A Turquoise nugget that has been cut
and polished along the bottom.
A vein of Turquoise in matrix.
Turquoise with Pyrite
from the Sleeping Beauty Mine near Globe, AZ.
CHEMISTRY CuAl6(PO4)4(OH)8 .2H2O Hydrated copper aluminum phosphate
CRYSTALLOGRAPHY Triclinic
CRYSTAL GROWTH AND HABITS Turquoise crystals are rare but form steep pinacoids. Most commonly Turquoise is cryptocrystalline and forms nodules.
COLOR AND OTHER OPTICAL PROPERTIES Turquoise is typically some shade of blue to bluish green or green. It is translucent in thin pieces to opaque.
HARDNESS 5 -6
SPECIFIC GRAVITY 2.8 - 2.9
LUSTER Dull to waxy, crystals are vitreous
STREAK White to pale blue
BREAKABILITY Conchoidal, usually producing smooth surfaces
OCCURRENCE Turquoise is produced in the alteration zone of copper deposits when potassium is present.
ASSOCIATED MINERALS Kaolinite, pyrite, montmorillonite
NAME from the French "turquie" for its color.