mineral
Orthoclase Feldspar
Orthoclase (KAlSi3O8)
AI-generated identification · may be incorrectHardness: 6 on Mohs scale; Color: typically flesh-pink to reddish-brown (as seen here); Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Two planes at right angles (90 degrees); Specific gravity: 2.55–2.63.
- Hardness
- 6 on Mohs scale
- Color
- typically flesh-pink to reddish-brown (as seen here)
- Luster
- Vitreous to pearly
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Physical properties
Hardness: 6 on Mohs scale; Color: typically flesh-pink to reddish-brown (as seen here); Luster: Vitreous to pearly; Crystal Structure: Monoclinic; Cleavage: Two planes at right angles (90 degrees); Specific gravity: 2.55–2.63.
Formation & geological history
Formed primarily in plutonic igneous rocks like granite and syenite, as well as in metamorphic rocks like gneiss. This specimen appears to be a weathered crystal fragment from a pegmatite or granitic source.
Uses & applications
Used extensively in the manufacture of glass and ceramics (porcelain), as a filler in paints and plastics, and occasionally as a gemstone (Moonstone) when featuring adularescence.
Geological facts
Orthoclase is one of the most abundant minerals in the Earth's crust. Its name comes from the Greek 'orthos' meaning straight and 'klasis' meaning fracture, referring to Its two cleavages at right angles.
Field identification & locations
Identify in the field by its distinct pinkish-tan color and blocky cleavage planes. It cannot be scratched by a steel knife (H<5.5) but can scratch glass. Common in mountainous regions with granitic outcrops.
