sedimentary

Possible iron-rich concretion or weathered ironstone

Goethite/hematite-bearing limonite concretion (tentative)

AI-generated identification · may be incorrect

Small rounded brown, dull-to-earthy specimen with an irregular surface and apparent dark metallic inclusions. Likely Mohs hardness about 4–6, but crystal structure, streak, density, and magnetism cannot be confirmed from the image.

Identified August 17, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed by iron minerals cementing sediment or soil around a nucleus during weathering; such concretions range from recent soil formations to ancient sedimentary rocks. Geological age is indeterminate.

Uses & applications

Primarily a field or teaching specimen; ironstone may be collected for mineral study, while larger hematite/goethite deposits are mined as iron ore.

Geological facts

Brown limonite is a mixture of hydrated iron oxides rather than a single mineral. A yellow-brown to reddish-brown streak and rusty interior would support this identification.

Field identification & locations

Common in weathered soils and sedimentary formations worldwide, especially near oxidized iron deposits. Test streak on unglazed porcelain, hardness, specific gravity, and attraction to a magnet; the image alone cannot exclude a manufactured clay or metal object.