mineral
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Hardness: 5-6 (Mohs scale); Color: Sky blue to apple green; Luster: Waxy to subvitreous; Crystal system: Triclinic (usually massive); Specific gravity: 2.6-2.9
- Hardness
- 5-6 (Mohs scale)
- Color
- Sky blue to apple green
- Luster
- Waxy to subvitreous
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Sky blue to apple green; Luster: Waxy to subvitreous; Crystal system: Triclinic (usually massive); Specific gravity: 2.6-2.9
Formation & geological history
Formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals, typically in arid environments within volcanic or sedimentary host rocks.
Uses & applications
Primarily used as a gemstone for jewelry, cabochons, beads, and ornamental carvings; historically significant for decorative cultural artifacts.
Geological facts
Turquoise is one of the oldest known gemstones, used by Ancient Egyptians as early as 3000 BCE. Its name comes from the French 'pierre turquoise', meaning 'Turkish stone', as it was first brought to Europe through Turkey.
Field identification & locations
Identify in the field by its distinct robin's-egg blue color and presence near copper deposits in arid regions. Collectors should watch for 'matrix' (veins of host rock) which often confirms authenticity, though many beads on the market are stabilized or dyed howlite.
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