Rock Identifier
Tumbled turquoise (Turquoise — hydrated copper aluminum phosphate, CuAl₆(PO₄)₄(OH)₈·4H₂O) — gemstone
gemstone

Tumbled turquoise

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

AI-generated identification · may be incorrect

Blue-green, opaque, waxy to subvitreous luster, commonly showing darker matrix veining; Mohs hardness 5–6, cryptocrystalline/triclinic aggregate, low-to-moderate specific gravity around 2.6–2.8. The rounded, polished form indicates tumbling, and the vivid color may be stabilized or dyed.

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Physical properties

Blue-green, opaque, waxy to subvitreous luster, commonly showing darker matrix veining; Mohs hardness 5–6, cryptocrystalline/triclinic aggregate, low-to-moderate specific gravity around 2.6–2.8. The rounded, polished form indicates tumbling, and the vivid color may be stabilized or dyed.

Formation & geological history

A secondary phosphate mineral formed in arid, oxidized copper deposits when phosphate-bearing groundwater alters aluminum-rich rock. Most deposits are geologically young relative to host rocks, commonly Cenozoic to Mesozoic.

Uses & applications

Used for cabochons, beads, carvings, and ornament; historically important in jewelry and cultural artifacts. Lower-grade material is often stabilized with resin for durability.

Geological facts

Natural turquoise can range from sky blue to green depending on copper, iron, and zinc content. Similar-looking dyed howlite or magnesite is common in the market.

Field identification & locations

Common sources include Iran, the southwestern United States, China, Mexico, Chile, and Egypt. Identify it by its opaque blue-green color, relatively soft surface, waxy luster, and possible matrix; hardness or solvent tests should be performed cautiously.