|
GEMS AND PRECIOUS STONES. 9
|
||
|
|
||
|
(chiefly moss agate), Iceland spar, garnet, and topaz; the last two amounted to only a few dollars in value.
Nevada
ranked second in the output of precious stones, showing a greater value
than for any other year since 1911. The most valuable gem mineral
produced in Nevada was turquoise, followed by opal and variscite.
California
was third in rank but had -an unusually small output. The gem minerals
mined were various forms of quartz (such as jasper, chalcedony,
bloodstone, and chrysoprase), beryl, diamond, epidote, lapis lazuli,
obsidian, rhodonite, spodumene, topaz, tourmaline, and vesuvianite. A
three-quarter carat diamond was found in Cherokee Flat, Butte County,
Calif.
Arizona
had a production whose value was only a few hundred dollars less than
that of California. The gem minerals produced include the copper-ore
gems (azurite, malachite, azurmalachite, and chrysocolla), garnet,
obsidian, peridot, opal, agate, jasper, and turquoise.
Maine produced beryl, garnet, amethyst and rock crystal, topaz, and tourmaline.
Colorado
produced calamine, amazonstone, fluorite, garnet, hematite, opal,
satin spar, phenacite, pyrite, various forms of quartz, topaz, and
turquoise.
From
Arkansas several hundred carats of diamonds were reported, including a
canary-colored octahedron weighing 17.85 carats, a clear flat stone of
11 carats, and several smaller stones weighing several carats each.
In
New York City garnet of gem quality was collected by Gilman S. Stanton
and James G. Manchester in November, 1918, on Riverside Drive, north
of West One hundred and sixty-fifth Street. The cut stones are deeper
red than the spessartites found on the same ridge about half a mile
farther north.1 A number of stones have been cut, the
largest about three-fourths of a carat in size. Chemical tests show
that the garnet contains both iron and manganese, being intermediate in
composition between almandite and spessartite.
In
Hawaii an area of decomposed lava contains numerous yellowish-green
crystals of peridot, which were cut in Honolulu into gems weighing as
much as a carat and a half each. The crystals were separated from the
sandy decomposed lava by sifting, and many also were brought to notice
by the action of rain. Four workmen are said to have obtained 30,000
fragments of peridot in five days' work.
FOREIGN OCCURRENCES.
DIAMONDS IN SOUTH AFRICA.
A large blue-white diamond, weighing 3881 carats 2
in its rough* state, has been reported as found at the Jagersfontein
mine, Orange River Colony, South Africa. Although small in conrparison
to the Cullinan diamond (3,052 carats), it will rank as one of the
world's largest diamonds. The Jagersfontein mine in 1893 yielded the
Excelsior, a diamond weighing 969 \ carats in the rough. For comparison it may be stated that the largest cut stone obtained from the Cullinan weighs 516£ carats.
>TJ. S. Gcol. Survey Mineral Resources, 1916, pt. 2, p. 894, 1918.
1 Presumably
" English carats." The weights of the older stones are given in English
carats. One English carat weighs 205.304 milligrams.
|
||
|
|
||