mineral

Possible weathered iron-rich rock or slag fragment

Indeterminate; likely limonite/goethite-bearing material, possibly iron slag

AI-generated identification · may be incorrect

Brown-black, irregular, and strongly weathered with earthy to submetallic luster; hardness may be about 4–6 for goethite/limonite. The image is insufficient to determine crystal structure, cleavage, density, or magnetism.

Identified August 14, 2026More mineral →

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Physical properties

Formation & geological history

Natural limonite/goethite forms by oxidation of iron-bearing minerals near Earth’s surface; slag instead forms from human smelting and may contain glassy phases and metal droplets. Age and geological setting cannot be established visually.

Uses & applications

Iron oxides are ores and pigments; slag has limited aggregate or collecting interest. An attractive polished or crystalline specimen could have modest lapidary value.

Geological facts

The rusty brown color suggests hydrated iron oxides, while black areas could indicate magnetite, manganese oxides, or vitrified slag. A magnet and streak test would help distinguish these possibilities.

Field identification & locations

Check whether it is magnetic, whether it leaves a yellow-brown to reddish-brown streak on unglazed porcelain, and whether it shows vesicles or glassy texture; these help separate natural ore from slag. Common natural sources include weathered iron deposits worldwide.