metamorphic
Micaceous schist
Mica schist, chiefly muscovite/biotite with quartz and feldspar
AI-generated identification · may be incorrectTypically gray to silvery, sparkly, foliated, and composed of platy mica flakes; Mohs hardness about 2–7 depending on minerals, with mica cleavage and a satiny to vitreous luster. The specimen appears fine-grained and strongly micaceous, though exact identification from the image is uncertain.
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Physical properties
Typically gray to silvery, sparkly, foliated, and composed of platy mica flakes; Mohs hardness about 2–7 depending on minerals, with mica cleavage and a satiny to vitreous luster. The specimen appears fine-grained and strongly micaceous, though exact identification from the image is uncertain.
Formation & geological history
Forms when shale or other mica-rich sediment is subjected to regional metamorphism, commonly during mountain building; ages range from Precambrian to younger depending on locality.
Uses & applications
Used locally as decorative stone, landscaping material, and aggregate, but strongly foliated pieces have limited construction value. Attractive specimens are collected for their glittering foliation.
Geological facts
Its visible sparkle comes from aligned mica sheets reflecting light; foliation records directed pressure and tectonic deformation.
Field identification & locations
Look for thin, peelable or reflective mica flakes, planar layering, and a tendency to split along foliation; distinguish it from phyllite by its larger visible crystals. Common in metamorphic mountain belts worldwide, including the Appalachians, Alps, and Himalaya.
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