mineral

Iron-rich weathered rock (likely limonite/goethite concretion)

Limonite–goethite mixture; chiefly FeO(OH)·nH₂O

AI-generated identification · may be incorrect

Brown to dark brown, earthy to dull luster, irregular/concretionary texture, and likely Mohs hardness about 4–5.5; specific gravity commonly 3.0–4.3, with no visible cleavage or crystal structure.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Forms as secondary iron oxides and hydroxides during weathering of iron-bearing rocks or in soils, bogs, and hydrothermal environments. Its age may range from recent soil formation to ancient deposits; the photograph alone cannot establish age.

Uses & applications

Used historically as iron ore and as a natural yellow-brown pigment (ochre); attractive specimens are collected but generally have little jewelry or construction value.

Geological facts

Limonite is a field term rather than a single precisely defined mineral, commonly consisting of poorly crystalline goethite and related iron oxides. Strong reddish-brown streak and possible attraction to a magnet can support identification if hematite or magnetite is present.

Field identification & locations

Common in weathered outcrops, iron-rich soils, mines, and stream gravels worldwide. Check for a yellow-brown streak on unglazed ceramic, high density, earthy texture, and rust staining; confirmation requires testing or analysis.