sedimentary

Weathered iron-rich concretion or ironstone nodule

Goethite–hematite limonite concretion (FeO(OH), Fe₂O₃, and hydrated iron oxides)

AI-generated identification · may be incorrect

Typically dense and rounded, with rusty brown, orange, yellow, and dark gray colors; earthy to dull/metallic luster and no visible crystal faces. Hardness is about 4–6 Mohs, with a reddish-brown to yellow streak and generally no cleavage.

Identified August 11, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when iron-bearing groundwater precipitated oxides and hydroxides around a nucleus, commonly in sedimentary soils or weathered rock; age may range from recent soil formation to millions of years. The image alone cannot establish a precise geological age.

Uses & applications

Mostly a collector curiosity or educational specimen; ironstone may serve as a low-grade iron ore, pigment source, or aggregate, but this small nodule has no practical industrial value.

Geological facts

The rounded shape and mottled rusty coloration strongly suggest an iron-rich concretion rather than a crystalline gemstone. A yellow-brown powder indicates goethite/limonite, while a red-brown streak suggests hematite.

Field identification & locations

Common in soils, river gravels, deserts, and sedimentary formations worldwide, especially Australia, Brazil, India, and the United States. Test streak on unglazed ceramic, heft, and magnetism; avoid confusing it with slag or man-made iron residue.