metamorphic
Mica Schist
Metamorphic rock dominated by muscovite and/or biotite mica
Hardness ranges from 2 to 4 on the Mohs scale depending on mineral content; colors include silvery-gray, brown, greenish, or black; exhibits a strongly sparkling or pearly luster due to abundant platy mica flakes; well-developed foliation known as schistosity; specific gravity typically between 2.7 and 3.0.
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Physical properties
Hardness ranges from 2 to 4 on the Mohs scale depending on mineral content; colors include silvery-gray, brown, greenish, or black; exhibits a strongly sparkling or pearly luster due to abundant platy mica flakes; well-developed foliation known as schistosity; specific gravity typically between 2.7 and 3.0.
Formation & geological history
Formed through regional metamorphism of argillaceous rocks such as shales and mudstones under elevated temperatures and pressures, typically during mountain-building events (orogenies) over geological timescales ranging from hundreds of millions to billions of years.
Uses & applications
Primarily used as a decorative stone, aggregate in construction, landscaping, and occasionally as a source of mica for industrial applications or as mineral specimens for collectors.
Geological facts
Mica schist is renowned for its characteristic 'schistosity,' a planar arrangement of mineral grains that makes the rock split easily into thin, irregular flakes. It often contains accessory minerals like garnet, staurolite, and kyanite, which are prized by rockhounds.
Field identification & locations
Easily identified in the field by its distinct foliation and the prominent, glittering reflection of light off abundant mica flakes on its surfaces. Commonly found in ancient mountain belts, shield areas, and metamorphic terrains worldwide.
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