T
URQUOISE is a
hydrated phosphate of alumina sometimes containing small quantities of
copper, iron, or manganese. Its hardness is 6, and specific gravity
2.75. The finest varieties, which generally do not lose their color
easily, have been for centuries found in small veins in a clay slate in
the vicinity of Nishapoor, Persia. Large quantities are brought from
Egypt, but this variety, although dark-blue when found, often changes
in a short time to a verdigris green.
This
mineral is found at Los Cerrillos, N. M. ; Turquoise Mountain, Cochise
County, Ariz.; Mineral Park, Mohave County, Ariz. ; near Columbus,
Nev.; Holy Cross Mountain, Col.; and Taylor's Ranch, Fresno County,
Cal. The first-named locality is part of a group of conical mountains
situated about twenty-two miles southeast of Santa Fe, N. M., and north
of the Placer or Gold Mountains, from which they are separated by the
valley of the Galisteo River. The rocks of which they are composed are
yellow and gray quartzite sandstones and porphyry dykes. Probably the
sandstones are of the Carboniferous period, and they are so much
uplifted and metamorphosed that the sedimentary character is partly
obliterated. William P. Blake describes the locality as being an
immense pit, with precipitous sides of angular rock, projecting in
crags, sustaining in the fissures a growth of
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