sedimentary

Waterworn ironstone pebble (likely limonite/goethite-rich)

Iron-oxide/oxyhydroxide-rich concretion, chiefly goethite (α-FeO(OH)) and/or limonite

AI-generated identification · may be incorrect

Rounded, smooth, dark brown to rusty ochre with a dull-to-submetallic luster; likely Mohs hardness about 4–6, but composition cannot be confirmed from the photograph. The visible cavity may be a natural pit or an inclusion that weathered out.

Identified October 16, 2026More sedimentary →

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Physical properties

Formation & geological history

Iron-rich material commonly forms by chemical precipitation, weathering, or cementation in sediments, then becomes rounded by water transport. Its geological age and exact formation environment cannot be determined from the image.

Uses & applications

Usually collected as a natural pebble; iron-rich ores are used in iron production, though this small specimen has no practical ore value.

Geological facts

Goethite and related iron oxides produce many yellow, ochre, and brown colors in soils and rocks.

Field identification & locations

Look for a heavy feel, rusty streak, and earthy fracture; a streak or hardness test would help distinguish ironstone from other brown pebbles. Ironstone pebbles occur in sedimentary deposits worldwide.