gems
exhibit wonderful flashes of green, blue, yellow, and red of various
shades. In some the color is uniform over the whole stone or over large
areas, changing as the gem is turned from green to red or from red to
blue, and so on. Some of the gems show a rich ultramarine blue in one
position with green or red in another. Many gems display various bright
colors arranged in patches, and each paten changes color as the stone
is turned. The brilliant flashes of peacock-feather colors obtained
from the opal of dark color yields a gem which might be called black
opal, but most of it is not iike the Australian gem of that name, since
it occurs in thick pieces and the colors are less localized. The
majority of the dark-colored gems, no matter how beautiful in reflected
light, become a rich reddish-brown color in transmitted light.
Lighter-colored opal with good color and fire is also found and cuts
into very beautiful gems.
CALIFORNIA.
The
following information concerning the opal deposit of the American Opal
Co., in San Bernardino County, Cal., was furnished to R. W. Pack, of
the United States Geological Survey, by Mr. F. Saminfeld,
superintendent of the mine, and kindly submitted for this report. The
head office of the company is in Pasadena, Cal. The mine is 25 to 30
miles northwest of Barstow, in sec. 36, T. 31 S., R. 45 E., and extends
into some adjoining quarter sections. The deposit has been worked for
about three years, and during 1912 employed from 3 to 5 men. It is
opened by a shaft 200 feet deep and by many feet of drifts and tunnels.
The best opal, and that which is mined, occurs at ground-water level,
about 200 feet deep, in a white volcanic tuff. This rock is not hard to
mine and holds up well in the workings, requiring no timbering.
According to Mr. Saminfeld about one-fourth of a ton of matrix and
rough opal is shipped every ten days or two weeks.
Mr.
F. M. Myrick, of Randsburg, Cal., kindly submitted specimens of
precious opal which he obtained from a prospect 15 miles west of his
bloodstone mine on Brown Mountain in the Death Valley region. This opal
is fight colored, and shows very' pretty flashes of green, blue, and
red. It is associated with chalcedony or agate.
AUSTRALIA.
The following notes are abstracted from a report by Consular Agent G. H. Prosser,1
at Adelaide, South Australia. The production of opal in Australia has
declined greatly and is now about 75 per cent less than during some
previous years. The value of the output in 1911 has been estimated at
about $300,000, of which $106,000 came from the White Cliff district
and the remainder from the Wallangulla field, in the Walgett division.
The total value of the opal produced since 1890 is estimated at
$6,529,377. The Australian black opal has come from mines at the head
of River Darling, in northern New South Wales, about 60 miles from the
village of Walgett. The output of black opal has grown smaller each
year, and during the first half of 1912 amounted to almost nothing. It
is not thought that the deposits are exhausted, but fewer miners are at
work and good finds are therefore less often made.
I Daily Cons, and Trade Repts., Sept. 21,1912.
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