metamorphic
Schist
Schist; commonly mica schist, composed chiefly of muscovite/biotite mica with quartz and feldspar
AI-generated identification · may be incorrectTypically medium- to coarse-grained, foliated, and strongly schistose, with visible mica glitter and layers that split along foliation. Hardness is approximately 2–3 for mica-rich surfaces and 6–7 for quartz; luster ranges from pearly to glassy, with variable gray, green, brown, or silvery color.
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Physical properties
Typically medium- to coarse-grained, foliated, and strongly schistose, with visible mica glitter and layers that split along foliation. Hardness is approximately 2–3 for mica-rich surfaces and 6–7 for quartz; luster ranges from pearly to glassy, with variable gray, green, brown, or silvery color.
Formation & geological history
Forms when shale or other clay-rich sedimentary rock undergoes regional metamorphism under directed pressure and elevated temperature, commonly during mountain building. Precise age cannot be determined from the image; schists range from Precambrian to modern tectonic belts.
Uses & applications
Used locally as building stone, wall stone, roofing or paving material, and decorative aggregate; attractive mica schist is collected but is generally not a high-value gemstone material.
Geological facts
Foliation results from aligned platy minerals, especially mica, producing its characteristic layered appearance. Common associated minerals include garnet, staurolite, kyanite, and chlorite.
Field identification & locations
Identify it by its pronounced planar layering, sparkly mica flakes, and tendency to break along foliation; distinguish it from slate by its coarser grains and from gneiss by less distinct light-dark banding. Common in metamorphic mountain belts worldwide.
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