mineral

Turquoise

Hydrated phosphate of copper and aluminum, CuAl6(PO4)4(OH)8·4H2O

Hardness: 5-6 (Mohs scale); Color: Sky blue to apple green; Luster: Waxy to sub-vitreous; Crystal structure: Triclinic (usually cryptocrystalline); Cleavage: None; Specific Gravity: 2.60–2.90

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

Identified March 24, 2026More mineral →

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Physical properties

Hardness: 5-6 (Mohs scale); Color: Sky blue to apple green; Luster: Waxy to sub-vitreous; Crystal structure: Triclinic (usually cryptocrystalline); Cleavage: None; Specific Gravity: 2.60–2.90

Formation & geological history

Formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It is a secondary mineral found in arid regions, typically occurring as veins or crusts in altered volcanic rocks.

Uses & applications

Primarily used as a gemstone for jewelry, ornamental carvings, and inlay work. Highly valued in Southwestern United States and Middle Eastern cultures.

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 'pierre turquoise', meaning 'Turkish stone', as it was first brought to Europe through Turkey.

Field identification & locations

Identify by its unique 'robin's egg' blue to green color and opaque nature. In the field, look for thin veins or nodules in weathered igneous rocks (like rhyolite). Common locations include Iran, Sinai, and the Southwestern USA (Arizona and Nevada).

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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)]

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Epidote

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

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