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.
