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PRECIOUS STONES.
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In chemical composition Spodumene is a lithium aluminium metasilicate, LiAl(Si03)2.
Spodumene
is usually found in crystalline rocks that have been formed under great
pressure, and it is frequently associated with such minerals as
Tourmaline, Magnetite, Beryl, Garnet, Monazite, Mica, and Quartz.
Two
rare colours of the ordinary variety from Brazil have been found
suitable for gem use. One is greenish-yellow and transparent, and was
for long mistaken for Chrysoberyl, and the other is transparent and
blue, and is found near Diamantina in Minas Geraes, and was mistaken
for Lazulite. Greenish-yellow transparent crystals have also been found
with Hiddenite in the United States.
The
variety Hiddenite was found near Stony Point in Alexander County, North
Carolina, in cavities in a granitic rock. There was a great demand for
the gem in the United States, and the supply from this locality soon
became exhausted. In value the gem is comparable to a good Diamond.
About
twenty years after the discovery of Hiddenite the variety Kunzite was
found, at a mine in the Pala mountains in San Diego county, California.
The crystals, apart from their beautiful colour, were remarkable for
their size and perfection, and the cut gem soon acquired as high a
value as almost any gem, over Pound: £200 being asked for some
specimens.
Most
of the specimens have been retained privately in America, but the
national collection in the British Museum and the American Natural
History Museum collection include fine specimens,
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