mineral
Orthoclase Feldspar
KAlSi3O8 (Potassium Aluminum Silicate)
Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach-orange; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at 90 degrees; Specific Gravity: 2.55-2.63.
- Hardness
- 6 on Mohs scale
- Color
- Pink, salmon, or peach-orange
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach-orange; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at 90 degrees; Specific Gravity: 2.55-2.63.
Formation & geological history
Formed in igneous environments like granites and pegmatites, as well as in metamorphic rocks like gneiss. It crystallizes from cooling magma and can be found in terrains ranging from Precambrian to Cenozoic.
Uses & applications
Used in the manufacture of glass and ceramics (porcelain), as a filler in paints and plastics, and occasionally as a gemstone (moonstone variety).
Geological facts
Orthoclase is one of the ten index minerals on the Mohs scale of mineral hardness. It is one of the most common minerals in the Earth's continental crust.
Field identification & locations
Identify in the field by its distinctive pinkish color and right-angle cleavage planes. It is commonly found in granitic mountainous regions like the Rockies or the Appalachians.
More like this
Other mineral specimens
Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Schist
Schist
Metamorphic
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic