Ch. 3: Precious Gem stones in 1912

Ch. 3: Precious Gem stones in 1912 Page of 93 Ch. 3: Precious Gem stones in 1912 Text size:minus plus Restore normal size   Mail page  Print this page
1050                              MINERAL RESOURCES., 1912.
gems exhibit wonderful flashes of green, blue, yellow, and red of various shades. In some the color is uniform over the whole stone or over large areas, changing as the gem is turned from green to red or from red to blue, and so on. Some of the gems show a rich ultra­marine blue in one position with green or red in another. Many gems display various bright colors arranged in patches, and each paten changes color as the stone is turned. The brilliant flashes of peacock-feather colors obtained from the opal of dark color yields a gem which might be called black opal, but most of it is not iike the Australian gem of that name, since it occurs in thick pieces and the colors are less localized. The majority of the dark-colored gems, no matter how beautiful in reflected light, become a rich reddish-brown color in transmitted light. Lighter-colored opal with good color and fire is also found and cuts into very beautiful gems.
The following information concerning the opal deposit of the Amer­ican Opal Co., in San Bernardino County, Cal., was furnished to R. W. Pack, of the United States Geological Survey, by Mr. F. Saminfeld, superintendent of the mine, and kindly submitted for this report. The head office of the company is in Pasadena, Cal. The mine is 25 to 30 miles northwest of Barstow, in sec. 36, T. 31 S., R. 45 E., and extends into some adjoining quarter sections. The deposit has been worked for about three years, and during 1912 employed from 3 to 5 men. It is opened by a shaft 200 feet deep and by many feet of drifts and tunnels. The best opal, and that which is mined, occurs at ground-water level, about 200 feet deep, in a white volcanic tuff. This rock is not hard to mine and holds up well in the workings, requiring no timbering. According to Mr. Saminfeld about one-fourth of a ton of matrix and rough opal is shipped every ten days or two weeks.
Mr. F. M. Myrick, of Randsburg, Cal., kindly submitted specimens of precious opal which he obtained from a prospect 15 miles west of his bloodstone mine on Brown Mountain in the Death Valley region. This opal is fight colored, and shows very' pretty flashes of green, blue, and red. It is associated with chalcedony or agate.
The following notes are abstracted from a report by Consular Agent G. H. Prosser,1 at Adelaide, South Australia. The production of opal in Australia has declined greatly and is now about 75 per cent less than during some previous years. The value of the output in 1911 has been estimated at about $300,000, of which $106,000 came from the White Cliff district and the remainder from the Wallangulla field, in the Walgett division. The total value of the opal produced since 1890 is estimated at $6,529,377. The Australian black opal has come from mines at the head of River Darling, in northern New South Wales, about 60 miles from the village of Walgett. The output of black opal has grown smaller each year, and during the first half of 1912 amounted to almost nothing. It is not thought that the deposits are exhausted, but fewer miners are at work and good finds are therefore less often made.
I Daily Cons, and Trade Repts., Sept. 21,1912.
Ch. 3: Precious Gem stones in 1912 Page of 93 Ch. 3: Precious Gem stones in 1912
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US Geol. Surv. 1912. Gemstones, Metals.
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