mineral

Turquoise

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

AI-generated identification · may be incorrect

Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal structure: Triclinic (usually massive or cryptocrystalline), Specific Gravity: 2.6-2.9.

Identified March 2, 2026More mineral →

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Physical properties

Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal structure: Triclinic (usually massive or cryptocrystalline), Specific Gravity: 2.6-2.9.

Formation & geological history

Secondary mineral formed in the oxidation zones of copper deposits by the percolating of acidic aqueous solutions through aluminous and phosphorous-rich rocks. Often found in arid climates like the Southwestern US and Iran.

Uses & applications

Primarily used as a gemstone in jewelry, decorative carvings, and inlay work for centuries. Non-gem quality material may be crushed for pigment.

Geological facts

It is one of the oldest known gemstones, used by Ancient Egyptians and Native Americans. It is the birthstone for December. The most prized color is 'sleeping beauty' sky blue with no matrix.

Field identification & locations

Identify by its unique 'robin's-egg' blue color and dark matrix (veins). In the field, look for it in weathered copper-bearing rocks. Note: much commercial turquoise like these beads is often stabilized with resin or is actually dyed howlite.