Rock Identifier
Iron-rich weathered rock, possibly limonite/goethite-bearing ore (Limonite (hydrated iron oxides; chiefly goethite, FeO(OH), with hematite and other oxides possible)) — mineral
mineral

Iron-rich weathered rock, possibly limonite/goethite-bearing ore

Limonite (hydrated iron oxides; chiefly goethite, FeO(OH), with hematite and other oxides possible)

AI-generated identification · may be incorrect

Typically brown, reddish-brown, yellow-brown, or black with earthy to submetallic luster; hardness about 4–5.5 Mohs, no distinct cleavage, irregular fracture, and relatively high specific gravity (~3.3–4.3).…

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Physical properties

Typically brown, reddish-brown, yellow-brown, or black with earthy to submetallic luster; hardness about 4–5.5 Mohs, no distinct cleavage, irregular fracture, and relatively high specific gravity (~3.3–4.3). The specimen appears porous, rusty, and strongly weathered, though the image cannot confirm its exact mineralogy.

Formation & geological history

Forms by oxidation and hydration of iron-bearing minerals, commonly in weathering zones, gossans, bog deposits, and lateritic soils. It may be geologically young as a weathering product, even when derived from older host rock.

Uses & applications

Used historically as iron ore and yellow/brown pigment; attractive pieces are collected, but it is not typically a jewelry gemstone.

Geological facts

Limonite is a field term rather than a single precisely defined mineral species; goethite is often its principal component. A yellow-brown streak and reddish-brown powder are characteristic.

Field identification & locations

Common in oxidized sulfide deposits and iron-rich soils worldwide. Confirm with a streak test on unglazed porcelain, magnetism testing, and ideally laboratory X-ray diffraction; avoid assuming native gold from its color.