metamorphic
Mica Schist
Mica Schist (primarily composed of Muscovite, Biotite, and Quartz)
Hardness: 3.5-4; Color: Silver, grey, gold, or brown sparkles; Luster: Pearly to metallic (glittery); Crystal Structure: Monoclinic (in flakes); Cleavage: Perfect basal (peels in sheets); Specific Gravity: 2.8
- Hardness
- 3
- Color
- Silver, grey, gold, or brown sparkles
- Luster
- Pearly to metallic (glittery)
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Physical properties
Hardness: 3.5-4; Color: Silver, grey, gold, or brown sparkles; Luster: Pearly to metallic (glittery); Crystal Structure: Monoclinic (in flakes); Cleavage: Perfect basal (peels in sheets); Specific Gravity: 2.8
Formation & geological history
Formed through the regional metamorphism of shale or mudstone under high pressure and temperature. The mica crystals grow perpendicular to the direction of pressure, creating the characteristic schistosity (layering).
Uses & applications
Used as garden ornamental stone, for filling material in construction, and as a source for ground mica in manufacturing electronics, paints, and cosmetics for its shimmer.
Geological facts
The word 'schist' is derived from the Greek word 'schízein', meaning 'to split', referring to how easily the rock can be peeled or broken along its flat layers of mica.
Field identification & locations
Identify in the field by its distinct 'glittering' or 'sparkly' appearance that appears to change as you tilt it in the sun. Commonly found in mountain ranges such as the Appalachians or the Alps. Look for visible flakes that can be scratched or peeled with a fingernail.
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