![Turquoise (Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]) — mineral](https://media.rockidentification.com/33348d08-a630-466a-8040-53d3b66a4ea3-compressed.jpg)
mineral
Turquoise
Hydrated phosphate of copper and aluminium [CuAl6(PO4)4(OH)8·4H2O]
Hardness: 5-6 (Mohs). Color: Sky blue to blue-green. Luster: Waxy to subvitreous. Crystal Structure: Triclinic (usually microcrystalline mass). Cleavage: Perfect (rarely seen in massive specimens). Specific Gravity: 2.6-2.9.
- Hardness
- 5-6 (Mohs)
- Color
- Sky blue to blue-green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5-6 (Mohs). Color: Sky blue to blue-green. Luster: Waxy to subvitreous. Crystal Structure: Triclinic (usually microcrystalline mass). Cleavage: Perfect (rarely seen in massive specimens). Specific Gravity: 2.6-2.9.
Formation & geological history
Formed as a secondary mineral by the percolation of meteoric water through weathered volcanic or sedimentary rocks rich in aluminum and copper, typically in arid environments near the surface. It is often found in the weathering zones of copper deposits.
Uses & applications
Primary use is in jewelry and decorative arts. It has been used for millennia for beads, cabochons, inlay work, and ceremonial objects. Low-grade specimens are often crushed or used for industrial craft purposes.
Geological facts
Turquoise is one of the oldest gemstones in human history, utilized by the Pharaohs of Ancient Egypt and the Aztecs. The sky-blue color is caused by copper, while green tints are usually caused by iron impurities or dehydration.
Field identification & locations
Identify in the field by its distinct robin's egg blue color and association with host rock like limonite or sandstone. Common locations include the Southwest USA (Arizona, Nevada), Iran, and China. Collectors should look for 'matrix' (the remnant host rock) which can verify authenticity against glass or plastic imitations.
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Green Apatite on Albite
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