metamorphic
Rounded gray metamorphic pebble, likely gneiss or mica schist
Quartz–feldspar–mica metamorphic rock; exact identification requires a close examination or thin section
AI-generated identification · may be incorrectSpeckled gray-and-black surface with visible granular/flaky texture, low-to-glassy luster, and rounded water-worn shape. Likely hardness about 5–7 Mohs, with no obvious cleavage at pebble scale; composition probably quartz, feldspar, and biotite or muscovite mica.
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Physical properties
Speckled gray-and-black surface with visible granular/flaky texture, low-to-glassy luster, and rounded water-worn shape. Likely hardness about 5–7 Mohs, with no obvious cleavage at pebble scale; composition probably quartz, feldspar, and biotite or muscovite mica.
Formation & geological history
Formed when quartz- and feldspar-rich rock was subjected to heat and pressure, producing metamorphic recrystallization and possibly foliation; its precise geological age cannot be determined from the image. The rounded form indicates later transport by a stream, shoreline, or glacial sediment.
Uses & applications
Commonly used as landscaping stone, aggregate, riprap, and decorative pebble; attractive pieces may be polished or used in crafts. It has little gemstone value unless unusually patterned or well polished.
Geological facts
The dark flecks are probably biotite mica or amphibole, while the pale grains are likely quartz and feldspar. A strong planar banding would favor gneiss; a distinctly flaky, schistose surface would favor mica schist.
Field identification & locations
Look for alternating light/dark mineral bands or aligned mica flakes, a hard gritty surface, and resistance to scratching by a steel knife. Common in ancient continental shields and glacial deposits worldwide.
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