mineral

Weathered iron-rich rock fragment

Provisional identification: limonite/goethite-rich material, likely an ironstone fragment

AI-generated identification · may be incorrect

Brown to yellow-brown, earthy to dull luster, irregular massive texture, and no visible crystal faces; hardness approximately 4–5.5 Mohs, with variable specific gravity around 3–4.3. The dark surrounding material may be host rock or soil, and the image is insufficient for a precise mineral determination.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms through oxidation and weathering of iron-bearing minerals, commonly as a soil or fracture coating and in ironstone deposits; formation age depends on the host geology and may range from recent weathering to ancient sedimentary concentration.

Uses & applications

Common ironstone may be used as low-grade iron ore, pigment, aggregate, or a teaching specimen; unexceptional fragments have little jewelry or construction value.

Geological facts

Limonite is not a single crystalline mineral but a mixture dominated by poorly crystalline iron oxyhydroxides, especially goethite. Yellow streak, rusty-brown powder, and attraction only if magnetite is present are useful clues.

Field identification & locations

Test the streak on unglazed porcelain: yellow-brown suggests limonite/goethite, while red-brown suggests hematite; a hardness test and magnet check help distinguish iron minerals. Common in weathered zones worldwide.