mineral

Limonite/goethite-rich ironstone

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

AI-generated identification · may be incorrect

Yellow-brown to orange, earthy and dull to submetallic, with irregular fracture and no visible cleavage; typically about 4–5.5 Mohs and relatively heavy (specific gravity roughly 3.3–4.3). The porous, rusty texture suggests an iron-oxide-rich specimen rather than a crystalline sulfide.

Identified August 19, 2026More mineral →

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Physical properties

Formation & geological history

Forms by weathering and oxidation of iron-bearing minerals, especially near-surface zones and gossans; its age depends on the host deposit and may range from recent soil formation to ancient ore-weathering zones. Commonly occurs as earthy masses, coatings, and botryoidal crusts.

Uses & applications

Used as an iron ore when sufficiently concentrated, and historically as ochre pigment; attractive pieces are collected but are generally not jewelry-grade.

Geological facts

Limonite is a field term rather than a single precisely defined mineral species, because it consists of poorly crystalline hydrated iron oxides. Its orange-brown streak and rusty appearance are characteristic.

Field identification & locations

Common in oxidized metal deposits, soils, bogs, and weathered rocks worldwide. Check for a yellow-brown streak on unglazed porcelain, substantial heft, and attraction generally absent or weak; exact identification may require X-ray diffraction.