![Turquoise (Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]) — mineral](https://media.rockidentification.com/32255a93-b057-41e2-bdc2-415c9997664a-compressed.jpg)
mineral
Turquoise
Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]
Hardness: 5-6 (Mohs scale); Color: Sky blue to turquoise green; Luster: Waxy to sub-vitreous; Crystal Structure: Triclinic (usually cryptocrystalline); Cleavage: Perfect (rarely seen in massive forms); Specific Gravity: 2.6-2.9.
- Hardness
- 5-6 (Mohs scale)
- Color
- Sky blue to turquoise green
- Luster
- Waxy to sub-vitreous
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Sky blue to turquoise green; Luster: Waxy to sub-vitreous; Crystal Structure: Triclinic (usually cryptocrystalline); Cleavage: Perfect (rarely seen in massive forms); Specific Gravity: 2.6-2.9.
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 in volcanic rocks or sedimentary phosphate-rich rocks. Most deposits are millions of years old.
Uses & applications
Primarily used as an ornamental stone and gemstone for jewelry (cabochons, beads, inlays). Highly valued by collectors and indigenous cultures, specifically in the Southwestern United States and Middle East.
Geological facts
Turquoise is one of the oldest known gemstones, used by Ancient Egyptians as early as 3000 BCE. The name is derived from the French 'turquois', meaning 'Turkish', as the stone first reached Europe via Turkey from mines in Persia.
Field identification & locations
Identify in the field by its robin's-egg blue color and waxy texture within veins of host rock (often limonite or quartz). Common locations include Iran, the Southwestern USA (Arizona, Nevada), China, and Mexico. Collectors look for 'Sleeping Beauty' blue or stones with unique 'spiderweb' matrix patterns.
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Metamorphic Rock
![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)]
mineral
Epidote
Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)
mineral