![Turquoise (Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]) — Mineral](https://media.rockidentification.com/d0892483-dae1-4491-8acc-1d222984d652-compressed.jpg)
Mineral
Turquoise
Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]
Hardness: 5.0–6.0 on Mohs scale; Color: Sky blue, blue-green, or apple green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (rarely seen; usually cryptocrystalline/massive); Cleavage: Perfect (rarely observed); Specific Gravity: 2.6–2.9.
- Hardness
- 5
- Color
- Sky blue, blue-green, or apple green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5.0–6.0 on Mohs scale; Color: Sky blue, blue-green, or apple green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (rarely seen; usually cryptocrystalline/massive); Cleavage: Perfect (rarely observed); 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 (aluminum-rich rocks near copper deposits). Generally found in arid climates. Geological age varies but often associated with Tertiary formations.
Uses & applications
Primarily used as a gemstone in jewelry (cabochons, beads, and inlay) and for ornamental carvings. It has high value for collectors, especially specimens with unique matrix patterns or vibrant sky-blue 'Robin's Egg' coloration.
Geological facts
Turquoise is one of the oldest known gemstones; it was mined by Ancient Egyptians as early as 3000 BCE. Its name is derived from the French 'turquois', meaning 'Turkish', as it first reached Europe via Turkish trade routes.
Field identification & locations
Identify in the field by its characteristic waxy luster and blue-to-green hue, often found as veins or crusts in volcanic rocks or altered limestones. Common locations include Iran (Nishapur), Southwest USA (Arizona, Nevada), and China. Collectors should look for the 'matrix' (veins of host rock) which can help distinguish natural turquoise from synthetic or dyed imitations like howlite.
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Mineral/Rock
Banded Gneiss (River Rock/Pebble)
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![Green Apatite on Albite (Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]) — mineral](https://media.rockidentification.com/2391a63f-fb20-47d5-af9a-2035851eb32e-thumbnail.jpg)
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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