Turquoise
(tû'r-koiz')
16th c.; fre. turquoyse; geo. Turkestan
Blue to blue-green mineral made of aluminum and copper, considered as a gemstone and used in jewelry in its polished blue form
Color
Light to dark blue to blue green
Family
Hydrous copper-aluminum phosphate
Chemical composition
CuAl6(PO4)4(OH)8 4H2O
Crystal system
Triclinic - Cryptocristalline
Hardness (Mohs scale)
5 - 6
Specific gravity
2,72 ±0,12
Refractive index
1,61 ±0,01
Optical character
Aggregate