sedimentary

River Rock

N/A - Generic term for water-smoothed rock

Smooth, rounded, dark gray to black color, fine-grained texture

Identified August 31, 2026More sedimentary →

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Physical properties

Smooth, rounded, dark gray to black color, fine-grained texture

Formed by water erosion in a river, stream, or beach environment over long periods, smoothing rough edges.

Landscaping, decorative stone, construction material

River rocks are not a specific type of geological rock but a description of their shape resulting from water action.

Identified by its smooth, rounded shape and lack of sharp edges, commonly found in riverbeds, streams, and beaches.

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Quartz pebble

Silicon dioxide (SiO2)

Sedimentary Sandstone

Arenite (Sedimentary Rock)

Generic Pebble / Rock Fragment

Lithic fragment / Weathered rock

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)