mineral

Red Feldspar (Orthoclase)

Orthoclase Feldspar (KAlSi3O8)

AI-generated identification · may be incorrect

Hardness: 6 on Mohs scale; Color: Reddish-pink to salmon; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions at 90 degrees; Specific gravity: 2.55-2.63

Hardness: 6 on Mohs scale
Color: Reddish-pink to salmon
Luster: Vitreous to pearly

Identified June 4, 2026More mineral →

Explore Red Feldspar (Orthoclase) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Hardness: 6 on Mohs scale; Color: Reddish-pink to salmon; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect in two directions at 90 degrees; Specific gravity: 2.55-2.63

Formation & geological history

Formed primarily in igneous rocks like granite and syenite through the cooling of silica-rich magma; also found in metamorphic rocks like gneiss. Common across many geological ages from Precambrian to Cenozoic.

Uses & applications

Used in the manufacture of glass and ceramics (porcelain), as a gemstone (moonstone/sunstone varieties), and as a common component in crushed stone construction.

Geological facts

Feldspar is the most abundant mineral group in the Earth's crust, making up about 60% of terrestrial rocks. The reddish color in this specimen is often caused by tiny inclusions of hematite (iron oxide).

Field identification & locations

Identify in the field by its distinct 90-degree cleavage planes and pink/red blocky appearance in granitic terrains. Commonly found in pegmatites and mountain ranges globally.