mineral
Turquoise
Hydrated phosphate of copper and aluminium: CuAl6(PO4)4(OH)8·4H2O
AI-generated identification · may be incorrectHardness: 5–6 (Mohs scale); Color: Sky blue, blue-green, or apple green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually occurs in massive or cryptocrystalline forms); Cleavage: Perfect, but rarely visible due to fine grain size; Specific Gravity: 2.6–2.9.
- Hardness
- 5–6 (Mohs scale)
- Color
- Sky blue, blue-green, or apple green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5–6 (Mohs scale); Color: Sky blue, blue-green, or apple green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually occurs in massive or cryptocrystalline forms); Cleavage: Perfect, but rarely visible due to fine grain size; 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 (copper sulfides and aluminum-rich rocks) in arid regions. Typically found in volcanic rocks or sedimentary environments enriched in phosphate.
Uses & applications
Primarily used as a gemstone in jewelry-making (beads, cabochons, and inlays), ornamental carvings, and high-value collectibles. It has also been used for over 5,000 years in decorative architectural tiles and cultural artifacts.
Geological facts
Turquoise is one of the oldest gemstones known to man, used by the Ancient Egyptians since the First Dynasty. Its name is derived from the French 'turquois', meaning 'Turkish', as the stone originally reached Europe via Turkey from mines in Persia.
Field identification & locations
Identify in the field by its distinct waxy luster and blue-to-green hue, often accompanied by dark 'matrix' veins of limonite or manganese oxide. Common locations include Iran (Nishapur), the Southwestern United States (Arizona, Nevada, New Mexico), and China (Hubei). Collectors should look for its association with copper ore deposits in desert climates.
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