sedimentary

River Rock

Sedimentary clast

Hardness varies depending on composition (often 5-7), brownish-gray color, dull luster, smooth weathered surface

Identified September 2, 2026More sedimentary →

Get a report just like this from any photo, free.

Physical properties

Hardness varies depending on composition (often 5-7), brownish-gray color, dull luster, smooth weathered surface

Formed by weathering and erosion of larger rock formations, subsequently smoothed by water transport in a river or stream

Commonly used in landscaping, construction aggregate, or decorative gardens

River rocks can be composed of various minerals depending on the source rock, often quartz, feldspar, or sedimentary rock fragments.

Identified by its rounded, smooth shape caused by water erosion. Found in riverbeds, streams, and beaches globally.

Fossil-bearing concretion, possibly containing a fossil shell or other organic inclusion

Calcareous concretion; exact fossil and host-rock composition are not identifiable from the image

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)