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 system: Triclinic (usually massive); 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 system: Triclinic (usually massive); Specific gravity: 2.6-2.9.
Formation & geological history
Turquoise is a secondary mineral formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It is commonly found in arid climates within volcanic or sedimentary host rocks.
Uses & applications
Primarily used as a gemstone for jewelry (beads, cabochons) and ornamental carvings. It has been used as a decorative stone for thousands of years.
Geological facts
It is one of the oldest known gemstones, used by the ancient Egyptians, Aztecs, and Persians. Turquoise is the traditional birthstone for December.
Field identification & locations
Identify by its unique 'robin's egg blue' color and dark, web-like matrix (veins of host rock). In the field, look for it in arid regions near copper deposits. Much modern turquoise is stabilized or dyed.
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