metamorphic
Likely micaceous metamorphic rock fragment
Probable phyllite or mica schist; quartz–muscovite-rich assemblage
AI-generated identification · may be incorrectGray-brown, fine-grained and sparkly with visible platy mica; likely Mohs hardness 2–3 across mica-rich surfaces, with quartz grains near 7. Displays silky to pearly luster and strong foliation/cleavage, but the small fragment limits certainty.
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Physical properties
Gray-brown, fine-grained and sparkly with visible platy mica; likely Mohs hardness 2–3 across mica-rich surfaces, with quartz grains near 7. Displays silky to pearly luster and strong foliation/cleavage, but the small fragment limits certainty.
Formation & geological history
Formed when shale or mudstone underwent low- to medium-grade regional metamorphism, generally during Paleozoic or Precambrian mountain-building; exact age and locality cannot be determined from the image.
Uses & applications
Commonly used locally for decorative stone, landscaping, roofing, and aggregate; attractive schist specimens may be collected but are usually low-value.
Geological facts
The glitter comes from aligned mica flakes reflecting sunlight. A strong foliation and tendency to split into thin plates distinguish it from ordinary sandstone or concrete.
Field identification & locations
Look for layered or wrinkled foliation, mica sparkle, and thin flaking; a streak test, hand lens, and hardness test would help separate phyllite from schist. Similar material occurs in metamorphic belts worldwide.
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