sedimentary
River Pebble
Lithified rock fragment (variable composition)
Hardness varies by mineral content (typically Mohs 6-7 for quartz-rich rocks); Color ranges from grey to brown; Luster is dull to sub-vitreous; Smooth, rounded crystal structure due to water abrasion; Specific gravity around 2.65.
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Physical properties
Hardness varies by mineral content (typically Mohs 6-7 for quartz-rich rocks); Color ranges from grey to brown; Luster is dull to sub-vitreous; Smooth, rounded crystal structure due to water abrasion; Specific gravity around 2.65.
Formation & geological history
Formed through the mechanical weathering, erosion, and long-term water transport of parent rocks in rivers, streams, and glacial outwash plains.
Uses & applications
Used in landscaping, decorative garden paths, concrete aggregate, and aquarium substrates.
Geological facts
The smoothing process of river pebbles is called rounding, which occurs as rocks collide with each other and the riverbed over hundreds of miles of transport.
Field identification & locations
Commonly found along riverbanks, lake shores, and dry stream beds worldwide. Excellent indicator of past water flow and high-energy depositional environments.
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