mineral
Iron-rich rock, likely limonite/goethite-rich ore
Goethite (α-FeO(OH)) and/or limonite (a mixture of hydrated iron oxides)
AI-generated identification · may be incorrectBrown to dark gray, earthy to dull luster, irregular fracture, and no obvious crystals; hardness is variable, roughly 4–5.5 Mohs for goethite. The photo alone cannot establish its composition or specific gravity.
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Physical properties
Brown to dark gray, earthy to dull luster, irregular fracture, and no obvious crystals; hardness is variable, roughly 4–5.5 Mohs for goethite. The photo alone cannot establish its composition or specific gravity.
Formation & geological history
Forms through weathering and oxidation of iron-bearing minerals, or by precipitation from iron-rich water. Such deposits occur in many geological periods and environments.
Uses & applications
Iron oxides are iron ore and are also used as pigments; this rough fragment has little apparent gem or decorative value.
Geological facts
“Limonite” is a field term for mixtures of hydrated iron oxides rather than a single mineral species.
Field identification & locations
Its rusty brown color and iron-rich appearance are suggestive, but confirm with tests or laboratory analysis; similar-looking rocks occur worldwide in weathered deposits and ironstone.
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