mineral

Yellow iron-oxide-rich mineral/rock fragment

Likely limonite/goethite (hydrated iron oxides; commonly approximated as FeO(OH)·nH₂O)

AI-generated identification · may be incorrect

Opaque mustard-yellow, earthy to dull luster, rough granular surface, and apparently massive rather than crystalline. Likely Mohs hardness about 4–5.5; streak testing would help distinguish yellow limonite from harder goethite or sulfur.

Identified August 25, 2026More mineral →

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Physical properties

Formation & geological history

Usually forms by weathering and oxidation of iron-bearing minerals, commonly in soils, cavities, and hydrothermal or sedimentary deposits; age varies widely from recent to ancient. The image alone cannot establish a precise geological age or species.

Uses & applications

Primarily a collector or teaching specimen; iron oxides are important iron ores and pigments, though this small piece has no practical construction or jewelry value.

Geological facts

Its vivid yellow color may result from hydrated iron oxides, but native sulfur, yellow ochre, or a phosphate mineral are possible alternatives. Limonite is a mixture rather than a single fully defined mineral species.

Field identification & locations

Check for a yellow-brown streak, moderate heft, earthy texture, and lack of metallic luster; sulfur is softer and often smells faintly sulfurous when scratched, while iron oxides commonly leave ochreous streaks. Common worldwide in weathered iron deposits.