mineral

Turquoise

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

AI-generated identification · may be incorrect

Hardness: 5-6 (Mohs scale); Color: Sky blue to apple green; Luster: Waxy to sub-vitreous; Crystal structure: Triclinic (usually cryptocrystalline); Cleavage: Perfect (rarely seen in massive forms); Specific Gravity: 2.6–2.9

Hardness: 5-6 (Mohs scale)
Color: Sky blue to apple green
Luster: Waxy to sub-vitreous

Identified March 14, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. Typically found in arid regions within volcanic rocks or sedimentary limestones near copper deposits.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons and beads) and ornamental carvings. Historically used as a pigment and for architectural decoration in various cultures.

Geological facts

One of the oldest known gemstones, it was being mined in the Sinai Peninsula by 3000 BCE. The name is derived from the French word 'turquois', meaning 'Turkish', as it was originally brought to Europe via trade routes through Turkey.

Field identification & locations

Identify by its unique 'robin's egg' blue color and often the presence of a dark 'matrix' (host rock veins). Commonly found in the Southwestern USA, Iran, China, and Egypt. Collectors should look for natural, untreated stones versus dyed 'howlite' or plastic imitations.