mineral

Iron-rich slag or weathered ironstone fragments

Probably hematite–goethite material; possibly industrial iron slag (Fe₂O₃/FeO(OH))

AI-generated identification · may be incorrect

Dark reddish-brown to black, earthy-to-submetallic luster, irregular fracture, and apparent rusty weathering; hardness roughly 5–6.5 if hematite/goethite, though slag may be variable and vesicular. No clear crystal faces are visible.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Natural hematite/goethite forms by oxidation and weathering of iron-bearing rocks, commonly from Precambrian iron formations; slag forms during historical smelting and is anthropogenic but still geological material. The image alone cannot distinguish them confidently.

Uses & applications

Iron ores are mined for steel production and pigments; attractive pieces may be collected, while slag is mainly of historical or lapidary interest and has little industrial value.

Geological facts

Reddish streak is characteristic of hematite, whereas goethite commonly produces yellow-brown streaks. Greenish patches could be secondary copper minerals, altered slag, or surface staining.

Field identification & locations

Test streak on unglazed porcelain, magnetism, density, and inspect for bubbles: strong vesicles and glassy surfaces suggest slag; a dense, earthy specimen with red streak suggests hematite-rich ironstone. Common worldwide, especially near mines and smelting sites.