metamorphic
Muscovite Mica Schist
Muscovite Schist (KAl2(AlSi3O10)(OH)2)
Hardness: 2-3 on Mohs scale; Color: Silvery-gray, white, or pale green; Luster: Pearly to metallic; Crystal Structure: Monoclinic with perfect basal cleavage; Specific Gravity: 2.7-3.0.
- Hardness
- 2-3 on Mohs scale
- Color
- Silvery-gray, white, or pale green
- Luster
- Pearly to metallic
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Physical properties
Hardness: 2-3 on Mohs scale; Color: Silvery-gray, white, or pale green; Luster: Pearly to metallic; Crystal Structure: Monoclinic with perfect basal cleavage; Specific Gravity: 2.7-3.0.
Formation & geological history
Formed through the regional metamorphism of pelitic sedimentary rocks (shales/mudstones) under medium-grade pressure and temperature conditions. It typically dates to various mountain-building events throughout Earth's history.
Uses & applications
Used as an electrical and thermal insulator in electronic equipment, as a filler in paints and plastics, and in joint compounds. Coarser specimens are collected for geological displays.
Geological facts
The name 'Muscovite' comes from 'Muscovy-glass', as the mineral was once used as a cheaper alternative to glass for windows in Russia. It can be split into extremely thin, transparent sheets.
Field identification & locations
Identified by its distinctive foliated texture and shiny, flake-like appearance that reflects light. Commonly found in metamorphic terrains like the Appalachian Mountains or the Alps. Look for the 'glitter' effect and the ability to peel off small flakes with a fingernail.
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