mineral

K-Feldspar (Potassium Feldspar)

Potassium Feldspar (Microcline / Orthoclase, KAlSi3O8)

Hardness: 6 on the Mohs scale. Color: Typically pink to salmon-red, sometimes white or gray. Luster: Vitreous to pearly. Crystal structure: Triclinic (Microcline) or Monoclinic (Orthoclase). Cleavage: Perfect in two directions at nearly 90 degrees. Specific gravity: 2.56-2.58.

Hardness: 6 on the Mohs scale
Color: Typically pink to salmon-red, sometimes white or gray
Luster: Vitreous to pearly

Identified August 5, 2026More mineral →

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Physical properties

Formation & geological history

Forms primarily in igneous rocks like granite, pegmatites, and syenites, as well as in metamorphic rocks through crystallization from cooling magma or high-temperature hydrothermal processes.

Uses & applications

Used in the manufacturing of ceramics, porcelain, glass, and as a mild abrasive in scouring powders. Specimen collectors value unique crystal formations.

Geological facts

Feldspars are the most abundant group of minerals in the Earth's crust, making up about 60% of the crust. The distinctive pink color is often caused by microscopic hematite inclusions.

Field identification & locations

Easily identified by its pinkish-red color, rectangular cleavage, and lack of reaction to acid. Commonly found in granitic pegmatites worldwide.

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Potassium Feldspar (Orthoclase)

Orthoclase (KAlSi3O8)

mineral