mineral
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Hardness: 5-6 (Mohs), Color: sky-blue to apple-green, Luster: waxy to sub-vitreous, Crystal structure: Triclinic (usually cryptocrystalline), Specific Gravity: 2.6-2.9
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Physical properties
Hardness: 5-6 (Mohs), Color: sky-blue to apple-green, Luster: waxy to sub-vitreous, Crystal structure: Triclinic (usually cryptocrystalline), Specific Gravity: 2.6-2.9
Formation & geological history
A secondary mineral formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It is often found in arid climates in hydrothermal veins and volcanic rocks.
Uses & applications
Primarily used as a gemstone for jewelry, ornamental carvings, and decorative inlays. Used historically by Native Americans and Egyptians.
Geological facts
Turquoise is one of the oldest known gemstones and was often buried with ancient royalty. The word comes from the French 'turquois' meaning 'Turkish', as the stone originally reached Europe via Turkey.
Field identification & locations
Identified by its robin's egg blue color and waxy appearance. Commonly found in Arizona (USA), Iran, and China. Collectors look for high 'hardness' and lack of matrix (the host rock webbing).
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