mineral

Feldspar (Orthoclase)

Potassium Feldspar (KAlSi3O8)

Hardness: 6 on Mohs scale; Color: Pinkish-orange (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-orange (salmon)
Luster: Vitreous to pearly

Identified June 27, 2026More mineral →

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Physical properties

Hardness: 6 on Mohs scale; Color: Pinkish-orange (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 igneous rocks like granite and pegmatite, and in metamorphic rocks. Created through the cooling of silica-rich magma or through hydrothermal activity. Found in various geological ages worldwide.

Uses & applications

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

Geological facts

Feldspar is the most abundant mineral group in the Earth's crust, making up about 60% of terrestrial rocks. The pink color is often due to trace amounts of hematite or structural defects within the crystal lattice.

Field identification & locations

Identify by its salmon-pink color, pearl-like luster on cleavage faces, and its ability to scratch glass but not quartz. Common in granitic terrains and river gravels.