated. Their parallel banding indicates a fragmental, but their chemical and their mineral composition indicate an igneous, origin. The only satisfactory reconciliation of these opposite sets of characters is to be found in that group of rocks intermediate between sediments and lavas, known as volcanic tuffs. In the opinion of the writer, then, the banded greenstone schists of the northern Mar- quette area are to be regarded as consolidated and highly metamorphosed diabase tuffs. These are intimately associated with the numerous contemporaneous flows of diabase and quartz porphyry, together with the tuffs of the latter rock; while all have been broken through by much younger dikes, both basic and acidic. ******* -Si-**** In order to obtain a clear idea of just how these ancient and much disguised tuffs acquired their present form and apparently dual character, it will be advantageous to ascertain what is known of analogous formations of comparatively recent date. Captain C. E. Dutton's descriptions of the fragmental rocks accompanying the Tertiary erupt- ives of the high plateaus of Utah are well suited to this purpose. He says, in speaking of the extent of these deposits : "Some of the mostinterestinglithological problems presented by the volcanic products of the high plateaus are those relating to the origin and development of what may be termed the clastic igneous rocks, or rocks apparently composed of fragmental materials of igneous or volcanic origin, but now stratified either as so-called tufaceous deposits or as conglomerates. These are exceedingly abundant in all of the great volcanic districts of the world, and often enormously voluminous. " How those of the high plateaus would compare, in respect to magnitude, with those of other regions, I do not accurately know, but absolutely their bulk is a source of utter astonishment. They cover nearly 2000 square miles of area, and their thickness ranges from a few hundred feet to nearly 2500 feet, the average being probably more than 1200 feet. Lavas are frequently intercalated, but much more frequently no intercalary lavas are seen, and in general they seldom form any large proportion of the entire bulk when they occur in conjunction with the clastic masses." Again, in speaking of the peculiar liability of such deposits to metamorphism, the same writer says: " A very striking characteristic of these clastic volcanic rocks, both the tufas and the conglomerates, is their great susceptibility to metamorphism. Not only have the beds in many localities been thoroughly consolidated, but they have undergone crystal- lization. These tufas and conglomerates, which are of older date, and which have been buried beneath more recent accumulations to considerable depths, rarely fail to show THE MOTHEK LODE REGION — GENERAL GEOLOGY. 13 conspicuous traces of alteration, and in many cases have been so profoundly modified that for a considerable time there was doubt as to their true character. "The general tendency of this process is to convert the fragmental strata into rocks having a petrographic facies and texture very closely resembling certain groups of igne- ous rocks. When we examine the rocks in situ, no doubt can exist for a moment that they are water-laid strata. The hand-specimens taken from the beds, which are extremely metamorphosed, might readily pass, even with close inspection, for pieces of massive eruptive rocks, were it not for the reason that the original fragments are still distinguishable, partly by slight differences in color, partly by slight differences in the degree of coarseness of texture. But the matrix has become very similar to the included fragments, holding the same kinds of crystals, and under the microscope it shows a ground-mass of the same texture and composition." The Alteration of Other Massive Rocks. — The greenstones are not the only massive rocks which have undergone a more or less complete alteration in the region of the Gold Belt. There are two rocks in par- ticular to which I wish to call attention. These are the calcareous rocks which constitute the great dolomitic vein, previously referred to, and a dark green, massive, extremely hard, and tough rock found at numerous places along the Gold Belt, notably in Calaveras County just east of San Andreas; near Dogtown, three miles from Angels; at Smith's Flat, west of Angels, and elsewhere. The ankerite or dolomite vein is usually distinguished by its great width and massive character, and the occurrence of more or less abundant mariposite; but in many places we find this hard, thoroughly crystalline rock has been com- pressed, sheared, and completely altered, passing over by gradual transi- tion to typical soft talc schist. A series of transition rocks of this character was obtained at the Pacific Mine, Placerville, El Dorado County, and is on exhibition in the Museum of the State Mining Bureau in San Francisco. Similar occurrences have been noted in a score of mines, from Mariposa County northward as far as Placerville, but collections from other mines have not been placed upon exhibition, because the occurrence is essentially the same in each case, and the space available in the Mining Bureau is already crowded. Concerning the other massive rock, hand-specimens were selected from the Ford Mine at San Andreas, also from a similar occurrence at the Smyth Mine near Angels, and slides cut for microscopic study. These prove the rock to consist of a matted aggregate of minute scales of talc, with a little calcite and magnetite. The rock, although the freshest obtainable, is very evidently not in its normal condition, but is an igneous rock which has already undergone considerable change. It may have been a gabbro or some allied eruptive rock, which, by a process of compression and shearing previously described, is now found changed into a typical massive crystalline granular or schistose steatite (soapstone). Undoubtedly, the alteration of massive rocks to a schistose or slaty condition is very much more common than is generally 14 CALIFORNIA STATE MINING BUREAU. supposed, but unfortunately too little attention had been given in the past to these phenomena. It has been noticed in several instances vi^here mine workings have been extended into the steatite masses, that not infrequently the rock is found to consist of a coarsely crystalline aggregate of semi-schistose, calcareous and magnesian minerals and to greatly resemble the partly altered ankerite and dolomite found along the Central Gold Belt. Notable instances may be found in the Ford Mine at San Andreas in Calaveras County, and at the Spanish Mine near Forest Hill in Placer County. As these rocks approach so nearly the dolomite of the Central Gold Belt, they may be considered as indicating the possible origin of the dolomitic veins from basic eruptives. THE SEVERAL DIVISIONS OF THE GOLD BELT. Throughout the entire length of the great synclinal trough of the Gold Belt are found the gold-bearing veins which constitute the so-called Mother Lode. It seems unfortunate that the name was ever given to this portion of the Gold Belt, as it conveys to the minds of those unfamiliar with the geological structure and veins of the region, an impression of a continuous, unbroken vein. That such a condition does not exist is well known to those familiar with these mines. There are through that portion of the State occupied by the counties extending from Mariposa on the south to the southern portion of El Dorado County on the north, at least four distinctly recognizable gold belts : That which skirts the low foothills along the Great Central Val- ley includes the copper deposits found at and near Green Mountain in Mariposa County, and southward in Madera County, those at Copper- opolis and at Campo Seco in Calaveras County, and at Ranlett in Amador County, and also the gold mines of Salt Spring Valley in Calaveras County. It may also be considered as embracing the gold mines near Hornitbs in Mariposa County, and those near lone in Ama- dor County. East of this a distance of 8 or 10 miles is found the most important gold-bearing belt of the State, which has received the name of " Mother Lode." This, it seems to me, it would be well to designate as the Central Lode of the Gold Belt. It must be understood and remembered in this connection that the gold-bearing veins are nowhere absolutely continu- ous and unbroken for a great distance, but that the so-called lode is frequently interrupted by its absolute disappearance for considerable distances. Lying east of the Central Lode, in Mariposa County, a distance of nearly 20 miles, and extending in a northwesterly direction, nearly THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 15 parallel with the Central Lode, and passing through Tuolumne and Calaveras Counties, is the third gold-bearing lode, which in Amador County has approached to within 6 to 10 miles of the Central Lode. This is known as the East Lode, and embraces many interesting and important mines. Still farther eastward lies at least one mineral belt which has been opened at several points, but of which comparatively little is known as yet. This might properly be named the Sierra Lode. It is the intention to fully investigate this important field in the future, as it is one of great promise. The veins are large, and carry sulphides of iron, lead, zinc, and copper, and also gold and silver. The Central Gold Belt. — It is with the Central Gold Belt we have chiefly to deal in this Bulletin, as lack of time precluded a thorough investigation the past season of the entire region comprising the Gold Belt. For years, in fact since its early history, the clay slates of the Mari- posa beds have been considered an absolutely essential feature and accompaniment of the important gold mines of the Central Gold Belt. The veins have been referred to as "contact veins," and in many sec- tions the immediate contact, or close proximity, of the Mariposa clay slates has been deemed indispensable to pay rock. Such, however, is apparently not the case in Amador County, where a,re situated the deepest and most productive mines. While it is possi- ble that some of these mines are confined wholly to the Mariposa clay slates, or occur at contact of the Mariposa clay slates and massive greenstones, or the amphibolite schists resulting from their alteration, if such be the case the instance is unknown to the writer, for without exception, the large number of accessible mines prove that the Mariposa clay slates form really no important feature as related to ore deposition, while thus far in Amador County, south of Plymouth, all development confined to the typical clay slates of the Mariposa beds has proven the fissures in that formation valueless, and these developments reach many thousands of feet of shafts and drifts. The fissures in which the ore deposits occur along the Central Lode, with no exception, so far as the writer is aware, cut the dip and usually, also, the strike of the inclosing rocks. The dip of the slaty and schistose formations is uniformly to the eastward, though at greatly varying angles, but usually between 50 and 80 degrees, while the dip of the vein fissures is always somewhat less in approximately the same direction. In the mines of Amador County are found a peculiar black slaty rock, often approaching closely in physical appearance the clay slates of the Mariposa beds. They may usually be readily distinguished by a peculiar pitted appearance. This feature ranges from rather coarse, 16 CALIFORNIA STATE MINING BUREAU. thickly scattered, knotty granules, to the fine dots resembling pin pricks — the finer grained and the more slaty in structure the rock, the finer are the pits. For years these rocks have not been distinguished from the black clay slates of the Mariposa beds, but the writer noticing that this peculiar slaty rock was of persistent occurrence with the most impor- tant ore-bodies of Amador County, determined to ascertain if possible what, if any, difference there was between these pitted slates and the smooth, satin-like slates of the Mariposa beds. With this object in view, several series of rocks were collected at various mines, showing complete transition from a massive or slightly schistose rock to a perfect black slaty rock, the specimen always showing the pits as above described, and being obtained from certain cross-cuts where the transi- tion was evident. These rocks were placed in the hands of H. W. Fairbanks, of Berke- ley, who prepared slides and carefully studied them with the aid of the petrographical microscope. This investigation resulted in proving that these peculiar slates and schists were the result of the shearing and alteration of tuffs (evidently diabase), and that the rock was originally of fragmentary origin, though made up of diabase material (augite, plagioclase, etc.). Their character is rendered perfectly evident under the microscope, and the change from one phase of alteration to the next may be clearly traced in the several rock sections. CLASSIFICATION AND DESCRIPTION OF ROCKS Collected toy W. H. Storms along Central Gold Belt. Determinations made by H. W. Fairbanks, A.B. Nos. 1 to 9, inclusive, From cross-cut 900-level, Keystone Mine, Amador County. No. 10. From tunnel east of Keystone Mine, Amador County. No. 11. From tunnel east of Keystone Mine, Amador County. No. 12. From west wall of Oneida Mine, Amador County. No. 13. From west wall of Oneida Mine, Amador County. No. 14. From east shaft of Kennedy Mine, Jackson, Amador County. No. 15. From east shaft of Kennedy Mine, Jackson, 900-level, Amador County. No. 16. From hanging-wall of Bunker Hill Mine, Amador County. No. 17. From Baliol Mine, Sutter Creek, Amador County. No. 18. From west wall of Argonaut Mine, Amador County. No. 19. From Carson Creek, Calaveras County. No. 20. From dike in Copperopolis Mine, Calaveras County. No. 21. From dike in Commodore Mine, San Andreas, Calaveras County. No. 22. From Ford Mine, San Andreas, Calaveras County. No. 23. From Ford Mine, San Andreas, Calaveras County. No. 24. From Smyth Mine, Angels, Calaveras County. No. 25. From Smyth Mine, Angels, Calaveras County. No. 26. From Pocahontas Mine, Logtown, El Dorado County. No. 27. From German Mine, El Dorado County. No. 28. From German Mine, El Dorado County. No. 29. From German Mine, El Dorado County. No. 30. From hill north of Church-Union Mine, El Dorado County. No. 31. From hill north of Church-Union Mine, El Dorado County. No. 32. From hill north of Church-Union Mine, El Dorado County. No. 33. From hill north of Church-Union Mine, El Dorado County. THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 17 Nos. 1 to 9, inclusive, are from the 900-foot level of the Keystone. Some of these have been supposed to be dikes, but Mr. Storms is unable to tell from the section given where the igneous rock ends and the supposed slate begins. A microscopic study of these rocks shows that in all probability they are all of sedimentary origin, a series of tuffs and slate, the tuffs being fragmental greenstones or diabases. No. 1. This rock to the unaided eye has every appearance of being a dike. Porphy- ritic crystals of augite are embedded in a tine green matrix. Under the microscope this rock has the appearance of being a tuff. The constituents are badly decomposed crj'stals of augite and cloudy masses of feldspar in a finely granular base. Granular magnetite is present. No. 2. To the eye this rock clearly betrays its tufaceous character. Its components are arranged in irregular layers. Under the microscope the tufaceous character is also seen. Augite crystals, granular magnetite, and cloudy tabular areas make up the rock. A large part of the matter of the rock is indeterminable, but there is no doubt that it is a diabase tuff. No. 3. In the hand-specimen, this rock shows its clastic origin in the alternating layers of greenish and argillaceous material. The green is probably tufaceous, and the black of the same composition as the slates. Both show signs of metamorphism in the presence of a pitted surface caused by little crystals. The exact nature of these could not be determined, but in all these slates they are characteristic of metamorphic action. Under the microscope this rock does not show clearly its origin. It might be either a sedimentary rock or an altered igneous one. It is made up of ragged, clear, and cloudy areas. A green mineral has the appearance of secondary hornblende. There are some augite grains. This is a fine-grained rock. Nos. 4, 5, G, 7, 8, and 9. These are all black slate. In section they are practically opaque. In some there are little crystals with clear borders and dark centers, crystals produced by metamorphism. No. 10. This rock might be taken for a fine-gi'ained eruptive greenstone, but under the microscope it has much the appearance of being a fragmental greenstone. The rock is much decomposed, but contains a large amount of augite and considerable granular iron ore. It is somewhat schistose, the crystals and cloudy masses being arranged along parallel lines. It is quite likely a fragmental rock. No. 11. Also an augitic tuff. The rock mass is made up largely of augite crystals thickly matted together with cloudy material and granular magnetite. The cloudy material in these tuffs may have been originally the mud resulting from the grinding up of diabase fragments. No. 12. This is an augite porphyrite, generally termed diabase or greenstone. The rock is much decomposed ; shows prominent crystals of augite, but the feldspars have almost completely disappeared in a greenish, cloudy mass. No. 13. Diabase or augite porphyrite. This is a fresher rock than the last, but of the same general cfharacter originally. It contains large crystals of augite, and smaller ones of feldspar in a cloudy decomposed ground-mass. The rock is somewhat talcose. No. 14. This is a medium-grained diabase. Under the microscope it appears to consist largely of augite, with some small decomposed crystals of feldspar and iron ores. No. 15. This is a fine-grained diabase tuff, and quite schistose. It is made up of augite grains, and faintly polarizing masses are arranged in layers with opaque seams between them. No. 16. This is probably a greenstone tuff. It contains much cloudy matter, augite crystals, others which were once feldspar, and some which resemble hypersthene. Mag- netite scattered through the rock. No. 17. This is a talcose schist derived from what was probablj' a fragmental green- stone or tuff. The body of the rock is made up of thickly matted rods and scales of talc. No. 18. Coarse diabase. This rock contains an excess of augite crystals fairly fresh in character, and a cloudy base in which outlines of feldspar crystals can be made out. It has been rendered schistose through pressure. No. 19. Layers of augitic tuff and dark slate. Under the microscope the layers are seen to be made up of cloudy indeterminable material, through which are scattered fragments of augite crystals. They make up half of the rock. The dark bands contain 2 MB 18 CALIFORNIA STATE MINING BUREAU. less augite and stringy opaque matter. They have the character of some of the slates except for the scattered augite fragments. No. 20. In the hand-specimen, Nos. 20 and 21 look much alike. The rocks are coarse grained, with their dark constitutents altered to a green scaly talcose mineral. They contain much feldspar and cubes of iron pyrite. Under the microscope No. 20 is seen to consist of an acid plagioclase feldspar, perhaps oligoclase, quartz, and a green mineral replacing hornblende, also magnetite. This is a much decomposed rock, but might be termed a quartz diorite. No. 21. Under the microscope this rock is seen to consist of a decomposed feldspar similar to No. 20, and green chloritic matter replacing some dark silicate, probably hornblende. This rock is also a diorite. No. 22. This is a massive green rock made up of an aggregate of fine talcose scales. Under the microscope it appears very similar to No. 24, but shows no clue to its original mineralogical constitution. No. 23. This is a green rock, which in the hand-specimen is almost massive ; made up of an aggregate of fine lustrous scales. Under the microscope the rock is seen to consist almost entirely of a matted aggregate of interlacing scales with the properties of talc. There is also a little calcite and magnetite. This rock, then, is mainly a hydrous silicate of magnesia, replacing some magnesia-rich igneous rock. The precise nature of this rock cannot be told, for all traces of the original constituents have disappeared. No. 24. This is a green talcose rock, showing dark gray and light green patches; the latter were probably once feldspar and the rock originally a gabbro. Under the micro- scope it appears to be made up of an interlacing matte of talcose scales. No. 25. This is a coarse rock, and to the unaided eye appears to be made up of feld- spar and chloritic hornblende. Under the microscope it appears to be made of cloudy feldspar, magnetite, and augite, partly altered to green hornblende. Might properly be termed a diorite, although it was once a gabbro when in a fresh condition. No. 26. This is a feldspar porphyry, with bronze-colored crystals of mica. Under the microscope the feldspar is seen to be plagioclase. The rock may have contained augite once. Strictly, it might be termed a diorite porphyrite. No. 27. This rock is very similar to No. 28. It contains more augite, and is quite fresh. No. 28. This is a grayish rock, with rather indistinct porphyritic crystals of feldspar. Under the microscope it shows porphyritic crystals of augite and feldspar in a fine granular ground-mass. This rock is very different from the greenstones. It is lighter colored and fresher. It might be termed an augite porphyrite, although the feldspar might make it an augite-diorite porphyrite. No. 29. This is a hard gray rock, with rather indistinct crystals of white feldspar. Under the microscope it appears to be badly decomposed, showing remnants of twined feldspar crystals, magnetite, and a dark constituent entirely decomposed. Might be termed a diorite porphyrite. No. 30. This is a feldspar-quartz porphyry, showing large crystals of quartz, feldspar, and a bronze-colored mica in a fine ground-mass. Under the microscope the quartz appears much corroded, and the feldspars clouded. The ground-mass is made up of a fine-grained aggregate of quartz and feldspar. No. 31. This rock contains hornblende, quartz, and plagioclase feldspar crystals in a granular ground-mass. In structure of components it lies between a granite and a porphyry and might be termed a granite porphyry. No. 32. This is a rather fine-grained greenstone or diabase schist. It consists under the microscope of augite, pale green feldspar, probably labradorite, and iron ores. The constitutents are much altered. No. 33. This is a quartz-feldspar porphyry. It contains crystals of twined feldspar (plagioclase), corroded quartz crystals, and a decomposed mineral possibly once horn- blende. There may be some decomposed mica. These constitutents lie in a fine granular ground-mass. H. W. FAIRBANKS, A.B. I THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 19 In every mine accessible along the Central Lode, from the Pocahontas near Drytown on the north, to the Muldoon south of the Argonaut near Jackson, where ore-bodies are found in contact with or in slaty rocks, these slates are observed to be of the character described, and which the microscopic study of Mr. Fairbanks proves to be the result of alteration of tuffs, and not of massive diabase, as had been supposed by the writer. The normal tuff is, however, massive, often fine-grained and containing crystals of augite, and difficult to distinguish from crystalline green- stone with the unaided eye; in this respect resembling the tufts of Michigan, described by Mr. Williams, and those described by Captain Button as occurring in the Great Basin region of Utah. The clay slates of the Mariposa beds are found in cross-cuts extending to the eastward and westward of the main fissures in these Amador mines. Usually the clay slates may be readily distinguished from the altered tufts, but often the slaty tuffs graduate by insensible degrees into the clay slates, so that no line of demarkation is discernible. It is rarely that the ore deposits are found in contact with the fine- grained clay slates, even for a short distance. In fact, the fissures, where passing through the clay slates are usually destitute of value in Amador County. This peculiar condition, however, appears to be local, as in Calaveras County the richest portion of the Gwin Mine is in a fissure cutting the black clay slates of the Mariposa beds, and in Mari- posa County the Princeton Mine is wholly in the clay slates of the Mariposa beds. In Amador County, however, it seems important to make the dis- tinction, in view of the results obtained from veins in the clearly recog- nized clay slates and the pitted slates (altered tuft's). Although the mines of the old Plymouth Consolidated Company at Plymouth have not been accessible for many years, the dumps show a large amount of the tufaceous slate, and there is little doubt these slates accompanied the ore-bodies. Four miles to the northward, however, the Kretcher vein of the Bay State Company and the veins of the Rhetta Company adjoining it on the south, occur in the typical clay slates of the Mariposa beds, and in these mines are good-sized veins of banded quartz carrying payable values. The Dolomitic Vein. — An important geological feature of the Cen- tral Gold Belt, and one which repeatedly appears from Mariposa to El Dorado County, is a great, dike-like vein of dolomitic mineral. This consists of carbonate of lime and carbonate of magnesia — a true dolomite — and in many places there is also found, in addition to the above minerals, carbonate of iron, forming ankerite. This material occurs in great vein or dike-like masses, and is a prom- inent feature of the lode in Mariposa and Tuolumne Counties and the southern part of Calaveras County. It also appears near San Andreas, 20 CALIFORNIA STATE MINING BUREAU. and again near Jackson in Amador County, reappearing near Placerville in El Dorado County. Mariposite is nearly always present, often in large amount. Its beautiful green color led early prospectors to believe it was copper carbonate. The mariposite is not colored by copper, but by chromium. The peculiar characteristics of the great dolomitic vein are no better shown anywhere along its length, perhaps, than at Coulterville and vicinity. Just below the village on Maxwell Creek, the great vein crosses that stream, which has cut a gap through it about 100 feet wide. On the south side of the creek is located the Louisa Mine, and imme- diately north of it is the Margaret, on the opposite side of the creek. Where the lode crosses the creek it has a width of 300 feet, and consists of an immense mass of ankerite, through which is disseminated the green, scaly mineral, mariposite. Large lens-shaped masses of quartz outcrop boldly from the ankerite, being somewhat harder than the latter. The lenses are irregularly distributed, but occur mostly along the hanging-wall and near the center of the vein. The large veins or lenses of quartz are separated by equally large or larger zones of the dolomitic mineral, which is interlaced in every direction by quartz veinlets and veins of varying size, making the entire mass a mineral zone or lode proper. One of the quartz lenses is nearly 20 feet in width, outcrops to a height of 25 feet, and is 300 feet long. A shaft sunk on the foot-wall side of it to a depth of 60 feet showed it to be thinning out ; but there is no doubt that it would be found replaced in depth by another lens of a similar character. South of this large cropping a small vein branches out into the hang- ing-wall diabase, striking northward and increasing in width until it disappears underneath Maxwell Creek. On the opposite side of the stream a large vein appears, which is apparently the northward con- tinuation of the one referred to. Through the center of the lode is a quartz vein 10 to 20 feet in width, and still west of it is another, but smaller vein. The entire western portion of the ankerite mass, constituting about one third of the whole width of the zone, is a perfect network of small quartz veins, stringers, and small bunches of quartz. A prominent feature of interest is the union of two of the largest quartz lenses near the center of the lode by a third large vein, which crosses the intervening ankerite diagonally. The two large veins are about 120 feet apart. Beginning near Maxwell Creek, on one of the large outcrops referred to, a careful examination discovers a seam in the quartz, along which gold may be seen almost every foot of the way. This gold seam can be followed some distance in a southerly direction to where the diagonal branch above referred to leaves it. This latter also shows gold along a similar seam, leading to the other large quartz THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 21 lens parallel to the first, and here, again, is a gold seam which may be followed if care be taken. Outside of the gold thus occurring, none was observed elsewhere by the writer, though it was said that prospects could be obtained by crushing certain portions of the rock and carefully pan- ning it. Southward from the section above described, the several large veins converge toward a central point on the ridge, which rises higher and higher, terminating in an immense mass of quartz at its apex. South- ward from this point the quartz is less prominent and the ankerite con- stitutes the major portion of the lode until another occurrence of quartz lenses is reached, which in each case, whether following the lode north or south, is much the same. Gold sometimes occurs in the ankerite and mariposite, when seamed with quartz. A brecciated, crushed condition of this rock seems to favor the gold, or, at least, rock of this character contains more gold than that which is massive and solid. The entire mass is low-grade, and ankerite wholly free from quartz is practically free from gold in this mine. The characteristics as above described are peculiar to the occurrence of the dolomitic vein wherever it appears. Often large masses of it are found crushed, sheared, and altered to talc schist or to a granular talcose mass, including many angular fragments of crystalline mineral. In the Rawhide Mine in Tuolumne County was found a notable excep- tion to the usually observed condition. At one place in this mine the ankerite and mariposite were found phenomenally rich in gold. As a matter of course, the description of the occurrence at Coulterville is not absolutely duplicated anywhere along the lode, but it is typical in its general features of the dolomitic vein throughout the length of the lode. In the Pacific Mine at Placerville, the talc schist resulting from the alteration of the dolomite contains 1 to 2 per cent of iron sulphide, but whether or not it is auriferous was, not ascertained. The mines of the Central Gold Belt, where not in the dolomitic vein, occur in black clay slates, in tufaceous black slates, and in amphibolite schist, and are described under their proper heading. The East Lode. — The mines of the East Lode, which are found from 6 to 18 miles east of the Central Belt, occur in the slates of the Calaveras formation and in grano-diorite. Some of the most important of these mines are found in the latter formation, and a description of their general characteristics is of interest. Granite areas in which gold-bearing veins occur are found in Mariposa County, near Kite's Cove; in Tuolumne County, near Groveland, near Columbia, and at Summersville and vicinity; in Calaveras County, at West Point and vicinity; in Amador, at Pioneer; in El Dorado, at several localities; and in Nevada County, at and near Grass Valley and Nevada City. 22 CALIFORNIA STATE MINING BUREAU. Veins in Granite. — In the several granite areas referred to occur a large number of veins, some of which appear entirely independent of all others, and in other instances are found systems of connected fissures, which were evidently produced by a common cause. These veins have definite characteristics, and the ores are noticeably similar throughout the entire granitic region referred to. They are usually easily dis- tinguishable by their physical appearance from the ores occurring in other formations, whether in the same vicinity or from some distant point. The strike and dip of these veins in granite are not at all uniform, in this respect differing greatly from the veins of the Central Belt, which almost universally strike west of north and dip easterly. In the granite areas the veins have no uniform strike, but are found from true east and west courses around to north, and at all angles between them. The dip is no more uniform than the strike. Whatever the direction of dip of a vein, it is usually not persistent at or near any particular angle, but varies from a low angle to nearly or quite perpendicular. Not infrequently, in depth a vein will dip in an opposite direction from that which it has at and near the surface. The veins occur along lines of fissuring. These fissures are found singly, in pairs, and in many places as zones of fracture of varying width, comprising several fissures having an ai3proximate parallelism. These fissures, singly and in groups, are often planes of movement, as evidenced by slickensides and gouge seams. In many cases these zones of fracture are found to consist of crushed granitic material, greatly altered, and in some instances containing vein quartz in a granulated condition, indicating that a movement of the rock-masses has taken place subsequent to the deposition of the quartz. In certain more rare cases, this brecciated or granulated quartz has been cemented by a still more recent infiltration of silica. In these crushed zones the feldspars are thoroughly kaolinized; the bi-silicates are altered to chloritic mineral, and the whole mass is soft and, when wet, sometimes mushy, forming dangerous ground to mine. Often it is gold-bearing, though seldom rich. In the same fissure plane or zone are found the concentrated mineral deposits forming the ore-bodies proper of the mines. In some places they lie at the side of these crushed, partially silicified zones, either in direct contact with them or separated by a strip or wedge of hard granite, but little altered. In other instances they are found as sepa- rate ore-shoots, connected with the previously described crushed zones only by a clay seam. Other masses of quartz occur in these fissures, which contain very little of either gold or sulphide mineral. These veins are undoubtedly the result of substitution of silica, cal- cite, and other minerals for the original soluble constituents of the granite, having been conveyed to the point of deposition by mineral THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 23 solutions, probably derived from a deep-seated source. The most com- plete replacement has evidently occurred where the Assuring and crush- ing have been greatest. The vein quartz is found exhibiting every phase of condition from a partial alteration of the granitic mass, almost a normal granite (though the feldspars are always carious, and a small percentage of finely divided iron sulphide may usually be observed), through the various stages of transition, finally reaching the most com- plete alteration to crystalline quartz, sometimes heavily impregnated with the sulphides of iron, lead, copper, zinc, and silver, with gold and other minerals more rare. Calcite is a frequent accompaniment, both in the quartz and in the crushed zones of granite. The vein quartz occurs in a variety of conditions — as a vitreous, colorless, granular rock ] a milk-white, semi-greasy kind ; a bluish-black variety, usually vitreous ; also in alternating bands of bluish and white rock, and as granulated quartz. All of these varieties are gold-bearing, and again all kinds are barren. All are associated with sulphide minerals, and all again occur with scarcely a trace of them. The banded varieties are usually of fair grade in gold, and the appearance of galena is often an index of value. Some of the zinc ores are also high-grade. The sulphide minerals con- tain from $50 to $1000 per ton in gold, and some are also correspond- ingly rich in silver, though the silver contents are usually relatively small. The sulphides are pyrite, marcasite, mispikel, chalcopyrite, galena, blende, and pyrrhotite. The latter is peculiarly characteristic of granite formations throughout California, particularly in the ore- bodies of larger size. Tellurides of gold occur sparingly in several localities. The ore-shoots vary greatly in width and length, though the veins sometimes have a width of 30 feet or more, as in the Black Oak Mine in Tuolumne County. Ordinarily, however, the shoots are less than 100 feet in length and average between 6 inches and 2 feet in width. Often the lenses have an average length of 20 feet, but succeed each other immediately, the ends often overlapping, thus forming prac- tically a continuous shoot of considerable length. Occasionally are found two veins approximately parallel and sepa- rated by 1 to 4 feet of granite in a more or less advanced condition of alteration, as is the case in the Good Hope Mine, near Ferris in River- side County. The branching tendency of the fissures is a pronounced characteristic. Usually one wall at least is well defined — generally the foot — the zone of fracture and crushing extending to various distances into the hanging-wall. Now and then a perfectly defined hanging-wall will be found, but progressing along this wall it is seen to diverge gradu- ally from the plane of the foot and its influence as a bounding plane is lost, another slip or wall taking its place. This continues indefinitely until the identity of the entire vein is lost in the numerous branching cracks which extend into the granite. Often a well-defined vein several 24 CALIFORNIA STATE MINING BUREAU. feet in width will thus pinch out to the merest crack, in which is found no sign of clay or of movement, and it requires the most careful obser- vation to follow it at all ; but usually by persisting in the general direc- tion of the course of the vein it may be found to reopen and new shoots of ore found. Sometimes, however, after drifting fruitlessly some dis- tance, a cross-cut is advisable. In some instances these pinches are several hundred feet long and the ground very hard. The formation of many short shoots of rich ore in portions of the fissure where the walls are several feet apart is an interesting feature. It is not uncommon to find a wedge of quartz forming on the foot-wall, which gradually widens to 1 or 2 feet when it leaves the foot-wall, crosses the fissured zone at a low angle, and joins the hanging-wall, where it thins out and is lost. Between the short shoot of ore thus formed and its parting from the foot-wall there may be found several stringers of quartz parallel with the foot, or the entire space may consist of a reticu- lated group of small veins and seams, while along the foot-wall a second wedge-shaped vein of quartz Avill appear, which will repeat the peculiari- ties of the shoot adjoining as described. The granite adjacent to the vein, and occurring as horses within it, is frequently gold-bearing to a considerable extent, sometimes in sufficient quantity to be visible to the naked eye. It is the custom to sort out the granite as waste, but it should be done with caution, for it not infrequently pays to send the entire contents of the vein to mill, when in the pay shoot. The fact that several old dumps have been worked at a profit is evidence that early methods were careless in this regard. In some respects these mines are worked at a disad- vantage, for it is easy to lose the vein where a pinch occurs, and it has led in numerous cases to the closing of what are probably good mines. What has been described as occurring along the vein horizontally is equally applicable to the fissure in depth, and a pinch in the shaft does not signify that the limit of the vein has been reached any more than it does when occurring in the face of a drift. These disadvantages are greatly oflset, however, by the high grade of ore, which is uniformly much higher grade than that in larger veins in other formations. Often the ores from the veins in granite may be shipped to distant smelters with profit after rough sorting. Dikes are of frequent occurrence throughout the granite area in the neighborhood of the mineral belt. They are of various types, but the most common are granitic dikes of coarse crystallization and dark green diorites of fine grain, extremely tough and hard. The former are char- acterized by the occurrence of masses and crystals of albite, tourmaline, and biotite. The peculiar, interwoven, grate-like structure of quartz and feldspar, known as graphic granite, is of frequent occurrence in these dikes. These granitic intrusions are usually older than the veins, THE MOTHER LODE REGION — THE SEVERAL DIVISIONS. 25 though there are exceptions. The diorite dikes, however, are generally- younger and cut the veins. The dikes, as a rule, cross the line of strike of the veins, though not always. Whether or not these dikes have any important influence on ore deposition is a question. In some instances ore-shoots are found lying with the granitic dikes, the downward pitch of the ore-body being coincident with the dip of the dike. The influx of large quantities of water is a usual accompaniment of the development of these veins. It often comes with a rush at unex- pected times. A mine may be developed to considerable depth and have encountered but little water, when without warning a blast will break into what is called by the miners a reservoir or pocket, though usually, in fact, a system of fissures filled with water derived from the surface. The deeper the point in the mine at which these water crevices are struck, the greater the force of the water. Often the lower levels are completely flooded, and weeks are required to pump out the water, but in time the reservoir is exhausted, and things resume their usual condition. Another water-rush may not occur in many months, and again in some places they have been found in quick succession. In one instance a water crevice was broken into in the Black Oak Mine in Tuolumne County at a depth of 600 feet. With considerable difficulty a bulkhead was constructed, and the pressure gauge indicated at one time a standing pressure of 180 pounds to the square inch, indicating that the height of this reservoir was not less than 400 feet. The flow being controlled by means of a valve, the pumps in time removed the water and a normal condition was again reached. After several months the bulkhead was torn out and a round of holes was drilled in the face and discharged, upon which the water again rushed into the mine work- ings in as great volume as before. The probability is that in some manner the vent to the reservoir had become clogged and the flow of water stopped. The force of the blast removed the obstruction, and the water again poured into the mine workings, but it finally was drained to a considerable extent. This shows the necessity for abundant capacity to handle water. Some claim that large flows of water are an indica- tion of valuable ore deposits, but there is really no apparent relation between ore deposits and large flows of water. The ore was deposited by ascending currents, and the water found in mines is always found coming down from the direction of the surface. Sometimes water may be seen bubbling up from the lowest levels of the mine as though from an ascending current, but a case of this kind is due to hydrostatic pressure, the water flowing in coming from some point higher, through a series of connected cracks or fissures. A peculiarity of these veins in granite near the surface may often be observed in the occurrence of open cracks traversing the vein in a hori- zontal direction, reaching from wall to wall, and dividing the vein into 26 CALIFORNIA STATE MINING BUREAU. blocks by a series of floors, as it were, at quite regular intervals of a foot or thereabouts, depending somewhat on the width of the vein. The blocks are separated by 1 to 4 inches of space, in which have accumu- lated clay and grit, quartz crystals, iron oxide, and other secondary products and gold. The amount of gold is largely in excess of the amount found in an equal weight of quartz of the vein itself in many cases. This peculiar occurrence is undoubtedly due to a sort of molecu- lar expansion of the granitic mass, chiefly due to the alteration of the feldspars, and in a less degree possibly to the change which has taken place in the other constituents of the granite caused by surface decay and meteoric agencies generally. It is an interesting fact, and afl:brds food for study and investigation. The occurrence of gold in the silt-like material lying on these floors may be due partly to the quartz itself, but more probably comes from the oxidized sulphides, and also in part perhaps by infiltration from the selvages of the vein, if not from the granite itself, which may have become gold-bearing by impregnation from the fissure. Attrition, due to movement, may also have been partly responsible for the occurrence of this gold. When the oxidized zone is passed and the granite becomes normal, these floors no longer appear. In many places the quartz is perfectly free from both walls, and again but one wall is free, the opposite side being frozen. In an equal num- ber of cases the vein is frozen on both walls. These variations are not constant, for a vein may be free at one place and frozen in another. These changing conditions may be considered as indicating something of the relation of the original fissure to the ore deposit. Where both walls are free, it is not unlikely that the ore is filling the space bounded between two fissures. Where one wall is free the mineralization has progressed along one side of the fissure plane only; and where both walls are frozen, it would seem to indicate that ore deposition progressed outwardly from a single crack, or possibly, in the case of a large ore.- body, the mineralization has impregnated the walls beyond the limiting planes of the fissured zone, to an extent suflficient to constitute ore, and has stopped only when the mineral solutions were unable to penetrate farther from the fissure plane itself. METHODS OF MINING. The mining methods in vogue on the Central Lode of California are not, in the opinion of the writer, those calculated to produce the best results, when viewed from the standpoint of economy. They are, with few exceptions, the methods of thirty, of forty, and of fifty years ago, and some of the practices are so primitive in their nature as to savor of past centuries rather than of decades. THE MOTHER LODE REGION — METHODS OF MINING. 27 A policy which obtains throughout the mining districts of California is that of demanding prompt returns from ore development, which is of course very desirable, but which in many cases works ultimately to the disadvantage of the owner, and the manager or superintendent is so completely handicapped that he is unable to make substantial head- way. There are certain districts where this demand for "immediate returns" does not act so disadvantageously, but in the mines of the Central Lode it is undoubtedly a short-sighted policy. The reason for this will become apparent when it is understood that with few excep- tions the ground is heavy — often swelling and crushing the heaviest timbers. The usual practice is to drive a cross-cut or drift from a station at the shaft to the vein. This may or may not at once encounter ore; if not, a drift is driven along the fissure, which must be timbered in the most substantial manner. These drifts are usually not less than 7 feet high, 4 to 5 feet wide at the top, and 7 to 8 feet at the bottom. These dimensions are all inside the timbers. It usually makes little difference whether the cutting is in ore or not, the ground is generally heavy. The fissures are often from 10 to 40 feet wide, and the miners (of Amador County particularly) are well acquainted with the danger, diflficulty, and expense attending this kind of mining. As soon as pay rock is encountered it is hoisted and sent to the mill, and the drift continues, while overhand stopes are started and development proceeds. It may be several hundred feet to the limit of the property, and is often over 1000 feet, and this heavy swelling — sometimes run- ning — ground must be kept open until the entire level has been explored and the ore to the level above all extracted and sent to the surface. An idea of the character of some of this ground may be gained from the statement that in a certain instance a drift of usual size being driven a distance of 200 feet, at the rate of 5 feet or more daily, under con- tract, could not be completed before it became necessary to return to that portion first driven for the purpose of retimbering. The timbers employed in holding ground of this character are usually 20 to 30 inches in diameter, and it is no uncommon thing to see these immense logs, a few weeks after being put in place, split, crushed, and broken as though they were incapable of offering any resistance to this all but irresistible force. The advisability of cutting the main gangways in the hard rock of the walls, either foot or hanging, and reaching the vein by a system of cross-cuts, is advised. This has not, as yet, at this writing, been attempted, but its feasibility and desirability can readily be appreciated when the character of the main fissure, as above explained, is understood. These main gangways, being driven in, say the foot-wall, should have cross-cuts extending at right angles to the direction of the main gang- way. These should be disposed at stated intervals for the purpose of 28 CALIFORNIA STATE MINING BUREAU. prospecting the fissure and to render accessible the ore discovered. In slate, the main gangways should be at a distance of 40 to 60 feet from the vein — where in greenstone, they may be driven nearer the vein. The cross-cuts should be driven at stated intervals, a greater or less distance apart according to the character of the ground adjacent to the vein- When the ground is very bad, the cross-cuts should be closer, and when less so, at longer intervals. In most cases, if driven at intervals of 240 feet, the distance will be found convenient. Raises should always be put through, connecting with the level above, before stoping is com- menced. Very often this important matter is neglected, owing, as pre- viously stated, to a desire to realize a profit on the ore as quickly as possible. These raises should be put in about 60 feet apart; this, beginning 30 feet from the point where the cross-cut reaches the vein, will admit of four raises within the 240-foot section suggested, the vein being worked 30 feet each side of the raise. When putting through raises, it is really an economical plan to sink a winze from the level above to meet the raise. By this means ventila- tion will be more quickly obtained, and the additional work which men can accomplish will soon pay for the increased cost of sinking the winze. Men will not and cannot perform the best work most expe- ditiously in a foul atmosphere, though this fact seems to be lost sight of by many mine-owners. In addition to the great disadvantage of foul air, when the raises are not put through, the heavy timbers must be hoisted through the raise into the stopes by means of block and tackle at great expense of time. If the. raise were through, the cost of handling these great timbers would be very materially reduced by lowering them through the raise from the level above to the floor of the stope where they are to be placed in position. With the lateral drifts and cross-cuts completed, and drifts driven on the vein, with raises through to the next level above, the work of stoping can be carried on at as many points as may be desired, and in a few weeks, or months at most, the greater portion of the excavation made on the vein, where not filled, will collapse and be closed up forever. This works no harm or inconvenience, as the main lateral drift remains open. When operating in this manner, filling for the stopes may be taken from the hanging-wall by driving an inclined raise into it and opening out a chamber. The rock broken in these chambers will pass by gravity down into the stopes beneath and fill them, little or no shoveling being necessary. This method of mining and filling, when properly carried out, will prove more safe and far less expensive than some of the methods heretofore employed in California mines. In some mines, if stoping be expeditiously prosecuted in the manner above suggested, no filling will be required, the timbers affording all the support necessary, but in most THE MOTHER LODE REGION METHODS OP MINING. 29 cases filling of the stopes is advised. Where the hanging-wall country adjacent to the vein has a tendency to cave, it may be that the inclined upraise for the purpose of obtaining filling for the stopes may be inex- pedient. In that case, a horizontal cross-cut may be driven to the solid ground of the hanging, that portion nearest the vein being securely timbered. The filling must then be distributed by means of wheel- barrows. nQetl^od of Woi'Klno v^eiVis in 61^^1(117° (ground, Fig. 2. These filling chambers may be worked with hand or power drills, large or small, as seems desirable. One of the greatest items of mining expense, as now practiced, is that of constantly relieving swelling or running ground, and retimbering. When the ore-shoot is attacked in sections by cross-cuts from the lateral drift, any particular section need remain open only a few months at most, instead of two, three, or more years, as now. 30 CALIFORNIA STATE MINING BUREAU. Another advantage may be derived by driving an intermediate level midway between the main levels, if the ground is particularly bad, and connecting with the cross-cut or gangway beneath by a raise. In this manner the floor of the lower main level need only be maintained about half the time that would be necessary if all ore were sent down to the main level through a mill-hole extending upward 100 feet more or less, and connecting two main levels. This plan would, of necessity, require that a raise be cut through solid rock from the vicinity of the main gangway to the foot- wall of the vein, reaching it about midway between two levels. Each of these raises would have an approximate height of 45 to 60 feet, and would cost, perhaps, when timbered, $500; but the expense of keeping open the level in the vein would soon offset this expense if the ground were very bad. As a matter of course, the super- intendent must determine when an intermediate level and auxiliary raise are justifiable. His experience with the ground in the fissure will dictate whether the plan suggested is advisable or not. The sketch (Fig. 2) on page 29 illustrates the idea. Timbering. — The timbers employed in the mines of the Central Lode are uniformly large — 18 to 30 inches in diameter — and the method of framing and placing them varies somewhat, but is usually, in the larger stopes, some modification of the system known throughout the world as the Nevada square-set. The placing of these timbers is accomplished often under great disadvantage, and, in some instances, with consider- able evident danger. The men selected for this work usually represent the finest type of physical manhood, for no others could accomplish the arduous task expeditiously. As to the relative merits of the respec- tive methods of framing these heavy timbers, it seems only necessary to say that those systems involving the least framing with ax and adz underground, and consequent smaller loss of time in placing timbers in position, are the methods best adapted to regular practice. In some mines an objection is raised to the employment of sills on the main floor of a level, for the reason that the sills rot before the stopes can be carried through from any level to the next above. In most cases there is no excuse for this. A reprehensible practice, which is found almost universal in these mines, is that of attempting to carry up stopes of too large a superficial area, and this practice is responsible for some disastrous caves which have occurred in various mines. A stope of smaller superficial area can generally be carried from one level to the next above more quickly and safely than a large one, and in most cases, even by the present "old-fashioned" methods of mining, a stope of small sectional area may be carried through in a few months — long before the sills become weakened by reason of decay. If the develop- ment of the mine were carried on well in advance of the extraction of the ore, it would not be found necessary to open these large stopes, as a num- J THE MOTHER LODE REGION — METHODS OF MINING. 31 ber of smaller stopes would supply the same amount of ore daily as is usually drawn from one, two, or three large stopes, and it would be found that ultimately the cost would be materially less, as in most cases there would be no loss of ore, no disastrous caves, and work could be accomplished more expeditiously and more cheaply. Filling. — There are few veins on the Central Lode where, by present mining methods, filling is not absolutely necessary, though by the adop- tion of the lateral foot-wall gangway system heretofore suggested, in some of the smaller mines, filling might to some extent be dispensed with, the walls being allowed to collapse after removing the ore. Mate- rial for filling is usually obtained from cross-cuts and drifts driven in prospecting, and from chambers cut in the walls of the veins — generally the hanging-wall. There are few veins on the lode so small as to make enough waste in stoping to fill the excavation. Ordinarily, all the rock removed from the pay-shoot goes to the mill, and filling must be obtained elsewhere. In some of the larger mines, where the veins are of great size — 40 to 100 feet or more in width — it is not uncommon to find the entire vein removed for a distance along its strike equal to and often much greater than its width, the entire area overhead resting upon the props reaching from the topmost set of timbers to the roof. There may be three, four, or more floors in place, and the stope may be found filled from the sill floor to within a floor or two from the top; but it is clearly evident that in a stope of the size indicated, this filling can afford but little if any support to the hanging-wall, and none at all to the back of the stope. Failure to recognize this fact has resulted disastrously in more than one mine. The filling must be placed in such manner as to support the back of the stope over as large an area as possible, and a portion of this filling at least must be placed by hand, for it is clearly evident that should any subsidence occur in a stope approximating 100 feet square, timbers cannot be depended on to support the great weight. In a stope having a width and length of 100 feet and carried up four floors in height, there would remain between the top set and the floor of the level next above (65 feet) not less than 50,000 tons of ore. Should this become ''dead weight," each post of the sets in place would have to sustain a load of several hundred tons of ore in addition to the weight coming from ore and filling in levels above, and to this must be added the greater pressure coming from the direction of the hanging-wall. This weight, or pressure, will vary greatly in different mines, depending upon the character of the ground, the condition of the walls, and to no small extent upon the angle of dip of the vein. Were the enormous weight of this great shifting mass of rock equally distributed, there would be less probability of a cave; but often, the weight being trans- ferred from point to point, owing to the mobility of the ground, the pressure upon some given point becomes greater than the timbers can 32 CALIFORNIA STATE MINING BUREAU. sustain, and a single line of sets once forced out of position renders the remaining sets less secure than before, and general collapse results; and most miners are familiar with the dangers and extraordinary expense incident to the recovery of a caved stope and the extraction of the shattered masses of ore from the zone above the cave. In veins having vertical walls the danger of caves is much lessened, but the mines of the California Gold Belt dip at all angles ranging between 30 and 85 degrees, the greater number being between 45 and 70 degrees, below the plane of the horizon. This being the case, the pressure upon timber sets is exerted diagonally and not directly downward upon the posts of the sets. Naturally this renders the square, or rectangular, sets less capable of sustaining the weight and pressure. In some mines diagonal braces are set in to take this hanging-wall pressure more directly, but timber will not hold it. In consideration of the above facts, the absolute necessity of filling becomes apparent, and the necessary preparations to this end should always be promptly made in order that the filling of the stopes be not too long delayed. Filling must be carried on contemporaneously with ore extraction; and in stoping, the excavations should be carried upward in sections of relatively small superficial area, the filling being packed as close to the back of the stope as possible. Where the veins do not greatly exceed 15 feet in width, the conditions are essentially changed, as in such cases the stopes may be timbered with stulls set slightly above a right angle to the dip of the walls. Most mines, where the walls are sufiiciently firm, are timbered in this manner when the distance between walls admits of it. The conditions are so variable in these different mines, and often in different parts of the same mine, that the methods of timbering embrace almost every phase known in practice. The various methods of timbering employed in California mines and elsewhere were described and illustrated by the writer in Bulletin No. 2 of the California State Mining Bureau, February, 1896. See also method of stoping and filling at Eagle-Shawmut Mine, Tuolumne County, in this bulletin. Drainage. — A very important factor in the economy of mining is the water encountered in the underground workings, and an ever-present question is the most inexpensive method of removing this incoming water from the mine. It is accomplished in three ways: — by natural drainage through tunnels; by means of pumps, or by bailing. This subject has been exhaustively treated in Bulletin No. 9 of the State Mining Bureau, by Hans C. Behr, M.E., and it is unnecessary to more than refer to it here. On the Central Gold Belt, and in fact throughout California, the large majority of mines bail water from sumps at the bottom of the shafts, or from tanks situated at various levels, where water descending from the surface and upper levels is caught. i THE MOTHER LODE REGION — METHODS OF MINING. 33 Where the inflow of water is large, and the shafts are poorly equipped with hoisting machinery, with crooked, rough tracks or skids, the prob- lem of bailing water, hoisting ore and waste, and carrying on develop- ment work — particularly that of sinking in the shaft — becomes a serious one, and sometimes it necessitates shutting down all work in the mine except that of sinking. Where this very undesirable combination of conditions is found, steam pumps are the most satisfactory, and it may be said that there is a growing tendency to the more extensive employ- ment of steam pumps in mines of the Pacific Coast. In many cases steam pumps are found replacing the Cornish pumps. In this connection, the following contribution will be of interest to mine managers generally. It was written by request for this bulletin by Mr. J. Renshaw, one of the foremost hydraulic engineers of the United States, and who has had a very extensive experience in mine- pumping operations where they were conducted on a large scale: SOME OBSERVATIONS AS TO THE RELATIVE ADVANTAGES OF CORNISH AND DIRECT-ACTING DUPLEX PUMPS FOR PERMANENT MINE PUMPING. By Mr. J. Renshaw, of Denver, Colorado. (Written by request for this Bulletin.) The following comparisons of the relative advantages of the higher grades of direct- acting, duplex steam pumps as compared with the old and well-tried Cornish system, refer to permanent pumping plants for mines in which the water is below the tempera- ture of about 70° or 75° Fahr. When the water is above that temperature, it is evident that the exhaust steam from the direct-acting steam pumps cannot be advantageously disposed of, and either the Cornish pump, or some other plan in which the motive power is located at the surface, must be used. Up to 1878 some one of the various modifications of the Cornish pump was exclu- sively used both in Europe and in this country. In that year, a simple cylinder, non- condensing, single-plunger pump at the Ontario Mine, Utah, with 12-inch plungers, 24-inch stroke, and 500 feet vertical lift, was altered into a compound, condensing pump by the addition of an expansion cylinder and a spool-shaped bushing put in the original cylinder, the space between the original bore and the outside of the liushing forming a steam jacket. This pump was, we believe, the first attempt toward a higher grade direct-acting steam pump located in lower workings for permanent mine pump- ing. It was thoroughly tested, first by the writer and then by the designer of a Cornish pump which had been selected by the writer to be put in, should the other not prove economical. It met with strong opposition, mainly from the builders of the Cornish pumps, both in California and the East, and with much skepticism of Eastern mine operators, principally, we think, with the belief that steam could not be conducted in pipes a long distance without a ruinous loss by condensation, and this idea held among many not familiar with the results of the compound, direct-acting, condensing steam pumps that had been put in, until 1884 and 1886, when they were put in a mine at Leadville and in one in Ishpeming, Mich., since which time very few Cornish pumps have been built in this country. In 1882 or 1883, a Cornish pump was built for the Ontario Mine, which is no doubt the best example of that style of pump built, at least in this country. The writer had no opportunity to test it, but the manager of the mine said that he thought it saved a little in steam over the crude, direct-acting, condensing steam pumps that had been installed in that mine. When asked if he was sure as to any saving in steam, he replied that he was not, and later advised a mine operator in Leadville to put in the direct-acting, duplex condensing pvimp as against the Cornish pump, as the difference in cost more than balanced the possible saving in steam. 3 — MB 34 CALIFORNIA STATE MINING BUREAU. We know of no publicly reported experiments having been made to determine the amount of condensation in steam pipes until a series was made by the New England Board of Underwriters, and reported in the transactions of the American Society of Mechan- ical Engineers. The result then had, on pipes covered with one inch of hair felt and that by a thickness of burlaps, coincided almost exactly with what we had determined at the Ontario Mine with the same thickness of hair felt covered with 10-ounce canvas. At the Wolftone Mine at Leadville, the condensation in 585 feet of 4-inch wrought-iron pipe, covered with ^ inch of asbestos paper, 1 inch of hair felt, and this covered with painted 10-ounce canvas, was 57.75 cubic inches per minute, or 8.396 cubic inches per minute for each hundred square feet of external pipe surface. Judging by past experience, there is little difference in "duty" between the best examples of Cornish pumps and the best examples of direct-acting, compound con- densing pumps, each, for say 1000 gallons per minute lifted 1000 feet vertically. With triple-expansion, direct-acting, condensing pumps with the initial steam pres- sure at the pump at 140 pounds, and the pump running at say 125 feet piston speed, the comparison would undoubtedly be much in favor of it over the Cornish pump. There are, however, other very important considerations to the mine operator as to the relative advantages of the two systems of pumping, besides a little difference in the steam economy. On a basis of 1000 gallons lifted 1000 feet per minute, the installed cost of the direct-acting pump will not reach 10 per cent of that for the Cornish pump. In most cases the working-out of the mine beneath the foundations of the Cornish pump engine will, by settlement, throw it out of line, it not being a self-contained machine like the direct-acting pump. So, also, with the "pit-work." Another very important consideration is the expansibility — if we may so call it— of the two systems. When the size of a Cornish pump is to be determined, a large margin for increase of water through greater depth or side workings has to be allowed for, and what this margin is to be is difficult to determine. As a rule, but one Cornish pump can be installed in the one-pump compartment of the shaft, and it cannot be replaced bv another without allowing the shaft to be flooded ; and it is a question if it could be taken out as fast as the water would rise. This would depend upon the amount of ground worked out. Frequently there is allowed a greater margin for increase of water than afterwards proves necessary, either from the ore-body giving out, or less water being encountered than expected. The interest on investment, and wear and tear of a larger machine than necessary, are important considerations. Or, it may be years be- fore the full capacity of the pump is called for. On the other hand, if too small a pump is put in, a new shaft has to be put down in which to install another and larger pump. Thus, the size of the pump has to be determined once for all. Not so, however, with the direct-acting pump. They need only to be bought as depth is attained or increase of size becomes necessary. If the pump proves too small, a larger one may be installed on the pump station and the smaller one moved down to a lower level where less ground has been opened, and so on, making pump stations every 500 or 1000 feet. If the column pipe for the first pump put in is not of sufficient size for the larger pump, there is generally room enough to put in a larger one, and the smaller pipe then used below for the small pump. The expenditure for pumps may thus be by increments as needed. As we have said, pump-shaft compartments are seldom large enough to install but one Cornish pump line, and "the eggs are all in one basket"; whereas with direct- acting pumps, two may be installed in the one station, both connected to one column pipe or each with its own, and in case of necessary repairs, one may be stopped and the other started. It is very comfortable for the mine operator to feel thus secure. If there are two or more compartments to the shaft, one of which is for pump, piping, and ladders, that compartment should be well bratticed from the adjoining hoisting compartment. The heat radiated from even the well-covered steam pipe tends to make that compartment an "uptake" and the hoisting compartment a "downtake," and thus fairly good ventilation is to be had in the pump station or level. We need hardly say that it is important to keep pipes and their bearers snugly to the sides of the shaft, so that there will be left a clear run for the rising of warm or foul air. When, through the decomposition of pyrites or other minerals, the water is too hot for the condensation of steam below, then either compressed air may be substituted for steam, electric, or rope-driven power pumps, or the Cornish pump must be used. With I THE MOTHER LODE REGION THE COST OF MINING. 35 the utilization of mountain streams as a source of power, and either electricity or com- pressed air to transmit it, comes a new feature in mine pumping which will be more and more used, as in miost of the metal-mining locations the cost of fuel is a " burning " question. The transmission of power to the station pump by electricity would present a simple solution of the difficulty were it not that the speed of the pump has to be varied, either because of increase of water by ground opened, or by the seasons affecting the surface water. We think this difficulty can be overcome without uselessly expend- ing power. The above is given as a summary of the relative advantages of the two systems of mine pumping, for a part of which we have to rely upon memory, but we are substan- tially correct. The Diamond Drill. — In a number of mines of the Central Lode the efficiency and great desirability of the diamond drill as a prospecting device has been repeatedly demonstrated. It has been used with good judgment and excellent results at the mines of the Wildman Company at Sutter Creek, and also at the Baliol Mine near Sutter Creek, Amador County; in the Lightner Mine, Angels, Calaveras County, and elsewhere; and there seems to be a more general disposition to employ this machine for the purpose indicated, as by its means ore-shoots may be located at a distance from the main mine workings, either in the hanging or foot wall, at a minimum of cost. Not only is the proximity or the absence of ore demonstrated, but the character of the barren rock through which workings must be driven in order to reach such deposits is also ascer- tained, and the cost of development thus approximately determined. The diamond drill may also be employed in locating old workings, making connections for ventilation, and even in draining old flooded workings. Its use cannot be too highly commended in a region where there are broad zones in which occur ore-shoots scattered at irregular intervals, and this feature is particularly characteristic of large portions of the Central Gold Belt. The diamond drill may also be used to advantage in both the gold and copper mines of the West Lode. THE COST OF MINING. Another consideration is the cost of mining. This is something which can never arbitrarily be determined until the character of the mine has been demonstrated. The width and length of the ore-shoot must be known, and the character of the walls ascertained. The probable quantity of water which will have to be handled is always problemati- cal, and, as a matter of course, the character of the walls and vein material itself will determine the method and expense of timbering. It is not uncommon to hear it said that in California mining and milling can be accomplished, under favorable conditions, for less than $1 per ton, but these conditions so rarely obtain, even in California, as to scarcely be worth mentioning, for they by no means constitute or illus- trate the typical features of California mining. There are mines in slaty rocks not particularly hard, where the veins are 3 to 7 feet in 36 CALIFORNIA STATE MINING BUREAU. width, which, being worked through tunnels and having free water power, are operated at a very low cost, but even this class of mines does not represent the majority — indeed, such constitute a very small minority. In the greater number of mines in this State operations are conducted through shafts, which necessarily increase the expense of mining. In the Central Gold Belt the mines vary so greatly in size, depth, char- acter of ore and wall-rocks, and quantity of incoming water, that a statement of cost would convey but little information, and comparison would be valueless unless accompanied by a complete knowledge of existing conditions and an itemized cost-sheet. At a number of larger mines elaborate cost-sheets are kept, and to a number of these the writer has been given the freest access. The cost of mining in the larger mines, under ordinary conditions, may be fairly represented by the cost-sheet of the Wildman Company at Sutter Creek, which has been kindly furnished by the superintendent, Mr. John Ross, Jr. DETAILED AVERAGE COST OF MINING ONE TON OF ORE For the Years 1896, 1897, 1898, at the Mahoney Mine of the Wildman Company. Total Cost for 134,886 Tons. Cost per Ton. Timbers Spiling -- Lumber Charcoal Candles Powder Fuse Caps Water Freight- Iron Steel and steel rails Hardware Oil - Grease and tar Coal Miscellaneous Power-drill machinery Surveying Cement -. Insurance .-. Taxes Wire rope -- Office supplies.-- -. Superintendence and labor Dollars. 24,499 18 4,913 05 1,017 57 1,242 01 1,840 59 4,386 75 780 16 186 05 7,538 00 1,338 42 1,224 24 1,417 27 3,139 48 775 37 117 27 229 57 3,241 69 2,346 90 667 50 15 00 103 77 737 63 636 28 97 67 160,003 58 $222,495 00 Cents. 18.163 3.642 .755 .92 1.365 3.252 .578 .138 5.589 .992 .908 1.05 2.328 .575 .087 .170 2.403 1.740 .495 .011 .077 .547 .472 .072 118.621 164.950 John Ross, Je., Superintendent. THE MOTHER LODE REGION — THE COST OF MINING. 37 DETAILED AVERAGE COST OF MILLING ONE TON OF ORE For the Years 1896, 1897, 1898, at the Mahoney Mill of the Wildman Company. Total Cost for ]31,901Tous. Cost per Ton. Shoes..- Dies Screens Quicksilver Hardware Water for power Freight Cyanide potassium Wood Charcoal, iron, and steel Oil Grease . Lumber Miscellaneous and coal Timbers ._- - Assay supplies Office supplies Expressage, bullion Hauling and loading sulphurets Silver-plating plates Insurance Taxes Plates Superintendence and labor Dollars. 2,310 00 2,078 63 441 97 870 14 1,199 05 10,699 60 1,064 00 162 00 220 88 97 74 63 95 23 13 67 34 1,529 46 17 95 516 59 275 73 391 16 2,354 65 281 50 423 14 701 11 86 49 16,791 58 142,667 79 Cents. 1.712 1.541 .328 .645 .889 7.931 .789 .120 .164 .073 .047 .017 .050 1.134 .013 .382 .204 .290 1.746 .208 .314 .520 .064 12.447 31.628 The above cost includes all repairs and equipment. John Ross, Jr., Superintendent. Following is the cost-sheet of the Gwin Mine, Calaveras County, for the month of July, 1900, which is kindly furnished by Mr. J. J. Craw- ford, secretary of the company: 38 CALIFORNIA STATE MINING BUREAU. DETAILED COST OF MINING, MILLING, AND SULPHURETS AT THE GWIN MINE FOR THE MONTH OF JULY, 1900. Mining And Trans- porting to Mill 7,965 Tons. Cost per Ton. Milling 8,000 Tons. Cost per Ton. SULPHURETS Concentra- tion, Trans- portation and Reduction Charges on 108. 54o Tons. Cost per Ton. San Francisco office — salaries, directors' fees, and expenses Management Mine office — salaries and expenses.. Labor Water Electric light Timbers Lagging Wedges Lumber Powder Fuse Caps Candles Drill steel Iron and steel. Tools and implements Hardware Charcoal Oils and lubricants Shoes and dies Screens Chemicals Average loss of quicksilver of four years Miscellaneous supplies. Survej'ing *Assaying apportioned *Blacksmith shoj) apportioned *Pumps and repairs apportioned *Power drills and repairs apportioned Legal expense * Equipment and construction... apportioned § Development apportioned Taxes apportioned Stable and animals apportioned Compressor — labor and supplies * Compressor apportioned *Telephone line apportioned *General improvements apportioned Hauling sulphurets and back freight on sacks. Reduction charges and railroad freight on sulphurets Total cost per ton For purpose of comparison, following items may be transferred from "Sulphurets" to "Milling " column : Labor Water Electric light.. Miscellaneous supplies .__ Assaying Total . $ cts. .0082 .0314 .0129 1.3886 .0650 .0013 .2754 .0692 .0103 .0050 .0470 .0080 .0020 .0335 .0085 .0014 .0055 .0201 .0035 .0072 .0008 .0341 .0301 .0017 .0025 .0413 .0045 .0370 .0082 .0272 .0210 .0012 .0100 $2.2236 cts. .0084 .0313 .0075 .0653 .0875 .0022 .0031 .0013 ^6065 .0003 .0017 .0600 .0007 .0002 .0070 .0020 ^0034 .0053 .0006 .0665 "oosi .0006 .0004 .0038 ^ cts. 3.418 .746 .051 .275 ^212 2.203 9.491 $0.3677 .0464 .0100 .0007 .0037 .0028 .4313 $16,396 $11,694 *Because of the deterioration of the machinery, etc., represented by these accounts, one per cent per month of their cost and repairs is inserted in this report. §The development is apportioned according to the estimated life of that part of the mine affected by it. THE MOTHER LODE REGION — MINING MACHINERY. 39 At the Kennedy Mine, Jackson, Amador County, it may be stated without particular reference to detail, that the cost of mining, milling, and all development work, including the new vertical shaft and expense of conducting chlorination works, is about $5 per ton. The details of the Kennedy cost-sheet are not available for publication, as the com- pany does not carry their cost-sheet out in all its minutia, being satis- fied with more general statements of cost and profit, but it may be stated that the great apparent discrepancy as compared with that of the Wild- man Company's sheet is due to the extremely unlike conditions obtaining in these two mines, which are not more than two miles apart. The Kennedy vein is much smaller than the great ore-shoots at the Wild- man, but in the former they are seldom without heavy swelling ground, which, under the system of mining carried on for years at the Kennedy and other similar mines, requires constant relief and frequent retim- bering. This comparison is made merely for the purpose of showing that comparisons of cost without a complete knowledge of the condi- tions affecting such cost, are practically meaningless, and are unjust to the mine managers who are willing to furnish such figures. It should be remembered in the case of the Wildman Company's sheet that it includes the years 1896-97-98, but does not include the years 1899-1900. Within the past two years there has been a very material advance in the cost of many mining supplies and in mining machinery. The mine cost-sheet would be affected particularly in the items of iron, steel, steel rails, hardware, power-drill machinery, wire ropes, etc., and the mill sheet would show a probable increase in cost of shoes, dies, screens, quicksilver, hardware, iron, and steel. This increase in cost of the items enumerated would raise the cost of both mining and milling, and as a matter of course, would affect all other mines in proportion to the magnitude of their operations. At those mines treating the largest quantity of ore per stamp the milling cost would be lowest, and at those mines hoisting the largest tonnage of ore to the number of men employed the mining cost would be lowest. Ordinarily, in the larger mines, the cost of timbering ranges from 30 cents to 50 cents per ton of ore extracted. MINING MACHINERY. There is found in the Gold Belt a great diversity of mining machinery from the crude windlass to magnificent plants costing many thou- sands of dollars. When it is determined to purchase a hoisting plant, it is always advisable to select such machinery as the conditions under which it is to work, and the object desired to be accomplished, shall justify. When it is the intention to sink a shaft to great depth, it is 40 CALIFORNIA STATE MINING BUREAU. the best policy to purchase light machinery at first, and at the depth of a few hundred feet, when necessary, to exchange this for heavier machin- ery, but nol heavier than seems absolutely necessary to accomplish the work in hand. Very heavy and expensive hoisting gear is not advisable for shaft-sinking, nor before the mine has been developed to a stage indicating the necessity of such a plant for the purpose of hoist- ing large quantities of rock within a limited time. For instance, it would scarcely be considered wise to equip a shaft through which it is expected to raise 400 tons of ore daily, with machinery capable of hand- ling ten times that amount. Heavy and expensive machinery is only justifiable when there is sufficient work for it to perform. There are, usually, at least two active periods in the life of a mine, which are distinctly separate. These are, first, the prospecting period; and second, the productive operating period; though many mines never pass the first stage. Among the large new enterprises in the Gold Belt, the operations of the Mariposa Commercial and Mining Company, on the Mariposa Estate, are worthy of more than passing notice. These people, with probably the largest available capital for mining operations in the State, are prospecting five mines on their property. Everything is being done in a thorough, workmanlike manner, at the lowest possible cost, without the exercise of parsimonious economy. The machinery in use is first class and exactly suited to the work for which it is being used; that is, prospecting. When the limit of utility of these machines has been reached, others of heavier design will be substituted, and the lighter machines employed elsewhere, but no great outlay for plant will be made until the development of the mines justifies it. In this respect, at least, the management of these properties is entitled to great credit. MINE BELL SIGNALS. It having come to my notice that in some localities the legalized code of mine bell signals is not in use, it appears important to call attention to the fact that the California State Legislature adopted a code of mine bell signals May 1, 1893, which should be adopted by all mines regard- less of custom or different practice elsewhere. There is a liability attached for the non-use of the legal signal code. For the benefit of California miners the legal signal code is here published. California Code of Mine Bell Signals. 1 bell, to hoist. See Rule 2. 1 bell, to stop, if in motion. 2 bells, to lower. See Rule 2. 3 bells, man to be hoisted; run slow. See Rule 2. THE MOTHER LODE REGION — MINE BELL SIGNALS. 41 4 bells, start pump if not running, or stop pump if running. 1 — 3 bells, start or stop air-compressor. 5 bells, send down tools. See Rule 4. 6 bells, send down timbers. See Rule 4. 7 bells, accident; move bucket or cage by verbal orders only. 1 — 4 bells, foreman wanted. 2 — 1 — 1 bells, done hoisting until called. 2 — 1 — 2 bells, done hoisting for the day. 2 — 2 — 2 bells, change buckets from ore to water, or vice versa. 3 — 2 — 1 bells, ready to shoot in the shaft. See Rule 3. Engineer's signal that he is ready to hoist is to raise the bucket or cage two feet and lower it again. See Rule 3. Levels shall be designated and inserted in notice hereinafter men- tioned. See Rule 5. For the purpose of enforcing and properly understanding the above code of signals, the following rules are hereby established : Rule 1. In giving signals make strokes on bell at regular intervals. The bar ( ) must take the same time as for one stroke of the bell, and no more. If timber, tools, the foreman, bucket, or cage are wanted to stop at any level in the mine, signal, by number of strokes on the bell, the number of the level first before giving the signal for timber, tools, etc. Time between signals to be double bars ( ). Examples: 6 5 would mean to stop at sixth level with tools. 4 1 — 1 — 1 1 would mean stop at fourth level, man on, hoist. 2 1 — 4 would mean stop at second level with foreman. Rule 2. No person must get off or on the bucket or cage while the same is in motion. When men are to be hoisted, give the signal for men. Men must then get on the bucket or cage, then give the signal to hoist. Bell cord must be in reach of the men on the bucket or cage at station. Rule 3. After signal "Ready to shoot in shaft," engineer must give the signal when he is ready to hoist. Miners must then give the signal of "Men to be hoisted," then "spit fuse," get into the bucket, and give the signal to hoist. Rule 4. All timber, tools, etc., " longer than the depth of the bucket," to be hoisted or lowered, must be securely lashed at the upper end to the cable. Miners must know they will ride up or down the shaft without catching on rocks or timbers and being thrown out. Rule 5. The foreman will see that one printed sheet of these signals and rules for each level and one for the engine-room are attached to a board not less than twelve inches wide by thirty-six inches long, and 42 CALIFORNIA STATE MINING BUREAU. securely fasten the board up where signals can be easily read at the places above stated. Rule 6. The above signals and rules must be obeyed. Any violation will be sufficient grounds for discharging the party or parties so doing. No person, company, corporation, or individual operating any mine within the State of California shall be responsible for accidents that may happen to men disobeying the above rules and signals. Said notice and rules shall be signed by the person or superintendent having charge of the mine, who shall designate the name of the corporation or owner of the mine. Section 3 of the law says: "Any person or company failing to carry out any of the provisions of this Act shall be responsible for all damages arising to or incurred by any person working in said mine during the time of such failure." THE MOTHER LODE REGION — AMADOR COUNTY. 43 AMADOR COUNTY. Since the publication of the last report of the State Mining Bureau on the mineral resources of the State, Amador County has taken a leading place in the movement toward modern mining practice. The old-time mining methods, in many cases, have been cast aside for more modern ideas, and it may be said that a new era in mining has only commenced. In this county are a number of the deepest mines in the State, as well as some of the most valuable. Since the early days of mining in this county, it has been the common belief that the essential feature of a paying mine in Amador was a contact of greenstone and black slate. The development of the last few years has proven that this is not abso- lutely necessary, for some of the best ore-shoots found in this county are in amphibolite schist, and not associated with any contact. Another erroneous impression has been that all ore-shoots must necessarily be found in connection with the black clay slates of the Mariposa beds. To such an extent has this belief obtained, that it was considered almost use- less to look elsewhere for paying mines. Investigation of the past season has demonstrated beyond a doubt that the clay slates of the Mariposa beds have little bearing upon the value of the ore deposits, and that the black slates found associated with these ore deposits are the result of an alteration of diabase tuffs, and may usually, if not always, be readily distinguished from the clay slates. Moreover, the ore deposits do not occur for any considerable distance on the contact of these slates and the massive greenstone, but are independent of them throughout the county. This subject has been treated at some length in the open- ing paragraphs of this volume. Between the southern limits of the town of Jackson and the Mokel- umne River on the Central Gold Belt, there are at present no mines which are paying, although active operations are in progress on several properties included in that section and profitable mines may be developed. The first mine, coming from the Mokelumne River north- ward, which may be included in the paying class, is the Zeila Mine. In this county, since our last report, a number of old mines have been reopened, after an idleness of years. The most important of these are the Oneida, Central Eureka, Lincoln, and Bunker Hill, descriptions of which will be found in the following pages. The Baliol Mine, near Sutter Creek, is a new mine which has been extensively equipped and developed since the publication of the last report. 44 CALIFORNIA STATE MINING BUREAU. Amador Queen No. 1. — This mine is 1^ miles south of Jackson. The shaft has been sunk to a depth of 1200 feet, with extensive development at the 160, 300, 500, 1100, and 1200 foot levels. All of the workings of the mine are in amphibolite schist. Heavy gouges are an important and characteristic feature of this mine. There is a broad zone of schist) much foliated and contorted, with the frequent occurrence of seams and veins of quartz, with occasional high values; galena and free gold ai;e often observed. Between the 1100 and 1200 foot levels a new shoot of ore has recently been discovered, which is one of the most promising observed in the mine. The shaft in this mine has two compartmentsj and is sunk at a cost of about $30 per foot. Power is furnished by water under a head of 270 feet, and transmitted by Manila ropes to the hoist. There are 15 men employed. The Jackson Exploration and Development Company (Ltd.), owners. James E. Dye of Jackson, superintendent. Amador Queen No. 3. — It is 1^ miles south of Jackson, and west of Amador Queen No. 1. The mine is opened through a cross-cut tunnel run 1000 feet to the vein, where a station has been cut underground and a double-reel hoisting plant installed. It is run by water power from a reservoir situated on the hill above, the pipe-line being conducted through an old shaft. There is a head of 312 feet at the hoist. A three- compartment winze has been sunk at a uniform angle below the adit) the vein dipping irregularly. In January last, the shaft was down 730 feet below the tunnel level. The vein occurs in amphibolite schist, and is chiefly interesting for the amount of arsenical sulphide (mispickel)> rich in gold, which it contains. This ore is shipped; all work done in the mine is performed by hand, no machines being in use. The prop- erty is equipped with a 20-stamp mill; 19 men are employed. The American Improvement Company of Toledo, Ohio, owners. John R- Philli]3S, superintendent. Anderson {New York) Mine. — It is 3 miles southwest of Jackson, near Jackson Creek. The mine consists of a number of ore-shoots or mineralized zones, which occur in a dense aphanitic rock, the exact character of which has not been determined — probably a diorite- porphyrite. The ores are found in the crushed portions of this mass, and consist of impregnations of iron sulphides, free silica, and gold- The oxidation of these deposits has resulted in the formation of silicious iron ores carrying free gold. The mine is developed by means of three tunnels: one a cross-cut, 900 feet in length; the second a cross-cut and drift, 300 feet; the third a drift, 150 feet. A winze has been sunk in the latter 70 feet in depth, with a cross-cut 100 feet. In addition to this there are numerous superficial pits and open cuts along the crop- pings. There is a building for a 20-stamp mill on the property. In this at one time a Huntington mill was in use, in which was crushed THE MOTHER LODE REGION AMADOR COUNTY. 45 2500 tons of this ore, but a mill of this tj^pe is not well suited to the extremely hard, dense ore found in this mine. A ditch carrying 400 inches of water, which at the mine has 300 feet head, is a portion of the property. W. G. Anderson of Jackson, owner. Butte Mine. — It is a prospect 5 miles southeast of Jackson, near Jack- son Butte; is opened by means of a tunnel, and has a 10-stamp mill. A small force at work. Not visited. Spagnoli Mine. — This is at Clinton. The property was being operated last spring by the Hobart Gold Mining Company of San Francisco. It has an old inclined shaft 110 feet in depth, and a new vertical shaft 220 feet in depth. The vein occurs in granite. The mine was not visited. S. N. Spagnoli of Jackson, owner. Peerless Mine. — It is 2 miles southwest of Jackson and about 3 miles south of the Kennedy Mine. An inclined shaft has been sunk at or near the contact of black clay slates of the Mariposa beds, Avhich occur on the foot-wall and a diabase tuff on the hanging-wall. At the surface was discovered a small vein of quartz, which prospected well in gold. There are 10 men employed. Peerless Mining and Development Com- pany of Jackson, owners. Henry Osborne of Jackson, superintendent. Kirhwood Mine. — A new property adjoining the Peerless on the south. It is in the prospective stage. Zeila Mine. — It is in the southern limits of the town of Jackson. Since the last report, the shaft has been sunk from 1160 feet, at which depth it had remained for some years, to 1506 feet, the lowest level being opened at 1350 feet. The mine was first worked about fort\^ years ago, and continuously for the last twenty-one years. The property has a 40-stamp mill, which was worked steadily for fifteen years, when the mortars of old style were replaced by modern heavy mortars, provided with liners, etc. A modification of the Nevada square-set system is emplo^'ed in timbering this mine. It is substantially the same as that used at the Utica Mine, Angels, Calaveras County, but was first intro- duced in the Zeila Mine. The Zeila ore-shoot occurs as a broad zone of amphibolite schist and quartz, 30 to 40 feet wide. The ground is heavy and expensive to hold. Never a rich mine, it has always, however, paid a small profit. Filling is necessary in working this mine, and is obtained from the vein and also from chambers cut in the hanging-wall. The chlorination works at this mine have been entirely replaced once, and the hearths renewed several times; a hearth usually lasts about five years. The manager states that the average expense of mining and milling at the Zeila is about $3 per ton. In recent years a canvas plant has been added to handle the tailings from the mill. 115 men are employed. Zeila 46 CALIFORNIA STATE MINING BUREAU. Mining Company of Jackson, owners. W. F. Detert of Jackson, superintendent. The Zeila Mill. — The mill, which is under the direction of B. F. Taylor, has 40 stamps which weigh 818 pounds, new. The rock is crushed at the hoist with Blake breakers 9x15 inches. The mill is supplied with Hendy Challenge feeders. The stamps drop 7-^ inches, 87 times a minute. The screen used is No. 16 brass wire. The discharge is 7^ to 9 inches high; it is regulated by the introduction of 2-inch differential chuck-blocks. The capacity is 4 tons daily. There is one inside plate on the chuck-block. The pulp from the screen falls against a splash board and drops upon an iron plate (the lip of the mortar), from which it drops 1 inch to an apron plate 51 inches wide by 30 inches in length; thence it passes to the sluice plates 16 inches wide by 120 inches in length. The pulp passes by launders to the vanners. The free gold constitutes but 35 per cent of the values. The plates are dressed daily and a clean-up made monthly. Experiments have shown that while finer crushing will result in saving more free gold, there is a greater loss of values in sulphides, due to sliming of the ore. The iron shoes and dies last 100 days, crushing 400 tons of ore. In the Zeila mortars there is a tendency of the center shoes and dies to wear more rapidly than those at the end of the mortar. Raw copper plates are used, and it is rarely the amalgamators have any trouble with copper salts or spots of any kind on the plates which have never been silvered. This is con- sidered due to the character of the ore, consisting largely of chlorite schist with quartz, and containing no rapidly decomposing sulphides. Mr. Tavlor, mill foreman, states that but twice has he ever detected visible gold in the ore. The sulphides occur to the amount of 24 per cent and have a value of about $100 per ton, which is in strong contrast with other mines where the average value of the ore is higher than at the Zeila. At the chlorination works, 7800 pounds of sulphides are treated daily in three charges of 2600 pounds each. The furnaces are 60 X 11 feet, inside measurements. The Plattner process is employed. The Zeila Canvas Plant. — The slimes plant is located at the mill. Owing to the fact that the issue from the mill is near the creek level, the tailings are elevated by a centrifugal pump to a height of 13^ feet to a hydraulic sizer or separator; 6^ inches (miner's) of water are required to run the pump under a head of 150 feet. The daily output of tailings consists of 32 inches of water and about 150 tons of sand, the output of a 40-stamp mill. The hydraulic sizer, which is a modification of the well-known German spitzkasten, is an invention of Mr. Hambric, who is in charge of the plant. The accompanying illustration (Fig. 3) will give an idea of the construction and operation of this device. The pulp falling into the separator, passes into the first upright pipe in the box, in which is a smaller pipe with a jet of water under pressure. This THE MOTHER LODE REGION — AMADOR COUNTY. 47 causes a violent ebullition of the sands, the coarser particles of which pass out at the bottom, the finer rising from the tube, re-entering the separator and passing onward to the second pipe, where it undergoes a similar operation by means of a second hydraulic jet. Here the sands pass out at the bottom, the slimes rising as before and passing out through a launder opposite the end at which they enter. The coarse material from the separator goes to two canvas tables, which accumu- late about 1-i tons of sulphides per month; the grade of these tables is 3 inches in 1 foot, which is the heaviest grade in the plant. Tailings from these tables go to waste. The finer pulp from the separator goes The- ManJ^RIC 6EPAf^ATOF^ Zeila c)Ll^iEs Plant. '^" Fig. 3. to the tables of the main plant, which are in a building 58x140 feet. The plant consists of 32 main tables, 10 x 12 feet, and 8 auxiliary tables, for the purpose of taking the overflow when purifying the tables of the main plant. The grade of these tables is 1^ inches to the foot. The pulp is divided into four equal portions outside the building, and is evenly distributed on an inclined plane provided with ribs 3 inches apart, ^ inch deep, and ^ inch wide. Along these channels the pulp flows to the canvas tables. There are eight divisions at the upper end, which grow less in number as each table is passed, until the last of the series is reached, where there is but one. At the head of each table is a Ze.ILA CaHVa§> PL-ANT.JacK-sop. PlST{^13UT0f^ A. Launde*^ , C ^o/ af hs-sd opspt^eader: P. Cleat aci'bss bo/, t. 5p)asb board. F: Can/as -l^blc. (3. $p reads 17 Frci. 4. C/)NVas TA3LEr Zeiua /^iuu. 5 = Spreader Fig. 5. THE MOTHER LODE REGION — AMADOR COUNTY. 49 distributing device illustrated in the accompanying sketches (Figs. 4 and 5). Throughout the length of the plant clear-water pipes are pro- vided with faucets opposite each distributer, and between each of two tables is a hose for washing the tables. At this plant the owners under- took a series of experiments, of which the chief feature was the discontinuance of purifying the material concentrated on the canvas, by washing off the lighter sands before collecting the Sulphides. At this writing (June 10th) the result of this experiment has not been ascertained. At the foot of the tables are two launders, one for waste, the other for sulphides collected on the tables. These are kept separate by means of a movable bridge or apron. The washings from the tables are re-concentrated on a belt machine, 1000 pounds being reduced to 900 pounds. All pulp from the tables is elevated by means of two HYDf^AULic Ejectoi^ or Pump a+ ZeiLAa)LiMEs Plant JacKson. - CaU Fig. 6. hydraulic ejectors, the construction and operation of which is illus- trated in the sketch (Fig. 6). The pulp passes to a box having the form of an inverted truncated pyramid, 4^ feet square at the top, 18x24 inches at the bottom, and 3^ feet deep. The construction and operation of this device is shown in Fig. 7, on p. 50. As previously stated, the practice of purifying at this plant has been discontinued; the experiment has demonstrated that by sending the concentrates from the tables to the pointed box effects a saving of from 12 to 15 tons per month, but it also results in lowering the grade of concentrates. The economic result, however, has not been determined. No. 8 canvas is employed in this plant, and lasts one year. Canvas for the complete plant costs $175. The wear and tear of the plant is stated to be about $25 per month; the 4 — MB 50 CALIFORNIA STATE MINING BUREAU. plant cost complete about $6,500. Groome & Hambric of Jackson, owners. Argonaut Mine. — One mile north of Jackson, adjoining the Kennedy on the south. The inclined shaft commenced in 1893 has now reached a depth of 1750 feet, at which point it was stopped by an injunction of the court, pending a settlement of litigation with the Kennedy Com- pany. Above this level the mine has produced a large amount of ore, which has been crushed in a 40-stamp mill with large profit. The shaft not being sunk on the vein, a series of raises have been driven, which prove this vein to be continuous from the surface croppings to ^/^ POINTED^OX ZetIL-A c)LIN\&S Pl/^nIT Fig. 7. the lowest workings. The mine is equipped with a heavy hoisting plant, capable of working to a depth of 2000 feet. It is run by water, the power being communicated by means of rope transmission. The litigation between the Argonaut and Kennedy companies, in which the former company is plaintiff, is still pending. The geology of the Argonaut, and of the Kennedy Mine adjoining, will be treated in a separate paragraph following the description of the Kennedy Mine. There are 140 men employed. Argonaut Mining Company of San Francisco, owners. J. B. Francis of Jackson, superintendent. Argonaut Mill. — The rock is crushed in the breaker at the hoist and delivered to the mill bins, from which it passes by chutes to Challenge THE MOTHER LODE REGION — AMADOR COUNTY. 51 feeders. The mill is in charge of Mr. B. Taylor. It has 40 stamps, which drop 7 inches, from 90 to 95 times per minute. No. 30 brass wire screen is used. The height of discharge is 8^ inches, which is kept as nearly uniform as possible by the use of several chuck-blocks. The capacity of the mill is somewhat variable, owing to changing character- istics of the ore, but it is about 3.25 tons per stamp daily. The quantity of water used in the battery also varies with changes in the ore. The apron plates have a grade of 2 inches to the foot, and the sluices If inches per foot. These are dressed daily; the mill is cleaned up monthly. Some experiments of an interesting character were made at this mill. The pulp was passed through a hydraulic sizer, the coarser material being sent to a Woodbury bumping-table, and the finer to Union and Woodbury belt machines. The coarse material treated by the bumper returned high values, and the fine material from the belts was of medium iNcuiMeD Canvas co/ered TA51-E- /O X II. Fig. 8. value. This probably represents the two classes of sulphide material found in this mine; a coarse, high-grade sulphide occurring in the quartz, and a fine, low-grade sulphide found in the slaty ores. Another experiment made at this mill was that of re-cleaning all the concentrates from fifteen machines by passing the concentrates of all these machines over one Union belt machine, with the result that 12 to 15 per cent of low-grade, silicious material, worth about $10 per ton, was segregated from the concentrates, which shows that previously a large quantity of material had been shipped away at a loss, as it con- tained less value than the cost of transportation and treatment. As the material thus segregated consists largely of quartz with gold, and a small amount of iron sulphide, it would seem that a considerable per- centage might be recovered by grinding the sands in some sort of mill or pan with quicksilver. The Argonaut Slimes Plant. — Mr. F. S. Groome has built and operates a slimes plant below the Argonaut mill — the pulp coming 52 CALIFORNIA STATE MINING BUREAU. directly from the mill to hydraulic separators, or spitzkasten, and pass- ing thence to the distributers, the construction of which is illustrated in the accompanying sketch (Fig. 8). In size, the tables of the main plant are 8x16 feet. The sized pulp is distributed to three sets of tables, the coarse going to a set of three tables; the medium, which constitutes the larger portion of the material, passing to sixteen tables, and the finest material to a third set of three tables. The fall of the tables treating the finest material is If inches in 12 inches; the grade of the medium tables is 1-| inches in 12 inches, and that of the coarse 1| inches in 12 inches; these grades are adjustable. The tables are covered with No. 8 canvas. Owing to the topograph}'' of the ground, it was not neces- sary to construct these tables in a series of steps lengthwise of the plant, as in the case of most plants of this character. The canvas is placed on the long lines of tables in a single piece, reaching the entire length of the plant, tacked at the edges, and then the entire floor is divided into a series of tables by tacking down 2-inch strips at regular intervals. The pulp is run for one hour on the canvas table; it is then shut off, and clear water turned on for about five minutes, when the sulphides are removed by means of a hose, usually taking one minute to the table. It takes one man forty-five minutes to make a complete round, and about fifteen minutes to look after the outside machines. In this plant, as at all others, at the foot of the tables is a double launder — one to carry the waste tailings, the other to carry the concentrates accumu- lating upon and washed from the tables. The concentrates from the tables are sent to an agitator, which re-sizes the material, the finer going to additional tables having a grade of 1-^ inches in 12, the coarser material going to a belt concentrator, the tailings from which are pumped to an outside table 24 feet in length, the overflow from which goes to a second set of three tables. The changes in the ore necessitate slight modifications in the treatment. About 125 tons of material are treated daily. Of the values that come from the mill, contained in the tailings, about 35 per cent is actually saved, 65 per cent escaping in the coarse quartz sand, the gold being evidently bound up in the quartz grains, Avhich would require a finer crusher to liberate it; but attempts made heretofore to save this gold at a profit have proven abortive. It would seem, however, that if this material were crushed in a mill of proper construction, operated at a minimum cost of power, it might yet afford a small profit. In the construction of this plant, green redwood was employed. The foundations were firmly bedded, and the entire plant constructed with greatest care. Kennedy Mine. — It is 1 mile north of Jackson, adjoining the Argo- naut on the north. This property has been repeatedly described in former reports of the State Mining Bureau, but as it is one of the most prominent mines in the State, it merits further mention. Th6 mine has THE MOTHER LODE REGION — AMADOR COUNTY, 53 been worked continuously since 1885, when work was resumed at a depth of 750 feet, to its present depth of 2300 feet vertical. About 36,000 tons of ore have been crushed annually for the past fourteen years, at an approximate cost of $4.50 to $5.00 per ton, which includes the cost of mining, supplies, insurance, taxes, superintendence, purchase of property, dead work, and new work. This excessive cost is due largely to the heavy swelling ground and the cost of keeping the mine open. Since the last report, the two main shafts have been sunk several hun- dred feet, and a new vertical shaft has been started on the hillside about 1900 feet east of the old workings. This shaft, in January, had reached a depth of 915 feet ; at this writing (June 12th), it is over 1300 feet deep. A cross-cut is being driven from the 2100-foot level of the Kennedy Mine to connect with the new vertical shaft. The general geological structure of the mine is referred to in a paragraph below, which also includes that of the Argonaut Mine adjoining. The distribution of ore-shoots in the Kennedy-Argonaut vein is of considerable importance to miners along the Gold Belt, as in these extensive workings it has been shown that ore-bodies are not absolutely continuous, either longitudinally or in depth, and that workings can be driven over the top and along either side of an ore-shoot, and beneath it, in fact completely surrounding it, in a barren fissure. There are ore- shoots in the Kennedy Mine that do not approach within sev- eral hundred feet of the surface. On the 2100-foot level a new shoot was recently discovered which started on the west or foot wall (diabase), dipping at an angle of approximately 40 degrees eastward with a trend to the southward, which is contrary to the usual trend of ore-shoots in this mine. The main north shoot is wholly distinct and separate from that on the south, and it is also distinctly different in character. At the south end of the south shoot, several small veins come in from the hang- ing-wall side, uniting with the main fissure, and these gradually build up the large south ore-body. The principal feature of interest at the Kennedy Mine at present is the new east shaft. The object of this expensive piece of work is to make the large bodies of low-grade ore exposed by development in the mine available at a decreased cost. This shaft has been sunk through hard greenstone at a rate approaching three feet per day. This was accomplished by the use of four machine drills, working three shifts. Arrangements were so made that the timber gang could work uninter- ruptedly while drilling was in progress below. The machines are set on two bars disposed near the end of the shaft, and after having been set in place a full round of holes is put in, from 28 to 35 in number, without taking down the machines. The holes are drilled from 5 to 6 feet vertically. The manner of pointing these holes is shown in the 54 CALIFORNIA STATE MINING BUREAU. accompanying diagram (Fig. 9). There is no hand-drilling, all work of squaring-up, etc., being done with machines. In this shaft 26 men are employed. The shaft is timbered throughout with 12x12 Oregon pine; sets 5 feet from center to center near the top, and in the lower portion 6 feet from center to center. The accompanying illustration (Fig. 10) shows the relation of the strike of the rocks to the position of the shaft. (Notice also the strike of rocks in the Oneida and Wildman shafts in this county — see Figs. 14 and 21.) An unusual feature in the new Kennedy shaft, not often found in shafts sunk in hard rock, is the bridge used in timbering; this is illus- trated in the accompanying sketches (Figs. 11 and 12). It was claimed by Mr. George W. C. Glass, who was in charge of this work, that this '' '' ! \ \ ^ / » t V \ N / - I / I / V Sh^ETCM sho^'ns rrjanner of jDlac'inp MAcHiNEr-f\ouES in h\ENr4EOy i>HAFT. Fig. 9. method of shaft-timbering greatly expedited matters and was less expensive than by the ordinary method. This manner of timbering shafts is not novel, but is usually employed in soft and not in hard ground; but as the bridges have been carried from top to bottom in this shaft, and as good headway has been made throughout, it is prob- able that this method has given entire satisfaction in this instance. The Kennedy Mill. — This mill contains 40 stamps, and is in charge of Mr. Webb Smith. The monthly capacity is about 4,000 tons. The stamps drop 7-5 inches 95 times per minute. The height of discharge is from 8 to 10 inches, three differential chuck-blocks being employed to keep these as nearly uniform as possible. The grade of the plates is 1^ inches to 12; 24-mesh brass wire screen is used in the battery, THE MOTHER LODE REGION — AMADOR COUNTY. 55 formerly 30-mesh. The amount of water employed in the battery is variable, depending on the character of the ore. Cast-iron, chilled, manganese, chrome, and hammered steel shoes and dies have been used in this mill. The steel shoes and dies have given the best satisfaction; the iron shoes last about 50 days, the steel 95 days, the latter crushing about 340 tons of rock. The plates are dressed daily, and the general clean-up is made monthly. There are 24 Frue vanners in use. The sulphides collected on these machines are treated in the chlorination works at the mine, having a daily capacity of Si tons. The average saving is about 94^ per cent, and the cost is said to be $7 per ton, paying high salaries to experienced men. The mortars used in the Kennedy mill were formerly of a wide type with double discharge, the rear discharge being closed for gold milling. These have all been replaced by narrow, lined mortars, designed by Mr- 5KE.TCH- sy^owino STf^lK&of P'OF^AOt^TIOW across HCennEDY VeRTiC-AL q^Ht^FT Fig. 10. Webb Smith, the mill foreman. The mortars are lined throughout, and have a plate on the feed lip which may be replaced when worn. There are 150 men employed. Kennedy Mining and Milling Company of San Francisco, owners. J. F. Parks, superintendent. Kennedy Slimes Plant. — All the tailings from the Kennedy mill go to a slimes plant, one of the first built and successfully operated on the Gold Belt. The design is that of Ct. G. Gates of Jackson, who has car- ried the concentration of slimes to as near perfection as may be wished. Mr. Gates has also designed an end-shake belt concentrator which does splendid work on slimes. This machine is used in recleaning the con- centrates from the canvas tables. The Gates plant is described at length in Bulletin No. 6, " California Mill Practices," by E. B. Preston. Since the publication of that bulletin, Mr. Gates has made no material change in the design of his plant or method of operating, although the plant has been entirely rebuilt. In its general features it is similar to that at the Zeila Mine. G. G. Gates of Jackson, Cal., owner. 56 CALIFORNIA STATE MINING BUREAU. GEOLOGY OP ARGONAUT-KENNEDY VEIN. In the Argonaut and Kennedy mines is found a perfect example of that class of mineral deposit known as, and called, a "true fissure " vein. -S'£>C7/o/^ (Q ^■^c7/y^ /■cy «Q '5 cQ i< «o ^^3C7/^/cr -^^hf-Tcf cy/^^ o^^ ^ ~ MFW^r #^^ S> C7f^f? By the term " true fissure" is meant a vein or fissure which cuts through rock formations of either similar or unlike character, wholly independ- ent of either the dip or the strike of the rocks which form the walls of THE MOTHER LODE REGION — AMADOR COUNTY. 57 the vein. Veins of undoubted fissure type do occur, however, which conform with strike or dip of the wall rocks, and in some instances with both. That the Argonaut vein is persistent for thousands of feet in both strike and dip is abundantly proven in the extensive workings of the Argonaut and Kennedy mines, the connection of their levels at numer- ous points showing clearly the identity and continuity of the vein in these mines. The geology of the vein is very simple and may be briefly stated. That geological horizon known as the "Mariposa Beds" (U. S. Geological Survey), which consists of deposits of clay slate and altered diabase Vei^tical Section at corrjer of N Posl- PlG. 12. tuff, is found intruded by dike-like masses of diabase. These dikes are of varying width, and appear to have been thrust in from the north- ward, where, at a distance of 1000 feet or thereabouts, to the northward- of the Argonaut shaft at the base of Reservoir Hill, the diabase seems to have almost wholly displaced the slates. To the westward of the most westerly of these slate strips is found a broad area of typical diabase (No, 18), mostly massive and granular, extending many thousands of feet to the northward and southward. When in their normal position and condition, we find the slates of the Mariposa beds along the Gold Belt almost universally dipping to the eastward and striking a few degrees west of north. In the Argonaut 58 CALIFORNIA STATE MINING BUREAU. Mine local disturbances have resulted in folding, faulting, and crushing these slates, the degree of foliation and alteration appearing in propor- tion to the amount of crushing and shearing to which the rock has been subjected. Whether or not the cleavage of the planes of the slates are coincident with the planes of sedimentation cannot be determined, nor is it important. At Sutter Creek it is known that they are not. (For illustration, see Fig. 20, page 67.) The diabase has also shared in this alteration from the same causes, namely, movement and fracture of the rock-masses due to tremendous compressive stress, resulting in a process of crushing and shearing of this hard, tough, granular rock, and its consequent alteration to splintery, schistose, and slaty rocks, with every phase of transition from granular normal diabase to chloritic schist and slate. (Amphibolite schist, U. S. G. S.) Diabase when so altered to a slaty condition forms the "gray slate " of the miners. The slaty structure developed in the tuffs is often so perfect that in some instances, particularly when found in the vicinity of the black clay slates where they have become blackened by meta- morphosing influences, it is extremely difficult and often impossible to distinguish one from the other by their physical appearance. For a description of this type of formation see "Schists and Metamorphic Rocks," by G. H. Williams. The vein can be followed continuously from its apex in the Argonaut claim to the lowest level of the mine without break or interruption of any kind. The apex or upper portion of the Argonaut Mine is wholly in massive diabase, which is found much decomposed for some distance on either side of the vein to a depth of several hundred feet, but for most part retaining its massive structure. (See Fig. 13.) In proxim- ity to the vein, an alteration to a splintery or schistose condition may often be observed, and impregnations of pyrite are of frequent occurrence where such alterations are found. In the hanging-wall diabase near the surface are found numerous small veins and seams of quartz, some of which lie nearly parallel with the principal fissure plane, but the greater number have a westerly dip extending upward from the fissure into the hanging-wall. Similar seams and vein-like sheets also occur in the foot-wall diabase, but usually in less number. These attendant sheets and veins of quartz are incidental to many veins elsewhere, and veiy frequently contain sufficient valuable material to entitle them to be included in the zone of pay rock together with the main fissure, when the entire zone of mineralization is, and very properly should be, considered as a single vein or lode. In making an examination of the vein structure and wall rocks in a raise extending upward from the 470-foot level to the adit (Pioneer tunnel) level of the Argonaut Mine, geological conditions were found to exist which at once determined the fact that the vein THE MOTHEE LODE REGION — AMADOR COUNTY. 59 occupies a "fault fissure," the hanging-wall having moved upward relatively to the foot-wall, constituting a "thrust" or "reverse" fault. There may possibly have been also a lateral movement along the fissure plane to the southward, striations found on the walls of the vein dip- ping to the northward tending to strengthen this belief. The amount of displacement as determined by measurement in the raise is about 125 fjncien}- R/vq^ Fig. 13. feet. The quartz occurs along this plane in a most persistent manner, and is rarely absent, even for a short distance. In width the quartz varies from 1 to 2 inches to upward of 30 feet. Where for a brief space quartz disappears in the raises above the 470-foot level, the gouge resulting from attrition caused by movement of these rock planes upon each other, which always accompanies this vein, clearly indicates the 60 CALIFORNIA STATE MINING BUREAU. plane of the fissure. In passing through these raises it may be noticed that where no quartz appears in the fissure on one side of the cutting, it may usually be found on the opposite side. No more conclusive evidence of a continuous vein than the fact that it occupies a fault plane could be desired. It may be contended that this vein occupies a contact fissure, but the conditions above described and the abundant evidence found on the several levels of these mines, indicate clearly that any contact is of purely local character, and that the fissure is absolutely independent of it, for the vein does not conform for any considerable distance in either mine, in either strike or dip, to the contact planes of the black slates and the diabase, or the schistose and slaty rocks resulting from its alteration. The dip of the vein varies from a comparatively small angle at the apex to about 67 degrees from the plane of the horizon in -=^ _ — __ ^^ -AmphMbolite --Scbisf — ^ — =• Sketch 5howi no relation^ of c)Tl^lK'E: of Af^PHl5014TE-S(;HISri> -to direction of NeW VEf^TlCAl^HAFT.- ONeiDA A^INEr— . Fig. 14. the lower levels, and in general at a somewhat less angle than that of the inclosing rocks. Oneida Mine. — It is l-j miles north of Jackson, adjoining the Kennedy on the north. Since the last report, a new vertical shaft has been sunk in the hanging-wall to a depth of 2050 feet. Ground was broken for this shaft January 13, 1896, and February 3, 1896, the shaft had reached a depth of 16 feet, when work was discontinued for the reason of bad weather. On March 9, 1898, the shaft had reached a depth of 1550 feet in two years and thirty working days, making a daily average of two feet. All this work was done by hand, excepting during a short time when machines were used, but their use was discontinued. This shaft was laid out to conform with the strike of the formation. (See Fig. 14.) In this respect it should be compared with the new vertical shaft of the Kennedy (see Fig. 10), and that of the Wildman at '"'^ gg ggg *? ??'*" Oneida Mine, Amador County. :i T4E Central Eureka Mine, Sutter Creek, Amador County. THE MOTHER LODE REGION — AMADOR COUNTY. 61 Sutter Creek (see Fig. 21). It is claimed that there is considerable advantage gained in sinking the shaft at right angles with the strike of the formation or diagonally across it. The timbers employed in timbering this shaft were 12x12 and 14x14 inches. The upper por- tion, in soft ground, is closely lagged, but the greater part is without lagging. Fig. 15. n7i9« Three ore-shoots have thus far been discovered in the mine, two of them near the shaft and the third north of it. The best ore developed is found on the 1500-foot level, although ore has also been developed on the 1700 and 1900 foot levels. The old incline shaft which was sunk by the former operators to a depth of 1350 feet has been cleaned 62 CALIFORNIA STATE MINING BUREAU. out, a great deal of it being found in a very bad condition. It was probably one of the most expensive and difficult jobs of opening an old shaft that has yet been found on the lode. The new vertical shaft and the old inclined shaft which will be extended downward, will be Station ^^/ c)HAPT.2ooo-ft- Level. Ooeida n^iV^e. Amado.-Co.CAu Fig. 16. connected at various levels. The vein crosses the vertical shaft at the 1900-foot station. Here the hanging-wall is diabase and the foot-wall black tufaceous slate. At the station there is a heavy gouge on the foot- THE MOTHER LODE REGION AMADOR COUNTY. 63 wall side, and a large vein of fine-looking quartz. In the sump 50 feet below the 2000-foot level, and at least 50 feet west of the vein, a thin, flat seam of quartz was found in the diabase of the foot-wall, containing coarse gold. This is an unusual occurrence, or at least one not hereto- fore observed along the Lode. The method of timbering stations in the Oneida Mine is shown in the accompanying illustrations. (Figs. 15 and 16.) • A new 60-stamp mill is in course of construction at this writing, early in June. It will be necessary to elevate the ore by some means, probably an inclined tramway, from the shaft to the ore floor of the mill; this might have been obviated by sinking the shaft on a ridge a short distance eastward from the present site of the shaft. A large, expensive hoisting plant forms a part of the equipment of this mine. Forty-three men are employed. The Oneida Gold Mining and Milling Company of West Virginia, owners. C. C. Derby of Jackson, superintendent. Since writing the above the mill has been completed, and 20 of the stamps dropped early in September, thus adding another producing mine to those operating in Amador County. South Eureka Mine. — This is one mile south of Sutter Creek, adjoin- ing the Oneida on the north. The north shaft is down 1800 feet, the south shaft 330 feet, connected with the 600-foot level by a raise. This vein occurs in black tufaceous slates and greenstone schists. The ore- shoots trend to the northward and vary greatly in size. The vein is very much disturbed by faults and flexures, which are difficult to understand in the present stage of development of the mine. One per- plexing peculiarity of this vein is the finding of rich masses of ore in a large vein of slaty gouge, which have no connection with any con- tinuous ore-shoot. Recently (spring of 1900), some very good ore has been discovered in this mine. Another peculiarity of the ore-shoots is that they are richest in free gold at the north end, while the south end of the shoots are of much lower grade. It seems characteristic of these veins that while they are broad, the values are disseminated. In many of the mines of this county, where the veins exceed 10 or 12 feet in width, the best portion is found next to the foot-wall. In some cases from 1 to 10 feet of rock will be found above the average in grade, while the remaining 15 to 25 feet in thickness will be practically value- less, consisting principally of white, massive quartz. In this mine the superintendent has arranged an ingenious device for hauling timbers into stopes above the level. This consists of two sheaves set above in the raise, with one sheave at the main gangway. A rope is passed over these sheaves and a bucket attached at one end. This bucket is hauled up into the stopes, and a heavy timber attached to the opposite end of the rope down on the level. When the bucket is filled with ore it acts as a counterbalance, and the timber can be hauled up with comparative 64 CALIFORNIA STATE MINING BUREAU. ease. The mine is provided with a 20-stamp mill, run by electricity furnished by the Standard Electric Company. The hoist is run by water power under 180-foot head, the power being transmitted by means of a wire rope 600 feet long. There are 30 men employed, except when the mill is running, when there are from 60 to 70. South Eureka Mining Company, owners. J. F. Parks of Jackson, superintendent. Central Eureka Mine. — This property adjoins the South Eureka on the north, half a mile south of the town of Sutter Creek. This mine, after an idleness of many years, was reopened by a new company in the fall of 1895. There were several shafts on the property at that time, the deepest being the south shaft, down 700 feet. Since that time the shaft has been continued to a depth of 1700 feet and a number of long levels opened. At about the 1000-foot level, several narrow and short shoots of high-grade ore were developed. As depth was attained and levels driven out, these ore-shoots were found to lengthen and increase in width while maintaining their values, until in the deepest portion of the mine the several short shoots have united, forming a single long shoot. At this writing (January, 1900), the Central Eureka Mine is one of great promise. The vein is the most simple in geological structure of any extensively developed mine on the Central Lode. It consists practically of a single fissure cutting in strike and dip the black tufaceous slates and amphibolite schist which form its walls. The mine has certain peculiarities which are noticeably persistent. One of these is the firmness and regularity of the hanging-wall. The wall is not absolutely straight in strike, but rolls more or less in a series of long swells. The gouge, which is always found on the foot- wall side, also has a sinuous course, swinging toward and away from the hanging-wall. When at some distance from the hanging-wall little or no ore occurs in the fissure, but upon its approach to the hanging- wall the long lenticular masses of quartz which constitute these ore- bodies, begin to form. Another feature of the vein is found in the increasing mineralization of the rock forming the hanging-wall upon nearing an ore-shoot. Although at the time of my visit no cross-cuts had been made in the hanging-wall country from the lower levels of this mine, there is little doubt that considerable portions of the mineral- ized zone of the hanging-wall will be found to make payable ore, although of comparatively low grade. A considerable quantity of the ore taken from the shoots above described has been milled, returning an average of about $70 per ton. The hoist is run by water power. A 10-stamp mill has been completed and is in operation. The mill has an extension for 10 additional stamps. In September the shaft had reached a depth of 1845 feet, and the vein is from 1 to 12 feet in width between the 1400 and 1800 levels. A new hoist is being put in, and the mill, rockbreaker, and exhaust fan are running by electricity. Cen- s^r-f*:^ _^>-.«i**'-"'?'~T''^' The Mahoney Mine, Sutter Creek, Amador County. Timbering in Caving Ground, Mahoney Mine, Amador County. THE MOTHER LODE REGION — AMADOR COUNTY. 65 tral Eureka Mining Company, owners. W. R. Thomas of Sutter Creek, superintendent. Wildman-Mahoney Mine. — This is at Sutter Creek. The property- consists of the Wildman, Mahoney or Hector, and Stewart claims, also the Waechter ranch to the eastward of these mines on which a new vertical shaft is being sunk. The development. at present is chiefly confined to the Wildman and Mahoney claims, which join and are operated through two inclined shafts. The Wildman is 1300 feet deep, the Mahoney 1000. The 1000-foot level of the Mahoney is equivalent to the 800-foot level of the Wildman. The ore-bodies of these mines, both great and small, appear to be confined to a definite zone lying between two reefs of Mariposa clay slates, although these latter appear not to be directly associated with the ore-bodies themselves. The zone included between the clay slates consists principally of amphibolite schist and tufaceous black slates. ^ In the southern portion of the Wildman Mine the ore zone is confined to narrow limits, but going northward it broadens, and in the Mahoney claim the vein splits into two sections, the east Good ore lying each side of a Sfl-diou^e in Wildrr^an H^i^e Fig. 17. branch going into the Stewart claim and the west into the Lmcoln. The idea seems to prevail that the mines of the Gold Belt of Amador County are simple fissures, which are easily followed and are regular and per- sistent. Just the reverse, however, is usually the case, as the ore-bodies are found disturbed by faults, and often contorted and displaced in a most puzzling manner. On the 300-foot level of the Mahoney Mine one vein follows a gouge 4 feet wide, on the hanging-wall of which the ore continues for a distance of 300 feet; going southward for some dis- tance the ore loses its value, but undergoes no physical change that is noteworthy. Noticing that the gouge contained small masses of good ore, from 20 to 400 pounds in weight. Superintendent Ross cross-cut into the foot-wall and found good ore in the opposite side. (See sketch, Fig. 17.) This was the only place known, up to that time, where pay ore was found in the gouge. The ore found on the foot-wall side of the zone was 15 feet wide, but its length has not been determined. These ore-shoots are known to overlap 25 feet at least, and probably much more. Another instance of irregularity was noticed in the Mahoney Mine 30 feet 5 — MB 66 CALIFORNIA STATE MINING BUREAU. above the 900-foot level, where is found what appears to be a displace- ment of a banded vein 15 feet in width, which, together with the inclosed slates, is contorted and cut off abruptly, the sheared end abutting against a solid vein of quartz 20 feet in thickness. (See Fig. 18.) The contin- uation of this faulted vein has not, as yet, been found above. The slaty material found underneath the banded vein is also gold-bearing in pay- ing quantities. A stope on the' 900-foot level of the Mahoney follows a well-defined, persistent wall for a long distance. This stope is 25 feet in width. A fissure crosses the ore-shoot at an angle of 65 degrees, dip- ping south. Beyond this was found the above described disturbance. I'^AULT on 900fr LevE-L. of ■tt7e Ma-HONEY AAirNE:,SutterCreel<.. Fig. 18. On the 1000-foot level of this mine, a stope follows what appears to be the wall above described, with large ore deposits on either side of the wall. The wall takes a slight flexure to the west, and the ore follows the wall on the foot side, while that previously followed on the hanging- wall side bears more to the east, and a slate horse separates them. In the main level, the drift continues south, and a new ore-shoot comes in from the east or hanging wall. A diamond-drill hole run west, here passes through 6 feet of slate and cuts 3 feet of quartz, which is suc- ceeded by 22 feet of slate and 6 feet of ore. This probably represents the two branches of the divided vein. The diamond-drill hole continues for a distance of 204 feet, where it cuts a vein of good ore 13 feet THE MOTHER LODE REGION — AMADOR COUNTY. 67 thick. This may be the downward extension of the ore dipping west- erly on the level above, though such a thing is far from certain. In the Amphibolite Schist -^- ^ zz ^-' , Sketch of- Vein in Wiloman Ajinet. sbov>/i9^ indepei9de9ce op Yelrp and Contacts Fig. 19. Wildman Mine, on the 800-foot level, is a 24-foot ore-body on the slate foot-wall. On the 1000-foot level of the Mahoney, what is evidently Slaty ClEAVAGEt - Pe\/©lopsd by |Dre&=.ure m fo\de.d §)ti'ata_ OF- /''^Af^lPOSA Beds -at i>une\- CreeK.-Arqador Co- C-^i-. Hof?izoNTAL- Section Fig. 20. this same ore-bodj is developed, but it lies 23 feet east of the slates (Fig. 19). These irregularities are only a few of those which occur 68 CALIFORNIA STATE MINING BUREAU. throughout this extensive property, and are simply mentioned to illus- trate the peculiarities and irregularities of the ore-deposits. A complete description of the mine, taken by levels, would fill a good-sized volume. The Wildman-Mahoney Mine labors under great disadvantage in being obliged to work through the old inclined shafts, that of the Wildman Mine being particularly bad, and the cause of what would be otherwise unnecessary expense. The completion of the new Emerson shaft, below described, will remedy this trouble, and the large bodies of ore, too low- grade to pay under existing conditions, can then be worked at a profit. Fig. 20 illustrates the contortion of slates and the subsequent devel- opment of slaty cleavage in Mariposa beds at Sutter Creek. The sketch is of an area 20 feet square. c)KETCW sF^oWi'r^o fjelaVier^ o^ StriKe of forrrjsitoqio Wildrr]aq Sf^afh Fig. 21. The Emerson Shaft. — The new, or Emerson, shaft, as it is called, is vertical, and is being sunk nearly 1000 feet east of the present Wildman inclined shaft. It is calculated that it will cut the Wildman vein at a depth of between 2300 and 2400 feet. It is difficult to give the exact depth, as through this section the lode flattens more or less in depth. It is now down over 700 feet. The ground passed through is diabase and diabase tuff, with some very hard gray slate (altered diabase), an occasional seam of black slate and stringers of barren quartz. The exca- vation outside of timbers is 8 x 20 feet, and is made across the stratifi- cation of the country — that is, the length of the shaft is east and west. (See Fig. 21.) Timbers used are all selected spruce, 12x14 inches, framed in the usual Comstock style, with the following exceptions: First, the wall-plates are placed with the 12-inch side vertical, and the dividers with the 14-inch side vertical. A dap is cut ^ inch deep in the wall-plate, top and bottom, for the center posts, which leaves 1^-inch footing and heading for the posts, as the 14-inch side or end of the divider comes against wall-plate and posts, thus giving more strength THE MOTHER LODE REGION — AMADOR COUNTY. 69 to the wall-plate and a better footing for the posts than would be the case if the divider were of the same width as the wall-plate. Second, as seen in sketch of divider (see Fig. 22), a 2-inch filling piece is in- serted behind each guide, which gives 4 inches to work on (in keeping guides true) in case of a squeeze in the shaft. The sketch of section of shaft (Fig. 23) shows a small "service cage" in the pump compartment for the use of foreman and pumpmen. It is to be run open on two sides, to facili- tate the handling of long lengths of pipe. All of the pipes are set on the side of the shaft opposite this cage. The ladders are each 15 feet long, inclined over each other, there being a landing at the end of each ladder, from center to center of Section ofQuid^sa'^/Oivider showing Filling Piece- Wildman Shafh Fig. 22. The shaft sets are 4 feet apart, or 5 feet wall-plates. The skip compartments are Fig. 23. WlLDA^A/SI ShAF-T. 4^ X 4i feet, and the pump and ladder compartments 4-| x 5 feet. The wall-plates and ends of dividers are so framed that the dividers are driven up into place instead of down, which prevents their being knocked out by blasts. 70 CALIFORNIA STATE MINING BUREAU. It is the intention to use skips that will carry 3 tons of ore at a load, making total weight of load (including cable and skip), starting at a depth of 2500 feet, about 6 tons. Foundations of stone and cement for permanent headgear have been built from bedrock to the level of the collar of the shaft. The temporary hoist and gallows frame now in use WiLDMAH Mill without ir^stde Platen*. Fi&. 24. at this shaft is so constructed and arranged that the permanent steel head frame can be erected over the shaft without interfering with the progress of work. The design of the proposed steel headgear is by E Chodsko, of San Francisco. If erected this year it will be the first of its kind in California. THE MOTHER LODE REGION — AMADOR COUNTY. 71 The Wildman Mill. — The mills of the Wildm an Company are operated with as great care as any in the State, and merit a detailed description. There are two mills, each of 40 stamps. In the Wildman mill the stamps weigh 850 pounds; these drop from 7 to 9 inches 96 times per minute; the guides are of iron; the height of discharge is 7^ inches, regulated by chuck-blocks, having a difference of ^ to 2 inches in height. A No. 2 punched tin screen is used. The capacity of the mill had been about 145 tons per day under the above conditions, but the height of discharge has been lowered not to exceed 6 inches for the purpose of experimentation. This will have a tendency to increase the capacity of the mill. The outside plates have a grade of 1| inches to the foot. Iron bar. Detaiu. Sectional Plate ON CHUC^^,SLOC^^. (^racKct- Old Style ^(reeM Pf^A/^t Wildr9a9A)ill. Detail,. /fanner of VVed^ir)^ Sc(\EEr( 1> NJAIN pT^Af^Er Fig. 25. There are 14 Frue vanners and 2 Triumph concentrators in use. The ore contains about 1 j-q per cent sulphurets, which are shipped to Selby's. They formerly used 11x48 inch No. 24 Russian iron and cold rolled steel screens, diagonal slot. Of these the steel screens proved the most durable. They now use a No. 2 punched tin screen having 225 holes to the square inch. These apertures have a slightly greater diameter than the slot of the No. 24 screen. Formerly the screen was secured flush with the outside of the frame, which was provided with an inside plate. The screen frames are now arranged as shown in the accompanying drawing (Fig. 24). The former method is shown in Fig. 25. The Hector or Mahoney Mill. — In this mill there are 40 stamps, which weigh 950 pounds. The height of the drop is from 7 to 9 inches 96 times 72 CALIFORNIA STATE MINING BUREAU. a minute. The height of discharge was formerly 6^ inches, but is now from 3^ to 4 inches, being adjusted by differential chuck-blocks. The Globe Iron Works guides are in use. A No. 2 punched tin screen is used, the capacity being 146 tons per day. Chrome-steel shoes and dies having 8^ inches diameter are used. There are 16 Frue vanners in the mill which concentrate the sulphides, these constituting ly^^j^ per cent of the rock. In the Hector mill the pulp falls from the batteries onto a 4-inch plate and drops to a second plate pitching backward, falling on the lip of the mortar below, in front of which is a 5-inch plate with a |-inch drop to the first apron plate 28 inches wide. The inside plates have been taken from the mortars and every effort made to in- crease the capacity of the mill, while giving the most careful attention to outside amalgamation. Below the first apron plate, the pulp falls into a trough 3 inches wide and 4^ inches deep, discharging through ten I'inch auger holes, then to a 3-inch board and onto plates 24 inches square, arranged in double parallel series. The pulp passes by two drops to two other sets of plates, at the foot of which is a mercury trap. Below the trap are sluice plates with three drops of 2 inches each. These plates are 12 feet long, at the lower end of which a second trap is arranged, from which the pulp goes to the vanners. 165 men are em- ployed in the mines and mills. The Wildman Gold Mining Company, owners. John Ross, Jr., of Sutter Creek, superintendent. Lincoln Mine. — It is at Sutter Creek. This property was worked in early days, a shaft being sunk 807 feet. To a depth of 350 feet, or thereabouts, it is said that the mine paid handsomely. At that depth a fault intersected the vein and all trace of it was lost. The present company re-opened the mine in the latter part of 1898. The old shaft was repaired, the workings cleaned out, and sinking resumed in Febru- ary, 1899. The shaft is now 1260 feet in depth. On the 500-foot level a drift has been extended several hundred feet, and a cross-cut run both east and west about 200 feet north of the shaft. That portion east of the main gangway is in tufaceous slate and diabase, and that to the westward passes through the black tufaceous slates, and then through a broad zone of hard, amphibolite schist, to the black clay slates of the Mariposa beds 315 feet west of the gangway. In this cross-cut are exposed three ore veins, one of which has been drifted for a distance of 168 feet. This vein is 110 feet west of the gangway. A second vein is encountered 135 feet farther west. This vein is from 6 to 20 feet wide, and carries a satisfactory grade of pay rock consisting of quartz and amphibolite schist with disseminated auriferous iron sulphide and free gold. It has been developed by a drift 200 feet long. The third vein lies about 70 feet to the westward of the last-mentioned vein, near the contact of the amphibolite schist and the clay slate of the Mariposa beds. It has not been developed as yet. As there appeared to be Lincoln Mine, Sctter Creek, Amador County. _>^ The Bunker Hii.l Mine, Amador County. THE MOTHER LODE REGION — AMADOR COUNTY. 73 some doubt as to what had occurred at the 350-foot level, when the mine was formerly operated, a careful examination of an old abandoned level extending from the shaft at 400 feet from the surface was made by- Superintendent Voorheis and the writer. An investigation at this point discovered the fact that a fault fissure had dislocated the vein. Cross Section- Lincoln A^ine: . §utferCrecK:-T^+n7ait7 &hafh-_ Pig. 26. The fault strikes nearly parallel with the vein, dipping to the eastward at an angle of about 58 degrees, and appears as a zone of fracture and movement 4 to 6 feet in width. To the eastward of this fault plane the schists and slates and the vein itself all have an easterly dip. Under- neath the fault plane, however, the entire country — schists, greenstones, 74 CALIFORNIA STATE MINING BUREAU. slates, and veins — dips strongly to the westward. In the west cross-cut north of the shaft on the 500-foot level, and in a west cross-cut south of the shaft on the same level, this condition is clearly in evidence. A cross-cut run westerly from the shaft at the 650-foot level shows the formation to be still pitching to the westward, though in a cross-cut at the 800-foot level it is standing nearly vertical, and on the 1200-foot level the formation has assumed nearly its normal easterly dip in the neighborhood of the shaft. On this level, at the face of the cross-cut 275 feet west of the shaft, it has a slight westerly dip. These workings show that the entire formation lying to the westward of the fault plane has been contorted from its normal position, having a westerly instead of an easterly dip, although as depth is attained the formations appear to assume their normal positions. The sketch (Fig. 26) illustrates the structural features of the Lincoln Mine. All the evidence obtainable leads to the belief that the rich vein worked from the surface slipped downward along the fault plane, and that its further extension down- ward must be sought in the country lying to the westward of the shaft, and it is the belief of the writer that the cross-cuts on the 500-foot level have intersected the vein which was dislocated by the fault at the 350- foot level. The mine is well equipped with steam hoist, air-compressors, machine shop, and other accessories, but has as yet no mill. In recovering the old Lincoln shaft, the settling of the ground had forced the shaft out of line, which necessitated the removal of a large amount of ground from the hanging-wall side of the shaft. To keep it in alignment this space was timbered in square sets, the number of the sets varying with the distance from the shaft to the solid ground. This has not been found to give any trouble. In swelling ground, such as is found in this mine and many others in this county, experience has demonstrated the advisability of cutting large stations and placing sets outside of the main station sets ; lagging openly — leaving spaces 8 to 10 inches between the lagging, which preferably, should be light. These light lagging, under pressure from the swelling ground or from a squeeze, will bend and eventually break thus giving sufficient warning before material damage results to the main members of the set. The open spaces are useful in cutting out and removing the swelling ground, and the lagging may be removed if necessary, but the main timbers will only occasionally require resetting or renewing. There are 24 men employed. The Lincoln Gold Mine Development Company of San Francisco, owners. E. C. Voorheis, superintendent. Mutual Mine. — On the summit of the ridge between Sutter Creek and Amador City. A vertical shaft has been sunk on this property to a depth of 400 feet (March 1, 1900). Cross-cuts are being run to prospect THE MOTHER LODE REGION — AMADOR COUNTY. 75 two veins, one of which lies in the black slate on the hanging-wall side of the shaft, and the other in greenstone schist on the foot-wall side. The hanging-wall vein has been reached and good ore found in a drift on the vein. In some surface workings very good ore was taken from the foot-wall vein. The mine has a substantial steam hoist, and is otherwise well equipped for prospecting. There are 15 men employed. Mutual Mining Company of San Francisco, owners. S. R. Porter of Sutter Creek, superintendent. Baliol Mine. — This is 1 mile east of Sutter Creek, and comprises a number of claims on patented agricultural lands, and covers a series of veins in amphibolite schist. An inclined shaft has been sunk to a depth of 750 feet, with levels at 200, 300, 500, and 700 feet and stations at 400 and 600 feet. In a cross-cut run easterly from the shaft, a distance of 380 feet, four of the veins have been intersected; No. 1, the foot-wall vein, is cut at a distance of 110 feet from the shaft, and is about 12 feet wide ; No. 2, 39 feet farther east, is from 7 to 17 feet wide ; No. 3, 35 feet eastward, is 60 feet wide ; and No. 4, 74 feet beyond the last, is 6 feet wide. Since February, 1900, a cross-cut east from the 500 station has discovered higher grade rock than any found in the veins above men- tioned. All stoping is done by means of machine drills. The diamond drill has been used with good results in this property, bore holes driven to the eastward having cut good-sized bodies of ore some distance from the main development of the mine. A large amount of ore has been stoped from three large open cuts, all showing a similar character of ore. The large veins resemble, somewhat, those of the Utica-Stickle mines of Angels. The foot-wall is diabase tuff, slightly schistose. The hanging- wall is also of this character, but farther east are intrusions of granitic rock. A granular-dike rock of light-gray color, much silicified, and containing about 2^ per cent sulphurets, constitutes, together with vein- like masses of quartz, the principal ore-shoots in this mine. Occasionally copper sulphide and arsenical sulphide ores are found. The property is equipped with a 40-stamp mill, the stamps weighing 1100 pounds, drop- ping 5 inches 102 times a minute. No. 35 mesh punched tin screens are used, the discharge being from 4^ to 5 inches high. The capacity of the mill is 4^ tons per stamp. Chrome-steel shoes and cast-iron dies are in use; one shoe will outlast three dies, the life of the shoe being 112 days. Risdon vanners are used for concentration. There is no canvas plant. The plates are 60 inches by 24 feet, with a l|-inch drop. The apron plates are on carriages, and may be rolled away from the front of the battery when necessary to clean up. The plates are dressed as often as neces- sary — usually twice in 24 hours. The proportion of free gold is variable, constituting from 40 to 70 per cent of the values. The sulphurets are shipped to Selby's. The mill and air-compressor are run by water power. The hoist is operated by air, the compressor being located at the mill. 76 CALIFORNIA STATE MINING BUREAU. It has an automatic hydraulic governor, made at the Knight foundry of Sutter Creek. This maintains a pressure at 80 to 100 pounds. The compressor is driven by a water-wheel under 452 feet head. There are 100 men employed. The Western Gold Mining Company, owners. W. H. Storms of Sutter Creek, superintendent. Potazuha Mine. — It is situated 1^ miles east of Sutter Creek, adjoining the Baliol on the west. The shaft has been sunk to a depth of 500 feet on the vein, with a sump 40 feet, by means of a small steam hoist. Levels have been run at 100, 200, and 350 feet; the shaft and levels are on the vein, which varies from a few inches to 12 feet in thickness. The foot-wall portion of the ledge has proven very rich. At the Zeila, Wild- man, and Baliol mills were made several runs of the rock from this foot-wall strip, which have produced about $15,000, averaging about $25 per ton, some of the ore running as high as $100 per ton. The hanging- wall portion of the vein is low grade. The mine is in the hands of a local company, which has spent $40,000 in its development. Heavier machinery will be required to sink to greater depth. At present the mine is idle from lack of funds to properly equip it, although it is expected to resume operations some time this year. The Potazuba Company of Sutter Creek, owners. W. J. McGee of Sutter Creek, sec- retary. Treadwell & Guliana Mine. — This is 8 miles east of the town of Sutter Creek. There are two veins in the property, on one of which, the Treadwell, there are two tunnels, one 700 feet, the other 300 feet in length; besides which there are numerous superficial cuts. The vein is from 1 foot to 12 feet wide, and has produced some high-grade ore. The Guliana vein was discovered in the bed of Sutter Creek, where it is 3 feet in width, showing free gold. There is a 30-foot shaft and a short tunnel on this vein. The mine is idle. The mill which was formerly on the property is dismantled. The mill contained 6 stamps, and was operated by water under 150-foot head with a 10-inch pipe-line. This did not apparently afford sufficient power to run the mill, and it was consequently shut down. Several years later, it is said, it was discov- ered that in some manner a piece of scantling had gotten into the pipe- line, descended by suction to the nozzle, clogging it, and reducing the power to the extent described. M. D. Nixon et al. of Sutter Creek, owners. Free American Mine. — This is 6 miles east of Sutter Creek, on a small vein of high-grade rock in Calaveras formation. In one place it is stated that the vein is 6 feet wide, and that the rock will run $25 per ton, and at the bottom of the shaft the vein is 8 feet wide in good mill- ing ore. The shaft has been sunk to a depth of 110 feet near Sutter Creek, and a drift extended out under the creek along the vein, with the THE MOTHER LODE REGION — AMADOR COUNTY. 77 result that the mine was flooded, the surface water probably coming directly from the creek. The property was provided with both water and steam hoist, a jackhead pump and a steam pump, both of which were operated as vigorously as the power would permit, in addition to bailing with the skip at the same time; but this combination failing to lower the water in the shaft, operations had to be abandoned. A light 10-stamp mill forms a portion of the equipment of the mine. Wilfred Dennis of Sutter Creek, owner. South Spring Hill Mine. — This property adjoins the Keystone on the south, and is in many respects similar to it geologically. After an idleness of about seven years, operations were resumed in June last, and at this writing (June 10th) the mill is about ready to start. It is said that good ore is being found at the north end of the mine. — South Spring Hill Mining Company, owners. John R. Tregloan of Amador City, superintendent. Soioth Keystone Consolidated Mine. — This is half a mile south of Amador City, adjoining the South Spring Hill. It is in the prospective stage. — J. A. Mclntyre of Amador City, owner. Keystone Mine. — This is at Amador City, and is one of the most extensively developed mines in the State. There are probably not less than 10 miles of underground workings in this famous old mine; but all work at present is confined to points above the 1000-foot level, although the shaft is 1575 feet in depth. The formation at the Keystone Mine consists of diabase tuff, tufaceous slates, and the clay slates of the Mariposa beds, the latter lying west of the principal veins. To the west of these clay slates, massive diabase is again found. The principal veins, however, are those occurring in the tufaceous slates. The main vein occurs along a fault plane, which has a variable dip from 35 to 65 degrees to the eastward and extending more than 2000 feet in a remarkably straight course. On the hanging-wall side of this fault plane occurs immense masses of diabase material and quartz, which in places is more than 100 feet in width. Considerable portions of this constitute payable ore, although there are large quantities which it will not pay to mine. This great, massive vein forms the hanging-wall of a banded slaty vein, which has produced a large amount of pay rock south of the main shaft. Between the 400 and 600 levels on this vein an immense stope covering a superficial area of 20,000 square feet has been cut, the vein in places being 25 feet in width. There are few timbers and but one or two pillars in this great stope, which has been open for years, which indi- cates how well this ground stands without artificial support. This is probably the largest open stope on the Gold Belt. This was being filled as rapidly as possible during my visit, in order that the large amount of ore known to lie in the overhanging (so called) wall may be mined 78 CALIFORNIA STATE MINING BUREAU. without danger. On the hanging-wall side of these veins is a green- stone formation several hundred feet in width, through which a cross- cut has been run from a neighboring gulch. Sections cut for microscopic study (Nos. 10 and 11) prove this rock to be diabase tuff. Lying between this massive tuff and a broad zone of black tufaceous slate is a dike of crystalline, granular diabase of normal t5'-pe. The tufaceous slates are from 400 to 600 feet in width, and constitute the zone of Assur- ing in which are found the several veins and ore-shoots of the Keystone Mine. The veins all intersect the inclosing rocks in strike and dip, the dip of the slates always being steeper than that of the veins, excepting where disturbed locally. The region of greatest disturbance is found in the western portion of this slate zone. The great quartz vein lying in the hanging-wall side of this zone is from 1 foot to more than 100 feet in width when measured at right angles to its dip. It is made up of great lenticular masses of quartz and brecciated quartz and diabase, having interior fissures or planes running nearly parallel with the strike of the vein. These are usually referred to as walls. Some of these masses are built up by the splicing of the lenses. On the 800- foot level, and a few feet distant in the east wall of this vein, is an interesting though small vein in a reef of pyritic, black tufaceous slate. Through the center of this reef is found a small irregular vein of quartz, with a small gouge and with numerous flat branching seams. The occurrence of arsenical iron sulphides is a marked and persistent feature of this little vein, but a more interesting feature is the occur- rence of pockets of gold, ranging in value from a few cents to over a hundred thousand dollars. The latter was obtained between the 800 and 900 levels. Within the past year, Mr. W. A. Prichard, the superin- tendent, has discovered a number of good-sized gold pockets in this vein. On the 800-foot level a dike of diabase intervenes between the great massive vein and the pocket vein above described, while on the 900- foot level, about 200 feet farther north, the diabase and reef of pyritic slate are passed through before the great vein is encountered. Arsenical sulphide was also discovered on the 900-foot level, in this vicinity. Although no pockets have been found on the 900-foot level, or below it, the indications are that the pocket vein is older than the great vein cutting across it, and that the pocket shoot may be found from the 900- foot level downward in the foot-wall of the great vein. In the large vein are found the widest stopes in the mine. West of this are two veins, separated from each other and the great vein by varying widths of tufaceous slates. These veins were also extensively worked in former years. A careful and detailed study of the Keystone Mine would undoubtedly furnish material for a book much larger than the volume in which this description is found. There are 90 men employed in the mine and mill. THE MOTHER LODE REGION-^AMADOR COUNTY, (9 Keystone Consolidated Mining Company of San Francisco, owners. W. A. Prichard of Amador City, superintendent. Keystone Mill. — The mill consists of 40 stamps, and two Griffin mills. The latter were formerly used in crushing the fine material from the mine, but are at present not in use. The mill is run by water power, and the hoist by steam. The mill is under the direction of C. E. Bunker. The stamps when new weigh 725 pounds. Prior to March 10, 1890, they were dropped 90 times a minute. A Pelton wheel was put in the mill at this time to run the concentrators independently, and the stamps were speeded to about 100 drops a minute, the height of the drop being from 7 to 7^ inches, and the discharge 7^ inches high. Nos, 6 and 7 CoRRUQATtD PLATfc- Chuck Block of- Keystone Mi lu, Ar-lo Device: for re^uiafm^ >^e.i6i-yi- oT discl-jar'd.e. Fig. 27. angle-slot steel screens are used. The chuck-blocks are arranged so as to drop half an inch at a time. A variety of shoes and dies have been tried here, including cast-iron, manganese, chrome, and hammered steel. The capacity of the mill per stamp is 24 to 3 tons per day, varying somewhat with the character of the ore. This low capacity is probably attributable to the light-weight stamps. The inside plate is curved, and 6 inches in width. The apron plates are 52 inches wide and 4 feet long, having a grade of 1^ inches in 12. Below this the plates are nar- rowed to 48 inches for a length of 10 feet, below which they are further narrowed to 30 inches and 24 inches long, with a trap at the bottom. Since February 1, 1900, numerous changes have been made in this mill. On an experimental battery, the chuck-block has been changed 80 CALIFOKNIA STATE MINING BUREAU. SO as to reduce the width of the mortar 2 inches, by placing the screen flush with the main frame. The stamps have been speeded to 100 drops a minute; the discharge has been lowered, and closer attention is being given to outside amalgamation. The apron plate has been widened to 60 inches for a length of 16 feet, and the grade of these plates has been reduced to 1| inches per foot. No water is added outside the batteries, as in all the others, and the inside-battery water has been reduced to the lowest possible amount. The lowering of the discharge would prob- ably have increased the capacity of the mill, but the decrease in the amount of battery water has a tendency to retard discharge. The capacity of this battery is about the same as that of the other batteries, but as a result of these changes, the tailings have shown a marked decrease in value, and it is the intention to adapt the entire mill to these changes. A new chuck-block with corrugated copper plate (see Fig. 27) has been introduced in this mill. Bunker Hill Mine. — It is 1^ miles north of Amador City. This prop- erty is a consolidation of the Bunker Hill and May Flower. On it is a shaft in the May Flower 350 feet in depth. The old shaft of the Bunker Hill was sunk to a depth of 800 feet; it had been closed for a number of years when it was re-opened in the latter part of 1899. The upper portion of the shaft was badly caved, which required a great deal of work to recover. A cross-cut tunnel was driven some years since near the base of the hill to connect with the old May Flower shaft at a station, and a branch driven beyond in the direction of the Bunker Hill. This latter has been continued to the Bunker Hill vein, it being the intention to drain the mine of surface water through this tunnel. There is also a shaft 400 feet deep on the south end of the property. The hanging-wall of the vein is a fine-grained grayish rock (No. 16), in places carrying considerable finely disseminated iron sulphide; this rock is diabase tuff, greatly altered. The slates found in the foot-wall are the result of alteration of tufaceous diabase, and bear the character- istic pitted marks which distinguish this class of slates in Amador. In its early history, the Bunker Hill is credited with a production of about $1,000,000 down to the 700-foot level. The shoots have a southerly trend. The mine is equipped with a substantial steam hoist, but as yet has no mill. 20 men are employed. The Bunker Hill Consolidated Mining Company, owners. C. R. Downs of Sutter Creek, superintendent. Fremont Mine. — This property, 1^ miles north of Amador City, com- prises the Fremont, Gover, and Loyal Lode, 4200 feet on the lode. The principal work on this property is on the Gover Mine, the main shaft of which is down 1500 feet on an incline, being 1050 feet vertical. There are ten levels, and in the lower levels of the mine there are developed large masses of low-grade quartz. In the early part of the present year, a new shaft was started on the Fremont claim. This is an inclined THE MOTHER LODE REGION — AMADOR COUNTY. 81 shaft, sunk at an angle of 51 degrees below the horizon. It is started in the hanging-wall of the vein, which it is calculated to intersect in depth. The close proximity of the old flooded works of the Gover will probably render the sinking of this new shaft a difficult if not dangerous operation; at least such has been the experience of others who have attempted to sink new shafts in the vicinity of old flooded workings. Gover Consolidated Gold Mining Company, 10 Market street, San Fran- cisco, owners. C. E. Purington of Amador City, superintendent. Phoinix Reduction Works (Chlorination). — This is at Dry town, and consists of a single reverberatory furnace, with all the essential vats, etc., for a complete plant of the Plattner type. (No barrel chlorination is practiced in this State.) The Dry town plant has a capacity of 3 tons daily, and treats custom ores only. There are 5 men employed. E. S. Barney of Drytown, owner and superintendent. In the chlorination process as practiced in Amador County, the auriferous sulphides which are derived from the ores by the various methods of concentration, are charged in reverberatory furnaces usually containing about 10 per cent moisture. The charge is moved forward on the hearth every eight hours, and a new charge introduced. These furnaces are from 60 to 65 feet in length and from 11 to 14 feet wide. Pine wood is used for fuel, the quantity required per ton of sulphides being one fourth to one third of a cord. The charge of ore ranges from 2000 to 2500 pounds. Three charges are introduced every twenty-four hours. A '"dead roast" is absolutely essential to a complete and suc- cessful extraction of the gold. Dampers are provided in the stacks, which are manipulated with the greatest care. When the sulphides take fire, and following the volatilization of the arsenic, should any be present, but while sulphur still remains, salt is added. After the pulp has been withdrawn, it is allowed to cool and is dampened, the proper amount of moisture being determined by com- pressing a quantity in the hand. If it fails to crumble, it contains too much moisture; if it crumbles rapidly, the amount of moisture is insufficient; but when the compressed ball slowly disintegrates, it is considered to have the proper amount of moisture. The pulp is charged in vats by being shaken over screens, the charge being from 4 to 6 tons. Chlorine gas is generated in lead-lined vessels, the following materials being employed: salt, 50 to 60 pounds; manganese dioxide, 30 to 40 pounds; sulphuric acid, added as long as gas is generated. When the vats have been charged with pulp, the gas is turned in, passing ,upward through the false bottom of the vat, penetrating the charge, and event- ually reaching the surface. Tanks are gassed until it shows near the surface of the charge, which usually occurs in from three to five hours, when the cover is luted on. The gas is shut off when it appears on the 6 — MB 82 CALIFORNIA STATE MINING BUREAU. surface. This period is determined by holding a bottle of anamonia near a small vent in the cover. Upon the appearance of the chlorine gas through this vent, a dense cloud of chloride of ammonium at once forms- Water is introduced through a hole in the cover, falling on a burlap sack. It is a common practice to allow the water to stand from one to two hours, when it is turned into the precipitating tank. The water is permitted to run until the iron sulphate solution fails to show the presence of gold, samples being taken from the vat. If the assay of samples shows that high values remain in the pulp, it must be removed from the vats and "regassed." The leaching vats are provided with a double floor; these are made with slats 1^ inches in width placed 18 inches apart. Upon these and at right angles to the first are laid 1-inch boards 4 inches wide, covering the bottom; these are 2 inches apart. Upon this floor is placed a quantity of quartz gravel (clean creek gravel being preferred), usually laid in courses, to a depth of about 6 inches. Upon this filter are laid the shoveling boards, 4 inches wide and 1 inch in thickness, they being separated by a space of 1 inch. These spaces are filled in with fine gravel which will pass a No. 12 screen. A solution of iron sulphate is employed to precipitate the gold from the chloride solution. The precipitate is washed and smelted with borax. Centennial Mine. — This property is 1^ miles northeast of Drytown. An inclined shaft has been sunk 565 feet, and sinking was in progress in April last. This shaft, started on the vein, passes into the foot- wall, and cross-cuts are run to the vein at the 150, 250, and 350 levels. On the first the vein was found from 8 to 8 feet wide; on the second, 18 feet; and on the third, about 2 feet. The shaft will be continued to a depth of 1000 feet. The formation is greenstone schist (after diorite). Centennial Mining Company, owners. L. A. Gross of Drytown, superintendent. The formation from the neighborhood of Drytown to Plymouth is largely amphibolite schist and diorite, tufaceous slates, and Mariposa clay slates. Many veins of quartz occur, both large and small, and also zones of amphibolite schist with quartz. There are many prospect holes of various depths throughout the region, but with the exception of those here mentioned, no operating mines. Plymouth Consolidated Mine. — This property is at Plymouth, and has been idle for many years, but within the past year the old dumps have been worked with profit in Huntington mills. These dumps were estimated to contain over 250,000 tons of rock. The reduction plant consists of four 5-foot Huntington mills with hydraulic sizers, Wilfley and Woodbury concentrators, and canvas plant. Power is furnished by water from the Hayward ditch under a head of 572 feet. The dumps THE M0THP:R I-ODE region — AMADOR COUNTY, 83 were moved at very low cost by cutting in at their base* and running an open cut directly into the end of the pile of rock. When a face of suf- ficient size had been exposed, a movable chute was placed against the face, by means of which all the rock above the level of the chute was easily delivered to cars beneath the chute. The rock was trammed to the mill, hoisted in the car by means of a hydraulic elevator, dumped onto the grizzlies, from which it passed to the rockbreakers, falling into a bin. From the bin, the rock was delivered to automatic feeders, thence to the mills. Diagonal slot screens from 12 to 20 mesh are in use. From the mill the pulp flows to the sizers, from which the coarse material goes to the concentrating tables and the slimes to the canvas plant. The principal source of value in the dumps is in the sulphurets, which average about 1| per cent. The free gold is caught with the concentrates, which are shipped to Selby's. The following statement is made by the manage- ment relative to the cost of working: Thirty Days' Milling, 3750 Tons. Cost of delivering rock to mill |375 00 Milling, including canvas plant 510 00 Water - 240 00 General expense 110 00 Total _.. $1,235 00 Total cost per ton 32 The New Western Mining and Reduction Company, owners. T. C. Woodworth of Plymouth, superintendent. Pocahontas Mine. — This property is 1^ miles east of Drytown, and includes the Pocahontas, Edson, and California, the owners holding a bond on the Maryland claim adjacent. A vertical shaft has been sunk on the Pocahontas to the depth of 620 feet, with six levels. The forma- tion is practically a black tufaceous, pitted slate, to the west of which lie the Mariposa clay slates. Over 1000 feet of cross-cuts have been run, extending from the Mariposa slates on the west to massive diabase on the east. The property is provided with a good steam hoist, and a 10-stamp mill run by water power. There are 6 men employed. The Pocahontas Improvement Company of Drytown, owners. Allen Mc Wayne of Drytown, superintendent. Pioneer Mine. — It is 1 mile south of Plymouth, and comprises a mile on the lode, which consists of two veins; the east or hanging- wall vein of massive quartz, and the west vein banded structure. The latter is usually the better vein. These veins occur in the black tufaceous slates An inclined shaft has been sunk 500 feet on the foot-wall vein, and in the several levels three shoots of ore have been developed. In some respects these shoots of ore are similar to those of the Central Eureka at Sutter Creek. The lower workings of the mine, however, are in low- grade ore, and appear to have reached a zone of little or no pay rock. 84 CALIFORNIA STATE MINING BUREAU. which seems to be a peculiar characteristic of many of the most impor- tant mines of Amador County. Geologically, the outlook for the future of the Pioneer Mine may be considered as encouraging, as there is no reason to anticipate that it may not at greater depth repeat the experi- ence of the Kennedy and Argonaut, Central Eureka, and other mines in this county. Dr. Thomas Boyson, owner. Philadelphia Mine. — It is 4 miles north of Plymouth, near the Bay State. Several years ago this mine was opened by means of a large cut and drift, when operations were suspended, and the mine remained idle until the spring of 1900, when a new double-compartment shaft was started 1000 feet south of the old open cut. This shaft had reached a depth of 80 feet early in June. Its hanging- wall is diabase; the foot- wall is black slate. The vein formation is 20 feet in width. There are kidneys of good rock on the foot-wall side. The shaft is equipped with a water-power hoist, capable of going 1000 feet. J. J. Crawford, Claus Spreckels Building, San Francisco, owner. Leased to -J. R. Roaf et al. of Toronto, Canada. Ivanhoe Mine. — It is H miles northeast of Plymouth. The mine occurs in a zone of amphibolite schist, and is developed by a ver- tical shaft 130 feet deep, and also by an inclined shaft 120 feet. It has a 20-stamp mill and a steam hoist. It has been described in former reports, and was closed down in the spring of 1900. Under bond to the Ivanhoe Gold Mining Company of Salt Lake. E. Brent of Sutter Creek, superintendent. Shenandoah Mine. — It is 1^ miles northeasterly from Plymouth. This interesting vein adjoins the Red Cloud, described in former reports, on the south. The formation is diorite, which, near the vein, is altered to amphibolite schist. The shaft, early in May, had reached a depth of 375 feet, partly on the vein, but the lower portion in the foot-wall. Drifts were run at the 200 and 375 levels, the latter from a cross- cut. There are two veins in this fissure, one a massive vein of quartz, the other a banded or ribbon vein. On the south side of the shaft the banded vein lies on the hanging-wall side of the fissure, but on the north side it is found on the foot-wall side, being separated from the massive vein by a small gouge. The massive vein appears to be the older, it having been broken and crushed by the movement of the rocks. The banded portion of the vein, however, is quite regular, and shows no structural indication of disturbance. In addition to gold, there are found iron, lead, and copper sulphides. The shaft has been sunk between two shoots of ore, which have a southerly trend. The mine is equipped with a steam hoist, but has no mill. There are 12 men employed. Shenandoah Mining Company of Sacramento, owners. S. K. Thornton of Plymouth, superintendent. THE MOTHER LODE REGION — AMADOR COUNTY. 85 Red Cloud Mine. — It is 14 miles northeast of Plymouth, adjoining the Shenandoah on the north. It has geological characteristics similar to those of the Shenandoah. It is idle. The shaft has been sunk to a depth of 365 feet, the upper portion of which was caved at the time of my visit. The surface croppings are exposed in cuts, and show two veins striking N. 13° W. and dipping 65 degrees to the east. The shaft appears to have been sunk at a point where a fault has displaced the vein, giving the appearance of two veins, whereas there is really but one. The Red Cloud Mining Company of Stockton, owners. Gowanus Mine. — It is 2 miles northeasterly from Plymouth. In this property there are several large lens-like masses of quartz striking through a much foliated amphibolite schist. These lenses have a width of from 1 to 8 feet, and occur across a zone of 150 feet or more in width. They appear to converge northward. The ore is granular, and of a dark blue color resembling some quartzite. It is said to mill $8 per ton. A three-compartment shaft (vertical) was being sunk during the spring of 1900, which was calculated to reach the vein at a depth of 200 feet. At this mine was found an unusual arrangement of a hoist- ing plant. The hoist, which is run by steam, is set opposite the end of the shaft instead of at the side. This was done with a view, it was explained, of leaving the ground for a permanent hoisting plant unobstructed, and of permitting the temporary plant to be operated until the new hoist could be placed in position. There are 8 men employed. Gowanus Mining Company, owners. Mr. Rogers of Plymouth, superintendent. Bay State Mine. — It is 4 miles north of Plymouth. There are several veins in this property. That known as the Bay State vein was formerly worked by the Ba}^ State Company to a depth of 830 feet; it was stoped from the 400 to the 600 level. At the 750 level a cross-cut was run east to the vein and two shoots of ore developed, one dipping north, the other south. The north shoot is a banded vein, the south more massive and mixed with slaty material. The sulphides found in the south shoot were high-grade in gold. At 460 feet west, on the 750-foot level, a west vein was discovered in the cross-cut, which is called the Kretcher vein. This vein was observed at a point 346 feet west of the shaft on the 300-foot level. The Kretcher vein has been developed for a distance of about 300 feet, and consists of banded quartz of good grade. At the time of my visit some improvements were being made in the shaft, but the mine was not in full blast. The shaft will be sunk an additional 300 feet. The mine is equipped with a good hoist, and has a 10-stamp mill and an 8-drill air-compressor, all run by water. The pumping is done by air. The mill has a capacity of 40 to 50 tons daily. A 24-mesh punched tin screen is used. The pulp passes directly from the battery to the vanners, of which there are four. The tailings 86 CALIFORNIA STATE MINING BUREAU. are stated to contain but 21 cents per ton, chiefly in free gold. The sulphides are shipped to the Drytown chlorination works. There are 12 men employed. The Globe Mining and Milling Company of Stockton, owners. .J. L. Bryson of Plymouth, superintendent. Rhetta Mine. — This mine is about 4 miles north of Plymouth, adjoin- ing the Bay State on the south. It is developed by means of a cross-cut tunnel about 600 feet in length. There are two veins on the property. One occurs at the contact of a diabase foot and a black slate hanging; the other branches out from this contact vein, striking northward in the hanging-wall slates. Both of these veins have been explored with satisfactory results, the ore being hauled to the Bay State mill at a cost of 30 cents per ten. A large amount of water is encountered, but this causes little trouble, as it passes out through an adit tunnel. From the Rhetta vein southward in the direction of Plymouth, a line of springs marks the occurrence of fissures at or near the contact of the slates with the greenstone, and although this section affords a good field for pros- pecting, very little has been done toward exploring. There are 8 men employed. Rhetta Gold Mining Company of Stockton, owners. J. L. Bryson of Plymouth, superintendent. Talc Mines. — About 6 miles west of Sutter Creek is an interesting occurrence of gold in foliated talc schist, which appears to be a structural alteration of serpentine. On the Tonzi and Waechter ranches there are several zones of this talcose rock, in which the gold occurs in extremely thin plates in the foils of the rocks, much of which is thin as the finest gold leaf; while presenting the appearance of richness, gold of this character is very deceptive. On the Tonzi ranch, Mr. Tonzi has erected an ingenious device for crushing this ore, and claims to have taken out considerable gold at various times from the best selected gold-bearing material found on his place. That this gold-bearing talc can be profit- ably worked, is extremely doubtful; it is possible that if a zone of sufficient size, carrying $5 or more per ton in gold of the character described, could be found, it might be profitably treated by some modi- fications of the cyanide process. Azula Mine. — This is 3i miles northeast of lone. It is a pocket mine in diabase, and has been worked with considerable success by its owners. Mining here is carried on in rather primitive fashion, but evidently with satisfactory results. The vein is from 16 to 18 inches in width, the small stringers going into the main fissure from the hanging- wall. Three men employed. Adams, Burris & Smith of lone, owners. Nugget Mine. — This property is near the Azula, and is similar to it. It has a small steam hoist, and a 5-stamp mill has been constructed since my visit to the property; it was idle at that time. -Dr. Adams et al. of lone, owners. THE MOTHER LODE REGION — AMADOR COUNTY. 87 Queen Mine. — This is in the same group with the Azula and Nugget, and is geologically similar to the others. It has a small steam hoist. Newman, Bagley & Frates of lone, owners. Ranlett Copper Mine. — It is located 3 miles northeast of lone. The ore-bodies occur in the greenstone schists in which are found many of the copper mines in this State. The ore is that most common to copper mines in the West, and is amenable to treatment by various smelting methods. The development of the mine, while not extensive as com- pared with the great gold mines of the State, is sufficienth'' so to show that it is a mine of considerable possibilities. An examination of the mine and maps, together with the statement made by Colonel Ranlett, indicates about 30,000 tons of ore in sight, including that now on the dumps. The ore may be divided into two classes: a vein of solid, mass- ive, yellow sulphide copper ore, distinctly separated from the adjoining rock, and in the foot-wall a zone of variable width, from 4 or 5 feet to 15 feet or more, in which occurs a large amount of iron sulphide, with a small percentage of copper sulphide. In this zone there are segregated bands of ore above the average of the zone in value, and which by rough sorting may afford a valuable product, though, of course, not so high a grade as that found in the massive vein. This ore contains considerable silica, and may become valuable as a flux in treating the more massive ore. The levels already opened are practically without cross-cuts; at least, such as have been made are not in ore, and others should be made in the foot-wall for the purpose of determining more fully the extent and value of the low-grade zone. Manila ropes are in use in this mine, steel ropes not having given satisfaction in former years; but I believe that as so many years have elapsed since steel ropes were employed here, it would be found that the modern steel rope would prove superior to the large, cumbersome Manila ropes now in use, even in the present old crooked shaft. I am positive that such would be the case in the proposed new shaft, which would be sunk at a uniform angle. A water-jacket smelter of 100 tons capacity daily was built at this mine during May and June, 1900. Not yet blown in, June 10, 1900. H. G. Ranlett of Ranlett, superintendent. 88 CALIFORNIA STATE MINING BUREAU. EL DORADO COUNTY. This county, which in past years has produced a very large amount of gold, is at present passing through a temporary period of inactivity, due partly to scarcity of water and to other causes not wholly apparent. There have been in the past in this county, and there are still, mines of undoubted merit, a statement abundantly proven by its history, and that the mines of El Dorado are exhausted cannot be entertained. Some large and extensively equipped enterprises have come into prominence and have been shut down since our last report, but the fact that there are those who have been led into unprofitable investment by reason of the exercise of too little caution should not, and probably Avill not, deter others from engaging in the legitimate pursuit of mining enterprises in this county on more conservative lines. No mining county in California, and no mining region on earth, is wholly free from these monuments of men's folly. It is a fact that in no county in California has mining _ been carried on at less expense than in some of the mines of El Dorado, and it still offers abundant legitimate and promising opportunities to those with both the capital and experience to handle large low-grade mines. In passing northward from Amador County into El Dorado, the Cen- tral Gold Belt, or so-called Mother Lode, appears to split up. The geo- logical conditions for adistance of five miles in El Dorado County are not wholly dissimilar from those of Amador, consisting essentially of massive outcrops of white quartz at or near the contact of slaty rocks and massive greenstones. These heavy outcrops of quartz are rarely gold- bearing in amount sufficient to constitute payable rock, and they are frequently accompanied, as elsewhere along the Gold Belt, by veins having a slaty structure, in which the gold contents are sufficiently high, in some cases at least, to afi'ord profit. When the neighborhood of the German Mine is reached, 5 miles north of the Cosumnes River, we find a new and strange intrusive rock — one with which we are not familiar in the region farther southward. A study of this region shows that in proceeding northward some of these rocks are of granitic type, ranging through grano-diorite and diorite to quartz-porphyry, and other porphyritic rocks. As we go farther northward, the rocks of this character increase in area, until in the neighborhood of Placerville they largely dominate all other kinds, although the rocks with which we are familiar farther southward (the greenstones) may still be found. On a prominent hill just north of the THE MOTHER LODE REGION — EL DORADO COUNTY. 89 Church Mine are large masses of rock of granitic type, of which a care- ful investigation was made. The granitic outcrop was found to be half a mile in width, striking with the general trend of the country in a northeasterly direction. On the eastward, large masses of diabase and amphibolite schist are found. A number of rock specimens were collected from various portions of this mass, and slides were prepared and studied by Mr. H. W. Fairbanks of Berkeley, whose report accom- panies this bulletin. This investigation shows that specimens selected at any particular portion of the mass, and assumed to represent the entire intrusion, would be very misleading, for, in the several slides made from specimens taken from difierent portions of the hill, we find rocks of a decided acid character, and also those of basic kind, with many intermediate phases. (Nos. 30, 31, 32, and 33.) The specimens Nos. 26, 27, 28, and 29 are of similar rocks from Logtown and vicinity. In some, hornblende is abundant, and in others augite is a prominent constitutent; in still others, both of these bi-silicates appear. Some of the rocks have abundant free quartz, in others none is visible to the unaided eye. They also vary greatly in the kind and amount of feld- spars they contain. Southward from this hill, in the direction of the German, Pocahontas, and Starlight mines, and the country about Log- town, are numerous intrusive dikes, large and small, of rocks of the above described characteristics, and in some of the masses rich gold- bearing deposits or veins have been discovered and worked, notably in the Pocahontas at Logtown. In the neighborhood of Placerville is found, near Diamond Springs, and extending nurthward beyond Placer- ville, another section of the great dolomitic vein which is characteristic of the Central Gold Belt in Calaveras, Tuolumne, and Mariposa Counties. Here is seen the same broad zone of dolomite, or ankerite, in which occurs an abundance of the beautiful, scaly, micaceous mineral, mari- posite. Although the Pacific Mine in Placerville has been idle and inaccessible for many years, the old dumps clearly show the character of the geological formation. In this mine the ankerite has been com- pressed, sheared, and deformed, the original material being altered into a perfect talc schist. When this occurs, mariposite usually disappears, or, if present, cannot longer be detected by its characteristic green color. Serpentine also accompanies this belt, which is not an uncommon accompaniment southward. In the Pacific Mine, the serpentine is frequently found altered to a dark-green talc schist, which may be readily distinguished from the white schist resulting from the altera- tion of the dolomite. The black slates found associated with the mineral veins between the Cosumnes River and Placerville are chiefly the result of the altera- tion of diabase tuffs, which has been described at length in the intro- ductory paragraphs of this bulletin. Mariposa clay slates are also 90 CALIFORNIA STATE MINING BUREAU. found. Owing to the very unsettled state of the weather and the diffi- culties and delays attending transportation in March, the investigation of this section was not carried north of Placerville until the summer season. German Mine. — It is 5 miles south of El Dorado. This was the first accessible develojDed mine going northward last spring in El Dorado County from Amador in which we find a material change in geological conditions. The general formation of the country consists, as it does farther southward, of massive diabase tuffs, amphibolite schists, and the clay slates of the Mariposa beds. Here we also find the black slates resulting from the alteration of the diabase tuffs which have been pre- viously described as being intimately associated with the ore deposits of the principal mines of Amador County. The gold-bearing veins of the German Mine are found inclosed in these tufaceous slates, and the vein structure does not differ materially from the veins of Amador. The clay slates of the Mariposa beds lie both to the eastward and to the westward of the main fissure, but not in contact with it. The most striking geological feature of this mine is the intrusion of acidic dikes, which present various phases ranging from quartz-porphyry to granite. There were evidently several intrusions of difierent ages. These intruded dikes have been sheared and have suffered deformation in a manner similar to that characteristic of the altered diabase. These dikes in width vary from a few feet to more than a hundred feet, and in more than one place the larger dikes were found to contain zones of crushed material into which free silica has infiltrated, together with iron sul- phides and gold, but to what extent the zones are gold-bearing has not as yet been determined. One intrusive mass which attracted my par- ticular attention was found above the 100-foot level. It has been intruded from the southward into the slates, and, as viewed in the mine excavations, it looks like the stern of a great ship as it appears when lying in drydock. A banded, slaty vein follows around this peculiarly curved intrusion, having the granite on one wall and the slaty tuffs on the other. The mine is equipped with a water-power hoist and a mill of 10 stamps. The stamps weigh 950 pounds, and drop 6 inches, 100 times a minute. The discharge is 7 inches high, and a 30-mesh brass wire screen is used. This mill has a capacity of 3^ tons per stamp. Below the battery plates, a shaking-riffle table has been introduced for the purpose of saving any amalgam escaping the plates. It is said to give satisfaction, A Wilfley concentrator is employed to concentrate the sulphurets, which constitute about H per cent of the ore. These are shipped to Selby's reduction works. German Mining and Milling Company of San Francisco, owners. C. 0. Richards of El Dorado, superintendent. THE MOTHER LODE REGION — EL DORADO COUNTY. 91 Buena Vista Mine. — It is 1 mile east of the German Mine, and 5 miles southerly from El Dorado. The veins are found in Calaveras for- mation — mica schist at this place. A small vein running parallel with the strike and dip of the schists has been followed for some distance in search of pockets, with satisfactory results. A former operator who prospected this mine, in some way was misled as to the value contained in a schistose zone impregnated with iron sulphides, and expended nearly .$50,000 on the property, doing considerable development work, erecting numerous buildings, and a mill. The rock proved almost valueless, and the mine was closed. The present owners, however, are doing well. C. 0. Richards of El Dorado, owner. Grant Hill of El Dorado, lessee. Last Chance Mine. — This vein is 1 mile east of Nashville, and is from 1 to 8 feet wide, occurring in the slates of the Calaveras formation. The vein has a beautiful ribbon structure, and has been developed by a tun- nel driven on the vein. A light-colored dike accompanies the vein. The property is equipped with a 2-stamp mill run by gasoline engine. The property is idle. A. C. Smith of Portland, Oregon, owner. H. E. Smith, in charge. The Center Mine. — Owned by a New York company, and is near the Last Chance. Idle. The Nashville Mine. — This mine is south of the Last Chance, and is equipped with a steam hoist. Idle. E. J. Baldwin of San Francisco, owner. Madelina Mine. — It is 5 miles south of Diamond Springs. This vein or zone is from 40 to 60 feet in width, in the Calaveras formation. There is a gouge and dike rock on the foot-wall. The ore is pyrrhotite, chalco- pyrite, and pyrite with gold. The ore is extremely hard, and a great portion of it contains a very large percentage of the sulphides mentioned. It offers a problem in economic metallurgy. The vein is developed by means of a cross-cut tunnel 90 feet to the vein, and a drift along the foot-wall 100 feet, connected by a raise 105 feet to the surface. Will- iams & Bier of El Dorado, owners. Noonday Mine (Copper). — This property, near the Madelina, when visited, was simply a prospect having a 15-foot shaft and several open cuts on a 7-foot vein consisting chiefly of iron and copper sulphides, the latter ranging from a trace to 25 per cent. It may be considered a promising prospect. Bonded to Dr. Procter of Placerville. Montezuma Mine. — At Nashville. This property after an idleness was about to start up in the spring of 1900. J. C. Heald of Nash- ville, owner. 92 CALIFORNIA STATE MINING BUREAU. Union Mine. — It is 3^ miles southeast of El Dorado. It was formerly known as the Springfield, and was operated by Alvinza Hayward to a depth of 1700 feet. Within the past two years the mine has been operated by a company, and a 30-stamp mill built. On another group of mines in the vicinity a new shaft was being sunk in March, 1900, and though less than 100 feet in depth, a 20-stamp mill was being erected. These properties are under the management of A. Harpending, and were the only ones visited during the season where inspection was denied and information refused. It was currently reported that a large amount of gold was being taken out, but I was unable to confirm this report. There are 45 men employed at these two mines. A. Har- pending of El Dorado, superintendent. Church Mine. — It is located 8 miles south of Placerville, and 2^ miles from El Dorado. Three veins occur in the slates; they are well defined, and have hard walls and a gouge on both foot and hanging walls. The two veins mostly developed are of variable thickness, laminated, and carrying considerable sulphurets. There is also an east vein, known as the Union, which is being worked near the south end of the property on the adjoining Union Mine. Surface prospects on this lead in various places give a result of from $2.35 to .$26 per ton. The vein worked by the former company was termed the Kidney vein, and has been worked to a depth of 1350 feet, taking out the best of the ore and leaving the low-grade ores. This vein averages 5^ feet in width, and the rock taken from it milled from $28 to $30 per ton. The prospective value of the mine is based on the value of the west vein, first discovered on the 350- foot level while sinking the shaft on the Kidney vein. There were milled from this ledge 3000 tons of ore taken from the various levels from the 350-foot to the 1200-foot level, which returned $2.50 per ton free gold and about 2 per cent sulphurets, worth $67 per ton; the tail- ings, owing to a lack of facilities in the mill, averaged $1.27. This vein in many places is from 14 to 20 feet wide, averaging 8 to 10 feet. The main shaft is 1200 feet deep vertically, with a 40-foot sump, and has three compartments. Stations are cut at each level. The mine is equipped with a water-power hoist, and is provided with 3000 feet of steel cable. The compressor has a capacity of five 3-inch drills. The pumping plant, consisting of plunger and jack-head pumps, has a capacity of 150,000 gallons per day, which is about double the amount of water the mine makes. The mill has ten 950-pound stamps, four Frue concentrators, clean-up barrel, pans, etc. The machinery is run by water power taken from a reservoir owned by the company; at the mill there is a head of 485 feet. Church Mine Development Company of San Francisco, owners. John Ross, Jr., of Sutter Creek, superintendent. Griffith Mine. — It is half a mile southeast of Diamond Springs and half a mile from the Larkin Mine. Since the last report, this mine, at THE MOTHER LODE REGION — EL DORADO COUNTY. 93 that time a mere prospect, has been elaborately equipped with hoist, mill, etc., and an expensive electric power plant, by a Scotch syndicate. After a few months of active operation, the mine was closed down and nothing has since been done there. It is locally reported that it did not pay. Griffith Mining Company of Glasgow, Scotland, owners. G. P. Gow of Stent, agent. Larhin Mine. — One-half mile east of Diamond Springs. The great dolomitic vein passes through this property, in addition to which there are several other, though less prominent, veins. It is upon one of the latter, which occurs in the hanging-wall slates of the dolomitic vein, that operations are at present being conducted. This vein is accom- panied by a small dike of diabase, and possesses the usual character- istics of veins in slate. The dolomitic vein is 80 feet in width, and is altered more or less to talc schist. The dolomite here appears to contain iron carbonate, and is properly ankerite rather than dolomite. The ankerite vein is also cut by dikes, a feature not observed elsewhere, and the foot-wall portion, for a width of several feet, is impregnated with quartz and pyrite, but no exploration had at the time of my visit been conducted on this mineral zone. There are several small veins in the amphibolite schist of the foot-wall, but these, too, remain unexplored. This mine has a 10-stamp mill, the stamps weighing 1000 pounds, drop- ping 110 times a minute. A No. 1 punched tin screen is employed. The discharge is 9 inches high, and the capacity of the mill under these conditions is said to be a little in excess of 3 tons per stamp per daj' of twenty-four hours. The ore contains 14 per cent of pyrites. These have been shipped to Selby's, but experiments with the cyanide process have demonstrated that the gold can be extracted from the sulphides by this means without preliminary roasting or other treatment. Of the gold obtained by amalgamation, about 55 per cent is recovered in the battery. An ingenious experiment has been tried by the superintendent with a view to prevent scouring of the inside copper plates. This consists of a cast-iron plate having the shape of a segment of a cylinder to fit the copper plate. It is \ inch in thickness, with slots ^ inch in width and 20 inches in length. Within these slots the amalgam accumulates and remains. Concentration is accomplished on a single Wilfley table. A vertical shaft has been sunk 600 feet, and a cage is in use. There are 35 men employed. Larkin Mining Company of San Francisco, owners. G. B. Jacobs of Diamond Springs, superintendent. Selby Mine. — It is 1 mile east of Diamond Springs, near the Larkin Mine. Idle. Marguerite Mine. — It is 1 mile east of Diamond Springs, near the Larkin Mine. Idle. 94 CALIFORNIA STATE MINING BUREAU. Tin Cup and Ribbon Rock Mines. — These mines are 2 miles south of Placerville, and are being operated under bond by A. Hayward of San Francisco. When visited, the main shaft was down 100 feet in "ribbon quartz " 5 feet wide showing gold, and for amount of work done it was considered the best prospect in that section of the country. There are 10 men employed. Since writing the above the shaft has been sunk to 200 feet and a heavier hoist installed. E. A. Davis of Placerville, super- intendent. Gentle Annie Mine. — It is 1 mile north of Placerville. This comprises a property 1000 feet by 1700 feet, covering five parallel veins, of which the principal one appears to be the dolomitic vein, which has been pre- viously described as characteristic of some portions of the Gold Belt. The mine, while extensively developed and equipped with a 10-stamp mill, has been idle since October, 1899, awaiting adjustment of the affairs of the Melton estate. There are two large air-compressors and a hoist, which may be operated by either water, air, or steam. B. G. Parlow of Placerville, superintendent. Revera Mine. — On Texas Hill, 3 miles east of Placerville. This is a drift mine, to which a bedrock tunnel was being driven 900 feet to the channel, which, on March loth, had penetrated a distance of 600 feet- The property is equipped with a mill having a Dodge pulverizer with a capacity of 125 tons daily, running 15 revolutions a minute; there is also in the mill a Krough shaking-riffle. The mill is run by water power under 169 feet head. A self-discharging tank was a feature of the works, so arranged as to sluice out accumulated tailings. Since writing the above the tunnel has reached the channel, and is reported to be in pay gravel. Parker Bros, of Placerville, owners. C. L. Parker, superintendent. Ellen Taylor Drift Mine. — It is 4 miles west of Indian Diggings. Sluicing and piping were in progress in the spring of 1900. There were 11 men employed. A. B. Spree kels et al. of San Francisco, owners. F. J. R. Dawson, superintendent. Umatilla Drift Mine. — This is in El Dorado County, 12 miles north- east of Plymouth, Amador County. The mine has been worked steadily for the past two years. The gravel channel varies greatly in width, and ranges from a few inches to 4 feet in thickness. The gravel is crushed in a Krough hexagonal mill, similar to the Dodge pulverizer, and has a capacity of 250 tons per day. Below this machine is a shaking-riffle, in which the gold is caught. The machinery is operated by water power. Umatilla Mining Company of San Francisco, owners. C. 0. Richards of Ono, superintendent. Placerville Slate Quarry. — It is 1^ miles north of Placerville. Here a quarry has been opened upon a reef of slate 150 feet or more in width. THE MOTHER LODE REGION — EL DORADO COUNTY. 95 standing nearly vertical. A large portion of this slate appears to be of merchantable quality. The slate, after having been prepared for mar- ket, is hoisted to the top of the hill on an inclined tramway, the car being run from the quarry track directly upon the car or giraffe. The tramway is double. On the opposite track from the giraffe is a car carrying a steel cylinder with a capacity of several hundred gallons. This is filled with water at the top of the incline, and when its weight overbalances the weight of the giraffe, carload of slate, and cable, it moves downward, hauling the car up the incline, its speed being con- trolled by a brake at the head of the tramway. The water cylinder discharges automatically at the foot of the incline, when the giraffe and car return to their places at the loading station. This company has taken contracts to furnish slate for the buildings of the Mountain Cop- per Company at Keswick, Cal.; for the Government, and elsewhere. There are 10 men employed. Placerville Slate Company, owners. G. W. Cummings of Placerville, manager, Pocahontas Mine. — It is 3 miles south of El Dorado. The vein, which lies at a low angle with a curving strike, occurs in a feldspathic porphyry (No. 26), through which is scattered many crystals of bronze- colored mica. This peculiar rock when examined in sections under the microscope is seen to be a diorite-porphyrite. The property was at one time well equipped with machinery, having hoisting works and a 10- stamp mill, but these have been removed and the mine has been idle for some time, although at one time producing handsomely. Q. A. Chase of San Francisco, owner. Minnehaha Mine. — This is 3 miles south of El Dorado P. 0., near Logtown. The vein occurs in quartz-porphyry much silicified, and containing a small amount of iron sulphide Avith coarse free gold. The vein strikes N. W. and dips N. E. about 10 degrees below the horizon. There is no parting between the vein and the country rock, the ore passing over gradually to the country rock. In one place along the surface in the hanging-wall was found a zone of porphyry with many quartz seams carrying gold. These were dipping toward the flat vein, but had not been reached in the mine workings. The rock is crushed in a 4-stamp mill. No concentrators were in use; 8 men employed. Minnehaha Gold Mining Company of San Francisco, owner. Froehlich & Perham of El Dorado, lessees. Starlight Mine. — Three miles south of El Dorado. The ore in this mine occurs in large lenses in a much altered, silicified diabase. There are several shafts on the mine provided with steam hoists, and there is a 10- stamp steam mill, which is supplied with ore from the several shafts by means of a rope tramway, having a capacity of 35 tons a day. The ten stamps weigh 1000 pounds each, and drop 6 inches 100 times a 96 CALIFORNIA STATE MINING BUREAU. minute. The discharge is 7| inches high. A No. 8 vertical-slot screen is employed. Concentration is eftected by the use of two Union machines and a canvas plant. The ore contains 2 per cent of sul- phurets — pyrite, galena, and arsenical sulphide. The value, how- ever, is chieHy in free gold. Starlight Gold Mining Company of San Francisco, owners. J. A. Vance of El Dorado, superintendent. Oro Fino Mine. — This property, which has been repeatedly described in former reports, was found working as usual. It is situated 5 miles south of Diamond Springs. The vein, which is 40 feet wide, consists of a dike-like mass of diabase breccia Avhich has become silicified and impregnated with finely disseminated auriferous pyrite. Many small seams of calcite traverse the rock in every direction. Both hanging and foot-wall country are diabase, but little altered even in close prox- imity to the vein. The vein material is extremely hard, and all ground is broken by machine drills, No. 1 Judson powder being used. A vertical shaft has been sunk to a depth of 200 feet, where it turns at an angle of 40 degrees and continues to a depth of 540 feet on the vein. The hoist is operated by compressed air. The mine has a mill of 30 stamps, which weigh, when newly shod, 1250 pounds. These drop 7 inches 105 times a minute. A 40-mesh punched tin screen is used, the capacity of the mill being 85 tons daily. No amalgamation is attempted inside the batteries. About one third of the values are in free gold, which is collected on the outside plates. The sulphides are concen- trated on belt machines, and are treated in a chlorination plant owned by the company. Its daily capacity is 4 tons. A rotary conical breaker of the Gates type, being cast extremely heavy, has been found satisfactory in crushing this unusually hard rock. This mine has recently been shut down. Hay ward & Lane of San Francisco, owners. E. T. Kane of Canyon P. 0., superintendent. Vandalia Mine. — This interesting mine is situated about half a mile northerly from the Oro Fino. It has come into renewed prominence since the publication of the last report. In many respects it is entirely unlike others of the Gold Belt, though mines of somewhat similar character are known in Arizona, Nevada, and other portions of the Great Basin country. A description of the old Vandalia Mine will be found in the Vlllth report of the State Mineralogist. When being worked at that time, the ore was considered free milling, but still so large a percentage of the values was lost in tailings that the character of the mine was essentially the same then as now, though richer. The large ore-shoots developed by the present owners are not amenable to amal- gamation, but the cyanide process, which has been applied in a rather rudimentary manner, has been found to operate satisfactorily. When the present owners first visited the property, they tested the old tailings dumps which resulted from the operations of former owners. THE MOTHER LODE REGION — EL DORADO COUNTY. 97 and these were found to contain upward of $15 per ton in gold. A series of cyanide experiments soon demonstrated the adaptability of this ore to that process. The tailings dumps were first worked, and paid handsomely. Then the ore-bodies were attacked, and work has con- tinued uninterruptedly since. The ore deposits are found in a highly silicious felsite, having a semi-schistose structure, and in many respects are not unlike the quartz schists found in the Calaveras formation, though these latter are gen- erally metamorphosed sandstones, and not of intrusive origin. The ore-shoots average over 80 feet in width and 300 feet in length, and cut both the strike and dip of the inclosing formation. The normal ore is essentially the quartz schist above described, heavily impregnated with iron sulphide, the oxidation of which has produced a mineralized zone extending from the surface to a depth of 100 feet or more, forming a reddish-brown iron cap or gossan. These ore-shoots are reached through adit tunnels, the lowest of which will, when extended, cut the ore-bodies 300 feet below their apex, and tunnels may be run at still lower points. The ore for most part, though heavily mineralized and oxidized near the surface, does not prospect at all in free gold, but always assays. The mill found in operation at this mine was of home construction, made by the owners themselves, and is a rude, though ingenious affair, but not well suited to the class of work it is required to perform. It consists essentially of a revolving hollow cylinder resting upon four wheels or carriers, and provided with iron bars arranged transversely to its length, having about -| inch space between them, similar to the Dodge pulverizer. In the interior of this cylinder are three so-called cams, which are really elevated ribs extending lengthwise of the cylinder and distributed at equal distances. The crushing device consists of three cylinders of iron, each 10 inches in length and 8 inches in diameter. These are connected at their ends by links, iron rods extending outwardly from each end of the connected cylinders to posts situated outside the machine. As the cylinder revolves, the cams, each in turn, lift the linked crushers until, clearing themselves, they fall backward a few inches, crushing the soft ore; this being repeated as long as the machine is in operation. The rock is fed through the open end of the cylinder, passing out between the bars, when crushed fine enough to pass the half-inch space between them. The machine is driven by a belt, power being furnished by a gasoline engine. As a result of this very coarse crushing, extraction of gold rarely exceeds 60 per cent. The cyanide plant is situated about 200 feet from the mill, at the foot of an inclined tramway. The plant consists of two clear-water tanks, two stock-solution tanks, six percolation vats of 10 tons capacity each, two gold-solution tanks, and two sump tanks, together with the neces- sary precipitation boxes. The ore from the mill is delivered to the 7 — MB 98 CALIFORNIA STATE MINING BUREAU. cyanide plant by cars running on a double tram, the cars working in balance. Between the line of percolation tanks is a track running the full length of the plant, with a turntable at the center. The ore is dumped directly into the tanks, and distributed by shoveling at a cost of 25 cents per ton, including the cost of tramming. The cyanide solu- tion is worked at about 0.25 per cent, with a consumption of 15 per cent cyanide. The ore is charged as described, and the solution turned in on top of the charge upon burlaps. It is allowed to stand three hours, when a valve is opened, and a pump connected with the weak solution in the sump tanks is started. This solution is pumped on at a rate equaling the progress of leaching, until the amount of solution charged is equal to the weight of the ore. The percolation process is usually completed in forty-eight hours. In the bottom of the precipi- tating-box an ordinary punched tin mill screen is placed, which keeps perfectly clean and shows no sign of corrosion. The cost of treatment is stated by the owners to be 50 cents per ton. Seymour & Staver, owners and managers, Shingle Springs P. 0. It is stated that this mine has recently passed into other hands, and is to be extensively equipped and operated. Fortuna Mine. — It is 5^ miles south of Shingle Springs, near the Oro Fino Mine. At the time of my visit last spring, the mine and 5-stamp mill were idle, but the owners were building a ditch in anticipation of resuming operations. Hale & Boughman of Canyon P. O., owners. Monitor Mine. — It is 3 miles south of Canyon P. 0. The vein occurs at contact of slate and greenstone. It has a shaft 60 feet deep, with a 50-foot drift at the bottom. The vein is 7 feet wide, and the rock is said to mill $6 per ton. The mine is provided with a steam hoist. C. E. Schenks of Canyon P. O., owner. Spanish Dry Diggings. — At this place, ^ mile northwest of Greenwood, a few men are making a living working the rich seams. No organized operations are in progress. Altman Mine. — Near Greenwood. The property comprises 3000 feet on the lode. The principal development consists of a tunnel 500 feet long, which gives 250 feet backs. The mineralized zone is about 100 feet wide, and is stated to mill -$3 per ton. A strip along the foot-wall, however, runs much higher. A 10-stamp mill formerly on the property burned. Two men are at work John Smith of Greenwood, owner. Gopher-Boulder Mine. — It is 1 mile north of Kelsey. The property was well equipped with electric power, but the generator house on Rock Creek burned. This is to be replaced. The mill contains 20 stamps and two 5-foot Huntington mills; these latV5r are stated to be equal to the 20 stamps in capacity. The vein is frAm 30 to 100 feet wide, but low- grade. A shaft has been sunk on the ^jein 250 feet, and a large open cut has been made in a zone of quartz and greenstone schist. Mining can THE MOTHER LODE REGION EL DORADO COUNTY. 99 be carried on here very cheaply, as the company owns its power. At the Dalmatia, a mile distant, mining and milling were formerly carried on at a cost below 50 cents per ton. The Gopher-Boulder is idle, but it was stated that work would, in all probability, soon be resumed. W. A. Bell of San Francisco, owner. W. H. Husband of Kelsey, manager. Hayward Hydraulic Mine. — At Indian Diggings, on an ancient channel. There is about 150 feet of gravel, overlaid by over 100 feet of volcanic ash . The mine was extensively worked during the spring and summer seasons by hydraulic methods. About 1000 inches of water is employed in washing. Plymouth Consolidated Mining Company, owners. Eureka {Strale) Slate Quarry. — This property, situated near the vil- lage of Kelsey, was in operation during the summer, employing 20 men. Steam-operated power drills are in use. A superior quality of slate is produced at this quarry. Eureka Slate Company, owner. W. A. Winsboro of Kelsey, superintendent. Zantgraf Mine. — It is 7^ miles east of Newcastle, Placer County, and has been in operation for fifteen years. The principal shaft is sunk at an angle of 45 degrees in grano-diorite. It is 1125 feet deep. There are 10 levels open in the mine. Power drills are employed. Two shoots of good ore are on the main fissure, with 300 feet of low-grade rock inter- vening. On the 300-foot level a cross-cut, run 150 feet west, encountered a parallel vein, in which a shoot of pay rock has been developed. The sulphides, constituting -i of 1 per cent, are high-grade, and with increas- ing depth it is stated that the percentage of sulphurets increases with- out any noticeable decrease in free gold. The north shoot on the main vein has been explored for a distance of 300 feet, and the face is still in good ore. The same shoot is being opened on the 300-foot level, where it is 600 feet long, and is also being developed on the 700 and 800 levels. On the 1100-foot level the shaft is in low-grade rock, but the north shoot is expected at the 1200, as it is pitching south. It is 150 feet from the shaft to the south shoot. The property is equipped with 25-stamp mill, and has a duplicate steam plant for both hoist and mill, though depend- ing, under ordinary conditions, upon electric power. The company owns its power plant, whicli is located on the American River half a mile distant from the mine. The machinery was being renewed the past summer at the time of my visit. The stamps in the mill weigh 1035 pounds, when new. A punched tin screen is in use; the capacity is about 5 tons per stamp, with a discharge 5 to 6 inches high. This large capacity is due, of course, to the unusually coarse screen. ^ Montauk Gold Mining Company of New York, owners. Edward Goodwin of Newcastle, superintendent. Jack Hanley Mine. — It is 2^ miles south of Greenwood. Prospecting is in progress. A rocking mill is in use. Four men are employed. C. A. La Graves of Greenwood, superintendent. 100 CALIFORNIA STATE MINING BUREAU. CALAVERAS COUNTY. In this county the mining industry is unusually prosperous, more so than in many years past. There are at work, and paying, no less than a dozen large mines, including three hydraulic mines, besides a great many small concerns, and a good deal of active prospecting is now in progress. Since the last report, a number of new enterprises have started up which are now idle, having proven unsatisfactory to the investors, but there are others which have, in a great measure, redeemed these more unfortunate ventures. Notable among the latter class is the Sheep Ranch Mine, which, after an idleness of nearly six years, has been reopened, and is again an active and, it is said, a profitable producer. The copper mines at Campo Seco are also being operated successfully, and in the Salt Sp'ring Valley at Hodson the Royal Consolidated Mines are being worked on a much larger scale than heretofore. On the whole, Calaveras County may be said to be in a very prosperous condition. The development and exploitation of the new ore-bodies found in the Utica-Stickle and Gold Cliff properties at Angels will give a new lease of life to these important producers, and the operations of the Melones Consolidated Mining Company at Carson Hill will be among the most extensive in the State when carried to completion. Gwin Mine. — It is 6 miles south of Jackson, Amador County. In its earlier history this mine was worked to a depth of 1540 feet through inclined shafts. Operations were suspended in the fall of 1882, and the property remained idle until 1894, when the present operators reopened the mine. A vertical shaft was started in the hanging-wall slates 485 feet from the vein. Work was commenced on May 1, 1894, and has progressed continuously since, with the exception of a period of about four months, when an attempt was made to unwater the old workings by means of a bore-hole to avoid flooding of the new workings from the old. It eventually became necessary to remove the water through the shaft of the old workings. This new shaft has continued to a depth of 1660 feet, having passed through the vein at about the 1200-foot level. There are tanks at the 300-foot level and at the 700-foot level. At the latter a cross-cut was run west from the station 374 feet, through slate to and beyond the vein, the foot-wall of which was reached 124 feet west of the shaft. At the 1000-foot level a cross-cut was run 69 feet west through the vein, which was here 15 feet 6 inches wide, the foot- wall being 58 feet west of the shaft. The foot-wall of the vein was THE MOTHER LODE REGION — CALAVERAS COUNTY. 101 encountered in the shaft 1245 feet from the surface. Cross-cuts in the lower levels run to the westward have encountered two small veins and two dikes of light-gray intrusive rock. The first vein encountered is very persistent in strike and dip, though usually small. It has pro- WFWW/ili MEtTHOD of T)N^3£RIN<^ in (5\A/1N A^lNErr FiG. 28. duced some rich ore. The ore-shoots of the main vein are of great length, varying in width from a few inches to 20 feet. Gouge is always present on the foot, and sometimes on the hanging-wall. The slates have a tendency to swell, and are the cause of considerable expense, 102 CALIFORNIA STATE MINING BUREAU. but cannot be compared in this respect to some of the Amador County mines. The vein is usually banded, and exhibits a branching tendency, there being many spurs running into the hanging-wall, but few into the foot. The lenses of quartz which are characteristic of this vein fre- quently build up a narrow into a large vein by splicing, and sometimes by overlapping. There is some black slaty material in the vein, but less than is found in many similar mines elsewhere. Large masses of the vein quartz are found crushed by pressure and movement, and in some places the quartz disintegrates rapidly from exposure by reason of the slaking of the carbonate of lime, which occurs in considerable quantities. The mine is systematically opened, and substantially timbered with Oregon pine. The framing of timber is mostly done by machinery. Filling for the stopes is usually obtained from the hanging-wall, and broken by machines in chambers excavated for the purpose. Where feasible, inclined raises are put into the hanging-wall, and the chambers opened out from the raise, the rock broken passing by gravity down the incline into the stopes beneath. Where the character of the hanging- wall adjacent to the vein is such as to cause the ground to cave readily, level cross-cuts are run from the stopes into the hanging-wall, and chambers opened out at a safe distance from the vein, the filling being carried to the stopes in wheelbarrows. The Gwin Mine is one of the best managed properties it was my pleasure to visit, everything being done systematically with a view to producing the best economic results. The sketch (Fig. 28) represents the method of timbering stopes in the Gwin Mine. I was told, when at the mine, that the management had under consideration the advisability of running a lateral drift in the foot-wall, and opening the mine something on the lines suggested in the first part of this bulletin, under the head of " Methods of Mining." Geologically, the Gwin Mine presents a striking contrast, when com- pared with the more important mines of Amador County. Here the vein occurs in the smooth, satin-like clay slates of the Mariposa beds, which are absolutely free from the pitted appearance so characteristic of the slates accompanying the ore-shoots of Amador County, which have been fully described under the head of Amador County, and also under the head of " General Geology of the Gold Belt." The formations encountered in sinking the Gwin shaft are diabase-tuff, clay slates, and small acid dike rocks. In the lower portion of the mine, a coarse, tufaceous rock, locally but erroneously called pudding-stone, has been encountered, which has been the cause of considerable difficulty in timbering, in carrying on mining operations. It is the intention of the company to make some changes in their shaft, and to sink to greater depth. What may be developed in this property at great depth is a matter of more than ordinary interest. Its present lowest level still lacks about 1000 feet of being as deep as the Kennedy, and it is a well- THE MOTHER LODE BEGION — CALAVERAS COUNTY. 103 Wedic known fact that the ore-bodies in the lowest workings of the latter show no deterioration in value. Gwin Mine Development Company of San Francisco, owners. J. J. Crawford, secretary, Spreckels Building, San Francisco; F. F. Thomas, Gwin Mine, Calaveras County, superintendent. Gtoin Mill. — The mill at" the Gwin Mine now comprises 80 stamps, and is operated under the direction of Mr. J. E. Taylor. The stamps when new weighed 850 pounds, and drop 6^ inches 92 times per minute. The height of discharge is from 7 to 9 inches, and is regulated by three chuck- blocks. No. 16 brass wire screens are in use, and last one month. The screens 6ci?£C-iM Ff?aM£ s-i'® changed daily, scrubbed and dried, so that practically the screens are daily as good as Qy^ucK ^L.Ocy( new, until worn oiit. The size (^wiN NJiNfe: of the screen opening is 5 inches by 48 inches (discharge area). All screens are secured to small frames, which are inserted above the chuck-block and beneath the front board of the main screen frame, being secured by a wedge. (See sketch, Fig. 29.) The capacity of the mill, under the above conditions, is 4i tons per stamp daily. To prevent scouring of the inside plate an iron rod is bolted to the plate. Its posi- tion is shown in the figure. The pulp from the battery falls onto the iron lip of the mortar, thence by a 3-inch fall onto a narrow board, and (ronfiar ^^j^ence outo the apron plates, which are 48 x 60 inches, set at the grade of 2 inches to the foot. Thence it passes to the sluice plates, which are 24x120 inches, having at the end a trap for the purpose of catching mercury and amalgam. From the plates, the pulp passes to the van- ner distributers, and from the van- ners the tailings go to waste. In the canon some distance from the mill a canvas plant was constructed by experimenters, some time since, but its use was discontinued. The sulphides, collected on the vanners, are heavy, probably coming from the quartz, and the values from the sulphides are largely confined to Fig. 29. 104 CALIFORNIA STATE MINING BUREAU. this class of material. A quantity of fine sulphides escapes with the tailings, which probably come from the slaty material. They are low- grade, and do not even justify the inexpensive further concentration on canvas tables. The concentration plant consists, in the original mill, of sixteen 4- foot Frue vanners, one of which is of special design called the " Gwin." In the 40-stamp addition recently made to the mill there are sixteen 6-foot machines, all of this special design. These machines have an iron frame with cross-rods both longitudinally and transversely of the machine, which gives it great rigidity, and demands little attention when having been properly adjusted. The sulphides contained in the ore range from 14 to 2 per cent. These are shipped to Selby's reduction works. Mr. Taylor states that the tailings escaping from this mill average about 25 cents per ton. The entire plant is run by water power, under a 400-foot head. A 6-foot Pelton wheel runs the 80 stamps, and a 24-inch wheel the concentrating machines. Power is dis- tributed from the line shaft, which is beneath the feeder floor, by vertical belts to the cam-shaft pulley. The power is transmitted from the main wheel to the line shaft by a hemp rope 5 inches in circumference. Space has been provided in the building for an additional 20 stamps, for which there is abundant power. An electric plant has been installed for lighting the property. The mortars in the old mill differ somewhat from those in the new mill, those in the new mill being narrower. The mortars are lined throughout with deep plates and are thoroughly modern. Sheep Ranch Mine. — This is at Sheep Ranch and on the east belt, 17 miles northeast of San Andreas. The mine was operated in former days by Haggin, Tevis, and Hearst, but was closed down in 1893, when a depth of 1200 feet had been reached, after producing about -$3,000,000. It remained idle until 1898, when it was reopened by the present owners, who cleaned out the old shaft, retimbered it, installed a new and heavy plant of machinery, and thoroughly equipped the mine, in the belief that it was not exhausted. They went into the old workings on the 1200- foot level; extended them; drove the Pioche tunnel to a connection with the shaft at the 300-foot level, and started upraises at various points on the 1200-foot level, and began at once taking out rich ore. A new 20- stamp mill has been built; two air-compressors, and an electric plant and machine shop have been provided. The property comprises twenty- one claims, which include five known veins. The formation is a rather coarse mica schist, cut by dikes of diorite and coarse-grained granite. The Sheep Ranch vein, which is, so far as known, the hanging- wall vein of the series, is from a few inches to 3 feet in width, averaging about 18 inches. The ore is generally high-grade, often showing free gold, one shoot in particular now being operated south of the shaft above the 1200- THE MOTHER LODE REGION — CALAVERAS COUNTY. 105 foot level, producing a dark blue, almost black, quartz, rich in free gold. The most of this rock is in demand by the manufacturers of jewelry, it thus paying far better than to crush it in the mill. The quartz usually occurs as a continuous waving vein, or as a succession of disconnected lenses, often contorted and twisted suddenly from its course, and when this occurs visible gold is usually abundant. The accompanying sketch (Fig. 30) represents a characteristic sec- \\»U\\\#i\\\\\\\A\\\\\' \ \V, ^A u ,\ W V \\\^j i \ \^VA\S\ \\\h\\ \\\\\\\V\\ Wm\ mmm 200-({-Lt\/E \\\\\\\WX\\ Vertical Cross SecVion o!^ ^MEE-P I^ANdH /^INE- shoWii^° charac^'eris'Ti d, Veir\ Pornr^a-Hor^. Fig. 30. tion of the Sheep Ranch vein. Each of the several veins in this prop- erty has considerable superficial development. A shaft is being sunk on the Lodi claim, one of the Sheep Ranch group, about 700 feet southwest of the main shaft. It is said that in former years very rich ore was taken from the Lodi vein. All machinery at the Sheep Ranch is operated by steam. Sheep Ranch Mining Company, owners, 320 Sansome Street, San Francisco. D. Gutmann, manager. Veritas {Bode or Fellowcraft) Mine. — At San Andreas. Since the last report, an inclined shaft (at an angle of about 55 degrees) has been 106 CALIFORNIA STATE MINING BUREAU. sunk 200 feet on a vein cutting through mica schist. At the 100-foot level a cross-cut has been run east to a zone of amphibolite schist and quartz, 4 to 8 feet wide. On the 200-foot level a cross-cut has been extended 135 feet east of the shaft to this vein, which is there 8 feet wide. The mine is equipped with a 10-stamp steam mill and water hoist, but is idle. On the hill, back of the shaft, is a zone of mineralized quartz schists, which prospects in gold, and is apparently the most promising part of the property, but nothing has been done with it in the way of development. Veritas Gold Mining Company, owners. F. J. Solinsky of San Andreas, agent. Commodore Mine. — One mile north of San Andreas, on the Mother Lode. A vertical shaft has been sunk 80 feet, thence continuing at an Cross Section showing succession of Pormations at^ (oMMODORfc A)iN&, lrTiile.N.of c>AN-AiNOC{eA&. CalaVeras Co. C-ai_. Pig. 31. angle of 75 degrees to the eastward to a depth of 300 feet. A level had been run north 250 feet April 1st, developing a wide zone of mineralized rock, which in its normal condition is quartz diorite (No. 21). This occurs as a wedge-shaped intrusion, coming from the north. Serpentine forms both the foot and hanging walls of this lode. To the westward, on the Masterson claim, is a broad zone of ankerite, so frequently men- tioned as occurring elsewhere, with its massive quartz outcrop and characteristic mariposite, and to the eastward of the serpentine the formation is a normal diabase. A cross-section is illustrated in the sketch (Fig. 31). The Commodore vein is somewhat of an anomaly in this region. It is a matter of interest to know that the quartz diorite, the alteration and mineralization of which form this ore-body, is almost identical, both mineralogically and in physical appearance, with a dike of quartz- THE MOTHER LODE REGION — CALAVERAS COUNTY. 107 diorite (No. 20) intruding the amphibolite schist in the Union Copper Mine at Copperopolis, in this county. On the hanging-wall side of the Commodore vein is a zone of crushed material, 4 feet in width, in which occur rhombic crystals of dolomite. These, upon being fractured, may be observed to contain visible particles of gold. The mine is equipped with a steam hoist. There are 10 men employed. Commodore Gold Mining Company of Stockton, owners. W. H. Clarey of San Andreas, superintendent. Illinois Mine. — It is 6 miles south of San Andreas, on the Copper- opolis road, near the Demarest Mine. Since the last report it has been equipped with a steam hoist and a 10-stamp mill. An inclined shaft has been sunk to a depth of 200 feet, and two levels opened. There are two veins, one running N. 5° E., and the other N. 30° W., converging northward. The formation is clay slate on the foot-wall, and amphib- olite schist on the hanging-wall. A banded vein occurs at the contact of these formations, and a brecciated gray ore in the schistose portion. Idle. B. K. Thorn of San Andreas, owner. Demarest Mine. — This is 6 miles south of San Andreas, near the road to Copperopolis. It is an old mine, which has been reopened since the last report was issued. An inclined shaft has been sunk to a depth of 640 feet, and still sinking in April, 1900. It has a steam hoist and a 5-stamp mill. A short shoot of very good rock has been encountered in the several levels of this mine, the formation in which it occurs being diabase. A gouge usually accompanies the vein. This, in the northern end of the mine, lies on the hanging-wall side of the quartz, on the 300- foot level. Some distance south of the shaft there is a sudden flexure of the walls of the vein, the gouge passing over to the foot-wall side of the quartz. A second shoot of what is said to be good ore is known to exist under the bed of the creek south of the main workings, but this has not as yet been reached under ground. There are 18 men employed.- The Demarest Gold Mining Company of Angels, owners. T. H. Fullen of Altaville, superintendent. The Ford Mine. — It is three fourths of a mile east of the Mother Lode, at San Andreas. The rock formation is chiefly chlorite schist, resulting from the alteration of diorite and possibly also diabase. The foot-wall (west) of the mineral belt of the Ford Mine is a hard, dense, quartz schist, often impregnated with iron sulphide (pyrite), which is usually auriferous, though at this place to a limited extent. The hanging-wall country is greenstone schist, not materially different from that exposed in the mine workings. There are two other rocks in the mine which lie near the foot-wall. These are, first, a hard, tough, dark-green rock (No. 23), composed of an aggregate of talc scales, often schistose, and in an extreme state of alteration passes over to talc schist and massive 108 CALIFORNIA STATE MINING BUREAU. steatite; second, a dolomitic rock (magnesian limestone), which is also much altered and passes over to talc schist.* This rock greatly resembles the ankerite of the Gold Belt, but shows no green mariposite. These two rocks are of structural importance only, as no ore has as yet been found in them. The Ford Mine may be described as a mineral belt consisting chiefly of chloritic and talcose schists, lying upon a quartz schist foot-wall, and having a hanging-wall of diorite, locally found altered into chlorite schist. The included belt is about 100 feet in width, and within it occurs large lens-like masses of quartz, and also vein-like sheets of quartz. The former are often found mixed with a gray rock which is a portion of the greenstone. These masses of quartz and frag- mentary greenstone are a common feature of many important mines of the California Gold Belt, and often constitute large and valuable deposits of gold ore; but there are many millions of tons of rock seemingly identical, which are of little or no commercial value, owing to the extremely low tenor in gold. In the Ford Mine, as elsewhere, these large deposits contain a variable percentage of iron sulphide (pyrite). The large quartz bodies range from a foot or two to nearly 100 feet in width. There is a small vein near the foot-wall side which appears to possess elements of value, but to what extent it is impossible to say. This vein has a strike west of north, dipping easterly with the main quartz bodies, but not connected with them down to the 400-foot level. This vein and the small feeders of quartz running into it have produced rock of phenomenal richness. It also contains considerable quantities of petzite (gold-lead-silver-bearing tellurium). The gold and tellurium occur, in this small vein and the stringers leading into it, in Avhat is known as an ore-shoot — that is, the distribution of the gold in the vein appears to be chiefly confined to a limited area, apparently 30 or 40 feet in length, and having a trend along the vein downward to the north at about 35 degrees from the horizontal. Gold has been found nowhere else in this vein than along the shoot as described. A persistent characteristic of this vein is the occurrence of thin films of iron sulphide incrusting the cracks and seams of the quartz. In this vein gold was found on the surface; south of the shaft on and above the 100-foot level; in the shaft at about the 100- foot level; in a winze sunk on this level north of the shaft; and in a drift north of the shaft on the 300- foot level, Avhere, I am informed, a $900 pocket was found. The repeated occurrence of the gold and tellurium at the points indicated, shows clearly the downward and northward trend of the ore-shoot. The mine is equipped with a steam hoist and 10-stamp mill. The mine is developed to a depth of 700 feet, and I am informed that the shaft is to *An investigation of similar rocks, near Forest Hill, Placer County, has led me to believe that the two rocks here described represent different stages in the alteration of the same rock. THE MOTHER LODE REGION CALAVERAS COUNTY. 109 be sunk 200 feet more. There are 10 men employed. Ford Mining Company of San Andreas, owners. D. Gutmann of San Andreas, manager. Angels Mine. — Is in the town of Angels, and is the second mine north of the Utica, and presumably on the same vein. It comprises a group of five fractional claims. The mine was worked extensively in former years, but until a year or more since has remained idle for many years. A vertical shaft has been sunk 350 feet, and three levels opened on a zone of amphibolite schist and quartz containing gold and auriferous iron sulphide. Only the north end of the property is in operation. The ore is crushed in a custom mill. The mine is equipped with a steam hoist. There are 40 men employed; 24 in the mine, Angels Quartz Mining Company of San Francisco, owners. 0. S. Buckbee of Angels, superintendent. Lightner Mine. — In the town of Angels, the first extension north of the Utica, and on the same vein. The Lightner is a fractional claim, on which a shaft has been sunk to a depth of 447 feet, and five levels opened. The vein consists of a zone of amphibolite schist and quartz, ranging from 10 to 90 feet in width, and is essentially the same as the Utica Mine, geologically. The gray, granular dike rock, characteristic of the Utica-Stickle Mine, which forms large masses of the best ore of that property, is also prominent in the Lightner. The mine is sub- stantially timbered with a modification of the square-set system. The property has a good hoisting plant, air-compressors, electric machinery, and a 40-stamp mill. The mill is operated by electricity, the hoist by steam. There are 50 men employed. The Lightner Gold Mining Company of Stockton, owners. V. W.' Miller of Angels, superintendent. The Lightner Mill. — This is a modern mill of 40 stamps, run under the direction of J. E. Reaves. It originally contained 20 stamps, but was enlarged to 40. Twenty of the stamps weigh, when new, 955 pounds, and twenty weigh 750 pounds. The height of drop of the heavier stamps is 7 inches; that of the lighter, 7^ inches. The number of drops is about 100 per minute; the height of discharge, 8^ to 9 inches. A No. 1 punched tin screen is used. The capacity under these conditions is about 5 tons per stamp daily (by car measurement). This tonnage is probably due to the peculiar character of the ore, which con- sists of a considerable quantity of chloritic schist and calcite, and sharp grains of quartz, which pulverize readily, the stamp cutting the softer material rapidly. The gold is mostly caught inside the battery. The apron plates are 24 by 48 inches; the sluice plates are divided and are 20 inches by 20 feet. No traps of any kind are in use. There are 20 Frue vanners — twelve 4-foot and eight 6- foot machines. The ore con- tains about 2 per cent of pyrite. The pulp from the batteries is divided, 110 CALIFORNIA STATE MINING BUREAU. but not sized, before going to the vanners. The speed of the concen- trating machines is controlled by means of a cone pulley. An experi- ment was made on a lower discharge (at 7^ incbes), which resulted in scouring of the inside plates. This was discontinued for the higher PocKEtT in ^\ILL c>CREE:N LiGHTNEtR M.ill, Angels, California. P = PocKc+T W. ' Iron Wedges. Fig. 32. discharges now in use. Chrome shoes and white iron dies are in use in this mill. The latter last five months, crushing 750 tons of ore. The concentrates at this mill are worked by chlorination at the Utica plant. An ingenious screen has been invented by Mr. Reaves, which is illus- trated in the accompanying sketch (Fig. 32). The screen is fitted with two pockets at the front, and these may be opened at will, and chips or other foreign matter removed by inserting the hand. The method of securing the screen to the frame is shown in the illus- tration. (Fig. 33 is an Chuck Block illustration of the Lightner chuck-block, with iron rods to protect the plate from scouring.) Utica- Stickle Mine. — It is at Angels. Since the last report, a vertical shaft has been sunk to a depth of 1370 feet. This shaft is located south and east of the old shafts, and is in the hanging- wall schists. It is substantially timbered throughout with heavy sets, and a large, expen- sive hoisting plant has been installed. This machinery sets on concrete foundations, which were constructed in the most substantial manner. For more than a year the lower levels have been flooded in the southern Ljc^htn&rMill. R.R. Iro^f^cds. Fig. 33. THE MOTHER LODE REGION — CALAVERAS COUNTY. Ill part of the property. When the new vertical shaft was completed it was found that the hoisting plant, with the use of which the shaft had been sunk, was incapable of doing more than handle the water coming in at that point, and it was determined to discontinue mining operations in the lowest levels until such time as it became possible to put in a heavy plant that would economically handle both the water and ore. Theorder for the newmachinery was promptly placed, and it should have been in position in August, 1899, but owing to the inability of the makers, the Union Iron Works of San Francisco, to furnish necessary material, due to scarcity of iron, the great hoist was not ready for operation until early in September, 1900. During the past year or more all mining operations in this property have been confined to the upper levels of the mine. The lower levels will now be unwatered and the large new ore-bodies discovered prior to the flooding of this portion of the mine will be worked vigorously. This property also includes the Madison and Gold Cliflf mines, situated half a mile west of the Utica-Stickle group. An extensive electric installation has been added to the Utica Com- pany's plant. The generators are located above Murphys, on the com- pany's ditch-line. The power is distributed to their various properties at Angels, where they also sell power and light the town. The Utica- Stickle and Gold Cliff mills are operated by this power, and also the mill of the Lightner Company, adjoining the Utica. Gold Cliff Mine. — This is one of the Utica group, and is being opera- ted through an inclined shaft 600 feet deep, sunk from the level of the old open cut. Four levels have been opened in this mine. The vein is found in a broad zone of amphibolite schist, with serpentine on the hanging-wall. The ore occurs in several zones, which overlap in the foot-wall going north. On the 400-foot level north of the shaft, the vein splits, being separated by a horse of diabase. Whether or not these diverging veins will re-unite is not known. The ore from the Gold Cliff Mine is crushed in the 40-stamp Madison mill. At the Utica Mine there is a 60-stamp mill, and the Stickle also has a 60-stamp mill, making a total of 160 stamps on the consolidated properties. There are 420 men employed in and about these works, distributed as follows: Utica, 125; Stickle, 90; Gold Cliff, 40; the mills, 25; chlorination and cyanide plant, 30; outside, 110. Hayward, Lane, and Hobart Estate of San Francisco, owners. J. L. Shinn, manager. The Madison Mine has been idle for some time. Utica Mills. — The three Utica mills are under the superintendence of W. J. Loring. The stamps of the Utica mills weigh 780 pounds; those of the Stickle, 835 pounds; and of the Madison, 920 pounds. These drop from 7 to 8 inches 105 to 107 times a minute. The height of dis- 112 CALIFORNIA STATE MINING BUREAU. charge in the Utica mill is 10 inches; Stickle mill, 7 inches; Madison, 5 inches. The Utica and Stickle mills are provided with No. 1 punched tin screens, and the Madison with No. 2. The capacity of these several mills will average about 5 tons per stamp daily. With the heavier stamps and low discharge of the Madison mill, it would be expected that the capacity of that mill would exceed that of the Utica or Stickle, but the Gold Cliff rock is much harder than that of the other mines. Mr. Loring gives the following description of the Utica 60-stamp mill, and the daily routine work, together with method of making monthly clean-up, etc.: The rock, as hoisted from the mines, is dumped at the head of the shaft over a grizzly made of 3-inch round iron bars, 10 feet long, placed 1| inches apart, and set at an inclination of 40 degrees. The bars are supported at each end by an iron casting, with recesses to receive them. Old stamp stems are used in the grizzly. At the lower end of the grizzly the rock passes to a Blake crusher 10 x 16 inches, being fed by gravity. One crusher of this size handles all the rock for the 60-stamp mill. One man is employed here on each ten-hour shift. The crusher and grizzly set over a 50-ton bin, from which ore is con- veyed to three bins of 200 tons capacity each in the mill by means of a dump car. The bins discharge into Challenge feeders. In the Utica mill they have made a practice of keeping on hand a new cam shaft with ten cams in place, which, in event of breaking the shaft, may at once take the place of the broken shaft. In case of such difficulty, much time is saved by this arrangement. The discharge in the batteries is 10 inches high; three differential chuck-blocks are in use, keeping the discharge as nearly uniform as possible. Manganese steel shoes are used; these are 10 inches long, 8^ inches in diameter of face, and weigh, new 177 pounds; when worn out, they weigh but 28 pounds; their life is about 296 days. The dies are made of hard iron, and last 120 days; they are 5 inches high, 8| inches in diameter of face, and 9^ x 9^ inches base area; they weigh 84 pounds, and after using, about one half of this. Round needle punched tin screens are used in sheets 10 x 14 inches; No. 1, or 30-mesh, has been found to give the best satisfaction, and lasts from 15 to 20 days. Before using, these are burned over a moderate fire of charcoal, for the purpose of removing the tin, to pre- vent amalgamation of the tin. This anneals the metal, and makes it a very tough, durable screen. A splashboard made of 1 x 12 inch clear pine, having the full width of the screen, is suspended to the screen frame by two eyestraps riveted to each end of the board and two hooks screwed to the screen frame. A strip of canvas 6 inches wide is tacked to the lower end of the board, to confine the splash to the apron. Underneath the screen is bolted an iron apron, which constitutes a por- tion of the mortar, and being an inch below the lip of the mortar. Ill . ! North Shaft and Mii.i., Utica Mine, Calaveras County. ■ The Keystone Mine and Mill, Amador City. THE MOTHER LODE REGION — CALAVERAS COUNTY. 113 permits the insertion of a rough board 1x12 inches, which lies flush with the upper edge of the lip of the mortar. Upon this the pulp from the screen falls, and it is considered a good amalgamator. After being in use a short time, it amalgamates quickly, but does not stand the jar as well as the copper plate. A splashboard of this kind can be cleaned in one eighth of the time required to clean a copper plate. The board is protected by a 2x6 inch board, extending across the apron, and having a |-inch hole bored at each end to receive two hooks fastened to the battery posts. Four inches below the board, on the apron, runs a trough in which are two apertures 3 inches square, through which the pulp passes to a copper plate 5 inches wide, with a pitch toward the mortar, whence it passes to the sluice plates, 2 feet wide and 22 feet long, covered with yg-i^^ch copper plates set on a grade of 2 inches to the foot. Each battery has two separate runs of these plates, set inde- pendently, provided with wedges to adjust the grade. Before putting on the plates, the tables are dressed down in the center about j-^ inch for the full length. This causes the pulp to run in angular waves across the plate. If the tables are left plain without the center depres- sion, it is a difficult matter to cause the pulp to be evenly distributed over the plate, as it usually flows to one side or the other. The first 8 feet of plate at the upper end of each sluice is raw copper, the remain- ing 14 feet being plated with 2^ ounces of silver to the square foot. The plating is done in the works of the company. The plates are cleaned every morning. A plug of soft wood is driven into one of the 3-inch holes of the cast- iron aprons previously described, causing the pulp to run through the trough and out of the other 3-inch hole discharging on the other plate. The plate to be dressed is first washed with clean water to remove sand then sprinkled with quicksilver, and rubbed vigorously with a whisk- broom for the purpose of loosening the amalgam. About once a week a weak solution of cyanide of potassium is used in dressing the plate. This operation must be done with care, as the application of too much cyanide causes the plates to become glazed and brittle, when they are no longer fit for the use for which they are intended. After the plates have been thoroughly rubbed with a whisk- broom, they are rubbed down- ward with a piece of pure India rubber -| inch thick, 4 by 7 inches in area. The amalgam is then taken up, together with the sulphides which may have adhered to the plates during the twenty-four hours. The plate is then lightly sprinkled with quicksilver at the head, and lightly brushed with a whisk-broom its full length. The last plate is always brushed upward from the lower end, to place any amalgam which should be hanging to the lower edge of the plate in a position where it may be seen and collected. By this method, two men can dress twenty-four 8 — MB 114 CALIFORNIA STATE MINING BUREAU. sluices, 22 feet in length by 2 feet wide, in from one and a half to two hours. For the purpose of saving the rich sulphurets which have adhered to the plates, and which are often worth $10 per pound, the amalgam col- lected each morning is cleaned in a tank used for that purpose only. At the end of the month this tank is cleaned out and the sulphurets are charged with 25 pounds of quicksilver, into an amalgamating barrel of 40 inches diameter and 48 inches long. This revolves for eight hours, at 14 revolutions per minute. The charge is taken out through the head with a dipper, is panned and settled. The amalgam is cleaned in the usual way, and the sulphurets sent to the chlorination works in a wooden bucket. At the lower end of the sluices is a tail-box, having the width of a double sluice, with a drop of 3^ inches, and a width of 5 inches on the bottom. This box has a wing its full length, with a pitch of about 45 degrees toward the sluice plates, and extends to within ^ inch of the bottom of the box. The wing causes the pulp to pass under it and keep the box clear at the bottom, catching any free quicksilver. From this opening extends a sluice 12 inches wide and 8 feet long, the upper end of which is provided with ^ x ^ inch riffles 2 inches apart, while below the riffles are 6 feet of silver-plated copper plates. This box has a grade of | inch to the foot, and from it the tailings pass to the concentrators. Each battery has three concentrators. There are in use in the several mills of the company fifty-four 4-foot Frue, six 4-foot Union, and six- teen 3 foot 10 inches TuUoch machines. A series of comparative tests was made some time since, which showed little difference in the value of the tailings passing the machines. Mr. Loring made special experi- ment with several of the Frue machines. The machine has a shaking- frame 12 feet long and 4 feet wide. The back roller was dropped 3 inches by putting a block of wood between the side rail and the bearing that supports the roller. Then a number of small rollers which carry the belt were taken out, reducing the total length of the concentrator to 8 feet from the center of the head roller to the center of the small roller. The belt from the small roller to the back roller had so much grade that nothing was saved on it, so that by this arrangement of the concentra- tors the effect was the same as though the machines were but 8 feet long. Tailings assays showed as follows: From the altered machine, 4x8 feet $0 33 per ton. From the unaltered machine, 4x12 feet.. -_. 41 per ton. This shows a saving of 8 cents per ton in favor of the short concen- trator. This being the case, it would appear that a 12-foot machine is unnecessarily long. On each concentrator is a discharge, which deposits the sulphurets in a box directly under the head roller of the machine, and from this box the concentrated sulphurets are removed daily. A THE MOTHER LODE REGION — CALAVERAS COUNTY. 115 car holding 900 pounds is used to convey 'them to the dump-house. Two samples are taken from each car with a 15-inch sampling iron, and after all concentrates for the day have been taken out and sampled, the aggregate sample is sent to the assay office, together with the aggre- gate of the samples of tailings, taken every three hours. These samples are assayed every day, and a record kept. The tailings from the con- centrator run through a flume three fourths of a mile long, and are passed over a slimes plant of the Gates type. The concentrates from the slimes plant are conveyed by wagon to the chlorination works, wliere they are worked in a cyanide plant attached to that department of the works. After a run of fifteen or twenty days, depending on the character of the ore, a general clean-up of the mills is made, as follows: The feed is shut off from three batteries until they have been "pounded out"; the stamps are then hung up, the water shut off, and two rectangular pans, 16x14 inches in area, 3 inches deep on one side and 2 inches on the other, are placed in front of each battery, the low side of each being slipped under one of the holes in the apron. These pans are made in this form to keep the upper edge as nearly level as possible when sitting on an inclined plane. The amalgam adhering to the screen frame is taken off with a scraper, and deposited in a gold-pan. The screen frame is then removed and washed; afterwards the chuck-block is taken out and placed in the clean-up room, to be cleaned; the wooden apron is then- scraped and the amalgam put into a bucket; the coarse battery sands are then shoveled into a box provided for that purpose, and the pans with the cleanings from the screen frame are successively put under each stamp, which is thoroughly cleaned of any amalgam found in key-ways or between the boss-head and shoe. After each stamp has been thor- oughly cleaned in this way, the amalgam is taken to the clean-up room, a check being kept on the weight of that from each battery separately. The dies are then removed and washed on the apron, and the batteries cleaned out, all the hard sand that has accumulated around the dies being put in an amalgamating barrel. After the mortar has been thoroughly cleaned, about half an inch of sand is spread on the bottom of the mortar, the dies are returned to their respective places, coarse sand packed in, and the chuck-block, which has been cleaned, replaced; the screen is replaced and keyed; the apron washed, and everything cleaned, down to the rectangular pans previously mentioned. These pans, and the buckets used around the battery, are washed into the amalgamating barrel. By the time the clean-up man has completed washing the buckets and pans, the man employed In looking after the self-feeders has started the cleaned-up battery, and has its neighbor ready to be opened. Three men on the batteries and three men in the clean-up room can clean up twelve batteries in three hours. When the 116 CALIFORNIA STATE MINING BUREAU., battery is first hung up, the small spreader plates are taken to the clean-up room, and the amalgam obtained is dropped into a tank, which, after the clean-up, is cleaned out and charged with other material in the amalgamating barrel. After the mill has been cleaned up, 150 pounds of quicksilver is put into the barrel, with sufficient water to give a depth of 12 inches over the charge. The barrel is then closed, locked and sealed, and the belt put on, which drives the barrel at 14 revolutions per minute. This charge is run 30 to 48 hours. Underneath the barrel is a tank of equal capacity, from whence a sluice 22 feet long and 12 inches wide with a grade of 1| inches to the foot, provided with silvered copper plates, con- veys the pulp and water to either of two settling tanks as desired. When the barrel has run its full time, it is stopped with the head up, the head removed, and a stream of clear water under high pressure turned in, causing the slimes to come to the top of the barrel, overflow, and fall into the tank beneath, from which they pass through the sluice into a tank of 2000 gallons capacity. When the slimes have been washed out, the water is shut off. A bucket is set under the If-inch plug-hole in the barrel, and the charge is drawn. The quicksilver first flows out, falling to the bottom of the bucket. A stream of water is kept running through the barrel to wash the sand through the discharge hole, and the bucket is thoroughly scraped, so that the sand will over- flow, leaving the amalgam in the bottom, the "iron" next, and the sand on top. The iron is taken out as it accumulates, and after it has all been collected, it is screened through a ^-inch screen and the screenings panned in the clean-up tank. The result is put back into the amalga- mating barrel at the next regular clean-up. The amalgam from the barrel is thoroughly cleaned and squeezed through white drilling. The amalgam balls weigh from 8 to 12 pounds, and retort about 38 per cent gold. The day before the buckets are to be cleaned, the accumulations on the sluice plates are scraped ofi" with steel scrapers made of old files turned at one end about 2 inches, and ground to a sharp edge. The first 8 feet of raw plate is scraped in this way, leaving the 14 feet of silvered plate to run six months more without scraping. Great care must be taken in scraping silvered plates, as the silver cuts easily, spoiling the plate and making low-grade bullion. The amalgam thus collected is put in a small amalgamating barrel 15 inches in diameter and 24 inches long, which is run 28 revolutions a minute, quicksilver being added, with enough water to make a thin paste of the charge. The charge is run for twenty-four hours, when it is drawn off in a bucket and cleaned in the usual way, the sulphurets being saved in the cleaning tank previously described. This amalgam yields from 28 to 30 per cent gold. Quicksilver is fed to the battery every hour; the amount being THE MOTHER LODE REGION — CALAVERAS COUNTY. 117 regulated by the value of the ore, and this must be judged by the amal- gamator from examination of the board directly under the splash of the battery, where the pulp first falls from the screen. Every ounce of quicksilver that is fed into the battery is weighed and recorded at the end of each shift, and at the end of the run the amount of quicksilver thus fed furnishes a basis for calculating the probable result of the clean-up before it is made. The retorts are lined with oak wood ashes, free from dirt; the ashes are sifted through a 30-mesh screen, and made into a paste Avith water; with this paste, the trays and retorts are lined, and the head thickly sealed. The ashes do not shrink like clay, to which it is superior in many ways. The mortars in the Utica mill are of an old-fashioned type, not having been provided with liners. After being in use several years, it was found necessary to do something if the life of the mortars was to be prolonged, as the ends were badly worn just above the dies The stamps were set 10 inches between centers, using 8^-inch shoes, leaving a space of 1^ inches between each two shoes. The 9-inch dies up to that time had a life of 59 days, and the chrome steel shoes were being used 191 days. In order to line these mortars, Mr. Loring reset the stamps, using a guide with 9^ inches between centers, and leaving | inch between stamps. In this manner 1^ inches were gained at each end of the mortars, allowing room for an end liner, which served to key the front and back liners. The back was filled with wood, carefully fitted in place with the liner, saving considerable Aveight of unnecessary iron. The back liner is 13 inches high, and stands at an angle of 11\ degrees, the foot being 1\ inches from the base of the die. These dies are made with 8|-inch face, while the shoes have but S^-inch face. It is claimed by Mr. Loring to give better results than when both shoe and die are of the same diameter. The chuck-blocks are made of wood covered with copper, I inch thick and 8 inches wide, the full length of the battery. In the center the copper is bent to fit the wooden block, the upper half being set at an angle of 45 degrees, the lower half standing vertically. At the lower edge of the block, and projecting ^ inch over the copper, is bolted a ^ x 1 inch iron strap the full length of the copper. At the bend in the copper^ or about 2 inches above the bottom iron, is bolted a second iron strap, "I X I inch, the full length. The bolts holding these iron straps are countersunk, and the iron bars act as a protection for the amalgam which accumulates between them, and it has also been found to prevent the scouring of the upper section of the plate. There are used 8^ gallons of water per battery of 5 stamps per minute, and in addition 2i gallons per minute outside for each battery. All chips, shoe wedges, and other wood used about the mill, are saved and burned in a 5 X 8-foot furnace constructed for that purpose. 118 CALIFORNIA STATE MINING BUEEAU. The furnace has a cement floor; above it are placed grate bars to the full size of the furnace. The furnace measures from cement floor to top of bars, 15 inches; from the top of bars to the top of the arch, 5 feet; at the top of the furnace is a charging hopper made of cast-iron, with a door to fit it. When the charge has been burned, the ashes are removed and screened to remove nails, etc., that may be in the charge. The ashes are put in the amalgamating barrel with 10 pounds of quick- silver, and ground for six hours sharp, as a longer time would probably cause the charge to "flour." From 6 ounces to 2 pounds of amalgam is obtained by this method every month. All the cleanings from the mill are put into this barrel and ground for such time as the case may require. In this way many thousands of dollars are saved around a large plant, by care. The amalgam from the chuck-blocks is ground in an iron mortar 12 inches in diameter, the muller of which has a con- nection made in such a way that it can be stopped or lifted as desired. It will grind a charge of 14 pounds, and has a speed of 65 revolutions per minute. The labor employed in the mill is as follows: One man to each shift of twelve hours, whose duty it is to look after the feeding of the batteries; one night amalgamator, who attends to the amalgamating and looks after the mill generally; one concentrator man on each twelve- hour shift, who attends to 36 concentrators; one day amalgamator and helper, who attend to the amalgamating and general repairs about the mill; one superintendent, who has charge of everything connected with the mills and plating works; thus seven men, besides the superintendent, operate a 60-8tamp mill. Owing to the fact that the company own their power, against which they make no charge for the plant or deterioration, the cost of milling at the Utica mills is very low, being, before the recent rise in the price of iron, about 14 cents per ton. W. J. Loring, superintendent, Utica Mills. The Utica Chlorination Works. — This plant consists of seven furnaces, having a daily capacity of 29 tons. F. C. Beedle is superintendent. Four of the furnaces are in constant operation. They are 72 x 13 feet, and have a capacity of 4| tons each daily. The material treated in these furnaces is iron sulphide, concentrated from the Utica-Stickle and Gold Cliff ores. The tanks are made of redwood held by |-inch round iron rods, each in three sections and secured with screw clamps. This method of clamping tanks draws the staves evenly, secures great firm- ness, and renders the tanks perfectly water-tight. The covers of the tanks are no longer "luted" on as formerly, but are provided with a downwardly projecting flange, which drops in an annular trough encircling the tank and filled with water. The accompanying diagram (Fig. 34) illustrates this construction of the air-tight water joint. The covers are raised by means of a chain block suspended from an over- head traveler. The tanks have a capacity of 5 tons each. . The pipes THE MOTHER LODE REGION — CALAVERAS COUNTY. 119 from the chlorine gas generators, which latter are very large, are so arranged that when the gas is turned into No. 1 tank, having permeated the ore below, it passes from the top of No. 1 tank into the bottom of No. 2, so that there is no waste of gas. In generating gas, 100 pounds of salt and 90 pounds of black oxide of manganese are used. To this, * sulphuric acid is automatically added, until it ceases to evolve gas. Liquid chlorine was at one time tried in these works, but Mr. Beedle said it was found to cost twice as much as making gas by the above described method, though otherwise satisfactory. The ore is introduced to the reverberatory furnaces containing 5 to 10 per cent moisture, in a charge of 2600 pounds. It is spread in a 2-inch layer on the first Explanation. 5. S-Taves forming vat. O. Outside ring, encircling vat. W. Space filled wifb water. Ft Plan§e extending downward from cover. H. P. Iron Hoop. Pilling piece. Section of Cover and 1op of Vat, Ch?lorination Works, UTICA MiNE.;ANG£LS, Cal. showing air-tt^ht w^ater joint. — Fig. 34. hearth. After two hours it is stirred, and later it is restirred three times before being raked forward to the second hearth. On the second hearth, 40 pounds of salt are added to the charge; on the third hearth, the ore, having been thoroughly roasted, is withdrawn from the furnace, cooled and charged into leaching-vats. One and one-quarter cords of wood are required to roast 5 tons of ore. Utica Cyanide Plant.— In this plant 8800 pounds of slimes obtained from the canvas plant are treated in eight hours. This is charged in steel tanks, and agitated 6 hours with a 5 per cent solution of potassium cyanide. The pulp is discharged into a vacuum filter, and is first washed with sump solution, and later with fresh water. The results are said to be entirely satisfactory. The auro-cyanides are precipitated on zinc shavings. Bovee Mine. — This property adjoins the Fox or Angels Mine on the north, at Angels. It has been idle for many years. The Marshall Mining Company, owners. E. P. Lynch of Angels, agent. 120 CALIFORNIA STATE MINING BUREAU. Perlina Mine. — At Altaville, northeast of the Angels Mine. It has an inclined shaft 75 feet deep, from which drifts have been run on the vein. The property has been superficially worked for years, the ore being crushed in a 4-stamp mill. The vein has never been cross-cut, and its width is unknown. As far as known at this writing, the vein has a width of from 4 to 12 feet, between two gouge seams. The formation is diabase and amphibolite schist. There are 3 men em- ployed. J. G. Maltman of Angels, owner. Great Western Mine. — At Altaville. It has a vertical shaft 220 feet deep, with drifts at 50, 100, and 200 feet south of the shaft, no work of consequence having been done to the northward. There is a stope at the 50 foot level and one at the 100-foot level. On the latter level, it is said the vein is from 8 to 20 feet in width. The hoisting machinery has been removed and the mine is idle. Seifert & Baumhogger of Angels, owners. St. Lawrence Mine (Bruner or Bald Hill). — This mine has been reopened since the last report, and an inclined shaft sunk 400 feet at an angle of 64 degrees; there is a level at 100 feet and another at 400 feet. An open cut on the surface exposes a shoot of ore 80 feet in length, which was worked down to a depth of 60 feet many years ago. The trend of this shoot is to the south, at an angle of 40 degrees; two other shoots are known to the northward. The formation is diabase and chlorite schist. The vein consists of a mixture of quartz and diabase, impregnated with auriferous iron sulphides and free gold. The mine is equipped with a steam hoist, but has no mill. The south drift at the 400-foot level had not renched the ore-shoot at the time of my visit, but drifting was in progress. St. Lawrence Gold Mining Company of Hanford, Cal., owners. A. J. Cameron of Angels, superintendent. Bolytho Mine. — This is 1 mile south of Angels, and has been men- tioned in previous reports. It was originally worked as a pocket mine, and as such produced several thousand dollars in gold. Expensive development was then undertaken, with a view to working it as a milling proposition, but up to this time the experience of the operators has been rather unsatisfactory. The last work performed was the sink- ing of a vertical shaft to a depth of 300 feet; this shaft passed through a succession of formations — diabase tuft" and tufaceous slate, character- istic of the Gold Belt, being most prominent. These formations are intruded by a dike of straw-colored rock, which is identical with the intrusive rock found in the Utica-Stickle, Gold Cliff, and other important mines in this section. The dike is from 30 to 40 feet wide, and carries much finely disseminated iron sulphide, which is doubtless auriferous, but to what extent is not known by the management, as no attention was paid to it, for the reason that it was not massive quartz. It is the THE MOTHER LODE REGION — CALAVERAS COUNTY. 121 intention of the company to cross-cut from the bottom of the shaft to the eastward and again intersect the dike, which is, undoubtedly, what- ever its value may be, the main ore zone of the mine. When this is done, long drifts will be run for the purpose of prospecting. Geolog- ically, this mine possesses many of the features common to the best mines of this section. In addition to this shaft, an inclined shaft has been sunk 300 feet on a west vein, and thousands of feet of drifting and cross-cutting have been done in the upper portions of the mine in search of pockets and pay rock. The vertical shaft is equipped with a steam hoist. Bolytho Mining Company, Appraiser's Building, San Fran- cisco, owners. E. P. Lynch of Angels, superintendent. Big Bonanza Mine (Harris or Oriole).— It is 1 mile south of Angels, and has been developed by a vertical shaft, which was 425 feet in depth May 1, 1900. A level has been run at 130 feet, 60 feet southeast, and another at 200 feet. The formation in which this mine occurs is augite diorite, in which occur fine-grained phenocrysts of hornblende and augite. This rock near the vein is altered to chlorite schist. The vein consists of a zone of quartz and schistose rock, dipping 75 to 80 degrees to the eastward. The mine is equipped with a substantial steam hoist, but has no mill. There are 15 men employed. Sinking is in progress. It has been recently reported that 30 feet of ore has been developed on the 400-foot level, 5 feet of which is high grade. Oriole Mining Com- pany of Stockton, owners. John H. Heard of Angels, superintendent, Drake Properties (Ltd.). — These are a mile southeast of Angels. Two shafts have been sunk— one 900 feet, the other 300 feet— vertically for the purpose of prospecting. The formation is diabase and black tufaceous slate, the latter being cut by a small dike with quartz and pyrite. Idle.- ^Drake Properties (Ltd.) of London, owners, F, J. Solinsky of San Andreas, agent. Tulloch Mine.— It is 2h miles south of Angels, After a long idleness it has been reopened and sinking is in progress in the shaft, which Sep- tember 1st was down 250 feet. Steam hoist. There are 12 men employed. Mr. Blevin of Angels, superintendent. Relief Mine.— It is 1 mile south of Angels. It has a cross-cut tunnel 165 feet long, and a winze sunk on a zone of schist 90 feet below the tunnel level. The mine has no machinery. Idle. Bonded to San Francisco company. Mr. Hogarth of Angels, owner. Melones Consolidated Mines. — This group of mines is on Carson Hill, reaching frohi the summit of that eminence to the Stanislaus River, and embraces seven claims extending along the lode for a distance of a mile. The claims are the Reserve, Last Chance, Melones, Enterprise, Mineral Mountain, Keystone, and Stanislaus. These mines were among the first worked in the county, and the several claims have been 122 CALIFORNIA STATE MINING BUREAU. developed to depths varying from superficial, though large cuts, to shafts 300 feet or thereabouts in depth. The development undertaken by the present owners consists in an extension of the South Carolina tunnel. (This property adjoins the Melones Consolidated on the east.) It was run through the Enterprise and Reserve ground under the large open cuts on the surface, and connection established. It is 621 feet below the collar of the Reserve shaft. This development has exposed large veins of ankerite and quartz with amphibolite schist, all of which is gold-bearing, with auriferous sulphides. To what extent these great veins are auriferous is of course a very important factor, viewed from the commercial standpoint. The values vary greatly, ranging from many thousands of dollars per ton to a mere trace of gold. Large samples taken systematically from cross-cuts on the veins show values varying from $1.50 to about $9, the greater portion running from .$2.50 to $3.50 per ton, though some portions average better than this, accord- ing to statements made by the management. A new tunnel (designated as No. 3), 6 feet 6 inches by 9 feet clear, was started to run under the South Carolina tunnel about 200 feet lower. This tunnel is now in about 3500 feet, and judging from the character of the formation passed through in the last 100 feet is nearing the vein. The tunnel cuts diagonally across the formation, and is being driven through the foot-wall country- It is perfectly straight, has a double track throughout, and. is a credit- able piece of mine engineering. Machine drills are in use, the com- pressors being situated near the mouth of the tunnel. There are still several hundred feet to run before this tunnel reaches a point beneath a winze sunk from the South Carolina tunnel. A raise of 65 feet from the new tunnel will make this connection at a point 1000 feet below the cropping on the summit of Carson Hill. The grade for a i20-stamp mill has been completed, and a large amount of machinery is on the mill site. The first attempt to construct a dam across the Stanislaus for the purpose of furnishing power for this property was a failure, and a new site was chosen a few feet higher up the stream. This is about 2| miles above Robinson's Ferry. The dam is being put in at this writing (September 1, 1900), and it is stated that no obstacles to its successful construction have been encountered thus far. The water diverted by the dam will be conducted by ditch and flume to a point opposite the mill site, and it is calculated to furnish power for the entire plant. This is one of the largest mining operations in the State, but much still remains to be done before it can be placed on an operating basis. Melones Consolidated Mining Company of Boston, owners. W. C. Ralston of Robinson's Ferry, manager. Last Chance Mine. — Near the town of Angels, on the southern limits. Nothing has been done here since the last report. It has an inclined shaft 73 feet in depth. G. C. Tryon of Angels, owner. THE MOTHER LODE REGION CALAVERAS COUNTY. 123 San Justo {Carson Creek) Mine. — The work in progress May 1, 1900, is in a south drift on the 250-foot level, where a new ore-shoot has been discovered. The mill, which had long been idle, was started up May 1st, and the chlorination works one month later. The mill has 40 stamps; 40 men are employed. The San Justo Mining Company, Parrott Building, San Francisco, owners. V. W. Miller of Angels, superintendent. Greek Mine. — Near the road between El Dorado and Railroad Flat, 20 miles from San Andreas. It is developed by a shaft 170 feet deep, with a drift 120 feet long at the 100-foot level. The vein cuts vertically through mica schist, and has the remarkable accompaniment of two dikes — the older a dark-green, hard diorite; the later, a light-colored, finely grained dike of acid type. The latter is usually found in contact with the vein, which is either banded or massive, showing in places coarse gold. The general tenor of the ore, however, is low grade. It is equipped with a steam hoist and a 5-stamp mill. Idle. Greek Min- ing Company of San Andreas, owners. F. J. Solinsky of San Andreas, agent. Bitter Mine. — This is 1^ miles north of Mountain Ranch, or El Dorado. It is opened by a tunnel 410 feet in length, driven on a small vein of granular quartz having a peculiar schistose structure. The rock is extremely hard and flinty. One shoot of ore developed by this tunnel and a raise produced considerable high-grade specimen rock. The vein strikes N. 30° W., and is intersected by a larger quartz vein, striking north and south and dipping 65 degrees east. This vein is dislocated by the smaller vein a distance of 40 feet. A small force was at work in the spring of 1900. Rodesino Estate of Mountain Ranch, owners. Bonded to S. Redmond of San Andreas. Blue Jay and Yellow Hammer Mines. — These mines are 2^ miles east of Mokelumne Hill, near the Calaveras River, and comprise 3100 feet on a banded vein in Calaveras formation. The vein is from 2 to 6 feet wide, cutting mica schist and slate. It is usually accompanied by a small acid dike. The property is in the prospective stage. F. Courtmarsh et al. of Mokelumne Hill, owners. Esperanza Mine. — It is 2i miles northeast of Mokelumne Hill. Devel- oped by an inclined shaft 1000 feet deep. The property is equipped with hoisting works, 30-stamp mill, and chlorination plant of three furnaces; motive power, water. Idle in the spring of 1900, but it was said that I the mine was about to resume operations. Esperanza Mining Com- : pany, 220 Sansome Street, San Francisco, owners. Prescott Ely of \ Mokelumne Hill, superintendent. ! Calaveras Mine. — It is 2^ miles north of Mokelumne Hill, near Big j Bar bridge. It was described in former reports as the Garner. The vein. 124 CALIFORNIA STATE MINING BUREAU. which occurs in diorite, is opened through an adit tunnel. A vertical shaft is being sunk from the surface, calculated to reach the vein at a depth of 350 feet, and a winze is being sunk below the tunnel, 70 feet north of this shaft. The vein strikes N. of E., dipping W. 57°. The ore is crushed in a 10-stamp mill, situated on the opposite side of the Mokelumne River, in Amador County, power being furnished by a tur- bine wheel, using about 1200 inches of water. The mill runs during the day only. At the mill an air-compressor furnishes power for drills used in the mine on the other side of the river. There are 24 men employed. Calaveras Gold Mining Company, owners. Peter Houghton of Mokelumne Hill, superintendent. North Star Drift Mine. — This is 2 miles south of Mokelumne Hill, on the Old Woman's Gulch blue lead. The channel has been reached by means of a cross-cut tunnel, in 1360 feet March, 1900. This tunnel is 6^ X 10^ feet. Nine men are employed, there being as yet no machin- ery. North Star Mining Company, owners. P. Schuman of Mokel- umne Hill, superintendent. Ellen Vannan Drift Mine. — This is half a mile below the North Star Mine in Old Woman's Gulch, and on the same channel. It is opened through an inclined shaft 195 feet deep. Six men are employed. W. J. Jackson et al. of San Andreas, owners. Green Mountain Mine (Hydraulic and Drift). — This mine was being operated by hydraulic process with success during the spring of 1900, under permit of the United States Debris Commission, employing 12 men during the day only. From a portion of this claim there have been shipped, within the past two years, 12 tons of quartz crystals, for which this mine has long been famous. These were placed with Tiffany & Co. of New York, who estimated their value at about $18,000. Several handsome and absolutely perfect crystal spheres have been cut from the crystals obtained in this mine, but the limit of the size of a perfect sphere has thus far been about 5^ inches. A statement was made to the writer by one of the owners, that Mr. Tiffany had said that if a crystal could be obtained which would cut a sphere 7 inches in diameter, which should prove to be absolutely faultless and without a flaw, such a sphere would have a valuation of $30,000. J. E. Burton et al., owners. J. McSorley of Mokelumne Hill, superintendent. Emery Hydraulic Mine. — Also known as the Rose Hill. One mile from Mountain Ranch. This mine is situated on a branch of the Fort Mountain channel. It was being operated in the spring of 1900 with 800 inches of water, and two monitors working twenty-four hours daily, two pits having been opened. No work was in progress in the south pit. The work in the north pit is being carried down stream, a long tunnel having been cut for drainage. The water pressure at the upper THE MOTHER LODE EEGION — CALAVERAS COUNTY. 125 pit was 300 feet, at the lower pit 400 feet. The company owns 2^ miles on the line of this channel. The bank has averaged thus far about 20 feet in height. From 2000 to 2500 yards are moved every twenty-four hours, when a full head of water is available. The owners have spent a large sum of money in perfecting their water-system, consisting of reservoirs, ditches, pipe-lines, etc. In the mine 10 men are emiDloyed; 15 on other work. Emery Gold Mining Company of Mountain Ranch, owners. Earle C. Emery of Mountain Ranch, superintendent. San Domingo Hydraulic {Jupiter) Mine. — This property was being worked in May, 1900, with two giants using 1500 inches of water under 150 feet head. The average of the season is estimated to be 1.25 yards per day per inch of water employed. The bank is nearly 100 feet high; the gravel is loose, and disintegrates rapidly under the powerful streams from the giants. The flume at this mine is 4 feet in width, 3000 feet long, and set on a 4-inch grade. The company owns about 2 miles on the channel. There are 8 men employed. The San Domingo Gold Mining Company, Parrott Building, San Francisco, owners. A. B. Thompson of Angels, superintendent. ■ French Hill Quartz Mine. — This is a prospect situated on the slope of the famous French Hill, about half a mile east of Mokelumne Hill. A cross-cut tunnel is being driven, which in March was in 400 feet. There are 5 men employed. J. E. Burton et al., owners. T. E. Mc- Sorley of Mokelumne Hill, superintendent. ■ Satellite Copper Mine. — This property is near Campo Seco. When visited in the spring, the inclined shaft was down 250 feet, and sinking. The hoisting is being done by means of a gasoline engine, which appears to give satisfaction. At this mine an 80-ton water-jacket furnace was found in full blast, operated by what is known as "partial pyritic smelting," under the direction of E. J. Fowler, metallurgical engineer. The furnace is of special design, constructed from plans made by Mr. Fowler, in which 80 tons of material are treated daily, of which 50 tons are ore, the remainder being flux. The charge consists of raw ore, roasted ore, slag, limestone, and low-grade matte. In what proportion these are charged was not learned. Mr. Fowler says that this method of pyritic smelting is entirely feasible and successful on ores of this class. The ores are chalcopyrite and pyrite. A little zinc is occasion- ally seen. The ore contains but little silica, and quartz is brought from the croppings of neighboring veins for flux. The Pennsylvania Man- ufacturing Company of Campo Seco, owners. A. C. Harmon of Campo Seco, superintendent. Borger Copper Mine. — Near Campo Seco, and in the principal mineral- ized zone of the district. A new shaft is being sunk on a promising copper vein by Mr. C. Borger of Campo Seco. C. Borger, owner. 126 CALIFORNIA STATE MINING BUREAU. Union and Keystone Copper Mines. — They are at Copperopolis, and comprise a mile of locations on the copper belt. The mines were worked extensively in former years, and produced a large amount of copper. The principal workings are down to a depth of 800 feet. The mines were closed down in 1893, and have since remained idle. They were unwatered in March, 1900, but further than this active operations have not been resumed. Union Copper Mining Company of Boston, Mass., owners. G. McM. Ross of Copperopolis, superintendent. Lightner Mine. — This is 2 miles southeast of Copperopolis. It has a strong iron gossan, which occurs in amphibolite schist. It is developed by several adit tunnels and shallow shafts. The ore in the oxidized zone is essentially gold-bearing, but being in the copper belt it is antici- pated that in greater depth in the sulphide zone more or less copper sulphide will be found. The mine has no machinery. Mr. Uren of Alameda, Cal., owner. Mr. Lillian of Copperopolis, superintendent. Royal Consolidated Gold Mine. — This is in Salt Spring Valley at Hodson, 3 miles northwest of Copperopolis. Since the last report this property has been extensively developed under new management. The former operators worked a vein which dij^ped to the eastward at a low angle, and confined themselves to the defined limits of the walls of that vein. The quartz occurred in a series of large lenses in a dike of dia- base. There are a number of nearly vertical transverse veins which come down frorft the hanging-wall, intersecting the flat vein and passing into the foot-wall, but, strange to say, no attention was given these steeply inclined veins by the former management. The present man- agement, however, undertook the exploration of the mine upon broader lines, extending raises into the hanging-wall and sinking winzes into the foot, with the result that large deposits of payable ore have been developed both above and below the original Royal vein. In this mine may be seen some of the largest stopes in the State. The mine is almost absolutely dry, some of the stopes being dusty. Comparatively little timber is employed in sustaining the ground, and in view of this fact the lack of substantial pillars is the cause of comment among visitors. Although this ground is among the best to "stand" of any I have seen in this portion of the State, there is a limit to which this method of mining may be carried with safety. A system of timbering and filling must soon be inaugurated to avert disaster, as well as to recover the large ore reserves in sight in this mine. The shaft has been sunk to 900 feet from the collar, and the lateral development is extensive. The property is equipped with a large steam hoist and a 40-stamp mill. There are 100 men employed. Royal Consolidated Mines (Ltd.), owner. J. C. Kemp van Ee of Hodson, manager. f THE MOTHER LODE REGION — CALAVERAS COUNTY. 127 The Royal Mill. — The mill of 40 stamps is under the direction of J. S. Shepard. In the old mill the 20 stamps weigh 850 pounds. In the new addition to the mill 20 stamps weigh 1150 pounds each. The old stamps drop 6-5 inches, and the new 5| inches, 104 times a minute. No. 1 punched tin screens (24-mesh) are used. The discharge is 4 inches high, and is maintained closely to this by the use of -^-inch slats beneath the chuck-block. The capacity of the mill averages 3^ tons per stamp daily. The 20 heavy stamps of the mill crush about 14 tons more in twenty-four hours than the light ones. It may be interesting to state that the capacity of this mill is determined by weighing every car of ore that goes into the mill. There are 8 Wilflej'', 3 Johnson, and 1 Frue concentrators. The pulp from the Wilfley machines and also that from the Frue is recleaned on two ^yilfley machines. The pulp from the Johnson concentrators is also sent over the Wilfley machines. This is a very unusual arrangement of concentrating tables, but is stated to work very satisfactorily, producing clean concentrates. At present the sul- phides are sent to Selby's reduction works. The company has under consideration the construction of an additional 60 stamps and a chlor- ination works at the property. 128 CALIFORNIA STATE MINING BUREAU. TUOLUMNE COUNTY. Since the last report was issued by the Mining Bureau in 1896, Tuolumne County has been the field of unusual activity in mining operations. Encouraged by the success of the Rawhide, Golden Gate, Black Oak, Jumper, and other important properties in this county, many new enterprises were inaugurated, and during the years 1897, 1898, 1899, Tuolumne County was giving employment to a large number of men; but, as has been the case elsewhere, some of these investments have thus far proven unremunerative, and in a few instances the propo- sitions have been abandoned permanently, though in other cases sus- pended operations will doubtless be resumed. A light rainfall through several successive seasons has caused a shortage of water-supply, which has also seriously affected the mining industry in this county, more so, apparently, than in the neighboring counties, for at this time mines which have been steadily operating for years are shut down owing to lack of water for power. As an offset to this unfortunate condition is the fact that several of the mines which have been in process of develop- ment are proving valuable properties, and will form welcome additions to the list of active producing mines of the county. Notable among these are the Eagle-Shawmut near Jacksonville, and the Densmore- near Columbia. There is considerable activity in the districts of smaller mines on the East Lode, and reports of good new properties in that region may be anticipated. There still remains a large territory unexplored in Tuolumne County, both on the Central Lode and on the East Belt. Besides these there are mines of known merit in the Sierras which must ere long attract the attention of capital. Passing southward from Calaveras County into Tuolumne at Robinson's Ferry, the Central Lode is found to continue in an almost unbroken line to the southern boundary of the county and beyond into Mariposa. There is a slight break in its con- tinuity near Tuttletown, and another break of about 1000 feet between Whisky Hill and the Dutch Mine, and still another near the foot of Priest's Hill on Moccasin Creek. There may be other interruptions in its continuity, but the instances mentioned are the most noticeable. In fact, the lode is practically continuous through this county; and, as elsewhere, it is characterized by its massiveness and distinguished by the persistent occurrence of massive quartz croppings and broad zones of ankerite. Some of the most important mines on this lode are found, not in this belt of ankerite and quartz, but in amphibolite schist on the THE MOTHER LODE REGION — TUOLUMNE COUNTY. 129 hanging-wall side of the ankerite zone. The Jumper and Eagle mines are notable examples. The East Lode in Tuolumne County occurs in the grano-diorite and slates. An intermediate belt lies between these two lodes, in which occur numerous pocket mines in greenstone, slate, and limestone. Mines of this class are prominent in the, vicinity of Sonora and near Big Oak Flat. Bown Mine. — This is the first mine in operation on the Central Lode south of the Stanislaus River. It is half a mile from Robinson's Ferry and 24 miles northwest of Tuttletown. A shaft had been sunk (June 27th) to a depth of 630 feet at an angle of 64 degrees. The vein, which was being developed, is 10 feet wide and lies underneath the ankerite zone, the foot- wall being schist and serpentine. The vein has a sinuous course and a banded structure, containing gold and auriferous pyrite. The shaft is in the foot- wall, the vein being reached by cross-cuts from the shaft at 200, 300, 400, and 600 foot levels. On the 400-foot level a cross-cut has been extended 128 feet beyond the vein into the hanging- wall. The property is equipped with steam hoist and a 20-stamp mill, in which are 8 Union concentrators. There are 20 men employed. Bown Mining Company of San Francisco, owner. W. J. Rule of Tuttle- town, superintendent. Jackass Hill. — Half a mile south of the Bown and east of the anker- ite zone are the pocket mines of Jackass Hill, the most important of which are the Karrington and Stenchfield. This property is worked by several sets of leasers, who pay to the owner a royalty on all gold taken out. The mines are reported to have been regular and large producers for several years past. James Gillis of Sonora, owner. Norwegian Mine. — It is 1 mile north of Tuttletown, overlooking the cafion of the Stanislaus. Arhona Mine. — It is at Tuttletown, about i mile east of the ankerite zone, in greenstone schist. The vein is from 8 to 10 feet wide, and is developed by a shaft 540 feet deep, and sinking in June. A 200-foot cross-cut tunnel intersects the shaft at 135 feet from the surface. Levels are run at 100, 200, 300, and 400 feet. The ore consists of massive quartz and pyrite. The mine is equipped with steam hoist and 10-stamp water- power mill. There are 12 men employed. This mine was worked many years ago by French people, who undertook to crush the rock in arras- tras, but the quartz was found too hard to crush readily, and it had remained idle for years when the present owners renewed operations. Equitable Mining and Milling Company of Stockton, owners. W. E. Brooks of Tuttletown, superintendent. Rawhide Mine. — This property, 3 miles north of Jamestown, which for several years past had attracted much attention by reason of its large 9 — MB 130 CALIFORNIA STATE MINING BUREAU. and continued output, has within the past year been involved in litiga- tion among the co-owners, and when visited very little information was obtainable, probably owing to pending lawsuits. The property was in operation, however. Usually about 100 men are employed. The surface plant consists of a large hoist, a 40-stamp mill, and chlorination works. Ballard, Martin & Nevills of San Francisco, owners. Harvard ( Whisky Hill) Mines. — These are a half a mile west of James- town, on the dolomitic zone, though the development of pay rock is principally in a zone of amphibolite schist on the hanging-wall side of the dolomite. There are two vertical shafts — one of 500 and one of 750 feet depth. These are connected by the 500-foot level from the south shaft. The veins of pay rock consist of silicious amphibolite schist of variable width up to 35 feet. The hanging- wall is amphibolite schist, hard and firm, not gold-bearing, or only slightly so; the foot- wall is serpen- tine. Hundreds of feet of levels have been driven in the ankerite zone, but the values are chiefly in the zone of greenstone schist. On the 500- foot level a cross-cut has been driven westward to the massive quartz vein, probably the downward extension of the "bowlder" vein seen on the surface. This cross-cut develops nothing of value. The property is equipped with steam hoists at both shafts, and a 60-stamp mill which is run by electricity. The mill has both Johnson and Dodd tables, which effect a clean concentration of the sulphides. A series of cyanide experiments is to be made, with a view to treating the sulphurets by that method. The apron and sluice plates are 6 feet wide, divided by a longitudinal strip down the center. The plates have a grade of 1^ inches to the foot. Thirty stamps were dropping at the time of my visit. There are two electric motors in the mill, each of 75 horse-power, each motor being calculated to run 30 stamps. Harvard Gold Mining Company, owners. J. P. Munger of Jamestown, superintendent. Dutch Mine. — It is at Quartz Mountain, and has been in continuous operation since 1893. The shaft has reached a depth of 1200 feet^ inclined at 58 degrees. There are ten levels in the mine. The develop- ment is chiefly upon a zone of ankerite and mariposite 60 feet in width, in which are many veins and lenses of quartz, bearing gold and auriferous pyrite, though in greatly varying quantities. The pay zone is usually found on or near the foot-wall side of the ankerite zone. The foot-wall country consists of amphibolite schist, gabbro, tufaceous slates, Mariposa clay slates, serpentine, and diabase. These are dis- tributed somewhat irregularly. The hanging-wall side is principally amphibolite schist, so far as could be observed. The pay shoots appear to cross the ankerite zone from foot to hanging wall diagonally, the intervening blocks of ground being much lower in grade. There is also a noticeable series of slips in the mine, which show that the hanging- wall side of the zone has in each case been forced upward. These slips THE MOTHER LODE REGION — TUOLUMNE COUNTY. 131 like the schists dip easterly, but flatter than the schists. Northward on the surface the ankerite extends for a distance of 1000 feet, then disap- pears beneath the alluvial of the valley, but considerable rock-exposures occur farther northward, and it is observed that the ankerite vein is not continuous to Whisky Hill. There is an interval of not less than 1500 feet in which it cannot be found, though reappearing on the north side of Woods Creek at the south end of the ridge known as Whisky Hill. The Dutch Mine is equipped with a large steam hoist, the compressor and mill of 20 stamps being run by electricity. There are 54 men employed. A cyanide plant was being constructed early in July to work the sulphides concentrated from the ores. Dutch Mining and Milling Company of San Francisco, owners. Albert Trittenbach of Quartz Mountain, superintendent. The App and Heslep Mines. — These join the Dutch Mine, and are situated on the northern end of Quartz Mountain. The vein consists of a large mass of ankerite and quartz, with a black slate hanging and diabase foot-wall. The main shaft is down 1000 feet, equipped with water-power hoist. The mill has 20 stamps, and was in operation during midsummer. There are 25 men employed. The App Con- solidated Mining Company of San Francisco, owner. Santa Ysahel Mines. — These occupy the southern end of Quartz Moun- tain, comprising several claims of irregular shape and size. The property was idle at the time of my visit, but it was reported that opera- tions were to be resumed. Santa Ysabel Mining Company of Boston, owner. E. A. Hardy of Quartz Mountain, in charge. Jumper Group of Mines. — This property is situated on a low ridge half a mile south of the village of Stent, and comprises the Golden Rule, New Era, and Jumper mines. The Jumper is the principal mine, and is being systematically worked. The Golden Rule has a large amount of development, as has also the New Era, the latter chiefly through the medium of levels extended into it from the Jumper. The general struc- tural geology of the mine is not wholly unlike that of other mines in the neighborhood. A cross-section taken in the Golden Rule in a long cross-cut gives a good general idea of the geological structure. Through the entire length of the hill the ankerite vein is prominent, with the usual accompaniment of large quartz lenses; all of this rock is very low grade in gold, however. The foot-wall country is diorite, separated from the ankerite zone by a dike of serpentine of variable width (about 100 feet). The ankerite is divided into two zones by the intrusion of a large dike of diorite similar to that forming the west country. East of the ankerite zone is a succession of diorite and diabase dikes, which in part are altered to amphibolite schist, and it is in this schist that the pay zone is found. Easterly from this the formation is amphibolite schist, 132 CALIFORNIA STATE MINING BUREAU. with dikes of granular diabase. This zone of schist is over 1000 feet wide. In the Jumper Mine the gold occurs in a dike accompanying the schistose zone, and in small veins and veinlets of quartz and calcite, scattered irregularly, but always within certain definite zones, the outer limits of which form the walls. The width of this zone varies from 4 or 5 to about 30 feet. In its earlier history an effort was made to work the mine by selection of the better from the poorer portions, but owing to the peculiar geological conditions obtaining the present manager deemed this method unsuited to the accomplishment of the best results, and the method of selection was abandoned for that of stoping everything between the walls. This might at first appear like an extravagant and unnecessary course to pursue, but the results have proven eminently satisfactory. The .Jumper is one of the best worked and best managed mines in the State. It is heavily and properly timbered. The walls are hard — that is, there is no trouble from swelling ground. The main shaft is down 1285 feet, and is equipped with air and electricity. Power drills are emplo3^ed. There are nine levels in the mine. The mill has 60 stamps, and has no concentrators, except one for experimental pur- poses. There are 125 men employed. Jumper Gold Syndicate of Glasgow, Scotland, owners. M. D. Kelly of Stent, superintendent. The Eagle-Shawmut Mine. — This property is 1 mile north of Jackson- ville, on the ankerite vein. Its distinguishing feature is the line of massive quartz outcrop which forms great, wall-like masses along the course of the vein. The hanging-wall country is amphibolite schist; the foot-wall is slate. The principal developments of the mine consist of a cross-cut tunnel driven 1 100 feet through the foot-wall country to the vein, and a shaft sunk at the tunnel level to a depth of 660 feet on the vein. The ankerite zone contains veins or lenses of quartz, which carry gold in paying quantities, besides which there is a broad zone of amphib- olite schist on the hanging-wall side, in which is a gold-bearing shoot. This rock contains 2 or 3 per cent of auriferous sulphide, and is one of the most important developments thus far made in the mine. The super- intendent, Mr. Charles E. Uren, has introduced what appears to be an excellent system of stoping and filling in this mine. His plan is to put a long raise to the surface from a point above the tunnel level. This raise is driven at an angle of about 65 degrees above the horizon, the slope being westerly. The formation and veins dip easterly at about 70 degrees. The walls are usually firm and hard. The incline above men- tioned reaches the surface in an open cut, where the rock (being barren ) is suited for filling, and may be quarried cheaply. Stopes are started and mining operations continued by cutting out the ground the full width of the vein in the form of the letter "A", the base being longitudi- nally of the vein and the angle at the apex being no less than 90 de- grees, in order that rock may readily run on the slope. The floor of this THE MOTHER LODE REGION TUOLUMNE COUNTY. ' 133 stope is heavily stuUed and covered with lagging. The winze passes directly through the apex of this triangular stope, and waste is sent down from the surface and the excavation filled. Stoping then progresses in "slices" on alternate sides of the winze or raise. These slices are from 15 to 20 feet in height, the pay rock passing down through mill- holes cut through from the level below, the ore-chutes being carried up by cribbing, keeping even with stoping operations, and the filling run in first one side and then the other, until the block is worked out. The levels below are worked in similar manner, the filling passing through the stationary loading chutes (at the levels) and across the track into the next winze beneath by use of an apron, which may be removed when desired until again required. This method demands a minimum amount of timbering and renders the mine safe as far as caves are concerned. It may be elaborated and extended from level to level and make avail- able a large amount of ore at low cost of mining. In addition to the ore deposits above referred to there is upon the surface a zone of amphib- olite schist, which contains a finely disseminated gold. Experiments have proven that this rock is amenable to the cyanide process. The mine is equipped with a 40-stamp mill, in which are 17 concentrators — Frues and Unions. The hoist is run by Avater power, and at present is situ- ated near the inner end of the long tunnel. It is planned to raise the shaft to the surface. The mine and premises are lighted by electricity. Ore is sent out of the mine in long trains of cars hauled by a horse. The cyanide plant has a capacity of 56 tons daily, a percolation plant of 50 tons, and an agitation plant of 6 tons. A chlorination plant was in course of construction in July. There are 100 men employed. Charles E. Uren, superintendent. Republican Mine. — It is ^ mile from Jacksonville, and comprises a group of claims on the main lode, the principal ones being the Repub- lican and Mammoth. The principal ore-shoot thus far developed is from 2 to 8 feet in width. There remains much of the hanging-wall country to explore, however, and satisfactory developments may be expected in that direction. A tunnel has been run 750 feet through the foot-wall country of the Mammoth claim to the vein, and a shaft sunk in the tunnel 430 feet. The main shaft in the Republican is down 400 feet, with four levels opened. The company has a mill of 10 stamps at the mouth of the Mammoth tunnel, though at present operating only the Republican, the ore being hauled by wagons. The mill has 4 Frue vanners. A large air-compressor is situated at the mill, a pipe- line running to the Republican shaft for the purpose of operating air drills. The mill and compressor are run by water power, the company owning a ditch and flume several miles in length; but owing to a scarcity of water the past three years, this power has not been available during the summer and fall months. The hoist at the Republican is 134 • CALIFORNIA STATE MINING BUREAU. run by steam. Water is removed from the mine by means of a valve bucket, which discharges automatically upon reaching the surface. This is accomplished by means of a tipple. The bucket is hoisted until it reaches a section of the skidway, which is movable, being secured in place by a strong iron rod passing through this section at a point some- what above its center. Being brought to a state of rest, the weight of the bucket and contained water causes the tipple to move from an inclined to a vertical position, the bucket being then let down until the center pin of the valve in the bottom resting upon the floor of the water-dump causes it to discharge its contents, which flow away; a counter weight upon the tipple causes it to resume its normal position, carrying with it the empty bucket, which may then again descend into the mine. There are 22 men employed. Republican Mining Com- pany of San Francisco, owners. T. F. McGovern of Chinese, superin- tendent. Clio Mine. — This is ^ mile south of .Jacksonville. It has recently been equipped with a new steam hoist and a 10-stamp mill, the boilers (generating steam for both hoist and mill) being located at the mill several hundred feet distant down the hill from the hoist. A shaft had been sunk 170 feet about the middle of July, at which time the mine was not in operation, all the work in progress being at the mill, which was in course of construction. J. E. Potter of .Jacksonville, owner and superintendent. Southward from the Clio, no mines are in operation on the Central Lode in this county, excepting some prospecting in one or two mines. Golden Gate Mine. — It is 1 mile southwest of Sonora, and is one of the principal mines of this county. It has been in continuous operation for ten years, and has been a large and steady producer. The formation is amphibolite schist, striking N. 10° E., dipping to the eastward. Through this the Golden Gate vein strikes about N. 60° E. The strike is some- what variable. The dip also varies from 35 to 65 degrees. Thus the vein does not conform in either strike or dip with the inclosing forma- tion. At three points in the underground workings of the Golden Gate Mine I found veins of quartz coming in from the hanging-wall side of the Golden Gate vein. One of these appears on the 200-foot level, 500 feet in a northeasterly direction from the shaft. This vein is from 6 to 8 feet in width, showing no indications of value. This vein has an appar- ent dip to the eastward of 50 to 65 degrees. It does not cross the Golden Gate fissure, but stops at the hanging-wall. Another instance of the occurrence of a vein in the hanging-wall is found on the 300-foot leveh 450 to 500 feet northeast of the shaft of the Golden Gate. Here is found a large stope with intermediate levels — one 20 feet above, the other 25 feet below, the 300-foot level. The mineral zone of the Golden THE MOTHER LODE ^REGION — TUOLUMNE COUNTY. 135 Gate Mine is here large, and the stopes are wide. At the point indi- cated a vein having a strike parallel with the Golden Gate fissure with a dip of 40 degrees to the northwest cuts completely through the Golden Gate fissure, passing into the foot-wall. This vein is about 2 feet in width. It shows no sign of valuable mineralization, and has not been worked, excepting where it intersects the stopes of the Golden Gate Mine. One other instance of the occurrence of a vein of quartz from the direction of the hanging-wall is found on the 400-foot level, where a small vein about 1 foot in width intersects the Golden Gate vein, pass- ing into the foot-wall. It is perpendicular, and cuts the Golden Gate vein near a right angle; it shows no sign of value. On the 500-foot level the main drift diverges, the hanging-wall branch following a gouge and the foot-wall branch following a small lens of ore. Thirty feet from the point of divergence in the foot-wall branch is a cross-cut extending nearly 100 feet into the foot-wall, all in the hard greenstone, with no ore. The principal shaft is down 700 feet, with a winze 200 feet below the 700-foot level at a point some distance northeast of the shaft. There are ten levels in the mine, three of which are above the collar of the shaft. Considerable development was in progress in these upper levels, some excellent ore being found. The property is equipped with hoist and 20- stamp mill, and has electric, steam, and water power. There are also a slimes plant and a chlorination works attached to the mine. Joseph Francis, who is foreman of the mine, has invented a simple device in the form of a swinging apron of iron for use on loading chutes, by means of which the chutes may be constructed so as to require less room than they usually do, the apron being turned upward or allowed to hang beneath the chute when not in use. The employment of these simple devices not only results in convenience, but also effects a saving of time and money. There are 70 men employed. Golden Gate and Sulphuret Mining and Development Company, owner. J. Fisher of Sonora, super- intendent. Densmore Mine. — It is 3 miles northwest of Columbia, overlooking and partly in the canon of the Stanislaus. The mine was discovered many years ago, but was developed in a superficial manner by the owner, who was unable to do more than assessment work on it. No one con- sidered it of more than nominal value. Within the past two years^ however, it has changed ownership a number of times, and it is being developed systematically. The formation is grano-diorite, and it is per- tinent to here remark that, regardless of the prejudice in the minds of some against granite as a yielder of profitable ore-bodies, some of the deepest and best mines in California, as well as elsewhere, are in granite or grano-diorite. On the Densmore a tunnel has been driven on the vein a distance of 400 feet and a shaft sunk 400 feet from the surface, inter- 136 CALIFORNIA STATE MINING BUREAU. secting the tunnel. This is at present the principal development and has exposed an ore-shoot 200 feet long, 400 feet high, with an average thick- ness of about 5 feet. In places it is 12 feet wide. This ore, it is stated, will average -ll? per ton. Some portions are heavily sulphuretted, and run from $150 to $250 per ton. Of this, former owners shipped during 1899-1900 over $26,000 worth, net. In addition to the above described development there are several other tunnels, shafts, winzes, etc. A main tunnel was being driven 200 feet lower than the one above referred to, which will deliver ore into the bin of the mill, which consists of two batteries of 2 stamps each, with one' Wilfley concentrating table. A cyanide plant of 10 tons daily capacity also forms part of the equipment. Though in a rugged canon, the mine is favorably situated for economic working, by means of adits, which will command over 600 feet of backs, and then another tunnel may be driven still lower if desired. A ditch owned by the Utica Company passes along the mountain side opposite the mine, and will afford a cheap power; and, taken altogether, it is one of the most favorably situated mines in the county. There were 20 men employed the latter part of June. Hayward & Lane of San Francisco, owners. L. R. Poundstone of Columbia, superintendent. Confidence Mine. — It is 12 miles east of Sonora, at an altitude of about 4000 feet, in the granite area lying east of the Calaveras formation. This is one of the most noted mines in the county, and has been worked for years, producing, it is claimed, upward of $5,000,000. The vein strikes N. 14° W., and dips east at 18° to 30°. The inclined shaft has reached a depth of 810 feet, with a winze 200 feet below the 800-foot level. The mine makes less than 60 gallons of water a minute. The vein varies from a few inches to 15 feet in thickness. The granite is much decayed from the surface to a depth of 300 feet, below which is found a hard, normal grano-diorite. A light-colored dike rock, frequently of pale-green color, due to chlorite, is usually an accompaniment of the vein. The ore is free milling, but contains a sulphide mineral difficult to concentrate. C3'anide experiments are being made on this mineral and also on the coarse sands which are separated from the tailings by means of a form, of spitzkasten. Seventy per cent of the material is coarse sand, containing 95 cents per ton. The remaining material goes to a Gates canvas plant. The total loss in tailings is $1.65 per ton. The slimes below the canvas tables still contain $3 per ton. This is the material to be experimented upon with the cyanide process, but, due to its extreme fineness, the percolation method cannot be employed. The property is equipped with a steam hoist and 30-stamp mill, of which 20 were dropping. A No. 24 punched tin screen is used, the discharge being from 7 to 8 inches high. The capacity is 3 tons per stamp. There are 3 concentrators with 6-foot belts, and 4 with 4-foot belts. Tailings are run onto the canvas tables 9 hours before purifying. The experi- THE MOTHER LODE REGION — TUOLUMNE COUNTY. 137 raent of purifying was tried, but proved unsatisfactory. ■^ Confidence Gold Mining Company of San Francisco, owners. N, Carmichael of Confidence, superintendent. Black Oak Mine. — It is -h mile southwest of Soulsbyville, on the East Lode, and includes the Black Oak, Carra, and Live Oak claims. The mine was discovered about 'thirty years ago, and during its early history gained little fame, but within the past five years it has come to be recognized as one of the most important mines in the State. It occurs in grano-diorite. The vein varies from 1 to 25 feet in width, and has several branches coming in from the hanging-wall side. These latter often contain heavy sulphide mineral of high grade. Thousands of tons of this class of ore have been shipped to Selby's. The deepest shaft is down 900 feet, at an angle approximately 65 degrees, the dip being westerly and the strike north and south. The vein is intersected at intervals by dikes of very hard dark-green diorite. These simply dis- place the vein. One at the northern end is evidently in the plane of a fault fissure, as the vein does not reappear on the north side of the dike, as in previous instances farther southward. The throw is presumed to be to the westward. If this assumption be correct, the Genevieve Mine, Wing about 4000 feet to the northward, may be the real extension of the Black Oak vein. The mine is equipped with steam and water-power hoist and a 30-stamp mill. A large slimes plant also forms an important feature in the beneficiation of the ores. The ores are quartz, containing iron, copper, lead, and zinc sulphides. Pyrrhotite, a magnetic iron sul- phide of bronze color, is a prominent constituent of the ores, and is characteristic of the granite veins on the East Lode. In the mill a 60-mesh screen is in use, the discharge being 6 inches high. The 30 stamps crush 35 tons daily, which is an unusually low duty for stamps in California, but is probably due to the hardness of the rock and the fineness of the screen. The management claims to be able to make a higher saving by fine crushing. There are 10 concentrators in the mill. The pulp from the batteries passes to the plates and thence to the vanners. Forty per cent of the gold is saved in the batteries. From the vanners all tailings go to the canvas plant, consisting of two floors 60 X 100 feet. From the canvas tables the pulp is elevated and sent to the cyanide vats, where it is charged by means of a mechanical device to insure an equal distribution of sands and slimes, and to pre- vent as far as possible the formation of channels in the charge. The pulp is treated by the percolation method for 80 hours, and then dis- charged through the side doors into the creek. A 60-ton tank is sluiced out in one hour with water under a 500-foot head. Sulphurets obtained from the vanners and from canvas tables are worked in a sepa- rate plant by agitation for a period of 36 hours, with an extraction of 94 per cent. The strength of cyanide solution employed on the tailings 138 CALIFORNIA STATE MINING BUREAU. is 0.25 per cent; that in the agitation process varies somewhat according to the value of the ore. There are 50 men employed. Scott, Dow & Co., owners. W. P. Scott of Soulsbyville, superintendent. Eureka Con. {Dead Horse) Mine. — It is on the East Lode, at Carters. The deepest shaft is down 1550 feet. The formation is mica schist of the Calaveras formation. The vein is from 1 to 12 feet wide, and con- sists of quartz and pyrite. The hoist and mill are run by water when available. The mill has 20 stamps of 900 pounds weight. There are 8 Frue concentrators in the mill. Formerly a canvas plant was opera- ted in connection with the mill, but its use has been discontinued. A cyanide plant on the property treats 2 tons of sulphides daily. This is on concentrates from van ners. ' The screen in the battery is 38-mesh. It is claimed that the extraction is about 90 per cent. There are 41 men employed. Alvinza Hay ward and Hobart Estate of San Fran- cisco, owners. E. T. Kane of Carters, superintendent. Providence {Gloster) Mine. — This property is 2 miles southeast of Car- ters, in the canon of the North Fork of Tuolumne River. Since the last report this mine has come into prominence as a rich producer. It was systematically opened during 1896-97, and equipped with hoist and milling plant, to accommodate which expensive grading and road- making were required, as the slope of the mountain is nearly 35 degrees. A mile and a half of road, reaching from the bottom of the canon to the mine, cost $5,000. The vein occurs in the black slates of the Cala- veras formation, and will average 5 feet in width in the pay shoot. The quartz contains li per cent of sulphides. The shaft is down 850 feet, with six levels. The mill has 10 stamps, but was not in operation in July last. Only development work was in progress in the mine. All power is steam, water being very scarce in that locality. There are 12 men employed, though the full force is 30 when the mill is in opera- tion. Tuolumne County Mining Company, owner. C. A. Holland of Carters, superintendent. Goldwin Mines. — This constitutes a group of three claims about a mile westerly from the Providence Mine, and 10 miles southeast of Sonora. The elevation is about 2000 feet. The strike is north and south, and the dip east. Geologically, the property consists of a broad-fissured zone with a system of parallel quartz veins of variable width, from 2 to 5 feet. The veins are often found accompanied by a light-colored dike. The formation is a fine-grained mica schist. The quartz vein is usually banded, and contains auriferous sulphides. A tunnel has been driven 850 feet on the vein and a shaft sunk 250 feet, in addition to which there are several short tunnels and winzes. The property is equipped with a substantial hoist driven by air, and a water-driven air-com- pressor. The company has constructed a dam in the caiion and built a THE MOTHER LODE REGION — TUOLUMNE COUNTY. 139 flume to the mill site, thus having free water-power. It is reported that this property has produced $150,000. It had been idle for many years before coming into the hands of the present owners. There are 25 men employed. Goldwin Con. Mines, owner. W. H. McClintock of Sonora, superintendent. Dreisam (liJaston) Mine. — It is on the East Lode, at Arrastraville. The vein is from 12 inches to 3 feet in width, and is in grano-diorite. A shaft had been sunk to 300 feet in July, and still sinking. The hoist is equipped with both steam and water power. The mill has two batteries of 6 stamps each, and two Frue concentrators. The mill is to be enlarged. There are 30 men employed. Dreisam Gold Mining Company of San Francisco, owner. W. Morehead, superintendent. Grizzly Mine. — It is 1 mile south of Carters, on the East Lode. The vein is 10 feet in width, has a banded structure in Calaveras slate, with the usual accompanying dike. The shaft is down 750 feet, with levels at intervals of 100 feet. The mill has 20 stamps, with 8 Frue vanners- Water furnishes power for both hoist and mill. From 16 to 20 men were employed in July. Grizzly Mining Company of San Francisco? owner. W. R. Hall of Carters, superintendent. Big Oak Flat District. — Since the last report there has been much activity in and near Big Oak Flat. A score or more prospects of greater or less prominence have been incorporated and a large sum of money expended in their equipment and development. As is usual in such cases, some of these have proven unsatisfactory and have been aban- doned, while others are still developing, with fair prospects. ' Longfellow Mine. — It is at Big Oak Flat, and is generally considered as being on the East Lode, though this section is really between the Central and East Lodes. The geology of the mine as described by the superintendent is as follows: There are two veins about 50 feet apart, the foot-wall vein being 10 to 12 feet wide and the hanging-wall vein 4 to 5 feet wide. There are many stringers of quartz in the slaty zone inclosed between these two veins. The formation is slate. A shaft had been sunk to 450 feet in July last. The surface equipment consists of a steam hoist and a 10-stamp mill, with Wiltley and Frue concentra- tors. A 30-ton cyanide plant was in course of construction the latter part of July, and the tailings are to be treated by that method. During the dry season water for milling is pumped from the Mississippi shaft sunk on a vein in the granite of Big Oak Flat. Longfellow Gold Syndicate of Glasgow, owners. A. P. Dron of Big Oak Flat, superin- tendent. 140 CALIFORNIA STATE MINING BUREAU. Mack Mine. — This adjoins the Longfellow on the east, and is on the same vein. The shaft is down 430 feet at 35 degrees. Four levels are opened, and the prospect is stated to be encouraging. The mine had a steam hoist but no mill in the latter part of July. There are 12 men employed. Mack Con. Mining Comj^any of San Francisco, owner. C. L. Lang of Big Oak Flat, superintendent. A Gold-Bearing Zone. — This is found about 1 mile west of Big Oak Flat, and extends for more than 15,000 feet along the mountain side, and presumably could be traced farther. The formation consists of a succession of black slates and diabase tuff. A description of the Criss- Cross claim will answer in a general way for all of the numerous claims along this belt for a considerable distance in either direction from it. In that property the formation consists of Calaveras slates, and reefs of diabase tuff. The slates occur in zones, some of which are relatively soft and contain disseminated iron sulphides. The remaining portion of the slates is usually hard, and less highly mineralized. The slates are also intruded by dikes of diabase and porphyry. There are devel- oped in this mine four zones of what are termed by the miners "mineral or metallic slates. " These zones are separated from each other by dikes of variable width, not exceeding 20 feet. The slates strike north 30"^ W., standing vertical. The entire formation is intersected by seams and veins of quartz, which strike about N. 30'^ E., dipping southeasterly at 60° to 70°. Some of these quartz veins, small at the surface, widen to 24 inches or more within a depth of 50 feet, and carry disseminated gold, proving that these are not exclusively pocket mines, as has been supposed. These vertical veins of quartz occur at intervals of 8 to 10 feet, having approximately a parallel strike. A second series of quartz veins is found lying nearly horizontal, cutting the slates, and intersect- ing the vertical veins. These veins occur at distances of 4 to 6 feet apart, dipping at a low angle to the westward, thus dividing the forma- tion into rhomboidal blocks. Frequently at the intersection of these highly-inclined and flat veins a slight dislocation may be noticed, indi- cating that there has been some movement of the formation since these veins were formed. The gold found in this property is, as far as known, confined almost exclusively to the zones of " metallic '" slates. In that portion of the property to the northward the steeply-inclined veins have been found to carry coarse gold in considerable quantity ; in fact, to such an extent that many thousands of dollars have been taken from rather superficial development by pocket-hunters. To the southward, however, the gold in the veins has been found chiefly in the nearly horizontal seams and veins, and these have all jDroduced largely. The cause of this difference in the occurrence of the gold has not yet been ascertained, but the fact that such is the case is of interest. As a result of the operations of the pocket-miners there has been accumulated in THE MOTHER LODE REGION — TUOLUMNE COUNTY. 141 the different dumps hundreds of tons of material, which, to the pocket- miner, is waste, but it has been found by repeated tests that all of these dumps carry considerable value in gold. It is an established fact that the slates on either side of vertical veins carry gold for a distance of 2 feet or more from the vein. This also seems to be the case with the horizontal veins. It may be that the gold-bearing zones constitute a milling proposition, and that not only the quartz veins, but the slates as well, may be mined and milled as a whole. In this respect these gold-bearing zones bear some resemblance to the Jumper Mine near Stent, in this county, where it has been found that the most economical, and withal the most successful method of operating is to mine all the material between the walls of the zone and the milling of all such material, there being practically no waste. 142 CALIFORNIA STATE MINING BUREAU. MARIPOSA COUNTY. Since the publication of the last report of the State Mineralogist, Mari- posa County has taken on more active life. The Mariposa Grant, cover- ing an area of about 70 square miles, which for many years had lain idle, has become the property of the Mariposa Commercial and Mining Company, which has undertaken the active exploration and development of at least five of the most important mines on the Grant. They are going about this in a business-like way, and the indications are that if there is any actual merit in the mines on the Grant it will be ascertained by the present operators. A hasty visit was made to this field of opera- tion in the latter part of May last for the purpose of investigating what had been done and what was expected of these mines in the future. Mariposa Mine.— This property, worked many years ago, it is reputed at one period with great success, but which had been idle for more than thirty years, has been reopened, and an inclined shaft sunk which had reached a depth 475 feet on May 15th. The shaft was carried down at a uniform angle, but the vein passed out into the hanging- wall at about 400 feet from the surface. In cutting a station at 475 feet, the vein was discovered in the hanging-wall. The walls are diorite-porphyrite, and very hard. The vein has little or no gouge, but generally breaks free ' from the walls. The center of the vein is usually massive, with a banded structure near the walls, and in some portions the entire vein shows the banded structure. It varies greatly in width, from a seam to 12 feet or more. It strikes N. 70° W., with a variable dip to the southward, which wall average about 60 degrees. Several hundred feet west of the new shaft a branch breaks into the foot-wall, striking N. 50° W. A shaft, now caved and filled with water, is sunk at the point of divergence. It is said that large amounts of gold were taken from this shaft in the form of pockets by the early miners. A report of Dr. R. W. Raymond, "Mineral Resources West of the Rocky Mountains," 1868, states that the Mariposa Mine was closed at that time, for the reason that mining operations were no longer profitable, though the rock contained nearly $10 gold per ton. It has been ascertained by careful sampling of the faces of the stopes abandoned years ago, that considerable bodies of rock were left, which averaged over $7 per ton, where the vein was from 2 to 4 feet in width. During the past summer a long drift on the 400-foot level has cut through a fine shoot of high-grade ore. The mine is equipped with steam hoist and air-compressor, steam pumps, and other THE MOTHER LODE REGION — MARIPOSA COUNTY. 143 necessary machinery. There are 28 men employed, Mariposa Com- mercial and Mining Company, owners, 320 Sansome Street, San Francisco. J. H. MacKenzie, Mount Bullion P. 0., general manager. The Princeton Mine. — This property, situated at Princeton, 6 miles northerly from Mariposa, has also been reopened after an idleness of many years. A new inclined shaft has been sunk to a depth of 600 feet, penetrating some little distance below the old workings, very little of which are at present accessible. Near the bottom of the shaft, two fine- grained, ash-colored dikes intersect the vein at an oblique angle. They have not '"thrown" the vein, simply passed through it. In the bottom of the shaft, at the time of my visit, the vein was about 4 feet in width, of beautiful banded quartz. The entire vein from the surface to the 600-foot level is inclosed in the typical clay slates of the Mariposa beds. These slates differ very materially from the black tufaceous slates so closely associated with the rich ore dej^osits of Amador County, and to which more particular reference is made under the head of Amador County. At this writing, the latter part of May, nothing more can be said of the Princeton Mine, and only the future development of the property can determine its real merit. The mine has an authentic record exceed- ing $3,000,000 to a depth of 600 feet. In the foot-wall country, lying immediately west of the Princeton vein, there are many veins, both large and small, of gold-bearing quartz, and this section it is the intention of the company to prospect. The mine is equipped with steam hoisting plant and machine shop, and a 10-stamp mill is being erected for the purpose of testing ores from the several mines of the Grant. The central office of the mines is located at Princeton. There are 30 men employed. In the middle of September the shaft was down nearly 900 feet, the vein averaging 3^ feet in width. J. H. MacKenzie, Mount Bullion P. 0., general manager. The Josephine Mine. — This property is about 3 miles north of Bear Valley, overlooking the Merced River, and immediately adjoins the " Pine Tree," with which its name is usually associated. This is also being operated by the Mariposa Commercial and Mining Company. The manager has placed a hoist underground, and sunk a winze 200 feet from the level of the "English" trail drift. A vigorous policy has been inaugurated, and the vein will be developed as rapidly as possible. It has been stated in numerous previous reports that the Josephine vein splits off to the westward from the Pine Tree vein ; that it continues upon an independent course for a distance of nearly 15 miles, rejoining the main lode near Pifion Blanco, 3 miles north of Coulterville. A careful investigation has led to the conclusion that the Josephine vein returns to and rejoins the Pine Tree vein within a distance of 3000 feet from 144 CALIFORNIA STATE MINING BUREAU. where it diverges, at what is called the old Fremont shaft. The error into which myself as well as others have been led was in presuming that a line of disconnected croppings represented the Josephine vein, whereas the croppings of the Josephine are absolutely continuous, and may be traced from its point of divergence from the Pine Tree northward to where it rejoins the Pine Tree vein. The hills are covered with a dense growth of chaparral, manzanita, and greasewood, and the tracing of this line of croppings was not an easy task, though not an impossible one. Both the Pine Tree and the Josephine veins are well exposed on the level of the English trail drift, where, taking a cross-section at a point 437 feet below the croppings at the Fremont shaft, it is found that the two veins converge on this level about 400 feet north of the point of meeting on the croppings, showing that the line of convergence is not vertical, but inclined to the northward. A cross-cut at the point where these veins converge on the English trail level, shows a body of quartz 40 feet in width, dipping uniformly to the eastward at an angle of 60 degrees. Along the drift which follows closely the Pine Tree vein, the two great veins are separated by a mere seam no thicker than a knife- blade. Northward, a mass of soft material composed of ankerite with mariposite and quartz, separates the veins by a few feet. Still farther northward the divergence is greater, and the Pine Tree vein shows a gouge 1 inch thick on the hanging-wall side of the vein. A cross-cut has been driven 25 feet eastward through a mass of crushed and highly altered ankerite to a second gouge containing fragments of this rock- mass. The gouge is from 1 to 2 inches thick, and is extremely tough, but soft. The wall beyond is polished like a mirror, and was formerly considered the hanging-wall of the vein. The material beyond the slip is identical with that in the cross-cut (crushed ankerite altering to talc). Serpentine occurs on the hanging-wall side of the vein on the surface over 200 feet distant. The serpentine approaches nearer to the vein, going northward, however, and in the tunnel driven near the Merced River, about 1000 feet lower than the English trail drift, lies on the hanging- wall side of a zone of material similar to that found in the cross- cut above referred to (the altered ankerite). The ankerite, containing mariposite, separates the Pine Tree and Josephine veins, and the material grows broader as the veins diverge, but where they are 80 to 100 feet apart and more, it does not fill the entire space between them — a gray rock, amphibolite schist, lying next the ankerite. The Josephine vein is distinguished everywhere along its course by what may be termed its fragmental appearance. A banded structure is frequently apparent, but mixtures of quartz and black slaty material are the most persistent features. J. H. MacKenzie, Mount Bullion P. 0., general manager. '^/ :•*. -^ Croppings of the Maripojsa Vein. Croppings of the Louisa Mine, Coulterville, Mariposa County. THE MOTHER LODE REGION MARIPOSA COUNTY. 145 Pine Tree Mine. — This adjoins the Josephine, and is 3 miles north of Bear Valley. One of the old tunnels driven by the former operators has been cleaned out and retimbered, and a hoisting engine set up under- ground about 600 feet from the mouth. Here a shaft has been sunk to a depth of 300 feet below the level. Ventilation is secured by an upraise through old workings above the hoist connecting with an upper tunnel. The engine is operated by steam carried in from the boilers at the mouth of the tunnel, the exhaust passing out through the raise. Owing to the careful manner in which the steam pipes have been packed, there is little condensation in the pipes, and the temperature at the station is Fig. 35. not uncomfortably warm. In sinking the shaft, a very interesting fault was discovered about 300 feet from the platform, the character of which is illustrated in the accompanying drawing (Fig. 35). The indications are that the formation on the hanging-wall side of the fault has slipped downward, and that if sinking were continued on that portion it would be found to cut out, though in what distance it is impossible to say. The foot-wall portion, however, will extend down- ward to indefinite depth. The shaft is being sunk through the heart of the ore-shoot opened by the old company, it being the purpose to ascer- tain as quickly as possible whether payable ore still remains in the 10— MB 146 CALIFORNIA STATE MINING BUREAU. mine, and if so, how much. The Pine Tree Mine is everywhere char- acterized by its massiveness and its entire freedom from slaty inclusions Iron pyrite occurs in the quartz, but is not abundant. The vein is usually well defined by smooth walls, the foot-wall being always, as far as observed, mariposite and ankerite. The hanging-wall side of the quartz vein is a granulated mass of rock, containing many fragments of what appear to be the ankerite. The real hanging-wall — normal country rock, i. e., slate, diabase, or serpentine — has not been cut on the English trail level. At the mouth of the old Pine Tree tunnel, now caved and inaccessible, the serpentine is found close to the vein. South- ward, up the hill, it is fully 200 feet away from the vein. In the river tunnel the serpentine forms the hanging-wall of the vein — that is, it lies on the hanging-wall side of the fragmental rock (crushed ankerite) referred to as occurring on the hanging-wall side of the quartz on the English trail level. In the river tunnel the Pine Tree vein splits up and makes good-sized quartz veins in this fragmental material. In places the quartz is confined to the foot-wall side, ranging in width from 4 to over 40 feet. In speaking of the vein the entire mass of ankerite with the included quartz lenses is meant, though commercially only that portion containing pay ore would be recognized as the vein. Roma and Sierra Blanca (Quartz). — Three miles northeast of Col- orado. A tunnel is being run 1400 feet to reach the vein. It had reached a length of 915 feet September 1, 1900, and is being driven through soft slate and schist at a cost of $4 per foot, including timber- ing. All work is by hand, and the tunnel is 5 by 7 feet clear. The timbers are obtained on the property. There are 12 men employed. Lew Anbury of Mariposa, superintendent. Mary Harrison. — This mine is on the southern portion of the Cook Estate, 2 miles south of Coulterville. It is situated on the great Dolomitic vein, the quartz occurring on the foot-wall side, being 4 to 6 feet wide. Both hanging and foot walls are diabase. Black clay slates (Mariposa beds) and serpentine also occur in the immediate vicinity of the vein. The deepest workings are down 900 feet, and still sinking in July last. The ore-shoot is stoped from the 700-foot level to the surface. The lower levels are extensive. A 40-stamp mill built on the Potosi Mine, one of the group owned by this company, crushes ore from the Mary Harrison Mine, with which it is connected by 4 miles of narrow-gauge railroad. No rock was being crushed at the time of my visit. Hoisting is done by steam. There are 75 men employed. In addition to the Mary Harrison, the company also owns the Louisa, Margaret, Potosi, Malvina, and numerous other claims on this large estate, but the above described is the only one in operation. Merced Gold Mining Company of Boston, owners. J. Mills of Coulterville, manager. » THE MOTHER LODE REGION — MARIPOSA COUNTY. 147 Bonanza Mine. — It is 5^ miles south of Coulterville, near the Merced River, on the Dolomitic vein. A cross-cut tunnel was in 280 feet in July last, running to intersect the vein, which was said to be 50 feet in width. The hanging-wall is slate and the foot-wall serpentine. A 20-stamp mill was in process of building, and a dam was being con- structed in the Merced River for power. There are 25 men employed. T. P. Brisland of Coulterville, manager. Murphy Mine. — It is 3^ miles south of Coulterville, on the main lode, having serpentine on the hanging-wall and slate on the foot, dif- fering in this respect from the Mary Harrison, which it somewhat resembles otherwise. A shaft had reached a depth of 145 feet the middle of July, and two levels had been started. The property is equipped with steam hoist, but has as yet no mill. There are 18 men employed. The Guffy-Galey Gold Mining Company of Pittsburg, Pa., owners. W. W. Elmer, superintendent. Black Hill {Pumpkin) Mine. — It is 1 mile north of Coulterville, and is in the prospective stage, a shaft having been sunk 60 feet, equipped with horse-whim. Some rich ore has been found in recent development. There are 5 men employed. John Boyd, owner. J. J. Dolan of Coul- terville, superintendent. Yosemite Hydraulic Mine. — It is 10 miles east of Groveland. The company has built 11 miles of ditch flume and pipe-line the past year, and made preparations to carry on hydraulic mining on an extensive ■scale; the scarcity of water, however, has affected operations seriously. When working full force 20 men are employed. W. J. Pender of Groveland, superintendent. 148 CALIFORNIA STATE MINING BUREAU. MADERA COUNTY. As it was necessary to pass through Madera County in going into Mariposa, a brief examination of two mines was made while in that county. In the neighborhood of Grub Gulch prospecting is actively being prosecuted, and also in the direction of Coarse Gold, but lack of time precluded visiting that section the past season. The Rex Mine. — This is a new property at Grub Gulch. It has been opened within the past few months. An inclined shaft has been sunk V&R-fiCAL Cross Section Rex ^Oinet Fig. 36. to a depth of 100 feet at an angle of 40 degrees to the eastward. At a depth of 50 feet from the surface in this shaft, the Rex vein, which is from a few inches to 14 inches in width and rich in free gold, was found intersected by another vein, known as the Bullion, which dips to the westward at an angle of 60 degrees, cutting the dip of the formation nearly at right angles and displacing the Rex vein. The formation in THE MOTHER LODE REGION MADERA COUNTY. 149 which these veins occur is mica schist. That portion of the Rex vein in the neighborhood of the shaft has been opened by a series of shallow pits, and by means of these the direction of its strike can be traced along the surface. After passing the Bullion vein, which in strike intersects the Rex vein at a low angle, the Rex vein does not appear in line with the croppings on the farther side of the Bullion vein. However, farther to the northward is a vein which has the physical characteristics of the Rex vein, and also carrying the same character of gold, and this vein has been traced for more than 1000 feet from its intersection with the Bullion vein, on the opposite side of which it can be no further recog- nized. There is little doubt that these two disconnected veins are identical, having been dislocated by the later Bullion vein. The accom- panying sketches (Figs. 36 and 37) illustrate this occurrence. As Pi^T^N o^ Re;( -anp Bullion Veins a4-(5rub<^ulcH\. madera Counry . Callfsmia^ 5bowir\4 pisplaceroenr of- R6-;< \/fc)H b/ "^ la-fer guLuioN VeiiS. Fig. 37. nearly as could be determined, the Bullion vein has displaced the Rex vein about 70 feet, its downward extension lying in the foot-wall and about that distance from the upper portion of the vein. Charles M. Ward and others of Grub Gulch, owners. iVe Flu8 Ultra Copper ikfme.— This property is 9 miles in a south- westerly direction from Raymond, on the San Joaquin plains at Daulton. It is an old property which has been reopened since the publication of the last report. Three shafts have been sunk on the mine, 125, 140, and 145 feet respectively. These are distributed along the vein for a dis- tance of 1000 feet. The formation is chiastolite schist. The zone of mineralization is 100 feet or more in width, in which there are several shoots of ore having an approximate parallelism with many ramifying branches. There are also dikes cutting the formation. The ore normally is an iron-copper sulphide, but in the zone of semi-oxidation, between the thoroughly oxidized gossan ores and the normal sulphide ores, oxidation is taking place very rapidly. This oxidation results in giving 160 CALIFORNIA STATE MINING BUREAU. out a large amount of heat, which occasions the mine workings to be unusually hot. The ore taken from certain shoots in this mine, when delivered on the dump, frequently takes fire within a few days by spontaneous combustion, and on several occasions has set on fire the cars in which the ore is transported to the smelter at Madera. A large dump situated at the south shaft has been burning for some time, and the ore now presents the appearance of an ore-pile which has been heap- roasted in the usual manner. In this mine was observed one of the very few underhanded stopes in the State. The method of working this mine illustrates to a marked degree the unfortunate policy commented upon in one of the first paragraphs of this bulletin, that of demanding immediate returns from development of ore. There are 40 miners employed in the mine, 15 on top, and 60 at the smelter, which is located near the town of Madera. The smelter was not visited. California Copper Company of 31 Nassau Street, New York, owner. Wm. Davidson of Daulton, superintendent. Several copper mines are being worked on Green Mountain about 10 miles northwest from Raymond, and there is one near White Rock, about 15 miles southwest of Mariposa. These mines are shipping high- grade, partly oxidized ores. They were not visited. INDEX. Page. Age of Calaveras formation 7 Age of Gold Belt 7 Age of Mariposa beds... .-. 8 Alteration in massive rocks 9 Alteration of basic rocks to steatite 14 Alteration of other massive rocks 13 Alterations of tuffs to schists and slates -- -. 19 Altman Mine 98 Amador County 43 Amador Queen No. 1 44 Amador Queen No. 2 44 Amphibolite schists ..- 8 Anderson Mine - 44 Angel Mine 109 Ankerite, Alterations of, to talc 21 Ankerite, Probable origin of _.. 13 Ankerite vein, General features of 20 App and Heslep Mines, The 131 Arbona Mine 129 Argonaut-Kennedy vein, Geology of .. 56 Argonaut Mill, Experiments in 50 Argonaut Mine 50 Argonaut Slimes Plant 51 Azula Mine 86 Baliol Mine 75 Banded schists 12 Bay State Mine 85 Bell signals 40 Bell signals, California code of 40 Big Bonanza. 121 Big Canon (see Oro Fino) 96 Black Hill (Pumpkin) Mine 147 Black Oak Mine, Water crevice in 25 Blue Jay and Yellow Hammer Mines. 123 Bolytho Mine 120 Bonanza Mine.. 147 Borger Copper Mine — 125 Bovee Mine 119 Bown Mine 129 Buena Vista Mine 91 Bunker Hill Mine 80 Butte Mine 45 Calaveras County 100 Calaveras formation 7 Calaveras Mine 123 Page. California bell signal code 40 California greenstone 8 Canvas plant, Zeila Mine 46 Carson Creek Mine (see San Justo) 123 Centennial Mine 82 Center Mine 91 Central Eureka Mine 64 Central Gold Belt 15 Central Lode 14 Chlorination works. Practice in Amador County 81 Chlorination works, Utica Mine 118 Church Mine 92 Classification of rocks 16 Clay slates at Gwin Mine 19 Clay slates of Mariposa beds 15 Clay slates. Relation of to veins 15 Code of bell signals in California 40 Commodore Mine 103 Condensation in steam pipes 33 Connecting levels 28 Contact veins 15 Contents 2 Copper mines (Ranlett) 87 Cornish pumps compared with steam pumps - 33 Cost of milling dumps, Plymouth Con. Mines 83 Cost of milling at Mahoney Mine 37 Cost of mining 35 Cost of mining at Kennedy Mine 39 Cost of mining at Mahoney Mine 36 Cost of mining and milling at Gwin Mine ... 38 Cyanide plant, Utica Mine 119 Cyanide plant, Vandalia Mine 97 Daulton Copper Mine (see Ne Plus Ultra) 149 Demarest Mine 107 Diamond drills. Use of 35 Dikes in granite 24 Dip of slate, schists, and veins 15 Dip of veins, Relation of, to mine methods 31 Direct-acting steam pumps compared with Cornish pumps 33 Divisions of the Gold Belt 14 152 INDEX. Page. Dolomite 1^ Dolomitic vein 13-19 Dolomitic vein, General structural fea- tures of — 1^ Drainage of mines - 32 Drake Properties (Ltd.) 121 Dresiam (Easton) Mine - 139 Dutch Mme 130 Dutton, Capt. C. E., quoted -. 12 Eagle-Shawniut Mine, The 132 East Lode, The... ---- --14, 21 El Dorado County 88 El Dorado County, Geology of -. 88 Ellen Taylor Drift Mine --- 94 Ellen Vannan Drift Mine 124 Emerson shaft, Timbering --. 68 Emerson shaft of Wildman Mine 68 Emery Hydraulic Mine 124 Eruptive rocks at Logtown 89 Esperanza Mine -- - 123 Eureka Slate Quarry. - 99 Experimental work, Keystone Mill 79 Fairbanks, H. W., Determinations by. 16 Fault in the Keystone Mine 77 Fault in the Princeton Mine 147 Fellowcraft (Bode, or Veritas) 105 Filling, Necessity of prompt 32 Filling of stopes 31 Filling, Where obtained 31 Ford Mine 107 Formation of mineral veins 22 Fortuna Mine.. 98 Free American Mine 76 Fremont Mine 80 French Hill Quartz Mine 125 Gentle Annie Mine 94 Geology of Argonaut-Kennedy vein ... 56 Geolog5' of Gold Belt 7 Geology of Keystone Mine. 77 Geology of Pine Tree-Josephine Mine. 145 Geology of the Vandalia Mine. 97 Geology of Wildman-Mahoney Mine.. 65 German Mine 90 German Mine, Peculiar intrusions in.. 90 Gold Cliff Mine Ill Gold-bearing zone, A 140 Gold Belt, Age of 7 Gold Belt, Central 15 Gold Belt, Geology of 7 Gold Belt, Divisionsof 14 Golden Rule Mine (see Jumper) 131 Gold in granite 24 Gold in talc 86 Goldwin Mines 138 Gopher-Boulder Mine 98 Page. Gover Mine (see Fremont) 80 Gowanus Mine 85 Granite areas .. 21 Granite, Dikes in . 24 Granite, Gold in 24 Granite, Ores in 22 Granite, Veins in 22 Great Western Mine. 120 Greek Mine 123 Green Mountain Mine (hydraulic and drift).. 124 Green Mountain Copper Mines 150 Greenstones of California similar to Michigan ... 8 Griffith Mine.... 92 Grizzly Mine 139 Gwin Mill, Practice at 103 Gwin Mine. 100 Gwin Mine, Clay slates in 19 Gwin Mine, Cost of mining and milling 38 Gwin Mine, Method of mining at. 100 Gwin Mine, Method of timbering at 102 Harris Mine (see Big Bonanza)... 121 Harvard (Whisky Hill) Mines. 130 Hayward Hydraulic Mine 99 Hector or Mahoney Mill 71 Heslep Mine (see App) 131 Illinois Mine 107 Illustrations, List of 3 Intermediate levels 30 Ivanhoe Mine 84 Jackass Hill 129 Jack Hanley Mine 99 Josephine Mine, Geology of .. 144 Josephine Mine, The 143 Jumper group of mines... 131 Kennedy Mill 54 Kennedy-Argonaut vein. Distribution of ore-shoots in 53 Kennedy Mine 52 Kennedy Mine, Geology of vein in .56 Kennedy Mine, New vertical shaft 53 Kennedy Slimes Plant 55 Keystone Mill 79 Keystone Mine 77 Keystone Mine, Geological structure of 77 Kirkwood Mine 45 Kretcher Vein (see Bay State).. 85 Larkin Mine 93 Last Chance Mine 122 Last Chance Mine (El Dorado County). 91 Letter of Transmittal 4 Lightner Mill 109 INDEX. 153 Page. Lightner Mine (at Angels) - 109 Lightner Mine (at Copperopolis) 126 Lincoln Mine 72 Lincoln Mine, Fault in 73 List of Illustrations 3 Lodi Mine (see Sheep Ranch) 104 Longfellow Mine - 139 Mack Mine 140 Madeline Mine 91 Madera County 148 Mahonej' Mill, Cost of milling at 37 Mahoney (or Hector) Mill, Practice in. 71 Mahoney Mine, Cost of mining at 36 Mahoney Mine, Geology of 65 Manila ropes in Ranlett Copper Mine. 87 Marguerite Mine 93 Mariposa beds, Position of 8 Mariposa County .._ 142 Mariposa Estate, Mining machinery on 40 Mariposa Mine 142 Mariposite 13 Mary Harrison Mine 146 Massive rocks, Alteration of 9 Melones Consolidated Mine 121 Merced Gold Mining Company 146 Metamorphic rock and schist... 8 Metamorphism of tuffs 12 Methods of mining 26 Mill practice at Utica-Stickle Mine 111 Mine bell signals 40 Mineral veins. Formation of 22 Mining, Cost of 35 Mining, Cost of at Kennedy Mine 39 Mining, Cost of at Gwin Mine 38 Mining, Cost of by Wildman Co. 86 Mining machinery. 39 Mining machinery on Mariposa Estate 40 Minnehaha Mine 95 Monitor Mine 98 Montauk Gold Mining Co. (see Zant- graf). 99 Montezuma Mine 91 Mother Lode 14 Murphy Mine.. 147 Mutual Mine 74 Nashville Mine 91 Ne Plus Ultra Copper Mine 149 New York Mine (see Anderson Mine).. 44 Noonday Mine (copper)... 91 North Star Drift Mine 124 Norwegian Mine 129 Nugget Mine 86 Oneida Mine 60 Oneida new shaft, Formations in 62 Ores in granite 22 11 — MB Page. Ore-shoots in Kennedy-Argonaut vein, Distribution of 53 Origin of ankerite 13 Oro Fino Mine.- 96 Pacific Mine, Placerville 13 Peerless Mine. 45 Perlina Mine _ 120 Philadelphia Mine 84 Phoenix Reduction Works (chlorina- tion) 81 Pine Tree Mine 145 Pine Tree Mine, Fault in 145 Pine Tree Mine, Geology of 146 Pioneer Mine 83 Pitted slates 15 Placerville Slate Quarry 94 Plymouth Consolidated Mine, Milling dumps of 82 Pocahontas Mine, Amador County 83 Pocahontas Mine, El Dorado County.. 95 Pocket Mines (see Jackass Hill) 129 Potazuba 76 Princeton Mine, The 148 Queen Mine 87 Ranlett Copper Mine 87 Rawhide Mine 129 Red Cloud Mine 85 Reduction Works, Phoenix 81 Relief Mine 121 Renshaw, J., on pumps 33 Revera Mine 94 Rex Mine, The.. 148 Rex Mine, Fault in the 148 Rhetta Mine. 86 Ribbon Rock and Tin Cup Mines 94 Ritter Mine 123 Rocks, Classification and description of 16 Rocks, Eruptive, at Logtown... 89 Roma and Sierra Blanca Mines 146 Royal Consolidated Gold Mine 126 Royal Mill, The 127 San Domingo Hydraulic (Jupiter) Mine 125 San Justo (Carson Creek) Mine 123 Satellite Copper Mine 125 Schists, Banded 12 Schists and metamorphic rocks... 8 Selby Mine.- 93 Shaft, Arrangements to ventilate 34 Shenandoah Mine _. 84 Sheep Ranch Mine 104 Sierra Blanca and Roma Mines 146 Sierra Lode -.. 15 Sills, LTse of in timbering 30 Slate Quarry, Eureka 99 154 INDEX. Page. Slate Quarry, Placerville 94 South Eureka Mine -.. 63 South Keystone Con. Mine 77 South Spring Hill Mine 11 Spagnoli Mine 45 Spanish Dry Diggings 98 Starlight Mine 95 Steam pipes, Condensation in 33 Steatite 14 Steam pumps compared with Cornish pumps 33 St. Lawrence Mine. 120 tStopes, Superficial area of 30 Structural geology of the Gold Belt ... 7 Swelling ground 27 Talc derived from alteration of ankerite 21 Talc mines.- 86 Timbering Emerson shaft, Wildman Mine 68 Timbering in mines 30 Timbering in new shaft, Kennedy Mine 54 Tin Cup and Ribbon Rock Mines 94 Transition rocks 13 Treadwell & Guliana Mine 76 Tuffs altered to schists and slates 19 TuUoch Mine 121 Tuolumne County 128 Umatilla Drift Mine 94 Union and Keystone Copper Mines 126 Union Mine _ 92 Utah, Eruption on high plateau of 12 Page. Utica Chlorination Works 118 Utica Cyanide Plant 119 Utica-Stickle Mill, Practice in Ill Utica-Stickle Mine 110 Vandalia Mine 96 Vandalia Mine Cyanide Plant 97 Veins, Formation of .- 22 Veins, in granite 22 Ventilation in shafts 34 Veritas Mine (Bode, or Fellowcraft) ... 105 Walls, Gangways in. 27 Walls of veins, Mineralization of 26 Water in mines. Relation of to ore 25 Waterjacket smelter at Ranlett 87 Whisky Hill Mines (see Harvard) 130 White Rock Copper Mines 150 Wildman Co., Cost of mining by 36 Wildman Co., Cost-sheet excludes 1899- 1900 39 Wildman Mill - 71 Wildman-Mahoney Mine 65 Wildman Mine, New vertical shaft at.. 68 Williams, G. H., quoted 9 Yosemite Hydraulic Mine 147 Zantgraf Mine 99 Zeila Canvas Plant, The 46 Zeila Mill, Experiments in 46 Zeila Mine 45