Slike strani
PDF
ePub

The water increased, and powerful engines, consuming much wood, were required to pump constantly at an expense of $100 per day to each of half a dozen companies. Foul air made it impossible for the miners to work rapidly in the deep drifts, and ventilation was expensive. These, and a multitude of other considerations, contributed to the panic and kept the general stock market down.

But such influences could not entirely govern the price of particular stocks.

Gould & Curry, which was sold for $900 per foot in July, 1864, advanced to $2,000 in April, 1865, and fell to $600 in October, 1866. Savage was $2,000 in April, 1865, and $1,100 in October, 1866. Of stocks, which were not noticed in the stock boards in the summer of 1864, Yellow Jacket rose in Apri 1865, to $2,590 per foot, and was sold in October, 1866, for $700; Belcher, worth $1,650 in April, 1865, was offered for $95 in October, 1866. Alpha, worth $2,100 in April, 1865, was worth only $50 in October, 1866, and Crown Point fell from $1,225 in April, 1865, to $900 in October, 1866. A fall of fifty per cent. or a rise of two hundred per cent. in the market value of a large mine within the space of six months has occurred in more than two score cases within the last five years, and it is easily understood that in such events fortunes are made and lost with great rapidity.

37.-SOME CHARACTERISTICS OF ESMERALDA, HUMBOLDT, AND REESE

RIVERS.

foot;

The stocks in all the other districts of Nevada were affected, and, it might almost be said, governed by the influence of those of Virginia City. While shares in the Comstock lode were high, so were those in mines elsewhere. At Esmeralda large masses of rich ore were found in the Wide West and Real Del Monte mines, and the price of their stocks rose to $400

per

but there, too, litigation, bad management, and the speedy exhaustion of the rich deposits near the surface were followed by a general collapse.

Esmeralda district, which yielded $500,000 annually for a couple of years, seemed to have been worked out, and all the explorations undertaken since 1864 have failed to show anything to compare with the ore opened in 1861 and 1862.

Several other districts in the vicinity, however, were found, and these promised to more than surpass Esmeralda in its best days. Humboldt had a history somewhat like Esmeralda.

A large body of rich ore in the Sheba mines brought the price of that stock up to $400 per foot, but they contained antimony, and could not be reduced without roasting, and the expenses of reduction, and litigation and the exhaustion of the rich body of ore, soon left the company insolvent; and since then the Humboldt district has been under a cloud, although inany of the veins will undoubtedly prove profitable in time.

The Reese River mines, discovered in June, 1862, include a number of districts, in which a great variety of veins and ores are found. The development has been slow, yet it is the opinion of intelligent men who have examined the lodes that several of them will take a high place in the production of silver after a few years.

The last of the silver districts of Nevada in the order of discovery is Pahranagat, in the southeastern corner of the State, which first attracted attention in the beginning of 1866. No bullion has yet been extracted there, but some fine ore has been found, and the quantity appears to be considerable.

38.-SUTRO TUNNEL PROJECT.

In 1865 it became evident that if the mining in the Comstock mines were to be continued for many years, it would be profitable, and even necessary, to have

H. Ex. Doc. 29-3

CO, 1866;"

[ocr errors]

a tunnel to drain the vein to a depth of 2,000 feet. Of the continuation of the mining there could be no reason to doubt.

The lode has the main geological characteristics which mark the greatest silver-bearing veins of Spanish America. It is a fissure vein that extends across several different formations, and at the richest place it separates two different kinds of "country" rock. It is of great length and great width. The general thickness and dip remain about the same, so far as they have been examined. The walls are distinctly marked. The inclination is about 45° to the horizon. There are large seams of clay-like substances along the sides, as though the sides had rubbed and ground part of the vein-stone to powder. Bodies of porphyry, many of them large and others small, are found in the vein-stone, looking as though they had cracked off the upper or hanging wall and fallen down.

The vein-stone, so far as traced, is about the same in all places, though the color varies from white and gray to brown. The ore is distributed irregularly, being found in some places in large masses and in others in thin seams. The general features of the lode are like those other great argentiferous veins, and mining geologists say that the class are inexhaustibly rich in silver. It is pre; un:ed that they are rich in ore far beyond any depth which miners can reach.*

* 39.-BARON RICHTHOFEN'S REPORT. The following is a quotation from “The Comstock Lode, its character and the probable mode of its continuance in depth. By Ferdinand Baron Richthofen, Dr. Phil., San Francis

" If we proceed to compare the Comstock vein with those best explored, it is evident that it differs in nature from a certain class of narrow veins, which, as those of Freiberg, Konigsberg, and Chañarcillo, in Chili, Pasco, in Peru, Catorce, in Mexico, and Austin, in Nevada, fill a number of small fissures, which are either parallel or intersect each other, and which exhibit in depth nearly the same character and richness as near the surface. It presents, on the contrary, all the characters of a second class of silver veins, which are prominent on account of their magnitude and unity, and exhibit, wherever they occur, one great mother vein, or veta madre,' surrounded, in most instances, by some smaller veins of little or no importance. To this class belong the veins of Schemnitz and Felsobanya, in Hungary, the Veta Madre, of Guanajuato, and the Veta Grandre, of Zacatecas, while the veins of Potosi, in Peru, and the Biscayna of Real del Monte, in Mexico, have to be referred more to this than to the former class. Notwithstanding their small number, these great mother veins furnish by far the greater portion of the silver produced throughout the world. They resemble each other in many points. All of them fill fissures of extraordinary width and length, and appear to be of very recent origin, and also to be intimately related to volcanic rocks, by which they are accompanied. Although the laws which govern the distribution of ore differ more or less for each vein, yet all of them have been found to be highly metalliferous to whatever depth explored; and it appears that nearly an equal quantity of silver is with most of them contained in each level, the vein of Guanajuato being an exception to this rule. It may be inferred that this will continue to be the case to an indefinite depth. There is, however, a marked difference in the concentration of silver, ores of extreme richness being usually accumulated in limited bodies in the upper levels, while in depth similar bodies recur greater in extent, but consisting of lower grades of ores. This is one of the principal reasons why, on all the veins mentioned, mining in upper levels has been so highly remunerative compared with the profits derived from deep workivg. Each ton of ore costs there but little to extract, and yields. a large amount of metal, while' raising the same weight from greater depth is more expensive, and at the same time a smaller amount of bullion is realized. The history of the Mexican mines is the best illustration of these relations. In former centuries counts and marquises have been made by the king of Spain whenever fortune enabled a single individual to accumulate enormous wealth in a few years. Mining then was confined to rich ores within a few hundred feet from the surface. In the present century, since greater depths have been reached, the Spanish crown, if it had still the sceptre of Mexico, would scarcely have found an opportunity of bestowing equal honors on fortunate mining adventurers, notwithstanding the unabated enterprising spirit of the population and the increased facilities of raising the treasures. And yet the production of the Mexican mines has anything but decreased. It appears, on the contrary, that it has never been so high as at the present time. Humboldt states that vastly the majority of the annual production of Mexico has through all times been derived from the mother veins alluded to above, and still at this day they furnish at least three-fourths of it, though each of them has repeatedly been abandoned as unprofitable. They would be inexhaustible sources of wealth if the increase of expenses attending the growing depth did not put a limit to all profitable mining.

“The equality of produce of the Mexican mines is probably partly due to the prevalence of true silver ores through all levels. The Hungarian offer less favorable conditions, as the The expense

The water which gathers in mines at Virginia City, although the deepest there is not half so deep as in many in Mexico, is very great, and a tunnel or adit-level is necessary to secure drainage and ventilation and procure a cheap mode of extracting the ore and of exploring the lode. Fortunately the lode is situated on a mountain side, and there is an opportunity of draining the lode to a depth of two thousand feet by cutting an adit three and three-fifths miles. The will be several millions of dollars, but the saving will be far more. Considerations like these led to the formation of the Sutro Tunnel Company, which received a franchise from the legislature of the State and a grant of land from ores, on account of the previously mentioned increase of lead and copper in depth, undergo a real deterioration. Yet they have evidently bad at upper levels their concentrated bodies rich

Such have been extracted at Schemnitz within the time of historical record, while their former existence at Felsobanya may be inferred from the shape and character of the old Roman works near the out-croppings.

“Let us now return to the Comstock vein, the veta madre' of Washoe, and examine what conclusions as to its future we are justified in drawing from the present condition of the explorations. In the first place, we have mentioned the fact that the ores through all the levels explored retain their character of true silver ores which they had near the surface. The amount of lead, copper, iron, and zinc has never been large in the Comstock ores, and these metals preserve now, at the lowest level, nearly the same relative proportion as formerly. Their increase, especially of lead, would be the most unfavorable indication for the future of the Comstock lode, as, besides the growing difficulty of metallurgical treatment, the conclusion would be justified that lead ores would more and more replace those of silver, and the limits of profitable productiveness would soon be reached. But as it is, no deterioration is to be expected, even if an impoverishment takes place. It thus approaches in its ore-bearing character the great mother-veips of Mexico, and is different from those of Hungary.. But even the reasons for an impoverishment are by no means so evident as might appear at first sight. There have been, it is true, bonanzas near the surface, which surpassed in richness all those worked upon in later times. As such may be mentioned the bonanzas of the Ophir, the Gould & Curry, and the western body of ore in Gold Hill. Their richness and the facilities of their extraction co-operated in making the latter exceedingly profitable. Yet the production of the Comstock vein did not, at the time when it was solely derived from these surface-bonanzas, reach the figure it attained after the exhaustion of their principal portion. One of the reasons is that then the ore was concentrated within narrow limits, while as the greater depth was attained the distribution of the ores was much more general, though their standard was lower. New bodies of ore had been discovered, commencing at a depth of from one hundred and fifty to three hundred feet below the surface, such as the continuous sheets of ore in the eastern part of the lode in the Gold Hill mines and the Yellow Jacket, and the similar-constit ated one in Chollar-Potosi. None of them contain, excepting a few narrow streaks or bunches, ores of equal richness with those of which the surface-bonanzas were composed. But their extent so far exceeds that of the latter as to make up, by the increased amount of daily extraction, for the inferior yield. The profits of working are of course greatly diminished. These bodies of ore have continued to the deepest levels reached in the Comstock mines, varying in width and extent, and also in their yield. The latter did not increase, but in some instances, as in the southern part of Gold Hill, decreased with the growing width of the deposit, while in others no material change is perceptible.

“Few new bodies of ore made their appearance below the level of three hundred feet. Foremost in importance among them are two bodies discovered at seven hundred feet below the surface of the Hale & Norcross works, one of which is on ground supposed heretofore to be unproductive.

Considering these facts exhibited by the Comstock vein itself, and comparing with them what is known about similar argentiferous veins, we believe ourselves to be justified in drawing the following conclusions:

“Ist. That the continuity of the ore-bearing character of the Comstock lode in depth must, notwithstanding local interruptions, be assumed as a fact of equal certainty with the continuity of the vein itself.

" 2d. That it may positively be assumed that the ores in the Comstock lode will retain their character of true silver ores to indefinite depth.

“3d. That it is highly probable that extensive bodies of ores equal in richness to the surface-bonanzas will never occur in depth.

“4th. That an increase in size of the bodies of ore in depth is more probable than a decrease, and that they are more likely to increase than to remain of the same size as heretofore.

“5th. That a considerable portion of the ore will, as to its yield, not materially differ at any depth from what it is at the present lower levels, while, besides, there will be an increasing bulk of lower-grade ores. We are led to this supposition by the similarity in character of all the deposits outside of the rich surface-bovanzas and the homogeneous nature which almos every one of them exhibits throughout its entire extent.

Congress, and met with the encouragement of the great companies mining on the lode, all of which signed contracts with the company binding themselves to pay a certain sum for every ton taken from their mines after the completion of the tunnel. Although the work has not been commenced, the project has fair prospects, and it occupies an important place in the history of mining in Nevada. The miners at Virginia City will never be content to abandon that plan of drainage.

40.-COLUMBIA BASIN AND CARIBOO MINES.

The first mines in what is now Idaho Territory were found in the bars of Clearwater river in the spring of 1860, and those of the Salmon river were opened in a few months later. The placers of Boisé were struck in 1862, those of Owyhee in 1863, and the quartz veins of Owyhee and Alturas began to attract attention in 1864. In eastern Oregon the placers of Powder and Burnt rivers were discovered in 1861, and those of John Day's river in the following year.

None of the Idaho or Oregon placers have proved so rich, so extensive, or so durable as those of California, although they have yielded considerable amounts of gold. The deep diggings of Cariboo, 500 miles from Victoria, in the upper part of Fraser valley, were discovered in 1859, and the placers in the shallow bars and creeks at the Big Bend of the Columbia, in the territory of British Columbia, in 1865, California had to send miners to all these places.

The number who went to Idaho was, probably, 20,000; and in 1866 at least 5,000 migrated to Montana.

It was also in this year that a rumor became current that rich placers had been discovered at Barbacoas, in New Granada, and the result was the migration and bitter disappointment of about a thousand men, who found nothing to reward their trouble.

“6th. That the ore will shift at different levels, from certain portions of the lode to others, as it has done up to the present time. More equality in its distribation may, however, be expected below the junction of the branches radiating toward the surface, when the vein will probably fill a more uniform and more regular channel. Some mines which have been heretofore almost unproductive, as the Central, California, Bullion, and others, have therefore good chances of becomiðg metalliferous in depth. But throughout the extent of the vein, it is most likely that the portion which lies next to the foot-wall will continue unproductive, as it did from the surface down to the lowest works, while the entire portion between it and the hanging wall must be considered as the probable future source of ore. As remarked in the foregoing pages, it is also probable that repeatedly, in following the lode downward, branches will be found rising from its main body vertically into the hanging wall and consisting of clay of quartz. Many of them will probably be ore-bearing. Such bodies of ore should be sought for, at all the mines, in what is generally supposed to be the eastern country. Experience in upper levels would lead to the supposition that such eastern bodies might carry richer ores than the average of the main portion of the vein.

7th. That the intervention of a barren zone, as is reported by.good authorities to occur at the Veta Madre of Guanajuato at the depth of twelve hundred feet, is not at all likely to be met with in the case of the Comstock lode. The argument which we have to adduce for this conclusion has some weight from a geological point of view. It is a well known fact that the enclosing rocks have usually great influence on the quantity and quality of the ores of certain metals în mineral veins, and that a rich lode passing into a different formation frequently becomes barren or poor. At the Veta Madre of Guanajuato a sudden decrease in the yield of the ore at the depth of twelve hundred feet attends the passage of the lode into a different formation, which from thence continues to the lowest depth attained. No such change can be anticipated for the Comstock lode, since the structure of the country seems to indicate the continuity of the enclosing rocks to an indefinite depth.

" In winding up these considerations, we come to the positive conclusion that the amount of nearly fifty million dollars, which have been extracted from the Comstock lode, is but a small proportion of the amount of silver waiting future extraction in the virgin portions of the vein, from the lowest level explored down to indefinite depth; but that, from analogy with other argentiferous veins, as well as from facts observed on the Comstock lode, the diffusion of the silver through extensive deposits of middle and low grade ores is far more probable than its accumulation in bodies of rich ore."

SECTION 2.

GEOLOGICAL FORMATION, ETC., OF PACIFIC SLOPE.

REPORT OF MR. WILLIAM ASHBURNER, MINING ENGINEER, MEMBER OF THE STATE

GEOLOGICAL SURVEY OF CALIFORNIA, &c.

1. Gold mining interest of California.--2. Characteristics of the gold-belt.-3. Northern

mining districts.-4. Mining in the sierras ; mills, expenses, &c.

1.-GOLD MINING INTEREST OF CALIFORNIA

1866.

SAN FRANCISCO, November In acordance with the request you made me some time since, I beg leave to submit the following report upon the present condition of the gold mining interest of California, so far as it can be ascertained. The absence of all published documents of a reliable nature, with the exception of those recently issued by the geological survey of the State, make it a matter of considerable difficulty to arrive at results which shall have the merit of being perfectly trustworthy, and the only means of obtaining them is by personal examination by competent individuals of the various gold fields throughout the State. Everybody will acknowledge that accurate statistics of the results obtained throughout the extensive mineral regions of the United States, particularly those where the precious metals are found, and published under the official sanction of the government, would be of the greatest value. If properly compiled they in themselves alone would go far to remove the great ignorance which prevails in the public mind with regard to many important facts bearing upon the question of mining, and enable people to judge for themselves how far the great majority of those wild assertions which are so frequently made by amateur visitors and newspaper correspondents are likely to be true. It is from this class of writers—who, from their education, are not qualified to weigh and appreciate the value of statements made to them, generally by interested and enthusiastic persons that nearly all the information which the public now possesses of the gold and silver mines of this country is derived.

It is universally conceded that the great objection to mining is its uncertainty, and that, while in some cases the profits are large, the risks are more than proportionably great, and the cautious capitalist hesitates before embarking upon a mining enterprise, feeling that a shroud of mystery envelops the whole question, and that he may be placing himself blindfolded in the hands of evil and designing persons.

The mineral resources of many of the States laave been under scientific investigation since 1830; but it was in 1844 that the first district for mining other minerals than coal and iron was opened up upon the shores of Lake Superior. Then followed a wild excitement in mines, which seems to have continued periodically since that time, upon the discovery of new and valuable mines. In 1863–64 attention was particularly directed to the silver and gold mines of Nevada and Colorado. No statements seemed too gross to be made, or too improbable to be believed. Tracts in the midst of the desert covered with sage brush, and miles distant from any mineral-bearing vein, were located, companies formed, prospectuses issued, and considerable sums of money actually expended in search of mines which by no possibility could exist in such places.

A thorough survey of the various mining districts which are now attracting so much attention both at home and abroad would confer incalculable benefit upon the country at large, and every means should be employed to bring before the public information of such a reliable nature that the capitalist may be guided in his investments, and the field of the prospector for new mines be restricted to

« PrejšnjaNaprej »