sedimentary

Likely lateritic ironstone (limonite/goethite-rich)

Goethite, α-FeO(OH), with possible limonite and clay impurities

AI-generated identification · may be incorrect

Small, rough, tan-yellow, earthy specimen with dull to slightly waxy surfaces and no obvious crystal faces. Goethite hardness is about 5–5.5 Mohs; color and hardness can vary in iron-rich mixtures. The image alone cannot confirm composition.

Identified September 25, 2026More sedimentary →

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Physical properties

Formation & geological history

Iron oxides and oxyhydroxides commonly form by weathering and concentration of iron in tropical soils and laterites; such deposits are generally geologically young relative to their underlying bedrock.

Uses & applications

Iron-rich material is an iron ore when sufficiently concentrated; small pieces are mainly of educational or modest collecting interest.

Geological facts

Goethite and related hydrated iron oxides often produce yellow, ochre, or brown colors in weathered rock and soil.

Field identification & locations

The reported Sri Lankan location makes lateritic ironstone plausible, but visual identification is uncertain; a fresh streak (often yellow-brown) and laboratory testing would help distinguish it from clay-rich rock or other minerals. Laterite and ironstone occur in many tropical regions.