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. DescripÂtions 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
MounÂtains. 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.
