igneous/metamorphic
Muscovite on Quartz (Mica host rock)
KAl2(AlSi3O10)(OH)2 (Muscovite) in SiO2 (Quartz)
Hardness: 2.5-3 (Mica) / 7 (Quartz); Color: Silvery-white to pale tan with pearly luster on flakes; Crystal structure: Monoclinic (Mica) and Hexagonal (Quartz); Basal cleavage (Mica peels into sheets).
- Hardness
- 2
- Color
- Silvery-white to pale tan with pearly luster on flakes
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Physical properties
Hardness: 2.5-3 (Mica) / 7 (Quartz); Color: Silvery-white to pale tan with pearly luster on flakes; Crystal structure: Monoclinic (Mica) and Hexagonal (Quartz); Basal cleavage (Mica peels into sheets).
Formation & geological history
Formed in felsic igneous rocks like granites or pegmatites and metamorphic rocks like schists during high-pressure crystallization of silica-rich melts or fluids.
Uses & applications
Used as an electrical insulator, in cosmetics (pearlescent effect), joint compound filler, and as decorative stone specimens.
Geological facts
Muscovite was once used for window panes in Russia (Muscovy), giving it the name 'Muscovy glass.' It is highly heat-resistant and does not conduct electricity.
Field identification & locations
Identify in the field by looking for silvery, 'glittery' flakes that can be flaked off with a fingernail embedded in a hard, white or glassy matrix. Found in pegmatite-rich regions like the Appalachians, Brazil, and India.
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