mineral

Iron-rich concretion or weathered ironstone

Limonite/goethite-rich iron oxide (hydrated FeO(OH)·nH₂O), possibly with hematite

AI-generated identification · may be incorrect

Brown to dark reddish-brown, earthy to submetallic luster, irregular botryoidal surface, and no obvious cleavage; hardness typically 4–5.5 Mohs, with high specific gravity around 3.3–4.3. The image is insufficient for a definitive identification.

Identified August 16, 2026More mineral →

Explore Iron-rich concretion or weathered ironstone 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

Forms through oxidation and weathering of iron-bearing minerals, commonly as soil concretions, cavity linings, or replacement material; age depends on its host deposit and may range from recent to ancient.

Uses & applications

Used historically as iron ore and earth pigment; attractive pieces are collected, but this rough specimen has little commercial value.

Geological facts

Limonite is a mixture rather than a single pure mineral, and commonly includes goethite and hematite. A reddish-brown streak and attraction to a strong magnet may support an iron-oxide identification.

Field identification & locations

Common in weathered outcrops, soils, mine dumps, and sedimentary iron formations worldwide. Check streak on unglazed porcelain, density, magnetism, and whether a fresh break reveals metallic gray hematite or yellow-brown goethite.