metamorphic
Likely mica-rich schist (possibly phyllite)
Muscovite–biotite schist; exact identification requires examination of a fresh surface
AI-generated identification · may be incorrectSilvery-gray, strongly reflective and foliated, with visible platy mica grains. Mica has Mohs hardness about 2–3 and perfect basal cleavage; rock hardness varies with its other minerals.
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Physical properties
Silvery-gray, strongly reflective and foliated, with visible platy mica grains. Mica has Mohs hardness about 2–3 and perfect basal cleavage; rock hardness varies with its other minerals.
Formation & geological history
Formed when clay-rich sedimentary or igneous rock was subjected to heat and pressure, aligning and recrystallizing mica. Its age cannot be determined from the photograph.
Uses & applications
Mica-rich rocks are mainly collected as specimens or used decoratively; schist is sometimes used as building or landscaping stone.
Geological facts
The glitter comes from light reflecting off numerous flat mica flakes; foliation records metamorphic deformation.
Field identification & locations
Look for a layered texture and flakes that sparkle and may peel along planes; quartz or other minerals can make the rock substantially harder. Mica schists occur in metamorphic belts worldwide.
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