sedimentary

Iron-rich concretion or weathered ironstone

Goethite–hematite-rich limonite (FeO(OH)·nH₂O / Fe₂O₃)

AI-generated identification · may be incorrect

Brown to reddish-brown, earthy to submetallic luster, irregular botryoidal/concretionary texture, and no obvious cleavage; hardness typically 4–6.5 Mohs, with relatively high density and a yellow-brown to red-brown streak.

Identified September 9, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when iron-bearing groundwater precipitated oxides and hydroxides around a nucleus, later weathering into a rounded concretion; age depends on its host sediment and cannot be determined from the image.

Uses & applications

Used historically as an iron ore and natural pigment; attractive specimens are collected, but it is generally unsuitable for jewelry or construction aggregate.

Geological facts

The porous, rusty surface and dark metallic patches are typical of mixed limonite, goethite, and hematite rather than a single pure mineral.

Field identification & locations

Common in weathered soils, sedimentary beds, stream gravels, and ironstone deposits worldwide; confirm with a strong reddish-yellow streak, magnet test, density, and laboratory analysis. The image alone cannot exclude a slag fragment or another iron-rich rock.