mineral

Limonite/Goethite nodule

Goethite (FeO(OH)) with Hydrated Iron Oxides

AI-generated identification · may be incorrect

Hardness: 4-5.5 (Mohs scale), Color: Brownish-yellow to dark brown, Luster: Dull to earthy, Crystal structure: Orthorhombic (often amorphous or microcrystalline in nodules), Cleavage: Indistinct, Specific Gravity: 3.3-4.3.

Hardness: 4-5

Identified June 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed through the weathering and oxidation of iron-rich mineral deposits in sedimentary environments. Common in swampy areas (bog iron), gossans (iron-hats over ore deposits), and as hydrothermal precipitates.

Uses & applications

Primarily used as a minor iron ore and as a source of ochre pigments for paints and cosmetics. Also collected as geological curiosities.

Geological facts

Limonite was one of the first pigments used by early humans in cave paintings. It is not a single mineral but a mixture of hydrous iron oxides, primarily goethite and lepidocrocite.

Field identification & locations

Identify in the field by its brownish-yellow streak and earthy texture. Often found in soil or as concretions in sedimentary rock layers. Collectors often look for pseudomorphs where limonite has replaced other minerals while keeping their shape.