metamorphic
Mica-rich metamorphic rock, likely schist
Muscovite–biotite schist; principally muscovite mica, biotite, quartz, and feldspar
AI-generated identification · may be incorrectVery shiny, platy layers with silver-white and brown-black reflective surfaces; mica has perfect basal cleavage and Mohs hardness about 2–3, while quartz is about 7. The foliated texture and sheet-like splitting are characteristic.
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Physical properties
Very shiny, platy layers with silver-white and brown-black reflective surfaces; mica has perfect basal cleavage and Mohs hardness about 2–3, while quartz is about 7. The foliated texture and sheet-like splitting are characteristic.
Formation & geological history
Formed when mica- and clay-rich sedimentary rock was subjected to elevated temperature and pressure during regional metamorphism, commonly during mountain building; age depends on locality and may range from Precambrian to Paleozoic.
Uses & applications
Used mainly as a decorative or educational specimen; crushed schist can serve as fill or aggregate, but its mica-rich structure limits high-strength construction use.
Geological facts
The metallic-looking sheen comes from aligned mica flakes rather than metal ore. Brown plates are typically biotite, while silvery plates are usually muscovite.
Field identification & locations
Identify it by strong foliation, glittering mica, and easy splitting into thin flakes; a glassy quartz streak may occur. Common worldwide in metamorphic belts, including the Appalachians, Alps, and Canadian Shield.
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