mineral

Feldspar

Potassium Feldspar (KAlSi3O8)

Hardness: 6 on Mohs scale; Color: typically pink, white, or salmon; Luster: vitreous to pearly; Crystal structure: Monoclinic or Triclinic; Cleavage: two planes at nearly 90 degrees; Specific gravity: 2.55–2.63

Hardness: 6 on Mohs scale
Color: typically pink, white, or salmon
Luster: vitreous to pearly

Identified February 24, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in igneous rocks such as granite and pegmatite through crystallization of magma, as well as in metamorphic rocks and some sandstones; geological age varies from Archean to recent.

Uses & applications

Used extensively in the manufacture of glass and ceramics, as a filler in paint and rubber, and occasionally as a gemstone (such as moonstone or amazonite).

Geological facts

Feldspar is the most abundant mineral group in the Earth's crust, accounting for approximately 60% of terrestrial rocks. The name is derived from the German 'Feldspat', meaning field rock.

Field identification & locations

Identified by its pinkish hue and blocky cleavage planes; found globally in mountainous and granitic terrains. Collectors should look for flat, shimmering surfaces (cleavage faces) that reflect light efficiently.