metamorphic
River Pebble (Gneiss or Quartzite variant)
Metamorphic rock specimen (likely Quartzite or Gneiss)
Hardness: 6-7 (Mohs scale), Color: Grey, tan, and cream bands, Luster: Dull to waxy, Structure: Granular to foliated, Cleavage: None, Specific Gravity: 2.6-2.7
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Physical properties
Hardness: 6-7 (Mohs scale), Color: Grey, tan, and cream bands, Luster: Dull to waxy, Structure: Granular to foliated, Cleavage: None, Specific Gravity: 2.6-2.7
Formation & geological history
Formed through the regional metamorphism of sedimentary sandstone (quartzite) or igneous rocks (gneiss). This specific specimen has been water-worn and smoothed by alluvial processes over thousands of years.
Uses & applications
Commonly used in landscaping, decorative ground cover, aquarium substrates, and occasionally as a tumbling medium or for craft painting.
Geological facts
The smooth, pill-shaped contour is the result of mechanical weathering in a high-energy water environment like a riverbed or shoreline, where constant tumbling rounds off sharp edges.
Field identification & locations
Identify by its hardness (cannot be scratched by a steel nail) and the distinct layering or banding visible on its surface. Common in river basins and glacial till deposits.
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