mineral

Turquoise

Hydrated phosphate of copper and aluminium, CuAl6(PO4)4(OH)8·4H2O

Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal structure: Triclinic (usually cryptocrystalline), Specific gravity: 2.6-2.9

Identified February 5, 2026More mineral →

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Physical properties

Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal structure: Triclinic (usually cryptocrystalline), Specific gravity: 2.6-2.9

Formation & geological history

Secondary mineral formed in the oxidation zones of copper deposit hydrothermal veins. It results from the percolation of meteoric water through aluminous rock in the presence of copper and phosphorus.

Uses & applications

Primary use is in jewelry and ornamental carvings. Highly valued in indigenous Southwestern American and Middle Eastern cultures for amulets and decorative inlay.

Geological facts

One of the oldest gemstones known to history, it was mined by Ancient Egyptians as far back as 3000 BCE. The name comes from the French 'turquois' meaning Turkish, as it was first brought to Europe through Turkey from Persian mines.

Field identification & locations

Found in arid regions such as Iran, Sinai, and the Southwestern US (Arizona, Nevada, New Mexico). In the field, look for opaque blue-green nodules or vein fillings in bleached host rock; can be distinguished from howlite by its sky-blue streak.

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