mineral

Feldspar (Orthoclase)

Potassium Alveolar Silicate (KAlSi3O8)

Hardness: 6 on Mohs scale; Color: Pinkish-tan or salmon; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.55-2.63

Hardness: 6 on Mohs scale
Color: Pinkish-tan or salmon
Luster: Vitreous to pearly

Identified June 14, 2026More mineral →

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Physical properties

Hardness: 6 on Mohs scale; Color: Pinkish-tan or salmon; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at nearly 90 degrees; Specific gravity: 2.55-2.63

Formation & geological history

Formed in intrusive igneous rocks like granite or metamorphic rocks. It crystallizes from cooling magma at high temperatures and can be billions of years old depending on the host formation.

Uses & applications

Used in the manufacture of glass and ceramics, as a filler in paint and plastics, and occasionally as a gemstone (moonstone/sunstone).

Geological facts

Feldspar is the most abundant group of minerals in the Earth's crust, making up about 60% of terrestrial rocks.

Field identification & locations

Identify by its blocky shape, salmon-pink color, and flat cleavage planes that reflect light. It is common in gravel pits and mountainous terrains.

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