mineral

K-Feldspar (Potassium Feldspar)

Orthoclase / Microcline (KAlSi3O8)

Hardness: 6 on the Mohs scale. Color: Typically pink, salmon-pink, or reddish-brown due to microscopic hematite inclusions. Luster: Vitreous to pearly on cleavage planes. Crystal Structure: Monoclinic (orthoclase) or triclinic (microcline). Cleavage: Two directions at nearly right angles (good cleavage).…

Hardness: 6 on the Mohs scale
Luster: Vitreous to pearly on cleavage planes

Identified July 31, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in felsic igneous rocks such as granites, pegmatites, and syenites through the slow cooling of magma, as well as in some metamorphic and sedimentary rocks.

Uses & applications

Used in the manufacturing of ceramics, glass, porcelain, and as a mild abrasive in scouring powders. Also collected as a mineral specimen.

Geological facts

Potassium feldspar is one of the most abundant rock-forming minerals in the Earth's continental crust. Its distinct salmon-pink color makes it easily recognizable in granitic rocks.

Field identification & locations

Can be identified in the field by its characteristic pink color, blocky crystal form, and two cleavage planes meeting near 90 degrees. Commonly found in pegmatite dikes and granite outcrops worldwide.

Other mineral specimens

See all

Sandstone (with potential mineral staining/concretions)

Arenite (SiO2 based)

sedimentary

Soil with Mineral Detritus and Quartz Fragments

Regolith / Silicate Mineral Aggregate

sedimentary

Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

mineral

Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral