mineral
Turquoise
Hydrated phosphate of copper and aluminium (CuAl6(PO4)4(OH)8·4H2O)
Hardness: 5-6 (Mohs scale), Color: Sky-blue to apple-green, Luster: Waxy to subvitreous, Crystal structure: Triclinic (usually cryptocrystalline), Specific gravity: 2.6-2.9
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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 cryptocrystalline), Specific gravity: 2.6-2.9
Formation & geological history
Formed by the percolation of meteoric water through aluminous rock in the presence of copper and phosphorus. Usually found in arid environments associated with volcanic rocks or sedimentary deposits.
Uses & applications
Primarily used as a gemstone in jewelry, decorative ornaments, and amulets. It is the traditional birthstone for December.
Geological facts
Turquoise is one of the oldest known gemstones, used by Ancient Egyptians, Persians, and Native Americans. It is the state gemstone of Arizona and New Mexico.
Field identification & locations
Look for its unique robin's-egg blue or green color with a waxy luster. In the field, look for thin veins or crusts in altered volcanic rocks in desert regions like the American Southwest, Iran, or China.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock