mineral
K-Feldspar (Microcline / Orthoclase)
Potassium Feldspar (KAlSi3O8)
Hardness: 6 on Mohs scale. Color: Typically pink, salmon-pink, reddish, or white. Luster: Vitreous to pearly. Crystal structure: Triclinic (Microcline) or Monoclinic (Orthoclase). Cleavage: Two directions at or near 90 degrees (good cleavage). Specific Gravity: 2.5 - 2.6.
- Hardness
- 6 on Mohs scale
- Color
- Typically pink, salmon-pink, reddish, or white
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 on Mohs scale. Color: Typically pink, salmon-pink, reddish, or white. Luster: Vitreous to pearly. Crystal structure: Triclinic (Microcline) or Monoclinic (Orthoclase). Cleavage: Two directions at or near 90 degrees (good cleavage). Specific Gravity: 2.5 - 2.6.
Formation & geological history
Formed predominantly in igneous environments such as granites, pegmatites, and syenites, as well as in metamorphic gneisses. Crystallizes directly from cooling magma or through hydrothermal processes.
Uses & applications
Widely used in the manufacturing of ceramics, porcelain, and glass, as well as a flux in pottery glazes. Occasionally cut into cabochons for jewelry (as amazonite or 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 distinct salmon-pink color is commonly caused by microscopic hematite (iron oxide) inclusions within the crystal lattice.
Field identification & locations
Easily identified by its characteristic salmon-pink color, blocky crystal habit, and distinct near-90-degree cleavage planes showing pearly luster on cleavage faces. Found globally in granitic pegmatites.
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Potassium Feldspar (Orthoclase)
Orthoclase (KAlSi3O8)
mineral