stituents
of the rock are a ferromagnesian mineral and granular ruby-colored
corundum. The occurrence of this ruby-bearing rock in northern
Transvaal, with the discovery of fairly large pebbles of ruby still
farther north, points to the probability of this gem being found in the
colony in the not distant future.
SAPPHIRE.
IDAHO.
The
occurrence of gem sapphire in Idaho has been announced by Dr. Robert N.
Bell, State inspector of mines. The sapphire was' first found in the
concentrates from the Rock Flat placer gold mine, near Meadows
post-office, in Washington County. The possible gem value of the stones
was first recognized by Doctor Bell, who sent specimens to Dr. George
F. Kunz for confirmation. The deposit is located on a high plateau
divide between the Salmon and the North Payette rivers. The occurrence
is thus described by Doctor Bell:"
The
general formation of the district is gneiss, and the corundum crystals,
which include some of excellent gem quality, seem to be derived from a
wide dike of basaltic clay formation with a peculiar spheroidal
structure. The gem stones are found associated with a great array of
pyrope garnets in the clean-up boxes of an old placer pit.
Some
beautiful gems have been found. They occur in a variety of colors, the
oriental amethyst shades predominating. Most of them have an opalescent
silky sheen and are not of high value, but would cut into excellent
cat's-eyes and star sapphires. Some bronze crystals would also make
handsome tiger-eye sets. Some small stones, however, of fine quality
have been found, which, when cut, are as large as one-half to 1 carat
and have a beautiful clear cornflower blue color. Others make brilliant
pink stones as large as 1J carats in weight after cutting. The crystals
also include some of poor red quality, but nothing as yet approaching a
true ruby color.
Doctor
Bell placed the value of sapphires from this locality sold in 1906 at
about $300. The highest price stone was a brilliant pink gem weighing
about 1-1/2 carats and valued at $20.
Development
work has been started on the dike formation and consists of a drainage
tunnel to cut the dike at a depth of 80 feet. Connection will
doubtless be made with the surface and the working of the deposit be
greatly facilitated.
Since
basaltic dikes, similar to the ones at Meadows, are common near the
placer deposits found in the eruptive granites of central Idaho, other
sapphire discoveries are likely to be made in placer mining,
especially in those places where opaque corundum has already been
found. For this purpose it would be well for the miners to examine
their concentrates for sapphires around Resort, in Idaho County; along
the Gold Fork and other tributary streams of the North Payette River,
in Boise County; in the Stanley basin, in Custer County; and at Pierce
City, in Nez Perce County.
NORTH CAROLINA.
A
few sapphire crystals were reported from the western counties of North
Carolina during 1906, though just what their value was has not been
learned.
