File:Turquoise (Blue Moon Mine, Candelaria Hills, West Of Tonopah, Nevada, USA) 3.jpg
The phosphate minerals all contain one or more phosphate anions (PO4 -3).
Turquoise is a hydrous copper aluminum hydroxy-phosphate mineral, CuAl6(PO4)4(OH)8·4H2O. It is a secondary mineral that forms near the surface, usually near copper deposits. The color ranges from bluish to bluish-green to greenish and the hardness is 5 to 6 on the Mohs Scale. Crystals are rare - turquoise usually forms very fine-grained masses.
Locality: Blue Moon Mine, Candelaria Hills, west of Tonopah, western Nevada, USA
Photo gallery of turquoise:
www.mindat.org/gallery.php?min= 4060