sedimentary or igneous

River Rock

Various, often Sandstone, Basalt, or Granite

AI-generated identification · may be incorrect

Hardness varies (often 5-7), color is gray/brown, luster is dull to slightly polished, shape is rounded and elongated

Identified September 2, 2026More sedimentary or igneous →

Explore 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 varies (often 5-7), color is gray/brown, luster is dull to slightly polished, shape is rounded and elongated

Formation & geological history

Formed through water erosion in riverbeds or beaches over thousands of years

Uses & applications

Used in landscaping, decorative stone, and construction

Geological facts

The rounded shape is a direct result of being tumbled by water currents, which naturally smooths the sharp edges.

Field identification & locations

Easily identified by its smooth, rounded surface. Common in riverbeds, streams, and beaches globally.

Other sedimentary or igneous specimens

See all

Pyrite

Iron Sulfide (FeS2)

mineral

Pebble (likely a type of sandstone or quartzite pebble)

Clastic Sediment (specifically, a rudite-sized clast). If the pebble is composed of a specific rock type, its scientific name would be that rock type (e.g., 'Quartzite pebble', 'Granite pebble', 'Chert pebble'). Given its appearance, it is likely a metamorphic quartzite pebble or a hard sandstone pebble.

Sedimentary rock