mineral
Feldspar (specifically Orthoclase)
Potassium Aluminum Silicate (KAlSi3O8)
Hardness: 6 on Mohs scale; Color: Flesh-pink to salmon; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two directions at 90 degrees; Specific Gravity: 2.55-2.63
- Hardness
- 6 on Mohs scale
- Color
- Flesh-pink to salmon
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 on Mohs scale; Color: Flesh-pink to salmon; 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 intrusive and extrusive igneous rocks like granite and rhyolite, as well as some metamorphic rocks. It crystallizes from cooling magma at high temperatures.
Uses & applications
Used in the manufacture of glass and ceramics, as a filler in paints and plastics, and as an abrasive in scouring powders. Gem-quality varieties (like Moonstone) are used in jewelry.
Geological facts
Feldspar is the most abundant mineral group in the Earth's crust, making up about 60% of its composition. The pink color in common granite is usually due to Orthoclase feldspar.
Field identification & locations
Identify by its distinct pinkish color and right-angle cleavage planes. It cannot be scratched by a steel nail but can be scratched by quartz. Common globally in granitic terrains.
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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