The west tunnel had reached, in October, a distance of about 1,100 feet from the forks. Here a displacement of the ledge was met with, and, having a large amount of ground open, the company postponed continuing the tunnel for the present. As many breaks have been found in the ledge, and all insignificant in extent of displacement, no special importance attaches to this particular one at the end of the west tunnel. The east tunnel seems to have lost the ledge in broken ground, some 350 feet from the forks. It has been continued to 800 feet without certainly finding the ledge proper. This is beyond the workings of the Manitowoc. During the year, while the west tunnel was driven ahead, the ledge has been stoped along its upper and western side, toward the north, (i. e., toward the entrance of the mine,) for about 150 feet on the gentle rise of the ledge, and at the other end for about 10 feet. There is, therefore, a stope 1,100 feet long, 10 feet high at one end, and 150 feet high at the other; only, instead of standing steeply, as in most veins, it is not very far removed from a horizontal position. The workings look, in this respect, more like a coal-bed than like a metal-mine. The above estimate of 1,100 feet of breast for stoping makes no account of the few and small barren spots caused by little "jumps," or displacements of the vein. The ground stoped out is filled mostly with waste, the necessary passages and dumping-spaces being left open. The average thickness of the ledge is 25 feet, the range being from 10 inches to 5 feet. The hanging-wall is very strong, and there is usually a convenient clay "gouge" between ore and slates. On the east side, and below the tunnel, the ledge has been worked out to a varying depth. At about 85 feet from the forks a passage is cut through, following the "sag," from the west to the east tunnel. The lowest point is about 20 feet below the tunnel-levels. A similar passage between the two tunnels, a few hundred feet farther south, would have to go much deeper. For about 100 feet southward from the lowest point referred to, quartz has been found, going downward to the east, and removed. And again, at various points in the tunnel, rich rock has been removed to the depth of 10 or 20 feet when discovered. For exploring the ground east of the west tunnel, it is reported an incline was sunk at a point about 900 feet from the forks, to the depth of 120 feet, on a uniform good ledge, dipping about 20 degrees east, with only one slight displacement. The yield of the ledge is remarkably regular in quality. The firstclass ore is worth $500 per ton and upward; the assay value of the millore about $60; and the yield by first process (Washoe amalgamation) about $33. There are large quantities of tailings, variously estimated in value at $250,000 to $1,000,000. An important economical improvement of the year has been the construction of a tramway from the mine down to the bottom of the cañon below. The loaded cars, carrying about one ton of ore each, descend by gravity, and pull up the empty ones. The descent of 1,900 feet occupies about five minutes. The saving is 24 miles of bad road in the distance, and about $1.25 per ton in the cost of transportation. The amount of ore extracted from the Arizona during the year is about 7,000 tons. The Arizona Association operates two stamp-mills, and a pan-mill for the treatment of tailings. The stamp-mills have ten stamps each, of about 700 pounds, dropping 8 inches. At the lower mill the rate of * One is owned, I believe, by another company, called the Silver Mining Company. running was 96 drops per minute. This was perhaps too fast, considering the extreme fineness (No. 40 wire) of the screens. The capacity of each mill is about 15 tons daily, or 1.1 tons at the lower, and about 1.3 tons at the upper, per horse-power developed at the stamp. tailings-mill will be mentioned below. The The North Star mine has been worked during the larger portion of the year. The ledge is much disturbed and broken up by porphyry, which surrounds and underlies the ground. The irregularity thus occasioned is the cause of the expensive and difficult working of the mine, as much prospecting is required and much quartz has to be moved, which needs much picking to obtain the required grade for milling or shipping ores. Thus far the works have not reached 100 feet depth. The mine is in limestone. The amount of ore extracted during the year is about 650 tons, of which about 7 tons have been selected for shippingore, the balance being treated at the Pioneer Mill, and yielding about $17,000. On the Henning, (an old claim, about a mile south of the Arizona), work was commenced in July, and has been prosecuted without interruption since. A tunnel has been run for about 150 feet on the ledge. The outcrop had spots of rich mineral; but the amount has been increasing steadily as the tunnel is driven into the hill. A few tons of the ore taken from near the mouth of the tunnel were worked by the Pioneer Mill, but, being poor, assayed only $25 per ton. The mine is in calcareous slate, similar to the Arizona country-rock. On the old Peru, now the Agamemnon, a drift has been run on the ledge in the upper tunnel for about 150 feet. Several tons of ore, rich in mineral, have been selected for trial, and await now more favorable weather for removal. Assays of pieces run from $45 to $500 per ton, with a good percentage of gold. A contract has been let to run 75 feet of drift and 75 feet of incline on the ledge for the ore to be taken out during the work. The mine is situated about half a mile southeast of the Arizona, in a deep ravine. The outcrops of the ledge can be traced for several hundred feet, crossing the hill east of the Arizona. It is in the metamorphic rocks of the country, quartzite and slates. The Eclipse is located on the main range of hills west of the district, at a short distance from the summit, and is in calcareous slate, which caps, with the limestone, the hill above. The tunnel driven to intersect the ledge was constructed during the year, and a good-sized, mineral-bearing ledge was found. Drifts were run, and sufficient quartz was taken out for a fair trial at the Pioneer Mill; but the result was not very favorable. The prospecting of other claims has not been carried far enough to render them worthy of special mention. The three stamp-mills in the district have been at work with little interruption during the year. The Pioneer has worked the old tailings in its reservoir, the North Star rock, and the tailings of about 2,000 tons of Arizona rock worked last year. The Arizona and the Silver Mining Company's mills reduced, until the end of October, rock from the Arizona mine. Since then the latter has worked the tailings lying in its reservoirs, and the former has worked rock three-quarters of the time and tailings the rest. During May and June the Arizona Association built a tailings-mill with six Varney pans, to work the tailings from the Arizona and the Silver Mining Company's mills. It is built between these two mills, and the tailings are brought to it in sufficient quantities by a one-horse wagon. An engine and boiler give the necessary motive-power, yet a C turbine 'wheel is connected with the machinery, worked by a 45-foot fall. It is the intention to work it with this power, when the water of the cañon is in sufficient quantity for the purpose. The mill works from 25 to 30 tons of tailings in twenty-four hours. The mere reworking of the tailings did not give the satisfaction expected, and an Akin furnace has just been completed to roast the tailings. The furnace is said to have worked well; but enough drying-surface had not been provided, so that the required quantity of tailings could not be dried in twenty-four hours for the run of the whole mill. This, together with the poor success of a machine for breaking up the tailings, led to the stoppage of the furnace, after four or five days' running. Another difficulty may be the fumes of mercury from the tailings while drying. The chlorination attained to 84 per cent. by the first working; but it cannot be said that this is the best result possible, for the furnace was not run long enough to regulate the working thoroughly. The bullion produced by the mills is as follows: From Arizona rock, by two mills, about....... The Pioneer Mill shipped from rock about. Total product about......... ... $225,500 00 72,000 00 12,500 00 36,000 00 346,000 00 There were shipped from the Arizona mines about 170 tons of select ore to San Francisco, netting $78,000. Star district.- One of the earliest and most furious mining excitements in the State of Nevada was that which followed the discovery of the Sheba mine and the organization of the Star district, ten yearsago. For a considerable period this cañon was the scene of an enthusiastic and busy industry; Star City became a flourishing mining town, with two hotels, an express office, daily mails, a telegraph-line to Virginia City, and a reported population of more than a thousand inhabitants. Yet in 1868, when I first visited the district, a decline as sudden and rapid as its rise had left of all this prosperity and promise no trace except the empty houses of the town; the abandoned mining-works, and the daily mail and the telegraph and express offices, which had not yet been removed. The collapse had been quick and apparently complete; yet a study of the deserted district led me to report at that time to the Government (see my Report on Mining Statistics rendered January 18, 1869, page 127) that it would certainly sooner or later receive attention again. This opinion was based partly upon evidences presented by the district itself, partly upon inferences from its history. It was notorious that the whole community had followed the fortunes of the Sheba mine. Scarcely any other in the district, except the De Soto, and perhaps one or two minor enterprises on the same belt with the Sheba, had been productive of anything more than assays and prospects. When the ore-bodies of the Sheba were exhausted, and the expensive prospecting-works of that company failed to disclose any continuation or repetition of them, the ruin of Star City was inevitable and immediate. But in this very circumstance was the ground of hope for the future. The successful re-opening of the Sheba mine would be certain to recall the prosperity which its close had driven away. Moreover, the evidence presented by the mine itself and its surroundings was sufficient to justify the expectation (which has since been realized) that the main deposit, outlying chambers of which had formed the basis of former operations, might be found by more careful and rational search. This point will more clearly appear from a description of the district. Star City is about twelve miles north of Unionville, at present the principal town of Humboldt County. The Star district lies on the eastern slope of a range of mountains, the highest peak of which (Star Peak) has an altitude of about 11,000 feet above sea-level. The deep, wide, and tortuous cañon runs from the summit of the range easterly to the broad, dry valley, and collects the waters of a considerable area into Star Creek, which carries 70 miners' inches in the dryest summer months and swells to 200 or 300 inches in the early summer, after the snows begin to melt. This stream flows across the outcrops of the metalliferous veins, which mostly course parallel with the range. The débris and gravel are perhaps 20 or 30 feet deep in the bottom of the cañon; and although the mainly argentiferous character of the ore-deposits of the district gave little hint of alluvial gold, yet a company of enterprising prospectors have recently commenced gulch-mining, and are reported to have opened very profitable, though limited ground. This occurrence of gold placers below the outcrops of silver-mines is not unprecedented. It will be remembered that the Comstock ledge in Nevada was discovered by following up the gulch deposits to which it had given rise. That vein has always since produced a considerable quantity of gold associated with its silver; but less auriferous silver-mines may still, in the course of time, have given rise to accumulations of gold in placers. The two metals habitually occur together in nature. In ascending the cañon, the sections of successive strata may be observed, showing a general north and south course, and a dip westerly, into the mountain. They consist of alternating quartzite, limestone, shales, and slates. The first formation crossed above the foot-hills is a metamorphic quartzite, gray when freshly broken, but changing on exposure to brown. The next layer above is a gray limestone, dipping west about 600, and bedded in layers of a few inches thickness, the whole group being about 100 yards thick. Overlying this is a large development of black limestone, in which several silver-bearing deposits have been discovered. This is succeeded by gray quartzite, and the latter, in turn, by black slate. Between the two formations last mentioned is a belt or channel, more than 200 feet wide horizontally, of bluish-gray silicious and calcareous rock, characterized by the prevalence of small threads of crystallized quartz, and (on all the cleavages) H. Ex. 211-14 coatings of talc. It was in this channel that the Sheba deposit was discovered, a few feet only from grass, and close under the hanging-wall, bounded, in fact, by the black-slate roof above, and by a well-defined horizontal floor in the veinstone below. The first and largest chamber having been worked out, one or two smaller ones were found close by, likewise lying upon the same floor and close to the hanging-wall. About $125,000 were extracted from these bodies, and very large sums were expended in the search for further deposits. Quite naturally, the floor which formed the lower limit of those already exploited was supposed to be a foot-wall, and it was expected that one would be again found, if found at all, hugging the hanging-wall as before. Consequently, all explorations were confined to this part of the belt, with the exception of a single cross-cut, which was run about 200 feet towards the underlying quartzite. At that time it was by no means certain that the whole belt between the quartzite and the slate belonged to one vein, and must be considered as veinstone. On the contrary, two other parallel claims were located on the surface, within these limits, upon small stringers or threads of ore, of no real independent importance. The futile exploring-drifts of the Sheba Company presented one indication which might have led, and did finally lead, to the discovery of the true nature and position of the vein. I refer to the fact that the numerous small stringers of quartz, and sometimes of ore, encountered in the veinstone mass, dropped away towards the distant east or footwall. This fact appeared insignificant at the time, in comparison with the encouragement given, by the large bodies already found on the hanging-wall, to further explorations in that part of the channel. These explorations were expensive, thorough, and utterly barren of results; and the company suspended operations (as so many companies do) just when the negative evidence accumulated would have led them inevitably to continue their search, if they had continued it at all, in the right quarter. After several years of abandonment, the property came into the hands of its present proprietors, and work was resumed under the direction of Mr. Samuel Stewart, superintendent of the well-known Arizona mine at Unionville, Mr. Richard Nash having immediate charge of the operations. The latter, who was for many months in the employ of the old Sheba Company, and possessed perfect familiarity with the history of their operations, has made good use of the experience of the past. After some further exploration along the hanging-wall, resulting in nothing more than the discovery of small outlying pockets-mere remnants of the old bonanza-he resolved to follow the indications of the slips and stringers in the veinstone, and to look for a main body further east than any workings had previously gone. Accordingly he drove a tunnel north ward into the belt from the cañon, and cross-cutting towards the foot-wall, considerably under the old works, struck, at a distance of about 650 feet from the tunnel-mouth, a large, well-defined, and rich vein. It is now perfectly clear that the numerous stringers and threads of quartz traversing the channel of veinstone drop to the foot-wall, upon which they unite to form the vein. The bodies found in the old Sheba mine were within the wide channel, but far outside of the ore-vein now disclosed. Such outlying chambers are of frequent occurrence in oredeposits of this character. The vein recently opened has been exposed by a drift for about 100 feet in length. Stoping has been carried on for about 25 feet above this drift, and a winze has been sunk below the drift about 15 feet. |