metamorphic
Weathered mica schist
Mica schist, commonly muscovite–biotite schist with quartz and feldspar
AI-generated identification · may be incorrectTypically medium- to coarse-grained, foliated, and sparkly, with platy mica giving a gray-brown, bronze, or silvery appearance; hardness is about 2–3 for mica and 6–7 for quartz, with strong schistosity and variable cleavage.
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Physical properties
Typically medium- to coarse-grained, foliated, and sparkly, with platy mica giving a gray-brown, bronze, or silvery appearance; hardness is about 2–3 for mica and 6–7 for quartz, with strong schistosity and variable cleavage.
Formation & geological history
Formed when shale or other clay-rich sediment was subjected to regional metamorphism, causing mica and other minerals to recrystallize and align; ages vary widely, commonly Precambrian to Paleozoic.
Uses & applications
Used locally as decorative facing stone, landscaping material, and aggregate, though its foliation limits structural applications; attractive pieces are collected but generally have modest value.
Geological facts
The visible glitter comes from reflecting mica flakes, while rusty coloration commonly indicates oxidation of iron-bearing biotite or sulfide minerals.
Field identification & locations
Identify it by its pronounced layered fabric, easy splitting along mica-rich planes, and glittery flakes; common in regional metamorphic belts worldwide, including the Appalachians, Alps, and Himalayas.
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