gemstone

Turquoise cabochon

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

AI-generated identification · may be incorrect

Blue-green opaque cabochon with dark brown/black matrix, waxy to subvitreous luster, cryptocrystalline structure, no visible cleavage, Mohs hardness 5–6, specific gravity about 2.6–2.9. The surrounding metal jewelry is silver-colored, but the blue centerpiece is the geological material.

Identified September 16, 2026More gemstone →

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Physical properties

Formation & geological history

Forms as a secondary mineral in arid, oxidized copper deposits, typically replacing aluminous or phosphate-rich host rock. Most turquoise formed in the Cenozoic, though deposits vary widely in age.

Uses & applications

Used mainly in jewelry, ornament, and carving. This appears to be a polished, set cabochon in a pendant or bracelet component.

Geological facts

Dark matrix is host rock preserved during formation; attractive spiderweb matrix can increase desirability, while dyed or stabilized turquoise is also common. The color is produced largely by copper.

Field identification & locations

Identify by its opaque blue-green color, relatively low hardness, light weight, and matrix pattern; avoid prolonged soaking, heat, acids, and harsh chemicals. Portugal near 38.8°N, 9.3°W is not a notable turquoise-producing region, so imported material or a turquoise imitation is likely; testing would be needed to exclude dyed howlite or composite material.