mineral

Turquoise

Hydrated copper and aluminum phosphate (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 March 15, 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

Formed as a secondary mineral by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It typically occurs in arid regions within altered volcanic rocks or sedimentary environments containing copper.

Uses & applications

Primary use is in jewelry, lapidary arts, and ornamental carvings. It is a popular gemstone for Southwestern and Bohemian style accessories.

Geological facts

Turquoise is one of the oldest known gemstones, used by Ancient Egyptians as early as 3000 BCE. Its name comes from the French 'turquois' meaning 'Turkish', as it was historically brought to Europe through Turkey from Persian mines.

Field identification & locations

Identify in the field by its distinct robin's-egg blue or green color and 'matrix' (veins of host rock like limonite or sandstone). Commonly found in the Southwestern USA (Arizona, Nevada), Iran, and China. Collectors look for high density and 'spiderweb' matrix patterns.

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral