Rock Identifier
Weathered iron-rich stone, possibly limonite-bearing sandstone or laterite (Limonite/goethite-rich material; composition commonly FeO(OH)·nH₂O with clay and quartz impurities) — mineral
mineral

Weathered iron-rich stone, possibly limonite-bearing sandstone or laterite

Limonite/goethite-rich material; composition commonly FeO(OH)·nH₂O with clay and quartz impurities

AI-generated identification · may be incorrect

Brown-yellow, dull to earthy luster, irregular massive texture, and no visible crystal faces or cleavage; hardness is variable, about 4–6 Mohs, with moderate to high density. The rounded, pitted surface suggests strong weathering or concretion formation.

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Physical properties

Brown-yellow, dull to earthy luster, irregular massive texture, and no visible crystal faces or cleavage; hardness is variable, about 4–6 Mohs, with moderate to high density. The rounded, pitted surface suggests strong weathering or concretion formation.

Formation & geological history

Likely formed by oxidation and hydration of iron-bearing minerals near Earth’s surface, producing an iron-oxide crust or concretion; age cannot be determined from the photograph. Common in lateritic soils, weathered rock zones, and iron-rich sedimentary deposits.

Uses & applications

Used historically as an iron ore and natural ochre pigment; attractive polished pieces may be kept as inexpensive geological specimens, but this appearance has little gem value.

Geological facts

Limonite is a field term rather than a single precisely defined mineral, commonly representing mixtures dominated by goethite and related iron oxides. A yellow-brown streak on unglazed porcelain would support identification.

Field identification & locations

Common in iron-rich weathering environments worldwide, including tropical laterite and gossan zones; test streak, density, and magnetism, and compare with sandstone or clay matrix before identification.