sedimentary

River Rock

Mixed lithology clast

Smooth, rounded shape due to water erosion. Color varies widely based on source rock, often brown, gray, or tan.

Identified August 30, 2026More sedimentary →

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Physical properties

Smooth, rounded shape due to water erosion. Color varies widely based on source rock, often brown, gray, or tan.

Formed by weathering and transport in streams or rivers over thousands of years.

Used in landscaping, decorative ground cover, and natural building materials.

River rocks are not a specific rock type but a description of shape and origin.

Found in riverbeds, stream banks, and glacial outwash plains. Easily identifiable by their smooth, rounded appearance.

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)