Rock Identifier
Iron-stained brown mineral/rock fragment (Most likely limonite/goethite-rich material (hydrated iron oxides), possibly weathered ironstone; exact identification requires testing) — mineral
mineral

Iron-stained brown mineral/rock fragment

Most likely limonite/goethite-rich material (hydrated iron oxides), possibly weathered ironstone; exact identification requires testing

AI-generated identification · may be incorrect

Brown to reddish-gold, earthy to dull/submetallic luster, irregular fracture, and no visible crystal faces; estimated Mohs hardness 4–6, variable specific gravity roughly 3–4.3. The image is insufficient to determine cleavage or crystal structure.

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Physical properties

Brown to reddish-gold, earthy to dull/submetallic luster, irregular fracture, and no visible crystal faces; estimated Mohs hardness 4–6, variable specific gravity roughly 3–4.3. The image is insufficient to determine cleavage or crystal structure.

Formation & geological history

Likely formed by oxidation and weathering of iron-bearing minerals, producing goethite and limonite; commonly develops in soils, veins, gossans, and weathered ore deposits, generally at shallow geological conditions and potentially at any age.

Uses & applications

Iron oxides are important iron ores and pigments; attractive polished pieces may be sold as decorative specimens, though this fragment appears primarily collectible rather than gem-quality.

Geological facts

Limonite is not a single mineral but a mixture dominated by hydrated iron oxides, while goethite is a defined mineral (FeO(OH)). Brown streak and rusty coloration are characteristic of oxidized iron.

Field identification & locations

Check whether it leaves a yellow-brown streak on unglazed porcelain, attracts weakly to a magnet if magnetite is present, and shows greater density than ordinary rock; common in iron-rich soils and mine dumps worldwide.