metamorphic
Mica Schist
Mica Schist (primarily Muscovite or Biotite within a foliated matrix)
Hardness: 2-2.5 (for mica crystals) to 6-7 (if quartz rich); Color: Silvery-gray, metallic, light brown; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal; Specific Gravity: 2.8-3.0.
- Hardness
- 2-2
- Color
- Silvery-gray, metallic, light brown
- Luster
- Pearly to metallic
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Physical properties
Hardness: 2-2.5 (for mica crystals) to 6-7 (if quartz rich); Color: Silvery-gray, metallic, light brown; Luster: Pearly to metallic; Crystal Structure: Monoclinic; Cleavage: Perfect basal; Specific Gravity: 2.8-3.0.
Formation & geological history
Formed from the regional metamorphism of shale or mudstone under intermediate to high temperatures and pressures. Most mica schists are from the Proterozoic or Paleozoic eras.
Uses & applications
Used as decorative stone, in roofing materials, and occasionally as a source of scrap mica for electronics and insulation. Specimens are widely collected by beginners.
Geological facts
The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to the stone's tendency to peel into thin layers.
Field identification & locations
Identify by its 'schistosity' or layered, sparkly appearance. It splits easily along planes. Often found in mountainous regions or metamorphic terrains like the Appalachian or Alpine belts.
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