![Turquoise (Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]) — mineral](https://media.rockidentification.com/d759b372-349e-4b5a-8a0f-0015d1d6c5e6-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 blue-green; Luster: Waxy to subvitreous; Crystal structure: Triclinic; Cleavage: Good to perfect (though rarely seen in cryptocrystalline form); Specific gravity: 2.60–2.90
- Hardness
- 5-6 (Mohs scale)
- Color
- Sky blue to blue-green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Sky blue to blue-green; Luster: Waxy to subvitreous; Crystal structure: Triclinic; Cleavage: Good to perfect (though rarely seen in cryptocrystalline form); Specific gravity: 2.60–2.90
Formation & geological history
Secondary mineral formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. Usually found in arid regions within volcanic or sedimentary rocks rich in copper and aluminum.
Uses & applications
Primarily used as an ornamental stone, in jewelry (cabs, beads, inlay), and as a collector's gemstone. Also historically used as a pigment and for cultural amulets.
Geological facts
Turquoise is one of the oldest gemstones used by human civilizations, dating back to ancient Egypt and the Persian Empire. The name comes from the French 'turquois' meaning 'Turkish,' because the stone reached Europe via Turkey.
Field identification & locations
Identify in the field by its distinctive 'robin's egg' blue color and presence in arid, copper-rich mining regions. Often associated with limonite (brown matrix) or quartz. Natural specimens are porous; many commercial stones are stabilized with resin.
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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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