metamorphic
Weathered schist or phyllite
Mica schist/phyllite; quartz–mica-rich foliated metamorphic rock
AI-generated identification · may be incorrectGray-brown, fine- to medium-grained, with visible foliation and shiny mica surfaces; likely Mohs hardness 2–3 for mica-rich layers and 6–7 for quartz grains. Displays a planar, layered texture and uneven fracture rather than strong cleavage in individual crystals.
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Physical properties
Gray-brown, fine- to medium-grained, with visible foliation and shiny mica surfaces; likely Mohs hardness 2–3 for mica-rich layers and 6–7 for quartz grains. Displays a planar, layered texture and uneven fracture rather than strong cleavage in individual crystals.
Formation & geological history
Formed when shale or mudstone underwent low- to medium-grade regional metamorphism, typically during mountain building; age cannot be determined from the image and depends on the local bedrock.
Uses & applications
Used locally as crushed stone, fill, flagstone, or landscaping material; attractive mica-rich pieces may be collected, but it is generally not a jewelry stone.
Geological facts
The specimen appears strongly foliated and weathered, with possible quartz veins or lenses. Distinguishing phyllite from schist requires examining grain size and sheen under magnification.
Field identification & locations
Common in metamorphic belts worldwide, including the Appalachians, New England, Scotland, and the Alps. Identify it by splitting along foliation, silky-to-glittery mica sheen, and resistance of quartz-rich grains to scratching; confirm with a hand lens.
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