sedimentary

Sandstone Pebble (River Rock)

Arenite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Tan, brown, or buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8.

Hardness: 6-7 Mohs
Color: Tan, brown, or buff
Luster: Dull/Earthy

Identified July 1, 2026More sedimentary →

Explore Sandstone Pebble (River Rock) 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; Color: Tan, brown, or buff; Luster: Dull/Earthy; Crystal structure: Clastic (sand grains); Cleavage: None; Specific Gravity: 2.2-2.8.

Formation & geological history

Formed through the accumulation and cementation of mineral particles or rock fragments of sand size. This specimen displays significant rounding caused by fluvial (river) or coastal erosion over centuries.

Uses & applications

Used in construction as a base material, landscaping, decorative pathways, and as an educational tool for learning about the rock cycle.

Geological facts

Sandstone can preserve fossilized footprints or ripple marks from ancient riverbeds. This specific shape is known as a 'clast' that has been smoothed by the mechanical action of water and other rocks.

Field identification & locations

Identified by its gritty texture (feels like sandpaper) and rounded, water-worn edges. Commonly found in riverbeds, deltas, and beaches. Collectors look for unique shapes or colors.