mineral
Feldspar (Plagioclase / Potassium Feldspar)
Feldspar Group (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)
Hardness 6 on Mohs scale, vitreous to pearly luster, white to off-white/cream with yellowish-brown staining, blocky crystal habit with distinct 90-degree cleavage planes.
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Physical properties
Hardness 6 on Mohs scale, vitreous to pearly luster, white to off-white/cream with yellowish-brown staining, blocky crystal habit with distinct 90-degree cleavage planes.
Formation & geological history
Forms in igneous rocks like granite and pegmatites through cooling magma, as well as high-grade metamorphic rocks.
Uses & applications
Used widely in manufacturing glass and ceramics, as an abrasive, and occasionally as a gemstone or ornamental stone.
Geological facts
Feldspar is the most abundant group of minerals in the Earth's crust, making up about 60% of terrestrial rocks.
Field identification & locations
Look for right-angle stair-step cleavage surfaces with a pearly or vitreous sheen; common worldwide in igneous and metamorphic terrains.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock