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PRECIOUS STONES
163
TURQUOISE
Is found in opaque masses in a matrix, in Persia, Mexico, the United States, Australia, and New South Wales.
It is amorphous, without cleavage, and conchoidal frac­ture.
Hardness, 6 (varies) ; specific gravity, 2.6 to 2.8.
Lustre waxy; opaque to slightly translucent.
Composition varies : phosphorus pentoxide, 33 ; alumina, 40; water, 19; copper, iron, and manganese oxides, 8.
It is affected by acids; becomes brown under the blow­pipe ; melts to clear glass with borax and salts of phosphorus; soluble in hydrochloric acid.
Color, all shades of azure and greenish blue; color is due to phosphate of copper.
Varieties: " old rock," said to retain its color perpetu­ally ; " new rock," which fades or changes to a greenish tint. Odontolite, or fossil turquoise, is not a true turquoise or min­eral, but fossilized tooth, bone, or ivory of the mammoth, colored by phosphate of iron, with which it is permeated. Callainite is a mineral of lighter color and less translucency.
Cut en cabochon.
Symbolizes prosperity, soul-cheer, December.
The color of all turquoise, whether treated for the pres­ervation of color or not, is liable under certain conditions, when worn, to assume a greenish tint.