mineral
Feldspar
Aluminosilicate (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)
Hardness of 6 on the Mohs scale, typically white, pink, grey, or beige in color, with a vitreous to pearly luster. It exhibits two directions of cleavage intersecting at or near 90 degrees and has a monoclinic or triclinic crystal system.
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Physical properties
Hardness of 6 on the Mohs scale, typically white, pink, grey, or beige in color, with a vitreous to pearly luster. It exhibits two directions of cleavage intersecting at or near 90 degrees and has a monoclinic or triclinic crystal system.
Formation & geological history
Feldspar is the most abundant group of minerals in the Earth's crust, forming primarily in igneous rocks such as granite, pegmatite, and basalt through cooling from magma, as well as in metamorphic and sedimentary environments.
Uses & applications
Widely used in the manufacture of glass, ceramics, pottery, and enamel, as well as in the production of filler for paint, plastics, and rubber. Certain varieties like labradorite or moonstone are used as gemstones.
Geological facts
Feldspar makes up about 60% of the Earth's crust. The name comes from the German words 'feld' (field) and 'spath' (spar), historically used by miners for a rock found in fields.
Field identification & locations
Readily identified by its rectangular crystal habit, distinct 90-degree cleavage planes, and a hardness that can scratch glass. Common globally and very typical for granitic pegmatites in Southern California.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Soil with Mineral Detritus and Quartz Fragments
Regolith / Silicate Mineral Aggregate
sedimentary
Limonite / Goethite (Iron Ore Mineral nodule)
FeO(OH)·nH2O / FeO(OH)
mineral
Schist
Schist
Metamorphic
Septarian Pebble
Septarian nodule / Concretion
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral