mineral

Industrial slag (iron/copper smelting slag)

Multiphase vitreous metallurgical slag; commonly iron-silicate glass with metal-oxide and metallic inclusions

AI-generated identification · may be incorrect

Black to gray, highly glassy and conchoidally fractured, with metallic bronze/copper-colored blebs and vesicles; hardness typically ~5–6 Mohs, no consistent crystal structure, and variable density. The rounded flow textures and shiny melt surfaces strongly indicate artificial slag rather than a natural ore or meteorite…

Identified September 13, 2026More mineral →

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Physical properties

Formation & geological history

Produced when furnace flux and gangue melt during historic metal smelting; it cools rapidly into glassy material, often with trapped metal or sulfide droplets. Its age depends on the smelting site, commonly historical or industrial rather than geological.

Uses & applications

Collected as industrial archaeology or lapidary rough and occasionally cut into cabochons; it has no standard construction value and should not be sold as a meteorite or native metal.

Geological facts

Copper-colored metallic-looking areas may be copper, bronze-like sulfides, iron oxides, or reflected glass—not necessarily native copper. Vesicles, flow bands, and heterogeneous composition are typical slag indicators.

Field identification & locations

Look for flow textures, bubbles, sharp glassy edges, and associations with mine dumps or furnace sites; a magnet may attract iron-rich portions. Professional testing such as XRF is needed for exact composition.