Page 72 - The Geology and Ore Deposits of Sierra County, New Mexico - Bulletin 10

MINING DISTRICTS 71
feet in the rhyolite, and the total depth may be considerably more. The mineralizing vapors or solutions that followed these fractures probably represent the last stage in the cooling of the rhyolite magma. They were apparently not very hot, carried no fluorine, boron or sulphur and very little silica, and were meagre in quantity and weak chemically, as shown by the small amount of wallrock alteration, lack of complete alteration of the feld- spars to kaolin, the occurrence of isolated clusters of mineral attached to the walls of the fissures, and by the tendency toward the building of large crystal or botryoidal masses about a rela- tively few centers of crystallization.
Stream tin occurs in the gravels at various places in the district, principally in Hardcastle, Squaw, Corduroy, Beaver and Taylor creeks. These gravels vary from 50 to 250 feet in width and from 6 to about 15 feet in depth. Water is scarce in most of the canyons, and many large blocks of rhyolite and basalt, which are mixed throughout the gravels, would interfere with placer operations. Systematic sampling of these deposits has been done in but a few places, and it is not yet certain that enough tin •could be recovered from them to make the operation profitable. The admixture of so much hematite is a handicap, as it is hard to separate the two minerals, and a product con- taining less than 50 per cent tin is hard to market.
HISTORY AND PRODUCTION
Stream tin was discovered in the district in 1918 by J. N. Welch, while prospecting for gold along Taylor Creek. Assays of the heavy black sand he had collected showed no gold but gave returns of 30 per cent tin. Early in 1919 he made locations near the caves on Taylor Creek, and Moliter & Crumley also located nearby ground at about the same time. During the sum- mer of 1919 the New Mexico Tin & Metals Co. of New York city took over these groups of claims, along with several other locations in the upper part of Taylor Creek. In 1919 F. P. Davis and A. D. McDonald located placer ground on lower Taylor Creek and on Squaw Creek, where a small area of rhyolite containing tin veinlets was also located. These men in 1920 found and located the placer and lode claims on Hardcastle Creek in the northeast part of the district. Prior to August, 1920, no pros- pecting had been done northwest of Corduroy Canyon, and very little had been done except near the mouth of Taylor Creek, on Squaw Creek, Hardcastle Creek, and near the McCarty ranch. Squaw Creek gravels had been tested in a systematic manner, and tests in other gulches had shown the presence of tin. In Taylor Creek, tests had reached only to water level, where there was a large underground flow of water along the valley. The development was confined to the more conspicuous deposits, but nowhere was sufficient work done to prove their commercial possibilities. In 1927, according to reports, five or six holes were