mineral
Feldspar (specifically Orthoclase)
Potassium Aluminum Silicate (KAlSi3O8)
Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at nearly 90 degrees; Specific gravity: 2.55-2.63
- Hardness
- 6 on Mohs scale
- Color
- Pink, salmon, or peach
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 on Mohs scale; Color: Pink, salmon, or peach; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at nearly 90 degrees; Specific gravity: 2.55-2.63
Formation & geological history
Formed in intrusive and extrusive igneous rocks through the cooling of magma, as well as in metamorphic rocks and some sandstones. It is a primary constituent of granite.
Uses & applications
Used in the manufacture of glass and ceramics (porcelain), as a mild abrasive in scouring powders, and occasionally as a gemstone (such as moonstone).
Geological facts
Feldspar is the most abundant group of minerals in the Earth's crust, making up about 60% of terrestrial rocks. The pink color in many granites is due to the presence of Orthoclase.
Field identification & locations
Identify in the field by its distinct pink color, pearly luster on cleavage faces, and its ability to scratch glass but be scratched by hardened steel. It is commonly found in mountain ranges and gravel.
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Sandstone (with potential mineral staining/concretions)
Arenite (SiO2 based)
sedimentary
Schist
Schist
Metamorphic
Epidote
Epidote | Ca2(Al2,Fe3+)(SiO4)(Si2O7)O(OH)
metamorphic
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock
Banded Gneiss (River Rock/Pebble)
Gneiss (specifically a banded variety often found as a river rock)
Metamorphic Rock