mineral

Orthoclase Feldspar

KAlSi3O8 (Potassium Aluminum Silicate)

AI-generated identification · may be incorrect

Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach-orange; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at 90 degrees; Specific Gravity: 2.55-2.63.

Hardness: 6 on Mohs scale
Color: Pink, salmon, or peach-orange
Luster: Vitreous to pearly

Identified July 14, 2026More mineral →

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Physical properties

Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach-orange; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at 90 degrees; Specific Gravity: 2.55-2.63.

Formation & geological history

Formed in igneous environments like granites and pegmatites, as well as in metamorphic rocks like gneiss. It crystallizes from cooling magma and can be found in terrains ranging from Precambrian to Cenozoic.

Uses & applications

Used in the manufacture of glass and ceramics (porcelain), as a filler in paints and plastics, and occasionally as a gemstone (moonstone variety).

Geological facts

Orthoclase is one of the ten index minerals on the Mohs scale of mineral hardness. It is one of the most common minerals in the Earth's continental crust.

Field identification & locations

Identify in the field by its distinctive pinkish color and right-angle cleavage planes. It is commonly found in granitic mountainous regions like the Rockies or the Appalachians.