Turquoise

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

Rock Type: mineral

Turquoise

Physical Properties

Hardness: 5-6 (Mohs scale), Color: Sky blue to apple green with dark matrix, Luster: Waxy to sub-glassy, Crystal structure: Triclinic (usually massive), Cleavage: Perfect (none visible in cryptocrystalline specimens), Specific gravity: 2.6-2.9

Formation & Geological History

Formed by the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals such as copper sulfides and feldspars, typically in arid or desert regions.

Uses & Applications

Primarily used as a gemstone for jewelry, cabochons, and ornamental carvings; also highly valued by collectors of Native American art.

Geological Facts

Turquoise is one of the oldest known gemstones, mined by the Ancient Egyptians as early as 3000 BCE. Its name comes from the French 'turquois' meaning 'Turkish', as it was originally brought to Europe via trade routes through Turkey.

Field Identification & Locations

Identify in the field by its characteristic blue-green hue, waxy luster, and association with copper deposits in dry climates. Look for 'matrix' (veins of host rock) interspersed within the mineral. Common locations include the Southwestern USA, Iran, China, and Egypt.

Identified on: 4/21/2026

Mode: Standard