metamorphic
Mica Schist
Muscovite/Biotite Schist
Hardness: 3.5-4 (Mohs); Color: Silvery-gray, greenish, or bronze-gold; Luster: Pearly to Vitreous/Metallic; Structure: Foliated (schistose texture); Cleavage: Perfect basal cleavage in individual grains; Specific Gravity: 2.7-2.9
- Hardness
- 3
- Color
- Silvery-gray, greenish, or bronze-gold
- Luster
- Pearly to Vitreous/Metallic
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Physical properties
Hardness: 3.5-4 (Mohs); Color: Silvery-gray, greenish, or bronze-gold; Luster: Pearly to Vitreous/Metallic; Structure: Foliated (schistose texture); Cleavage: Perfect basal cleavage in individual grains; Specific Gravity: 2.7-2.9
Formation & geological history
Formed through the regional metamorphism of pelitic rocks like shale or mudstone. Subjected to medium-to-high pressure and temperature, it typically forms during mountain-building events (orogenies). Most specimens range from hundreds of millions to billions of years old.
Uses & applications
Used primarily as decorative stone, in construction as flagstone, and occasionally in the production of sparklers or cosmetics (if rich in muscovite). It is a popular 'study specimen' for geology students due to its distinct foliation.
Geological facts
Schist is characterized by having more than 50 percent platy and elongated minerals. The word 'schist' is derived from the Greek word 'schízein', meaning 'to split', referring to the ease with which the rock can be layered or split.
Field identification & locations
Identify in the field by its intense 'glitter' or shimmer under sunlight and its tendency to flake into thin, brittle sheets when poked with a steel nail. Common in the Appalachian Mountains, Scotland, and the Alps. Look for visible mineral grains (muscovite, biotite, quartz).
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