mineral
Likely weathered iron-rich stone
Uncertain; possibly limonite/goethite-bearing rock
AI-generated identification · may be incorrectSmall rounded brown-black specimen with earthy to dull luster and apparent granular texture. Likely hardness about 4–6 Mohs, no visible cleavage, and moderate-to-high density; exact properties require testing.
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Physical properties
Small rounded brown-black specimen with earthy to dull luster and apparent granular texture. Likely hardness about 4–6 Mohs, no visible cleavage, and moderate-to-high density; exact properties require testing.
Formation & geological history
Probably formed by oxidation and weathering of iron-bearing minerals, producing limonite and/or goethite; age depends on its parent rock and cannot be determined visually.
Uses & applications
Common pieces have little industrial or jewelry use, though iron oxides are ores and pigments; attractive specimens may be collected as curiosities.
Geological facts
Brown-yellow to dark rusty coloration commonly indicates hydrated iron oxides. A reddish-brown streak on unglazed porcelain would support an iron-oxide identification.
Field identification & locations
Field identification: test streak, magnetism, hardness, and density; limonite/goethite may leave a yellow-brown streak, while a strong magnet response suggests magnetite or iron-rich material. Common worldwide in soils, weathered outcrops, and mine zones.
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