mineral
Feldspar (Plagioclase / Potassium Feldspar)
Feldspar Group (KAlSi3O8 - NaAlSi3O8 - CaAl2Si2O8)
AI-generated identification · may be incorrectHardness 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
Gneiss or Schist
Gneiss or Mica Schist with Garnet
Metamorphic
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Calcite–fluorite mineral specimen with iron-oxide staining
Calcite (CaCO₃), likely fluorite (CaF₂), with possible quartz and iron/manganese oxides
mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Pegmatite with Tourmaline and Quartz
Igneous Pegmatite
igneous
Granite
Granite (Phaneritic intrusive igneous rock)
igneous