sedimentary

Rounded gravel / river pebbles

Polymictic alluvial gravel, commonly quartz-, feldspar-, and lithic-rich clasts

AI-generated identification · may be incorrect

Individual pebbles are gray to brown, rounded, and generally dull to slightly glassy; hardness varies roughly Mohs 3–7 depending on composition. The clasts are millimeter- to centimeter-sized and lack a single crystal structure or uniform cleavage.

Identified August 26, 2026More sedimentary →

Explore Rounded gravel / river pebbles in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Formation & geological history

Produced by mechanical weathering and prolonged abrasion during transport in rivers, beaches, or glacial outwash; the visible gravel is a young unconsolidated Quaternary deposit, though its constituent rocks may be much older.

Uses & applications

Used for drainage, landscaping, pathways, concrete aggregate, erosion control, and aquarium decoration; attractive uniform pebbles have modest craft or decorative value.

Geological facts

Roundness indicates repeated transport and impacts, while mixed colors and textures indicate multiple source rocks. Dark lighting makes precise mineral identification difficult from the image alone.

Field identification & locations

Identify by its loose, rounded, mixed lithologies and absence of cementation; common in river channels, alluvial fans, beaches, and commercial landscaping yards. A hand lens, streak test, and hardness testing can distinguish quartz-rich pebbles from softer carbonate or volcanic clasts.