mineral
Feldspar (Orthoclase)
Potassium Feldspar (KAlSi3O8)
Hardness: 6 (Mohs scale), Color: Salmon pink to orange-tan, Luster: Vitreous to pearly, Crystal Structure: Monoclinic, Cleavage: Two directions at 90 degrees, Specific Gravity: 2.55-2.63
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Physical properties
Hardness: 6 (Mohs scale), Color: Salmon pink to orange-tan, Luster: Vitreous to pearly, Crystal Structure: Monoclinic, Cleavage: Two directions at 90 degrees, Specific Gravity: 2.55-2.63
Formation & geological history
Forms primarily in igneous rocks like granite and pegmatites through the cooling of magma, as well as in metamorphic rocks like gneiss. Found globally in continental crust.
Uses & applications
Used in glassmaking and ceramics to lower melting temperatures, as an abrasive in scouring powders, and occasionally as a gemstone (monstone/sunstone varieties).
Geological facts
Feldspars are the most abundant group of minerals in the Earth's crust, making up about 60% of terrestrial rocks. The name is derived from the German 'Feldspat'.
Field identification & locations
Identify by its blocky pink appearance and distinct cleavage planes that reflect light. It is common in gravel and weathered granite outcrops.
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Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock
![Biotite Schist (Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]) — metamorphic](https://media.rock.id/9ca564b5-bc87-402b-965a-69b21f9aa6bf-thumbnail.jpg)
Biotite Schist
Biotite-rich Schist [K(Mg,Fe)3AlSi3O10(F,OH)2]
metamorphic