metamorphic
Muscovite Schist
Mica Schist (KAl2(AlSi3O10)(OH)2)
Hardness: 2-2.5 (Mohs scale), Color: Silvery-white to gray, Luster: Pearly to vitreous, Crystal structure: Monoclinic, Cleavage: Perfect basal cleavage, Specific Gravity: 2.7–3.0
- Hardness
- 2-2
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Physical properties
Hardness: 2-2.5 (Mohs scale), Color: Silvery-white to gray, Luster: Pearly to vitreous, Crystal structure: Monoclinic, Cleavage: Perfect basal cleavage, Specific Gravity: 2.7–3.0
Formation & geological history
Formed through the regional metamorphism of pelitic rocks (shales and mudstones) under medium grade pressure and temperature. This specimen displays high-grade mica alignment known as schistosity.
Uses & applications
Historically used as glass (muscovy-glass) due to heat resistance, now used in electrical insulation, cosmetics for shimmer, construction materials, and as fillers in paint and rubber.
Geological facts
Muscovite is the most common mica. In Russia, large sheets of it were used for windows in the 16th century instead of glass, which is where the name 'Muscovy-glass' originated.
Field identification & locations
Identify by its sparkly, flaky appearance and the ability to peel off thin, transparent sheets with a fingernail or needle. Found in mountain ranges such as the Appalachians, Alps, and Himalayas.
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