Rock Identifier
Blue-green gemstone cabochon, likely turquoise or chrysocolla (Turquoise: CuAl₆(PO₄)₄(OH)₈·4H₂O; chrysocolla: hydrated copper aluminosilicate (variable composition)) — gemstone
gemstone

Blue-green gemstone cabochon, likely turquoise or chrysocolla

Turquoise: CuAl₆(PO₄)₄(OH)₈·4H₂O; chrysocolla: hydrated copper aluminosilicate (variable composition)

AI-generated identification · may be incorrect

Small polished opaque blue-green cabochon with vitreous-to-waxy luster; hardness is approximately Mohs 5–6 for turquoise and 2.5–3.5 for chrysocolla. The visible metal setting and highlights prevent confident identification of crystal structure or specific gravity.

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Physical properties

Small polished opaque blue-green cabochon with vitreous-to-waxy luster; hardness is approximately Mohs 5–6 for turquoise and 2.5–3.5 for chrysocolla. The visible metal setting and highlights prevent confident identification of crystal structure or specific gravity.

Formation & geological history

Turquoise forms as a secondary copper-phosphate mineral in arid, oxidized deposits, commonly millions of years old; chrysocolla forms in oxidized copper zones. Common sources include Arizona, Nevada, Iran, Mexico, Chile, Peru, and Australia.

Uses & applications

Used in jewelry and ornamental objects; turquoise is generally more durable and valuable, while chrysocolla is often stabilized or mounted protectively.

Geological facts

The blue-green color comes primarily from copper. The photograph shows a mounted, polished stone rather than a natural hand specimen, and color alone cannot distinguish turquoise from chrysocolla or dyed material.

Field identification & locations

Test cautiously: turquoise is opaque, relatively hard, and often has matrix veining; chrysocolla is softer and may scratch easily. Reliable identification requires hardness, density, magnification, and sometimes spectroscopy.