metamorphic
Rounded gray river pebble, likely quartz-rich metamorphic rock
Probable quartzite or quartz-rich schist; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectHardness approximately 6.5–7 Mohs, gray to silvery, fine-grained with a dull to weakly silky luster and possible mica flecks. It is water-worn and lacks visible cleavage or distinct crystal faces; quartz is likely dominant, with mica and feldspar possible.
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Physical properties
Hardness approximately 6.5–7 Mohs, gray to silvery, fine-grained with a dull to weakly silky luster and possible mica flecks. It is water-worn and lacks visible cleavage or distinct crystal faces; quartz is likely dominant, with mica and feldspar possible.
Formation & geological history
Likely formed when quartz-rich sandstone or sediment was metamorphosed under heat and pressure, then eroded and rounded in a stream or glacial deposit. The rock’s geological age cannot be determined visually.
Uses & applications
Commonly used as landscaping gravel, decorative stone, aggregate, and occasionally lapidary material; this small pebble has minimal commercial value.
Geological facts
The silvery sheen may indicate muscovite or chlorite mica, while the pale gray mass suggests abundant quartz. A streak, hardness, acid, and magnified-grain tests would improve identification.
Field identification & locations
Common in riverbeds, beaches, glacial tills, and gravel deposits worldwide. Scratch testing with a steel knife and glass can distinguish quartzite: it should scratch glass and resist a knife; estimated value is $1–$5 as a specimen, or negligible in bulk.
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