gemstone

Polished turquoise cabochon

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

AI-generated identification · may be incorrect

Typically blue-green to green with dark matrix; waxy to subvitreous luster and cryptocrystalline structure. Mohs hardness 5–6, no obvious cleavage, and specific gravity about 2.6–2.9; this specimen appears polished and possibly stabilized or treated.

Identified August 21, 2026More gemstone →

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Physical properties

Formation & geological history

Forms as a secondary phosphate mineral in arid, oxidized copper deposits, commonly replacing aluminum-rich host rock. Most deposits are Cenozoic to older, with notable material from Iran, the southwestern United States, China, Egypt, and Mexico.

Uses & applications

Used primarily for cabochons, beads, carvings, and ornamental objects; historically valued in jewelry and cultural artifacts. Lower-grade turquoise is often stabilized with resin to improve durability.

Geological facts

Its blue color comes mainly from copper, while greener tones may reflect iron substitution or weathering. Natural turquoise commonly contains brown or black limonite, chert, or host-rock matrix.

Field identification & locations

Identify by its opaque blue-green color, relatively low hardness, waxy surface, and matrix; glassy luster, bubbles, or excessive uniformity can indicate imitation. Avoid acids, heat, harsh chemicals, and prolonged soaking.