gemstone

Turquoise

Turquoise - CuAl6(PO4)4(OH)8·4H2O

Hardness: 5-6 (Mohs scale); Color: Sky blue, bluish-green, to apple green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually massive/cryptocrystalline); Cleavage: Perfect (rarely seen due to cryptocrystalline nature); Specific Gravity: 2.6-2.9

Hardness: 5-6 (Mohs scale)
Color: Sky blue, bluish-green, to apple green
Luster: Waxy to subvitreous

Identified July 17, 2026More gemstone →

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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. Often found in arid regions within volcanic or sedimentary rocks rich in aluminum and phosphorus.

Uses & applications

Primarily used as a gemstone for jewelry, including cabochons, beads, and carvings. Significant in Southwestern and Middle Eastern decorative arts.

Geological facts

Turquoise is one of the oldest known gemstones, used by Ancient Egyptians as far back as 3000 BCE. The name comes from the French 'turquois', meaning 'Turkish', as it first reached Europe via Turkey.

Field identification & locations

Identify in the field by its distinct robin's egg blue or greenish-blue color and waxy appearance. Commonly found in copper-rich deposits in Iran, the Southwestern United States, China, and Egypt. Collectors look for 'spiderweb' matrix patterns formed by surrounding host rock.