mineral
Orthoclase Feldspar
KAlSi3O8 (Potassium Aluminum Silicate)
Hardness: 6 (Mohs scale); Color: Salmon-pink, flesh-colored, or white; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at right angles; Specific Gravity: 2.55-2.63
- Hardness
- 6 (Mohs scale)
- Color
- Salmon-pink, flesh-colored, or white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 (Mohs scale); Color: Salmon-pink, flesh-colored, or white; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Two planes at right angles; Specific Gravity: 2.55-2.63
Formation & geological history
Formed in igneous rocks like granite and syenite through the cooling of magma, as well as in metamorphic rocks. It is one of the most abundant minerals in the Earth's continental crust.
Uses & applications
Used in the manufacture of glass and ceramics, as a mild abrasive in scouring powders, and occasionally as a gemstone (such as moonstone).
Geological facts
Orthoclase is a defining mineral for level 6 on the Mohs scale of mineral hardness. Its name comes from the Greek for 'straight fracture,' referring to its two cleavage planes at 90 degrees.
Field identification & locations
Identify in the field by its distinct pinkish color, porcelain-like luster, and lack of striations (which distinguishes it from plagioclase feldspar). It is commonly found in granitic pegmatites and mountain ranges worldwide.
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sedimentary
Schist
Schist
Metamorphic
Sandstone with Mineral Veining or Crust
Sedimentary Sandstone (mostly SiO2 with Fe2O3 tinting)
sedimentary
Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral
Gypsum (variety Selenite or Alabaster)
Calcium sulfate dihydrate (CaSO4·2H2O)
Mineral
Nephrite Jade
Nephrite
Mineral/Rock