sedimentary

River Stone (Sandstone or Siltstone)

Sedimentary Rock (Clastic)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs scale), Color: Brownish-tan to earthy grey, Luster: Dull/Earthy, Grain size: Medium to fine, Texture: Gritty, Structure: Massive/Rounded due to abrasion.

Identified July 6, 2026More sedimentary →

Explore River Stone (Sandstone or Siltstone) in the encyclopedia →

Identify your own rocks.

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

App Store Google Play

Physical properties

Hardness: 6-7 (Mohs scale), Color: Brownish-tan to earthy grey, Luster: Dull/Earthy, Grain size: Medium to fine, Texture: Gritty, Structure: Massive/Rounded due to abrasion.

Formation & geological history

Formed by the accumulation and lithification of sand-sized mineral particles (usually quartz or feldspar). The rounded shape indicates significant mechanical weathering and transport by water in a river, stream, or beach environment.

Uses & applications

Commonly used in landscaping, construction aggregate, decorative garden features, and sometimes as a base for stone painting or engraving.

Geological facts

River stones are shaped by a process called saltation, where rocks bounce along the bottom of a river bed, slowly wearing away sharp edges until they become smooth and elliptical.

Field identification & locations

Identify by its smooth, rounded surface and gritty texture. Found globally in river valleys and glaciated plains. Collectors often look for unique shapes or colors.