mineral
Raw turquoise
Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O
AI-generated identification · may be incorrectOpaque blue-green to green, commonly with brown/black limonite or matrix veining; waxy to dull luster and cryptocrystalline structure. Mohs hardness 5–6, no prominent cleavage, specific gravity about 2.6–2.9.
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Physical properties
Opaque blue-green to green, commonly with brown/black limonite or matrix veining; waxy to dull luster and cryptocrystalline structure. Mohs hardness 5–6, no prominent cleavage, specific gravity about 2.6–2.9.
Formation & geological history
Forms as a secondary mineral in arid, oxidized zones of copper deposits when phosphate-bearing groundwater alters aluminum-rich rock. Most deposits are Cenozoic to younger, though turquoise can form over varied geological ages.
Uses & applications
Used as a cabochon, bead, inlay, and ornamental stone; lower-grade material is used for carvings and collector specimens. Stabilized or reconstructed turquoise is common commercially.
Geological facts
The vivid blue color reflects copper, while iron commonly shifts it toward green. Natural turquoise is porous and may darken or absorb oils, so avoid harsh chemicals and prolonged soaking.
Field identification & locations
Common localities include Iran, Arizona and Nevada, China, Mexico, Chile, and Egypt. Distinguish it from dyed howlite or plastic by its natural matrix, moderate hardness, and non-vitreous appearance; laboratory testing is needed for certainty.
