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 (usually massive); Cleavage: Perfect (rarely seen); Specific Gravity: 2.6-2.9.
- 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 (usually massive); Cleavage: Perfect (rarely seen); Specific Gravity: 2.6-2.9.
Formation & geological history
Formed by the percolation of meteoric water through aluminous rock in the presence of copper and phosphorus. Frequently found in arid or desert climates as veins or nodules in weathered volcanic rocks.
Uses & applications
Predominantly used as a gemstone for jewelry, including rings, necklaces, and pendants, and for ornamental carvings.
Geological facts
Turquoise has been valued for thousands of years; it was used by the ancient Egyptians as early as 3000 BCE and is the traditional birthstone for December.
Field identification & locations
Identified by its distinctive blue-to-green color and waxy luster. In the field, look for it in arid regions near copper deposits. Collectors should check for stabilization treatments or imitations like dyed howlite.
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