mineral

Turquoise

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

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 May 28, 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 by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. Commonly found in arid regions within volcanic rocks or sedimentary phosphate deposits.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads) and for ornamental carvings. Occasionally used in industrial pigments.

Geological facts

Turquoise is one of the oldest known gemstones, used by Ancient Egyptians and Persians. The name comes from the French 'turquois' meaning Turkish, as it was first brought to Europe through Turkey.

Field identification & locations

Identify by its unique 'robin's egg' blue color and dark matrix veins (often limonite or manganese oxide). Found in Iran, Southwestern USA, China, and Egypt. Collectors look for uniform color and absence of treatment.

Other mineral specimens

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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

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

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

mineral