mineral

Turquoise

Turquoise (CuAl6(PO4)4(OH)8·4H2O)

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

Hardness: 5–6 Mohs
Color: Sky blue to blue-green
Luster: Waxy to subvitreous

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 copper minerals. It occurs in arid climates within sandstone or volcanic rock cavities.

Uses & applications

Primarily used in jewelry (cabochons, beads, and inlay work) and as an ornamental gemstone. High-grade specimens are highly sought after by collectors.

Geological facts

Turquoise is one of the oldest known gemstones, used by the Ancient Egyptians since the First Dynasty and the Aztecs in Mesoamerica. It is the traditional birthstone for December.

Field identification & locations

Identify by its unique 'Robin's Egg' blue color and presence of a 'matrix' (veins of host rock like limonite or quartz). Commonly found in the Southwestern US, Iran, China, and Egypt. Collectors should look for uniform color and lack of artificial stabilization.