metamorphic
Weathered foliated metamorphic rock, likely schist or gneiss
Micaceous schist/gneiss; composition likely quartz, feldspar, mica, and altered mafic minerals
AI-generated identification · may be incorrectTypically gray-brown with sparkly mica, irregular foliation, and a rough granular texture; quartz and feldspar are Mohs 6–7, mica 2–3. The specimen appears strongly weathered and may contain a dark amphibole- or biotite-rich band.
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Physical properties
Typically gray-brown with sparkly mica, irregular foliation, and a rough granular texture; quartz and feldspar are Mohs 6–7, mica 2–3. The specimen appears strongly weathered and may contain a dark amphibole- or biotite-rich band.
Formation & geological history
Formed when preexisting sedimentary or igneous rock underwent elevated temperature and pressure, producing mineral alignment and banding. Precise age and locality cannot be determined from the photograph.
Uses & applications
Used locally as building stone, landscaping rock, aggregate, and decorative slabs; attractive foliated pieces are collected but usually have modest value.
Geological facts
The glitter is probably reflected light from mica cleavage surfaces rather than metallic mineralization. Weathering has accentuated the lighter quartz-feldspar matrix and darker mineral-rich zone.
Field identification & locations
Identify by testing for visible foliation, mica flakes, and alternating light/dark mineral bands; a streak test, hardness test, and fresh broken surface would distinguish schist from gneiss. Common in regional metamorphic belts worldwide.
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