mineral

Turquoise

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

Hardness: 5-6 (Mohs scale), Color: Sky blue to apple green, Luster: Waxy to subvitreous, Crystal Structure: Triclinic (usually massive), Cleavage: Perfect (rarely seen), Specific Gravity: 2.6-2.9

Identified May 25, 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), Cleavage: Perfect (rarely seen), Specific Gravity: 2.6-2.9

Formation & geological history

Turquoise forms as a secondary mineral through the percolation of acidic aqueous solutions during the weathering and oxidation of pre-existing minerals. It is typically found in arid climates within volcanic or sedimentary host rocks.

Uses & applications

Primarily used as a gemstone for jewelry, decorative carvings, and inlays. It is highly valued in Southwestern American and Middle Eastern cultures for its aesthetic and traditional significance.

Geological facts

Turquoise is one of the oldest gemstones in human history; it was mined by the Ancient Egyptians as far back as 3000 BCE. It is the birthstone for December.

Field identification & locations

Look for its characteristic 'robin\'s egg blue' color and waxy appearance. Often found near copper deposits in veins or as nodules. Collectors should look for stable color and presence of host rock matrix (spiderweb patterns).

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Epidote

Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)

metamorphic

Nephrite Jade

Nephrite

Mineral/Rock

Banded Gneiss (River Rock/Pebble)

Gneiss (specifically a banded variety often found as a river rock)

Metamorphic Rock

Biotite Schist

Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]

metamorphic

Green Apatite on Albite

Fluorapatite [Ca5(PO4)3F] on Albite [Na(AlSi3O8)]

mineral