mineral

Turquoise

Hydrous phosphate of copper and aluminum (CuAl6(PO4)4(OH)8·4H2O)

Hardness: 5-6 (Mohs); Color: Sky-blue to apple-green; Luster: Waxy to subvitreous; Crystal Structure: Triclinic (usually massive or microcrystalline); Cleavage: Perfect (rarely seen in massive forms); Specific Gravity: 2.6-2.9.

Hardness: 5-6 (Mohs)
Color: Sky-blue to apple-green
Luster: Waxy to subvitreous

Identified February 22, 2026More mineral →

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Physical properties

Formation & geological history

Turquoise is a secondary mineral formed by the percolation of acidic aqueous solutions through weathered aluminum-rich rocks in arid regions, often in the presence of copper and phosphorus. Most deposits date back to the Cretaceous or Tertiary periods.

Uses & applications

Primarily used in jewelry as cabochons, beads, and inlay. It is also a significant specimen for collectors and holds historical value for its use in amulets and ornamental masks.

Geological facts

It was one of the first gemstones to be mined; the Sinai Peninsula in Egypt was a source as early as 3000 BCE. The blue color comes from copper, while green hues are caused by iron or dehydration.

Field identification & locations

Identify by its distinct robin-egg blue to green color, often with a 'matrix' of brown or black host rock. Commonly found in the Southwestern USA (Arizona, Nevada), Iran, and China. Collectors should look for vibrancy of color and lack of stabilization treatments.

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