metamorphic
River Pebble (Gneiss or Granite)
Metamorphic Rock (likely Gneiss or Granitic composition)
Hardness: 6-7 (Mohs), Color: Mottled grey, white, and tan, Luster: Dull to slightly waxy, Crystal Structure: Granular/Crystalline, Specific Gravity: approx 2.6-2.7
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Physical properties
Hardness: 6-7 (Mohs), Color: Mottled grey, white, and tan, Luster: Dull to slightly waxy, Crystal Structure: Granular/Crystalline, Specific Gravity: approx 2.6-2.7
Formation & geological history
Formed through high-grade regional metamorphism of igneous or sedimentary protoliths. Frequently found in riverbeds where water has rounded and polished the specimen over thousands of years.
Uses & applications
Landscape decoration, aquarium substrate, construction aggregate, and educational specimens.
Geological facts
This specimen is a 'water-worn' pebble, meaning its rounded shape is the result of thousands of miles of transport in a high-energy river system.
Field identification & locations
Identify by its rounded, smooth surface and salt-and-pepper mineral arrangement. Commonly found in river basins, glacial deposits, and coastal beaches.
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