mineral

Weathered iron-rich rock fragment

Likely limonite/goethite-rich concretion or oxidized sulfide fragment; exact identification requires testing

AI-generated identification · may be incorrect

Brown to yellow-brown, earthy to dull luster, irregular granular texture, and no visible crystal faces; likely Mohs hardness about 4–6, with moderate-to-high density. Iron oxides commonly leave a yellow-brown streak and may be weakly magnetic if magnetite is present.

Identified September 2, 2026More mineral →

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Physical properties

Formation & geological history

Probably formed by chemical weathering and oxidation of iron-bearing minerals, producing limonite and goethite; such material can develop in soils, sediments, mine waste, or weathered ore zones. Its precise age and source cannot be determined from the photograph.

Uses & applications

Usually a common field specimen with little commercial value; iron oxides are important ores and pigments, while attractive botryoidal pieces may be collected.

Geological facts

Limonite is a mixture rather than a single mineral, commonly dominated by goethite and hydrated iron oxides. Surface texture and color can change substantially as it weathers.

Field identification & locations

Check for a yellow-brown streak on unglazed porcelain, hardness against a steel nail, density, and magnetism; a professional analysis or acid test may distinguish it from oxidized sulfide, slag, or other iron-rich material. Common in weathered rocks worldwide.