mineral
K-Feldspar (Potassium Feldspar)
Potassium Feldspar (Microcline or Orthoclase), KAlSi3O8
Hardness of 6 on the Mohs scale; color typically pink, white, or salmon; vitreous to pearly luster; monoclinic or triclinic crystal structure; exhibits two directions of cleavage at or near 90 degrees; specific gravity ranges from 2.5 to 2.6.
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Physical properties
Hardness of 6 on the Mohs scale; color typically pink, white, or salmon; vitreous to pearly luster; monoclinic or triclinic crystal structure; exhibits two directions of cleavage at or near 90 degrees; specific gravity ranges from 2.5 to 2.6.
Formation & geological history
Forms primarily in igneous rocks such as granite and syenite through the slow cooling of magma, as well as in pegmatites and metamorphic rocks like gneisses.
Uses & applications
Widely used in the manufacture of ceramics, porcelain, and glass, as well as a flux in various industrial applications and occasionally as a minor gemstone or lapidary material.
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 in many granites and K-feldspar specimens is caused by microscopic hematite inclusions.
Field identification & locations
Identified easily by its light pink to salmon color, blocky crystal form, and two cleavage planes intersecting at nearly 90 degrees. Found worldwide in granitic terrains.
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Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral