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 subvitreous, Crystal structure: Triclinic (rarely macro-crystalline), Specific gravity: 2.6-2.9

Identified May 3, 2026More mineral →

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Physical properties

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

Formation & geological history

Formed by secondary enrichment processes in arid regions through the infiltration of moisture through copper-bearing rocks. It is found in hydrothermal veins and altered volcanic rocks, often dating to the Tertiary or Cretaceous periods.

Uses & applications

Primarily used as a gemstone in jewelry, ornamental carvings, and silver smithing (particularly in Native American jewelry). Low-grade material is used for cabochon manufacturing.

Geological facts

Turquoise has been mined for over 6,000 years, with the oldest mines located in the Sinai Peninsula of Egypt. It is one of the first gemstones to be mined and was used as an amulet by the ancient Aztecs and Persians.

Field identification & locations

Identify in the field by its distinct robin-egg blue or green color and waxy appearance. Commonly found in the Southwestern US (Arizona, Nevada), Iran, and China. Collectors should look for 'spiderweb' matrix patterns which can increase desirability.

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