mineral
Feldspar (Potassium Feldspar / Orthoclase)
KAlSi3O8 (Potassium Aluminum Silicate)
Mohs hardness of 6, salmon-pink to reddish-orange color, vitreous to pearly luster, monoclinic or triclinic crystal structure, perfect cleavage in two directions at near 90 degrees, specific gravity 2.56-2.58.
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Physical properties
Mohs hardness of 6, salmon-pink to reddish-orange color, vitreous to pearly luster, monoclinic or triclinic crystal structure, perfect cleavage in two directions at near 90 degrees, specific gravity 2.56-2.58.
Formation & geological history
Forms primarily in felsic igneous rocks such as granite and pegmatites through cooling magma, as well as in high-grade metamorphic rocks and detrital sedimentary rocks.
Uses & applications
Widely used in the manufacture of glass, ceramics, pottery glazes, porcelain, and mild abrasives. High-grade gem varieties (like moonstone or sunstone) are used in jewelry.
Geological facts
Feldspars are the most abundant group of minerals in the Earth's continental crust, making up about 60% of terrestrial rocks.
Field identification & locations
Identified by its distinctive salmon-pink color, blocky cleavage faces that reflect light, and hardness of 6 (scratches glass). Common worldwide in granitic terrains including Brazil, India, Madagascar, and North America.
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Arenite (SiO2 based)
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Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
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Schist
Schist
Metamorphic
Septarian Pebble
Septarian nodule / Concretion
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Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary