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PEECIOUS STONES.
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813
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CHRYSOPRASE. ARIZONA.
John
L. Riggs, of Chloride, Ariz., reports the occurrence of chryso-prase
near the summit on the west slope of the River Range or Black
mountains, Mohave County. The deposits are about 20 miles west of
Mineral Park. Two claims have been taken up and are owned by Mr. Riggs
and the Walker Brothers. Mr. Riggs kindly sent a set of labeled
specimens, among which were the following minerals and rocks:'Country
rock, decomposed, fine-grained, light-colored porphyry with small
quartz phenocrysts. Perlitic volcanic glass with associated dark-red
jasper. Red jasper or chert gangue mineral in chrysoprase veins.
Brecciated vein matter composed of black flint, red and brown jasper,
gray and white chalcedony, and small chrysoprase particles of rich
green color. Brecciated brown and gray chert cut by two seams of
pale-colored chrysoprase and white chalcedony. Breccia composed of
white and gray translucent chalcedony, red jasper, and dark-colored
chrysoprase, adhering to decomposed light-colored porphyry; this
material is part of the vein. Dark-green chrysoprase, rather cloudy, in
milky-white chalcedony or chert, some with a reddish-purplish color. A
mass measuring 6 by 3 by 3 inches and smaller pieces of finely granular
apple-green chrysoprase; float material. Only a limited amount of
prospecting has been done and
E
art of this is only
assessment work, so that the deposits have not een proven. Judging from
color and quality exhibited by some of the small seams and patches of
chrysoprase, it is reasonable to hope for high-grade gem material. So
far the latter has been found only in pieces too small to be of much
value for cutting. The large lumps of low-grade chrysoprase, occurring
as float on the surface, may find a use in cheap jewelry. Some of the
brecciated specimens, with the several colored varieties of chalcedony
and jasper, would yield handsome small ornamental stones. Portions of
the white, purplish, and translucent gray chalcedony with streaks of
chrysoprase would yield an odd though attractive semiprecious stone.
CALIFORNIA.
Some
of the chrysoprase mines of Tulare County, Cal., were operated during
1908. Among these were the Venice Hill mine and the Porterville mine;
the latter was described in this report for 1906. The Himalaya Mining
Company, of New York, owns the Porterville mine and cuts the high-grade
gem material obtained. The remainder is shipped to Germany for cutting.
A. A. Prim, of Visalia, also operated a chrysoprase deposit at Venice Hill, owned by Franklin Playter, of Boston, Mass.
DATOLITE.
A
quantity of massive datolite is obtained from certain of the Lake
Superior copper mines each year and a portion is used for gem
purposes. Datolite is a basic orthosilicate of boron and calcium and
commonly occurs in white or colorless crystals. Otto Borreson, of
Hancock, Mich., submitted samples from the Franklin mine for
examination. This material comes from the upper levels of the mine and
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