mineral

Potassium Feldspar

K-Feldspar (Orthoclase/Microcline), KAlSi3O8

AI-generated identification · may be incorrect

Hardness: 6 (Mohs); Color: Pink, salmon, or tan; Luster: Vitreous to pearly; Crystal structure: Monoclinic or Triclinic; Cleavage: Two directions at 90 degrees; Specific gravity: 2.55-2.63

Hardness: 6 (Mohs)
Color: Pink, salmon, or tan
Luster: Vitreous to pearly

Identified July 16, 2026More mineral →

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Physical properties

Hardness: 6 (Mohs); Color: Pink, salmon, or tan; Luster: Vitreous to pearly; Crystal structure: Monoclinic or Triclinic; Cleavage: Two directions at 90 degrees; Specific gravity: 2.55-2.63

Formation & geological history

Forms primarily in igneous rocks like granite and pegmatite through the cooling of magma, as well as in metamorphic rocks and some sandstones.

Uses & applications

Used in the manufacturing of glass and ceramics (porcelain), as a mild abrasive in scouring powders, and occasionally as a gemstone (moonstone/amazonite).

Geological facts

Feldspar is the most abundant mineral group in the Earth's crust, making up about 41% of its mass by weight. The pink color is often caused by micro-inclusions of hematite or defects in the crystal lattice.

Field identification & locations

Identify in the field by its distinct pink/flesh color, two cleavage planes meeting at nearly right angles, and its inability to be scratched by a steel knife (hardness). It is found worldwide in continental crust exposures.