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); Cleavage: Perfect, but rarely seen in massive forms; Specific Gravity: 2.6-2.9.

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

Identified March 27, 2026More mineral →

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Physical properties

Formation & geological history

Formed as a secondary mineral by the action of percolating acidic solutions during the weathering and oxidation of pre-existing minerals (chemically precipitated mineral). It is often found in arid climates within volcanic or sedimentary rocks rich in aluminum and phosphorus.

Uses & applications

Primarily used as a gemstone in jewelry (cabochons, beads, and inlay) and for ornamental decorative objects. It has also been used historically as a pigment and for architectural decoration.

Geological facts

Turquoise is one of the oldest gemstones in history, used by Egyptian Pharaohs and the Aztecs. The 'matrix' seen in many specimens (like the brown veins in the image) is actually host rock, such as limonite or sandstone. Most turquoise on the market today is 'stabilized' with resin to improve durability and color.

Field identification & locations

Identify in the field by its distinct waxy luster and robin-egg blue to green color. It is typically found in desert regions like the Southwestern United States (Arizona, Nevada), Iran, and China. Collectors should check for stabilization treatments and the presence of a natural matrix.

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

Green Apatite on Albite

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

mineral

Epidote

Epidote - Ca2(Al2,Fe3+)3(SiO4)3(OH)

mineral