metamorphic
Weathered quartz-rich metamorphic rock, likely gneiss or schist
Quartz–feldspar–mica gneiss/schist (tentative; image resolution limits certainty)
AI-generated identification · may be incorrectGray-brown, coarse-grained, irregularly banded specimen with glassy gray quartz and darker mica-rich patches; quartz hardness ~7, feldspar ~6, mica ~2–3, generally nonmetallic with uneven cleavage and variable foliation.
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Physical properties
Gray-brown, coarse-grained, irregularly banded specimen with glassy gray quartz and darker mica-rich patches; quartz hardness ~7, feldspar ~6, mica ~2–3, generally nonmetallic with uneven cleavage and variable foliation.
Formation & geological history
Formed when quartz- and feldspar-bearing sedimentary or igneous rock underwent regional metamorphism at elevated temperature and pressure, commonly during mountain building; age depends on locality and may range from Precambrian to younger.
Uses & applications
Used locally as crushed stone, aggregate, building stone, or decorative material; attractive polished pieces may be collected, but this specimen appears ordinary.
Geological facts
Gneiss typically shows compositional banding, whereas schist has more obvious platy mica alignment; weathering can obscure either texture.
Field identification & locations
Look for alternating light quartz/feldspar bands and dark mica-rich layers, visible foliation, and a granular texture; common in ancient continental shields and metamorphic mountain belts worldwide.
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