sedimentary

General Gravel (River Rock/River Stones)

Mixed Lithic Sediments (Conglomerate Clasts)

AI-generated identification · may be incorrect

Hardness: Varied (usually 5.5-7 Mohs); Color: Tones of brown, tan, grey, and ochre; Luster: Dull to earthy; Crystal Structure: Mostly microcrystalline; Cleavage: None/Irregular; Specific Gravity: Approx 2.6-2.7.

Hardness: Varied (usually 5
Color: Tones of brown, tan, grey, and ochre
Luster: Dull to earthy

Identified April 12, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the mechanical weathering and erosion of pre-existing rocks (igneous, metamorphic, and sedimentary). These pieces have been smoothed and rounded by the action of moving water in rivers or streams over hundreds to thousands of years.

Uses & applications

Used primarily in landscaping, drainage systems, construction aggregate, aquarium substrate, and decorative garden paths. Larger or more colorful specimens may be used for rock painting.

Geological facts

River rocks are often found in 'alluvial deposits.' They tell the geological story of the upstream environment from which they were washed. Their smooth edges are a result of 'attrition,' where rocks collide and wear each other down while being transported by water.

Field identification & locations

Identify by their smooth, rounded edges and water-worn surfaces. Commonly found in riverbeds, lake shores, and glacial till. Collectors can find them anywhere there is current or historical water flow.