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Ch. 2: Precious Gem stones in 1893

Ch. 2: Precious Gem stones in 1893 Page of 36 Ch. 2: Precious Gem stones in 1893 Text size:minus plus Restore normal size   Mail page  Print this page
694
MINERAL RESOURCES.
ex-Governor Bradford L. Prince, of New Mexico. It is contemplated to work the claim under the name of the New Mexico Turquoise Com­pany, but since October 6, no developments have been made.
Mr. M. W. Porterfield, of Silver City, New Mexico, has found traces of turquoise on the surface half a mile from the Azure mine, in the Burro mountains, 15 miles south of Silver City, and has made excavations to the depth of about 18 feet. The turquoise has the characteristic green color of that in the Burro mountains. Whether any fine material will be found by further digging is a question.
Two other groups of turquoise mines are described by Mr. William E. Hidden as occurring in New Mexico. (See American Journal of Science, November, 1893, vol. 46, pp. 400-402, and the Jewelers' Circular, November 1 and November 8, 1893.) The first group is 15 miles south­east of the Azure Company's mines, in what is known as the Cow Spring district. Some prospecting had been done for turquoise, and 60 miles in a southerly direction the locality showed evidences of prehistoric workings; the matrix containing the trachyte is very similar to that in . the Burro mountains. The nearest railroad station, 22 miles north of this locality, was abandoned because of the scarcity of the blue—the only valuable—shades of turquoise, the scarcity of water, and the arid condition of the surroundings.
The most important locality observed by Mr. Hidden is in Doiia Ana county, in the Jarilla mountains, l50 miles east of the Burro range The mines are situated here in an arid and desolate region, Las Cruces being 50 miles west, and El Paso 50 miles south. The turquoise is described as occurring in trachyte containing minute crystals of quartz implanted in fine crystals of pyrite, granular jarosite and gypsum coating some of the same. A shaft 70 feet deep has been sunk on the contact with the porphyry, and turquoise was traced all the way down. This is the light green material called " Shoo-ar-me " The writer believes that the phosphoric acid of the turquoise may have been derived from the limestone beds, adjacent to the trachyte, that may have cov­ered this trachyte at no very distant date, and suggests that the oxida­tion of the pyrite evidently resulted in the decomposition of the kaolin, limonite, gypsum, and jarosite, and that this is a produet of a subse quent kaolin, the kaolin being earlier, and the turquoise a secondary formation, basing his opinion upon the fact that the majority of tur­quoise deposits are semiglobular or reniform in outline, although compact masses are found wholly occupying small cavities.
The tendency of the turquoise is said to be toward the blue, more so than at the two other localities, although green varieties were observed which were attributed to alteration. The turquoise found at a depth of 25 feet or taken from rock was of a rich blue, but it rapidly faded after being detached from the matrix and becoming dry. At all three of the localities described by Mr. Hidden the discoveries were due to the investigation of old turquoise workings which had been considered
Ch. 2: Precious Gem stones in 1893 Page of 36 Ch. 2: Precious Gem stones in 1893
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US Geol. Surv. 1893. Gemstones, Metals.
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