mineral
Turquoise
CuAl6(PO4)4(OH)8·4H2O (Hydrated copper and aluminum phosphate)
AI-generated identification · may be incorrectHardness: 5-6 Mohs. Color: Sky blue to blue-green. Luster: Waxy to sub-vitreous. Crystal structure: Triclinic. Cleavage: Good to perfect (though rarely seen in cryptocrystalline forms). Specific gravity: 2.6-2.9.
- Hardness
- 5-6 Mohs
- Color
- Sky blue to blue-green
- Luster
- Waxy to sub-vitreous
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Physical properties
Hardness: 5-6 Mohs. Color: Sky blue to blue-green. Luster: Waxy to sub-vitreous. Crystal structure: Triclinic. Cleavage: Good to perfect (though rarely seen in cryptocrystalline forms). Specific gravity: 2.6-2.9.
Formation & geological history
Formed as a secondary mineral by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals like copper sulfides and aluminum-rich silicates. It is typically found in arid regions within volcanic rocks or sedimentary phosphate deposits.
Uses & applications
Primarily used as a gemstone for jewelry (cabochons, beads, and inlay) and ornamental carvings. It has been used for millennia for decorative and ritualistic purposes.
Geological facts
One of the first gemstones ever mined, with some mines in Egypt dating back to 3000 BCE. The name is derived from the French word for 'Turkish', as the stone originally reached Europe via Turkey from mines in Persia.
Field identification & locations
Identified by its unique 'robin's egg' blue color and often presence of 'matrix' (veins of host rock like limonite or quartz). Commonly found in Iran, the Southwestern United States, China, and Egypt. For collectors, look for uniform color and high density; it is often imitated by dyed Howlite or Magnesite.
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