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PRECIOUS STONES.
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799
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and cavities varying in size up to 2 or 3 inches in width and roughly parallel to the planes of schistosity. The cavities are generally rilled with natrolite, with or without benitoite or carlosite, or both. Natrolite is not always accompanied by benitoite, though benitoite has not been observed without natrolite. The associations of the minerals indicate that the crystallization of the benitoite and carlo-site was previous to the complete deposition of the natrolite.
Development work consists of a tunnel 50 feet long and several open cuts, the largest of which is 10 feet deep, 4 feet wide, and 14 feet long, following the strike of the schist. The gems are removed by pounding up the richer portions of the matrix and picking out the crystals or fragments remaining, or large crystals are chiseled out at the expense of the smaller ones. Since benitoite is rather brittle, a large percentage is lost in this operation.
As reported to the Survey, the production in 1907 amounted to about 15 pounds of rough benitoite, a large part of which was not suitable for cutting. Up to January 1, 1908, 350 carats of gems had been cut from this material.
BERYL.
The production of beryl gems, as aquamarine, blue beryl, golden beryl, rose or pink beryl, and white beryl, was chiefly from California, North Carolina, Colorado, and Maine, with small amounts from New Hampshire, Pennsylvania, and Connecticut.
CALIFORNIA.
The California output came from near Ramona, Mesa Grande, and Pala in San Diego County, and Riverside, Riverside County. Descriptions of some of the localities in San Diego County are given under the notes on the gem minerals of southern California (pp. 43-48). Mr. C. O. Johnson describes a the occurrence of new deposits of beryl about 2 miles east of Riverside at the base of the Box Springs Mountains. The beryls are of a good aquamarine color, some approaching the emerald in depth of color. The best material was found on the land of F. D. Mears in a pegmatite formation cutting diorite or gabbro. Dark-green colored mica is also found with the bend, but not lepido-lite, as generally occurs in the gem-bearing pegmatites of southern California. About 20 pounds of rough material, part suitable for cutting, was obtained before development work was stopped through financial troubles.
COLORADO.
Beryl from Colorado was reported as aquamarine, chiefly from the gem mines in Royal Gorge and Mount Antero, Chaffee County, by C. A. Beghtol & Co. Mr. J. D. Endicott reports the discovery of four deposits of aquamarine-colored beryl, some suitable for cutting, associated with rose quartz, about 6 miles north of Texas Creek, Fremont County.
IDAHO.
Mr. Ernest Schernikow, of New York, reports the finding of two good blue beryl crystals near Lewdston, Idaho. These crystals were obtained from an Indian squaw who would not reveal their source.
a Personal letter, dated April 24,1908.
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