industrial byproduct
Ferrochrome Slag
Anthropogenic slag (Fe-Cr alloy waste)
Hardness: 6-7 (Mohs); Color: Metallic dark blue to olive green with iridescent sheen; Luster: Sub-metallic to vitreous; Structure: Amorphous or microcrystalline; Vesicular texture (contains small gas bubbles/holes).
- Hardness
- 6-7 (Mohs)
- Color
- Metallic dark blue to olive green with iridescent sheen
- Luster
- Sub-metallic to vitreous
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Physical properties
Hardness: 6-7 (Mohs); Color: Metallic dark blue to olive green with iridescent sheen; Luster: Sub-metallic to vitreous; Structure: Amorphous or microcrystalline; Vesicular texture (contains small gas bubbles/holes).
Formation & geological history
Formed as a byproduct of the smelting process used to produce ferrochrome from chromite ore. The molten waste cools rapidly, often resulting in a glass-like or metallic finish. Primarily found near industrial smelting sites.
Uses & applications
Used as a construction aggregate, in road building, and as ballast in railways. Occasionally collected as a curiosity due to its colorful iridescent patina.
Geological facts
While it appears like a rare mineral or meteorite, the presence of spherical bubbles (vesicles) and its metallic luster are hallmarks of man-made industrial slag. It is extremely common in regions with heavy mining and smelting history.
Field identification & locations
Identify by looking for small bubble pits on the surface and a weight that is denser than common rocks but lighter than pure metal. It is non-magnetic unless it contains high residual iron levels.
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