sedimentary

Weathered iron-rich river pebble

Ferruginous chert or ironstone (hematite/goethite-bearing silica-rich rock)

AI-generated identification · may be incorrect

Hardness roughly 5–7 Mohs; brown to ochre, dull earthy-to-submetallic luster, fine-grained and non-cleavable. The rounded shape, pitting, and rusty coloration indicate prolonged water abrasion and iron-oxide weathering.

Identified September 14, 2026More sedimentary →

Explore Weathered iron-rich river pebble 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

Likely formed when silica-rich sediment or chert became impregnated and cemented by iron oxides during groundwater or surface-weathering processes; the precise geological age cannot be determined from the image. It was later rounded in a river, beach, or glacial deposit.

Uses & applications

Usually collected as a display specimen; ironstone and ferruginous chert may be used locally as aggregate or low-grade iron ore, but this individual has little industrial value.

Geological facts

Iron-bearing minerals such as goethite, limonite, and hematite produce the brown-orange coating. The small cavities may reflect weathered-out grains or gas/solution voids.

Field identification & locations

Look for a heavy feel, rusty streak or powder, possible weak attraction to a magnet, and resistance to scratching with a steel knife; acid reaction should be absent. Common in iron-rich stream gravels and weathering zones worldwide.