metamorphic
Mica Schist
Mica Schist
Hardness: 3.5-4 on Mohs scale; Color: Silvery-gray, black, or earthy brown; Luster: Pearly to sub-metallic; Crystal Structure: Foliated; Cleavage: Perfect basal cleavage in individual mica grains; Specific Gravity: 2.7-2.8
- Hardness
- 3
- Color
- Silvery-gray, black, or earthy brown
- Luster
- Pearly to sub-metallic
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Physical properties
Hardness: 3.5-4 on Mohs scale; Color: Silvery-gray, black, or earthy brown; Luster: Pearly to sub-metallic; Crystal Structure: Foliated; Cleavage: Perfect basal cleavage in individual mica grains; Specific Gravity: 2.7-2.8
Formation & geological history
Formed through high-grade regional metamorphism of clay-rich sedimentary rocks (shales or mudstones) under moderate to high temperature and pressure. It often dates back to Paleozoic or Precambrian orogenic events.
Uses & applications
Used primarily in construction for crushed stone, decorative garden stones, and occasionally as a source of flakes for specialized industrial insulation or fillers in paints and plastics.
Geological facts
The word 'schist' is derived from the Greek 'schistos' meaning 'split', referring to the ease with which the rock can be split into thin plates along its foliation planes. It is the intermediate stage between phyllite and gneiss.
Field identification & locations
Identify in the field by its distinct 'schistosity'—a sparkly, foliated texture caused by the parallel alignment of large mica flakes. Commonly found in mountain belts such as the Appalachians or the Alps.
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