gemstone

Polished turquoise

Turquoise — hydrated copper–aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O

AI-generated identification · may be incorrect

Opaque, pale blue to blue-green with brown/black matrix; waxy to subvitreous luster and cryptocrystalline structure. Mohs hardness 5–6; no prominent cleavage; specific gravity about 2.6–2.9.

Identified August 9, 2026More gemstone →

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Physical properties

Opaque, pale blue to blue-green with brown/black matrix; waxy to subvitreous luster and cryptocrystalline structure. Mohs hardness 5–6; no prominent cleavage; specific gravity about 2.6–2.9.

Formation & geological history

A secondary phosphate mineral formed in arid, oxidized zones above copper deposits, commonly replacing aluminosilicate host rock. Most deposits are Cenozoic to younger, though turquoise occurs in older mineralized terrains as well.

Uses & applications

Used for cabochons, beads, carvings, and ornamental polished stones; historically important in jewelry and ceremonial objects. Lower-grade material is also used for decorative specimens.

Geological facts

The brown webbing is iron- or manganese-stained host-rock matrix, while green coloration commonly reflects iron substitution for copper. Stabilized or dyed turquoise is common commercially, so appearance alone cannot confirm treatment.

Field identification & locations

Likely turquoise based on its blue-green color, opaque waxy surface, and dark matrix; test cautiously because hardness and treatments vary. Major sources include Iran, Arizona and Nevada, China, Mexico, and Chile.