
mineral
Weathered iron-rich rock, possibly limonite-bearing sandstone or altered volcanic rock
Limonite/goethite mixture; exact host rock is indeterminate from the image
AI-generated identification · may be incorrectBrown-yellow, earthy to dull luster, irregular massive texture, and no visible crystal faces or cleavage. Likely Mohs hardness about 4–5.5, with moderate-to-high density; a yellow-brown streak and reddish-brown powder would support iron oxides.
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Physical properties
Brown-yellow, earthy to dull luster, irregular massive texture, and no visible crystal faces or cleavage. Likely Mohs hardness about 4–5.5, with moderate-to-high density; a yellow-brown streak and reddish-brown powder would support iron oxides.
Formation & geological history
Formed by oxidation and weathering of iron-bearing minerals near Earth’s surface, commonly producing limonite and goethite coatings or replacements. Such material can form from the Cenozoic to much older rocks and commonly accumulates in soils, weathering zones, and hydrothermal deposits.
Uses & applications
Used historically as an iron ore and natural yellow-brown pigment; attractive specimens may be collected, but this example appears common and non-gem quality.
Geological facts
Limonite is not a single true mineral but a variable mixture of hydrated iron oxides, often dominated by goethite. Its color can range from yellow ochre to dark brown or nearly black.
Field identification & locations
Common in weathered iron-rich rocks worldwide, including lateritic soils and oxidized ore zones. Test streak on unglazed porcelain, magnetism, and acid reaction; avoid damaging the specimen without permission.
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