mineral

Polished turquoise

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

AI-generated identification · may be incorrect

Opaque blue-green with brown matrix/limonite spots and a waxy to dull luster; typically cryptocrystalline and massive, with Mohs hardness 5–6 and specific gravity about 2.6–2.9. The rounded, glossy form indicates a polished or tumbled specimen.

Identified August 17, 2026More mineral →

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Physical properties

Formation & geological history

Forms as a secondary mineral in arid, oxidized copper deposits when phosphate-bearing groundwater alters aluminum-rich host rock. It is geologically young relative to its host rocks, commonly forming from the Cenozoic onward.

Uses & applications

Used for cabochons, beads, carvings, inlay, and ornamentation; historically important in Indigenous Southwestern jewelry and Egyptian artifacts. It has little industrial use beyond decorative applications.

Geological facts

Color ranges from sky blue to green depending largely on copper, iron, and zinc content; brown matrix is natural host-rock material. Major sources include Iran, the southwestern United States, China, Chile, and Mexico.

Field identification & locations

Identify it by its opaque blue-green color, low-to-moderate hardness, waxy luster, and copper response; it is not reliably identified by appearance alone because dyed magnesite and howlite are common imitations. Avoid acids, prolonged soaking, and ultrasonic cleaning.