Turquoise
Bishop Mine
Campbell County, Virginia
Area of specimen displaying crystals measures 13cm x 9cm
Turquoise CuAl6(PO4)4(OH)8.4-5(H2O)
Phosphate; hydrous phosphate of copper and aluminum; may contain some iron
Color and Luster: Sky-blue, bluish green, apple-green; waxy, dull, streak white, pale green
Hardness: 5-6
Cleavage: None
Fracture: Conchoidal
Crystals: Triclinic; crystals rare; usually compact, reniform, stalactitic, incrusting, thin seams, disseminated
Photo by Mary Sutherland
Descriptions taken from
The Audubon Society Field Guide to North American Rocks and Minerals