metamorphic
Muscovite Schist
Mica Schist (primarily KAl2(AlSi3O10)(OH)2)
Hardness: 2.0-2.5 (mica) to 7 (quartz). Color: Silvery-gray, brownish, or golden with iron staining. Luster: Pearly to metallic. Structure: Foliated with distinct layering. Cleavage: Perfect basal cleavage in the mica flakes.
- Hardness
- 2
- Color
- Silvery-gray, brownish, or golden with iron staining
- Luster
- Pearly to metallic
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Physical properties
Hardness: 2.0-2.5 (mica) to 7 (quartz). Color: Silvery-gray, brownish, or golden with iron staining. Luster: Pearly to metallic. Structure: Foliated with distinct layering. Cleavage: Perfect basal cleavage in the mica flakes.
Formation & geological history
Formed through the regional metamorphism of pelitic sedimentary rocks (shales or mudstones) under medium grade pressure and temperature. The mica crystals grow perpendicular to the direction of pressure.
Uses & applications
Historically used as windows (Muscovy glass) and currently used as an insulator in electrical components, a filler in paints and plastics, and as a landscaping stone.
Geological facts
The name 'Muscovite' comes from Muscovy glass, a term used in Elizabethan England for the mineral because of its use in medieval Russia as a cheaper alternative to glass in windows.
Field identification & locations
Identify in the field by its 'shimmery' or glittery appearance due to the alignment of flat mica flakes that reflect light. It has a 'scaly' texture. Common in mountain ranges like the Appalachians or the Alps.
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