Mineral-like byproduct (Technogenic)
Iron Slag
Anthropogenic Iron oxide/Silicate composite
Hardness: 5-7 Mohs; Color: Dark grey, brown, or black with iridescent or rusty patches; Luster: Metallic to vitreous; Structure: Amorphous or glassy; Vesicular (pitted) surface; Specific Gravity: 2.5–4.0.
- Hardness
- 5-7 Mohs
- Color
- Dark grey, brown, or black with iridescent or rusty patches
- Luster
- Metallic to vitreous
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Physical properties
Hardness: 5-7 Mohs; Color: Dark grey, brown, or black with iridescent or rusty patches; Luster: Metallic to vitreous; Structure: Amorphous or glassy; Vesicular (pitted) surface; Specific Gravity: 2.5–4.0.
Formation & geological history
Formed as a byproduct of iron smelting or historical metalwork. It consists of the glass-like leftovers after a metal has been separated from its raw ore. Age is usually modern to historical (Industrial Revolution era).
Uses & applications
Historically used as road ballast, railroad fill, and occasionally as aggregate in concrete. In modern times, it is often recycled or kept as an educational curiosity.
Geological facts
Commonly mistaken for meteorites due to its dark color, heavy weight, and magnetic properties. It often contains trapped gas bubbles (vesicles), which real iron meteorites almost never have.
Field identification & locations
Identify by looking for air bubbles (vesicles), flow textures, or glassy surfaces. It is often found near old railways, foundries, or historical port cities. A magnet will usually stick to it if unrefined iron is present.
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