mineral

K-Feldspar (Microcline / Orthoclase)

Potassium Feldspar (KAlSi3O8)

Hardness: 6 on the Mohs scale. Color: Typically pink, salmon-pink, or reddish, sometimes white or grey. Luster: Vitreous to pearly. Crystal Structure: Triclinic (Microcline) or Monoclinic (Orthoclase). Cleavage: Two directions of perfect to good cleavage at nearly 90 degrees. Specific Gravity: 2.5 - 2.6.

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

Identified July 28, 2026More mineral →

Explore K-Feldspar (Microcline / Orthoclase) in the encyclopedia →

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Physical properties

Formation & geological history

Forms commonly in felsic igneous rocks such as granite and syenite, as well as in pegmatites and metamorphic gneisses through the cooling and crystallization of magma rich in potassium and silica.

Uses & applications

Used in the manufacture of ceramics, porcelain, glass, and as a mild abrasive in scouring powders. Gemstone varieties like amazonite are used in jewelry.

Geological facts

Feldspars are the most abundant mineral group in the Earth's crust, making up about 60% of terrestrial rocks. The characteristic pink color is typically due to microscopic hematite inclusions.

Field identification & locations

Easily identified by its distinctive pink color, blocky crystal habit, and two cleavage planes meeting at nearly right angles. Commonly found worldwide in pegmatite dikes and granitic terrains.

Other mineral specimens

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Sandstone (with potential mineral staining/concretions)

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sedimentary

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Limonite / Goethite (Iron Ore Mineral nodule)

FeO(OH)·nH2O / FeO(OH)

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Schist

Metamorphic

Septarian Pebble

Septarian nodule / Concretion

sedimentary

Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral