Igneous or Metamorphic

Granite or Granitic Gneiss River Rock

Granite / Gneiss

AI-generated identification · may be incorrect

Hardness: 6-7, Color: Gray, tan, and black mottling, Luster: Dull (weathered) to somewhat shiny depending on mineral grains, Crystal structure: Granular, interlocking, Cleavage: None for the rock as a whole

Identified June 1, 2026More igneous or metamorphic →

Explore Granite or Granitic Gneiss 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

Formation & geological history

Formed from the slow cooling of magma deep underground (granite) or the metamorphism of pre-existing rocks (gneiss). The rounded shape is due to fluvial (river) transport and weathering.

Uses & applications

Used in landscaping, construction aggregate, and hardscaping.

Geological facts

River rocks are shaped by the continuous tumbling and abrasion caused by flowing water, which smooths out their rough edges over time.

Field identification & locations

Identify by its rounded shape, mottled appearance indicating different mineral grains (quartz, feldspar, mica), and hardness. Commonly found in riverbeds, glacial till, and landscaping deposits.