the
stone by which the wood has been replaced is the much-sought opal. A
series of these Nevada wood-opal replacements has been put on view in
the Morgan Hall of Minerals, in the American Museum of Natural History,
New York, where all steps in the process of the transformation of wood
to opal may be seen. A unique specimen is of dark smoky color which,
when it catches the light at a certain angle, reflects a dull glow of
red and orange, almost as if there still burned in it some of the fires
of the extinct volcano which was perhaps the first factor in its
metamorphosis.
MEXICO.
Opal
mining in the vicinity of Queretaro, Mexico, in a district that has for
many years furnished nearly all the opals sold in the Republic, showed
renewed activity in 1919. Most of the gems are sent to dealers in
Mexico City, who in turn ship them to the United States.
NEW SOUTH WALES.
The discovery of black opal at Tintenbar, about 7 miles from Ballina, New South Wales,12
caused much local excitement and a rush of applicants for miners'
rights and permission to enter private lands. The Melbourne Age states
that nearly a hundred claims have already been pegged. The geologic
formations in the locality are slates and sandstones capped by basaltic
lava flows, of which there are at least three. The opal consists of
loose pieces, ranging in size from that of a pea up to that of a
good-sized walnut, which are found in the soil and in highly decomposed
volcanic rock at depths ranging from 3 to 6 feet. It is evident that
the opal occurs as the filling of cavities in the volcanic rock and
that it can probably be worked at a profit only where the containing
rock has been softened by weathering.
Up
to September, 1919, most of the opal found was of the transparent
variety, but black opal of a very different type from the Lightning
Ridge stone is also obtained.
QUARTZ.
CALIFORNIA.
Rose quartz has been found in mining feldspar,13
5 miles from Hale Station, on the line of the Lemon Cove & Visalia
Electric Railroad (Southern Pacific), shipping point Exeter, Tulare
County, Calif. The operators are Lawton & Cone, 503 Market Street,
San Francisco.
MAINE.
Large
quantities of pure, colorless quartz, gems from which are very
brilliant and flawless, are reported by Mr. Robert F. Bickford, Norway,
Me., to have been obtained from the Mount Apatite feldspar quarry
owned by the Greenlaw Corporation. One large piece of smoky quartz cut
a 2-1/2 or 3 inch ball, and another specimen, without flaws, measured
6 inches in length and 2-1/2 inches in diameter.
« Commerce Repts., Jan. 29, 1920.
13 Information furnished by C. G. Yale, of the D. S. Geological Survey.
