mineral

Potassium Feldspar (Orthoclase)

KAlSi3O8 (Potassium Aluminum Silicate)

Hardness: 6.0 on Mohs scale; Color: typically pink, salmon, or peach-colored; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.55-2.63.

Hardness: 6
Color: typically pink, salmon, or peach-colored
Luster: Vitreous to pearly

Identified June 9, 2026More mineral →

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Physical properties

Formation & geological history

Forms in igneous rocks like granite and syenite through the cooling of silica-rich magma; also common in high-grade metamorphic rocks. It is one of the most abundant minerals in the Earth's crust.

Uses & applications

Primarily used in the manufacture of glass and ceramics (porcelain); also used as a mild abrasive and occasionally as a gemstone (moonstone variety).

Geological facts

Feldspar makes up about 41% of the Earth's continental crust by weight. The pink color is often due to trace amounts of hematite or impurities within the crystal lattice.

Field identification & locations

Identify by its salmon-pink color, blocky cleavage planes, and hardness (it will scratch glass but cannot be scratched by a steel knife). Commonly found in mountain ranges and as a primary component of pink granites.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Schist

Metamorphic

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