metamorphic
Mica Schist
Mica Schist (predominantly Muscovite KAl2(AlSi3O10)(OH)2 and Quartz SiO2)
Hardness: 3.5-5 (Mohs scale); Color: Silvery-gray, white, or light green; Luster: Pearly to sub-vitreous; Structure: Foliated with large visible mica flakes; Cleavage: Perfect basal cleavage in mica components; Specific Gravity: 2.8-2.9
- Hardness
- 3
- Color
- Silvery-gray, white, or light green
- Luster
- Pearly to sub-vitreous
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Physical properties
Hardness: 3.5-5 (Mohs scale); Color: Silvery-gray, white, or light green; Luster: Pearly to sub-vitreous; Structure: Foliated with large visible mica flakes; Cleavage: Perfect basal cleavage in mica components; Specific Gravity: 2.8-2.9
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under intermediate to high grades of pressure and temperature. It typically dates to various orogenic (mountain-building) events throughout Earth's history.
Uses & applications
Used historically as a building stone for walls and decorative facades; occasionally used in the production of grounding materials or as a source of scrap mica for industrial insulation.
Geological facts
The word 'schist' is derived from the Greek word 'schizein', meaning 'to split', referring to the rock's ability to be easily split along its foliated mineral planes.
Field identification & locations
Identify in the field by its 'glittery' or 'shiny' appearance due to the alignment of mica plates. It is commonly found in metamorphic crystalline basement rocks and mountain ranges like the Appalachians or the Alps.
