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GEMS AND PRECIOUS STONES.
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1073
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quartz,
and partly altered shreddy biotite crystals in a groundmass composed of
similar minerals, and grains and veinlets of jarosite or an allied
mineral. A somewhat kaolin-like mineral clouds parts of the section. A
section of turquoise matrix showed similar minerals with a veinlet of
secondary quartz, much sericite, and limonite stains.
Turquoise
occurs in seams, veinlets, and a series of nodules and plates in joint
planes and fracture zones in the decomposed rock. Also in patches in
quartz veins and impregnating decomposed rock. The turquoise scams cut
the rock in various directions. From the irregular shape of the
workings it was not possible to determine what position the best
turquoise leads occupied. It is probable the best gem was found in a
rather limited area in a fracture zone somewhat like a chimney deposit.
Much quartz with occasional rough crystals is associated with the
turquoise. Limonite and a little hematite stain the quartz and
turquoise matrix yellowish and brown. The presence of jarosite was
recognized after a similar occurrence was determined by Sidney Paige of
the United States Geological Survey, in turquoise matrix from the Burro
Mountains, N. Mex. The yellow grains and seams were identified by
comparison with crystallized jarosite found in a cavity in a quartz
veinlet.
As
usual with turquoise deposits, a variable grade of turquoise was found.
Only fragments and small pieces of veinlets of gem turquoise were left
around the mine, but a sufficient variety was seen to form an opinion
of the quality of the gem. Considerable low-grade turquoise was seen.
The greater part was soft and pale blue, and some might be called
semiturquoise. Part was bluish-green and quite hard. The semiturquoise
was associated with badly kaolinized soft rock. Some hard pure blue
turquoise, that would yield beautiful gems, was observed. This was
light baby blue to fairly dark blue. Matrix turquoise, with a variety
of markings and colors, occur in the mine and would yield gems showing
blue to greenish-blue turquoise, with white, gray, yellow, and brown
matrix.
VARISCITE.
There
was a large decrease in the production of variscite in 1911 from the
two preceding years. This mineral was found at so many localities in
the deserts of Nevada and such large quantities were mined that the
market was overstocked. The production reported to the Survey was about
540 pounds, as compared with 5,377 pounds in 1910 and 7,135 pounds in
1909. Some of the variscite was reported with the rough gem value and
some was given as cut gems. The value of the production in 1911,
estimated in part, is placed at $5,750, as compared with $26,125 in
1910. The principal value of the variscite production was from Utah,
where the "amatrice" variety is still being mined and cut in some
quantity. A production was reported from the Maguire utahlite mine, the
first discovered in Utah.
No
production of variscite was reported from the Edison&Bird mine
north of Lucin, Utah, but a quantity was obtained during assessment
work and in opening a newly discovered deposit just southwest of the
original four claims. The new deposit is on the Sentinel claim
overlapping the southwest corner of the Protection claim, as described
in this report for 1910. A specimen from the new claim was sent to the
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