mineral

Ironstone / limonite-rich rock

Limonite, chiefly hydrated iron oxides (FeO(OH)·nH₂O), commonly mixed with goethite and hematite

AI-generated identification · may be incorrect

Ochre-orange to brown, earthy to dull luster, irregular fracture, and porous or massive texture; hardness about 4–5.5 Mohs, with relatively high specific gravity (~3–4). It may leave a yellow-brown streak and is commonly weakly magnetic if hematite or magnetite is present.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Forms by weathering and oxidation of iron-bearing minerals, often as a soil or cavity coating and as a cement in sedimentary rocks. It is generally geologically young relative to its parent rock and can form in groundwater-rich environments.

Uses & applications

Used historically as an iron ore and widely used as a natural yellow-brown pigment; attractive pieces are collected, though it is not typically a gemstone or construction stone.

Geological facts

The term “limonite” describes a variable mixture rather than one single mineral species. Its rusty color results from hydrated iron oxides produced during chemical weathering.

Field identification & locations

Identify it by its ochre color, earthy texture, heavy feel, yellow-brown streak, and reaction to weathering; common in iron-rich soils, altered rocks, and mine areas worldwide. Exact identification would benefit from streak, magnetism, and hardness tests.