mineral

Limonitic ironstone / weathered iron-rich rock

Goethite–limonite aggregate; principally FeO(OH)·nH₂O with possible hematite (Fe₂O₃)

AI-generated identification · may be incorrect

Yellow-brown, earthy to dull luster, massive and porous, with irregular fracture and no visible cleavage; typical hardness is about 4–5.5 Mohs, though friable areas may be softer. The dark patches likely contain iron oxides or manganese oxides.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Forms by intense oxidation and weathering of iron-bearing minerals, commonly in soils, laterites, gossans, and altered ore deposits. It is generally young relative to its parent rock and may form at or near Earth’s surface over extended weathering periods.

Uses & applications

Used historically as an iron ore and pigment (ochre); attractive pieces are collected, but this rough specimen has little commercial value unless assays show significant iron, gold, or other metals.

Geological facts

Limonite is a field term for hydrated iron-oxide mixtures rather than a single precisely defined mineral. Yellow ochre coloration commonly comes from goethite and fine-grained hydrated iron oxides.

Field identification & locations

Identify it by its yellow-to-brown earthy color, heavy feel, rusty streak, and tendency to stain porous surfaces; a streak test on unglazed porcelain should be yellow-brown. Common in lateritic soils, mine gossans, and weathered iron deposits worldwide.