mineral

Potassium feldspar

Orthoclase or microcline; KAlSi₃O₈

AI-generated identification · may be incorrect

Typically salmon-pink to reddish-brown, with a vitreous to pearly luster and prominent cleavage in two directions near 90°. Mohs hardness 6, monoclinic (orthoclase) or triclinic (microcline), and specific gravity about 2.55–2.63; the image appears to show a massive, weathered feldspar specimen.

Identified September 21, 2026More mineral →

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Physical properties

Formation & geological history

Forms by crystallization from silica-rich igneous melts, especially granite and syenite, and occurs in metamorphic rocks and pegmatites. Potassium feldspar is abundant in Precambrian and younger continental crust.

Uses & applications

Used in ceramics, porcelain, glass, glazes, abrasives, and mineralogical specimens; attractive varieties may be cut as gemstones, including orthoclase and amazonite (green microcline).

Geological facts

Feldspar is the most abundant mineral group in Earth’s crust. Pink coloration commonly results from iron impurities, while perthitic intergrowths and cleavage are characteristic of potassium feldspar.

Field identification & locations

Identify it by pink or cream color, blocky cleavage, hardness near 6, and inability to scratch glass easily or be scratched by a steel knife. Common localities include granitic terrains and pegmatites worldwide, notably Madagascar, Russia, Brazil, India, and the United States.