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|