sedimentary

River Rock

Mixed composition, often quartzite, sandstone, or basalt

Hardness varies (often 6-7), brownish-gray color, smooth and tumbled appearance, weathered surface

Identified July 29, 2026More sedimentary →

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Physical properties

Hardness varies (often 6-7), brownish-gray color, smooth and tumbled appearance, weathered surface

Formed through mechanical weathering and water transport in rivers or streams

Landscaping, decorative stone, construction aggregate

River rocks are shaped by constant tumbling in water over years, giving them their characteristic smooth, rounded look.

Found in riverbeds, streams, and glacial deposits. Identifiable by their smooth, rounded shape.

Fossiliferous Sedimentary Rock

Sedimentary limestone with invertebrate fossil imprint

Sandstone or Siltstone

Arenite (if sandstone)

Sandstone

Arenite

Quartz pebble

Silicon dioxide (SiO2)

Shale

Shale (clastic sedimentary rock)

Shale (or Mudstone/Siltstone)

Sedimentary Mudrock (SiO2, Al2O3 base with clay minerals)