mineral
Feldspar (Orthoclase/Microcline)
Potassium Feldspar (KAlSi3O8)
Hardness: 6 (Mohs scale), Color: Pinkish-red to salmon, Luster: Vitreous to pearly, Crystal Structure: Monoclinic or Triclinic, Cleavage: Two planes at nearly 90 degrees, Specific Gravity: 2.55-2.63
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Physical properties
Hardness: 6 (Mohs scale), Color: Pinkish-red to salmon, Luster: Vitreous to pearly, Crystal Structure: Monoclinic or Triclinic, Cleavage: Two planes at nearly 90 degrees, Specific Gravity: 2.55-2.63
Formation & geological history
Formed in igneous rocks like granite and pegmatites, as well as metamorphic rocks. This small grain is likely weathered from a larger granitic source and deposited as beach sand.
Uses & applications
Used in the manufacture of glass and ceramics, as a filler in paint and rubber, and as an abrasive. Polished varieties (like moonstone) are used in jewelry.
Geological facts
Feldspar is the most abundant mineral group in the Earth's crust, making up about 60% of the terrestrial rocks. Pink feldspar is what gives many granites their characteristic reddish hue.
Field identification & locations
Identify in the field by its distinct pink/salmon color, blocky cleavage, and hardness (will scratch glass but can be scratched by quartz). Commonly found in riverbeds and on beaches near granitic mountains.
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Mineral
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Mineral/Rock
Granite
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