Gambar halaman

enumerate here in full, since I have given credit throughout the report in the appropriate places to all who have contributed to its pages.

Free transportation was furnished to me in my official capacity by the Central Pacific Railroad Company and the Colorado Stage Company; and the powerful assistance of Wells, Fargo & Co.'s vast express system was generously placed at my disposal in the prosecution of many inquiries which would otherwise have been hopeless. During a prolonged experience of travel west of the Missouri River, I have never failed to receive at the hands of the agents of this house a ready personal courtesy and a most intelligent appreciation of my work.

No one can be more sensible of the imperfections of this report than I am. The intense labor of preparing so large a volume in so short a time gives rise by natural reaction to a dissatisfaction in the mind of the author greater than that which the casual reader is likely to experience. Yet I venture to hope that, in spite of many defects, this volume will not fall behind its predecessors in interest and value. I have the honor to be, yours respectfully,


United States Commissioner of Mining Statistics.


Secretary of the Treasury.



[blocks in formation]
[blocks in formation]

For the first time this county has entered the list of those producing bullion, and though the shipments are as yet small, they bid fair to improve rapidly.

The mines are situated forty-two miles northeast of the town of San Diego, in a range of mountains known as the Isabella Mountains. They were discovered late in the fall of 1869-it is said by a party of prospectors returning from Arizona-and the extraordinarily rich ore from the ledges first located, among which the Washington seems to be the most prominent, caused considerable excitement on the Pacific coast in the spring and early summer. This threatened to grow into a regular stampede at one time, but subsided soon when it was found that the riches were not available without the aid of considerable capital. Several districts were, however, organized, and a town, Julian City, sprang up at once in the heart of the region.

C. A. Luckhardt, M. E., who visited the locality early in 1870, reports to me the following:

Cuyamac or Julian mining district is situated in San Diego County, California, a distance of forty-two miles by stage-road, in a northeasterly direction from San Diego City, in a range of mountains called the Santa Isabella Mountains, which course north and south, lying between the Pacific Coast range and the San Bernardino range of mountains, and have an elevation of 3,000 feet above sea-level. It was located in the early part of 1870, and created much excitement, caused by exaggerations of the richness of the gold veins discovered. The Cuyamac Mountain, part of the Santa Isabella Mountain, is thickly covered with nut-pine timber, abounds in sweet-water springs, and has many very fertile plateaux covered with verdure. Julian City, the center of the district, contains about two hundred houses and tents, with a population of four hundred, which, however, is very varying. The main mass of the Cuyamac Mountain consists of mica slate and hornblendic porphyry, coursing northeast and southwest, standing almost vertical, and bounded westward by basaltic rocks, which have overflowed its western boundary of garnet porphyry. The veins are very numerous, lie on the western and southwestern slopes of the mountain, and run in almost every conceivable direction, subject to the irregularities of the hornblendic porphyry. The larger veins run northeast and southwest and are imbedded in the slate. Their dip is from 70° east to almost vertical. They are narrow and have no bold outcrop, and only in places have clearly defined walls been laid open. They have quartz as gangue, vary from to 3 feet in width.


Although many locations have been made, it must not be supposed that each represents a vein. Many claims are often on the same vein, and many have nothing more than a few detached boulders, embedded in alluvium and debris, for a foundation. Gold is the only precious metal which the veins carry; accompanying it are traces of antimonblende,

which has been erroneously mistaken for silver ore. The gold occurs in grains and also in thin flakes, and is about 790 fine. It is disseminated very sparingly in the gangue, but occurs in rich pockets at intervals. No base metal accompanies the gold; the quartz is in most instances perfectly white and dense, not even stained by iron, although pyrites occur in traces in some veins. Besides many others, the Washington, Hidden Treasure, Headen, Helvetia, are the most noteworthy. They vary from 18 inches to 24 feet in width, and have yielded rich pockets containing from to 14 tons of ore, but their average ore will not exceed $25 per ton.

Two stamp-mills, after the Washoe pattern, comprising fifteen stamps, have been erected in this district, and are doing well at present. The district is new, and explorations in depth are very limited, not exceed ing 80 feet in any mine, and as far as work has progressed the veins show less gold in depth than at the surface, and pockets occur less frequently. In this respect Cuymac district is similar to the Aurora mining district of Esmeralda, Nevada, which also yielded in its infancy considerable gold near the surface, but not one mine has ever been profitably worked.

The geological features of the country lead to expect substantial veins which will last in depth, but they are narrow, and it can only be hoped that through economical management their owners may meet with success and be enabled to explore them sufficiently to prove their actual merit.

Leaving Cuyamac district and descending the southwestern slope of the mountain for four miles, the low hills binding the Santa Isabella Valley are encountered; here placer-mining has been carried on, but abandoned, the gold being very thin and flaky, and too sparingly depos ited to pay.

Since Mr. Luckhardt's visit more mills have been erected in this region, among which is a Wilson steam stamp-mill. It commenced to run in the middle of June, and ran most of the time until November, though it had to lie idle often, in common with all the mills, because there was no ore to crush. In this respect the San Diego gold region has undergone the same experience that hundreds have gone through before, and it is surprising that after all the experience gathered elsewhere these blunders should be repeated to-day. I mean the erection of mills far ahead of the capacity of the mines before the latter are opened.

Mr. Dougine, the manager of the Wilson steam stamp-mill, has made a number of experiments with from 60 to 90 pounds of steam and a varying number of drops, &c., but obtained the best results with 70 pounds of steam and 206 drops per minute. On August 10 he crushed 10 tons 800 pounds of Hayden rock in eight hours forty-five minutes, using one cord of wood, (oak.) On August 11, 8,590 pounds of the hardest rock obtainable were crushed in five hours, with 65 pounds of steam. On August 12, with 68 pounds of steam, to crush 10,800 pounds of ordinary rock, required four hours fifty minutes. In July, 51 tons were crushed in forty-seven hours. The average amount of ore which can easily be crushed in a day (of twenty-four hours) is 28 tons, with a No. 6 slot-screen, and using not over three cords of 4-foot wood; the average consumption of fuel is one cord to 10 tons of ore. The durability of the mill is very great, no breakage having occurred, and there being no signs of any probability of a breakage. In every part the mill has worked wonderfully well. It took just six days to set up the machine ready for work. It is simple, durable, economical, and efficient. Taking these points into consideration, and not forgetting its comparatively

« SebelumnyaLanjutkan »