mineral
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Hardness: 5–6; Color: Sky-blue to green; Luster: Waxy to subvitreous; Crystal system: Triclinic; Streak: Bluish white; Specific gravity: 2.6–2.9
- Hardness
- 5–6
- Color
- Sky-blue to green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5–6; Color: Sky-blue to green; Luster: Waxy to subvitreous; Crystal system: Triclinic; Streak: Bluish white; Specific gravity: 2.6–2.9
Formation & geological history
Secondary mineral formed in the alteration zone of copper deposits through the percolation of meteoric water in arid environments.
Uses & applications
Primarily used as a gemstone for jewelry, ornamental carvings, and in historical lapidary work.
Geological facts
It is one of the oldest known gemstones, used by the Ancient Egyptians and Persians. The name comes from the French 'turquois' meaning 'Turkish'.
Field identification & locations
Identify by its waxy luster and specific robin's-egg blue color. Found in arid regions like Iran, Southwestern US, and China. Collectors should check for stabilization treatments.
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