Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula CuAl6(PO4)4(OH) 4H2O. It is rare and valuable in finer grades and has been prized as a gem and ornamental stone for thousands of years owing to its unique hue.

Color Opaque, Light to Dark Blue or Blue-Green
Mohs scale hardness 5.0 - 6.0
Specific gravity 2.60 - 2.80
Refractive index 1.610 - 1.650