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MINERAL RESOURCES.
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J.
B. Stott kindly sent in specimens of opal from a deposit being tested
by himself near Austin, Lander County. The specimens consisted of
common white opal, yellowish opal, lilac-tinted opal, and milky opal.
Some of the specimens displayed a faint flash or fire when viewed in
certain positions. Mr. Stott reports a 100-foot incline sunk on the
deposit in which the quality of the opals improves with depth. The opal
occurs as a core in balls of partly silicified rock whose nature could
not be determined. The specimens examined contained cores of opal
1-1/2 inches through in balls 3 to 4 inches in diameter. Mr. Stott
states that the opal-bearing balls occur in a seam of blue clay, about
2 feet thick, between black and red lava beds.
UTAH.
James
V. Brooks, of Milford, has sent to the Survey a specimen of banded red,
brown, yellow, gray, white, and colorless opal. The exterior of the
specimen had a white sintery coating or crust as if deposited by a hot
spring or similar agency. The specimen measured 2-1/2 inches by
1 inch by three-fourths of an inch in thickness and was evidently
broken from a large slab. The opal is common opal and does not display
any fire. It is highly colored, resembling the rich colors of jasper.
The specimen shows interrupted periods of deposition, as some of the
layers are flat and straight as in onyx, and the others are wavy and
cut through portions of the onyx-like bands. This opal takes a good
polish and might be used for small ornaments, mosaics, or even curio
jewelry. It is not unlike richly colored Mexican onyx or onyx marble
in appearance.
AUSTRALIA.
. New South Wales.—The
value ° of precious opal produced in New South Wales in 1907 amounted
to £79,000, which is greater than for any other year since 1903. The
White Cliffs division of the opal region furnished £66,000 and the
Lightning Ridge field in the Walgett division supplied the remainder.
Queensland.—The production b of
opal in Queensland during 1907 is estimated at £3,000, the same as in
the two preceding years. For several years previous to 1904 the
production was much greater, and the total production since 1890 is
estimated at £158,695. During seasons of drought the opal production is
large, as the farmers take up mining as a means of livelihood. During
1907 the season was favorable for crops, and the opal production was
consequently small.
PERIDOT.
ARIZONA.
Peridot
suitable for gem purposes is found in two regions in Arizona. The first
one discovered was that north of Fort Defiance, in the Navajo Indian
Reservation, about which little has been written. The other region is
near Rice, or the old Talklai post-office in the White Mountain Apache
Indian Reservation. At the latter locality the peridots are found in
the original basaltic rock matrix, as well as loose in the soil. In the
Navajo Reservation gem peridot is
• Ami. Rept. Dept. Mines, New South Wales, 1907, p. 59.
* Aim. Rept. Under Secretary of Mines, Queensland, 1907, p. 18.
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