
mineral
Turquoise
Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O
AI-generated identification · may be incorrectBlue-green, opaque, waxy to subvitreous luster; Mohs hardness 5–6, cryptocrystalline structure, no visible cleavage, and specific gravity about 2.6–2.9. The orange-brown areas may be matrix or iron staining; the piece appears polished or tumbled.
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Physical properties
Blue-green, opaque, waxy to subvitreous luster; Mohs hardness 5–6, cryptocrystalline structure, no visible cleavage, and specific gravity about 2.6–2.9. The orange-brown areas may be matrix or iron staining; the piece appears polished or tumbled.
Formation & geological history
Forms as a secondary phosphate mineral in arid, copper-rich, weathered volcanic or sedimentary rocks, generally by low-temperature groundwater alteration. Most deposits are geologically young compared with their host rocks, commonly Cenozoic.
Uses & applications
Used as a cabochon gemstone, beads, carvings, and decorative objects; historically important in jewelry and ceremonial artifacts. Lower-grade material is also used for inexpensive inlay and polished specimens.
Geological facts
Its color comes mainly from copper, while iron can shift it toward green or brown. Natural turquoise is commonly stabilized with resin, and dyed imitations or reconstructed turquoise are widespread.
Field identification & locations
Identify it by its opaque blue-green color, relatively soft surface, waxy luster, and often brown or black matrix; it should not show glass-like transparency. Common sources include Iran, the southwestern United States, China, Mexico, Chile, and Egypt.
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