mineral

Polished turquoise cabochon

Turquoise, hydrous copper-aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

AI-generated identification · may be incorrect

Blue-green opaque, waxy to subvitreous luster, polished oval cabochon with dark brown matrix. Mohs hardness 5–6; triclinic mineral, commonly cryptocrystalline, with no prominent cleavage and specific gravity about 2.6–2.9.

Identified September 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms as a secondary mineral in arid, oxidized copper deposits, where phosphate-bearing groundwater alters aluminum-rich rock. Deposits are commonly Cenozoic to Precambrian in age, depending on locality.

Uses & applications

Used extensively in jewelry, ornament, carvings, and inlay. Most commercial material is stabilized with resin; dyed substitutes and reconstituted turquoise are also common.

Geological facts

The blue color comes mainly from copper, while greener tones may reflect iron. The visible matrix may be host-rock remnants or vein material and is not diagnostic by itself.

Field identification & locations

Likely turquoise based on its opaque turquoise-blue color, brown matrix, and cabochon form; confirmation requires hardness, density, magnification, and preferably spectroscopy. Important sources include Iran, Arizona, Nevada, China, Chile, and Mexico.