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Show MINING DEPARTMENT j . .-..............--4..-.-a",------'......:--.-...............,......,...4...t. 'TUNGSTEN DEPOSITS OF IX YO ! COUNTY, CALIFORNIA The notable tungsten deposits nnur liishop, the principal town of Owans Valley. Cal., are described in a report re-port just issued by the United States Geological Survey, Department of the Interior. These deposits ate mined in Deep Canyon, which traverses trav-erses an isolated group of hills at the base of the Sierra Nevada. Sim ilar groups of hills farther soutn in Owens Valley are known by distiact- ive names, such as the Alabama Hills, and the name Tungsten Hills has been suggested for the group in which the principal tungsten deposits depos-its have been found. The hills reach an altitude of G.000 feet, or about 1,500 feet above the floor of Owens Valley, but they are dwarfed into insignificance in-significance by the mighty range behind be-hind them, which towers to 13,01)0 feet. Tungsten ore was first found in place in August, 1913, on the Jack-rabbit Jack-rabbit claim, near the present center of mining activity. Three partners, who were mining placer gold in Deep Canyon, found that the concentrates con-centrates they obtained were difficult to clean because the gold was invariably in-variably accompanied by a heavy white mineral. This troublesome material proved to be scheelite, one of the chief ore minerals of tungsten, and when its identity and value be came known search for it was soon begun. It is reported that after all the quartz float in the area adjoining adjoin-ing Deep Canyon had been broken open in Vain during a search that covered eighteen months, the scheelite schee-lite was finally found in its rock matrix ma-trix by J. G. Powning, who, while out hunting, recognized the long-sought long-sought mineral in an outcrop of garnet gar-net rock on which he had just shot ! a rabbit, an incident to which the j discovery claim owes Its name. At this place the scheelite is embedded ' in the blackish garnet rock in par- j tides somewhat larger than those commonly found in the ore bodies of the district, but it is neither so prom- j inent nor so obviously recognizable that it would have been found had it not been the special object of search. The discovery that the scheelite oc-1 curs in the garnet rock, however, ' made prospecting for tungsten yiy simple. The blackish garnet, masses on the bare hills contrast notably with the prevailing gray and reddish granite and are therefore easily rer- lognized. They were soon staked am! were then tested for tungsten, and in tliis way ore was found at many places. As a rule this srheelite is so ! inconspicuous that the largest ore j body, although it crops out prominently, promin-ently, was at first unfavorably reported report-ed on by competent engineers, because be-cause they were unable to ascertain, its trend and consequently its width and length. The deposits, although found in 1913, remained practically unknown until the spring of 191G. when their exploitation was energetically begun. l!y midsummer two mills, having a total daily capacity of 400 tons, had been completed and were in active operation. The ore consists of scheelite. garnet, gar-net, epidote, quartz and other minerals. min-erals. The country, rock is prevailingly prevail-ingly granitic, but it includes isolated masses of limestone which became j mineralized soon after the liucrna that now forms the granitic rock was I intruded into them. The metallic vapors then given off from this magma mag-ma altered the limestones to masses of garnet-carrying subordinate schee-j lite, and these altered rocks are the tungsten deposits now under exploitation. exploi-tation. The ore bodies that are now mined are from 20 to 60 feet wide j and from 150 to 2110 feet long. The; ore carries from 1.5 to 2 per cent of j tungsten trioxide. The area in which j scheelite-bearing deposits have been found forms a belt about 20 miles! long, but the prospecting now going! I on will doubtless extend the dimen-1 sions of the field. These deposits, like those discovered discov-ered in recent years in Humboldt county, Nevada, are of the contact-metamorphic contact-metamorphic class, a well-known source of copper and iron but until lately not widely recognized as a possib.e source of tungsten. ' The report, which is entitled "Tungsten Deposits of Northwestern ' Inyo County, Cal." by Adolph Knopf, is issued as Bulletin 640-L and can j be had free on application to the Di-1 rector. U. S. Geological Survey. Washington, D. C. |