Rock Identifier
Polished turquoise-bearing rock (Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, likely in a brown host rock or matrix) — mineral
mineral

Polished turquoise-bearing rock

Turquoise, CuAl₆(PO₄)₄(OH)₈·4H₂O, likely in a brown host rock or matrix

AI-generated identification · may be incorrect

Blue-green to green, waxy-to-dull luster, opaque, cryptocrystalline and massive; Mohs hardness 5–6, specific gravity about 2.6–2.8, with no visible cleavage. The dark brown matrix and mottled turquoise veining suggest natural turquoise rather than dyed material.

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Physical properties

Blue-green to green, waxy-to-dull luster, opaque, cryptocrystalline and massive; Mohs hardness 5–6, specific gravity about 2.6–2.8, with no visible cleavage. The dark brown matrix and mottled turquoise veining suggest natural turquoise rather than dyed material.

Formation & geological history

Turquoise forms as a secondary copper-aluminum phosphate in arid, oxidized zones of weathered copper deposits, commonly in volcanic or sedimentary host rocks. Most deposits are Cenozoic to Mesozoic in age, though the exact specimen locality cannot be determined from the image.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; lower-grade matrix material is also sold as lapidary rough. It has modest value unless the turquoise is vivid, hard, well-polished, and from a recognized locality.

Geological facts

Turquoise’s blue-green color comes primarily from copper, while iron commonly shifts it toward green and matrix creates the webbed appearance. Similar-looking dyed magnesite, howlite, and composite turquoise are common substitutes.

Field identification & locations

Common sources include Arizona, Nevada, New Mexico, Iran, China, and Mexico. Field identification favors blue-green color, opaque waxy texture, brown/black matrix, and hardness sufficient to resist a fingernail; destructive tests should be avoided.