Mineral-like byproduct
Iron Slag
Anthropogenic Vitreous Silicate (Byproduct of Smelting)
Hardness: 5-6 (Mohs); Color: Dark grey, black, or metallic; Luster: Sub-metallic to glassy; Structure: Amorphous/vesicular; Cleavage: None; Specific Gravity: 2.8 - 4.5.
- Hardness
- 5-6 (Mohs)
- Color
- Dark grey, black, or metallic
- Luster
- Sub-metallic to glassy
Identified More mineral-like byproduct →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs); Color: Dark grey, black, or metallic; Luster: Sub-metallic to glassy; Structure: Amorphous/vesicular; Cleavage: None; Specific Gravity: 2.8 - 4.5.
Formation & geological history
Formed during the industrial smelting process where impurities (like silica and alumina) are separated from molten metal ore. It is an artificial rock rather than a natural geological formation.
Uses & applications
Historically used for road ballast, concrete aggregate, and track bedding. Occasionally used in rustic landscaping or as a historical artifact in archaeological contexts.
Geological facts
Slag is often mistaken for meteorites due to its dark, melted appearance and occasional magnetic properties, but its internal bubbles (vesicles) are a clear indicator of industrial origin.
Field identification & locations
Identify in the field by looking for gas bubbles, flow textures, or a glassy fracture on broken edges. Commonly found near old railroad tracks, industrial sites, and historical foundry ruins.
More like this
Other mineral-like byproduct specimens
Slag
Anthropogenic glassy silicate
Mineral-like byproduct
Slag
Anthropogenic Vitrophyre (Iron or Smelting Slag)
Mineral-like byproduct
Iron Slag
Anthropogenic Iron oxide/Silicate composite
Mineral-like byproduct (Technogenic)
Slag (Industrial Glassy Byproduct)
Anthropogenic silicate byproduct (Slag)
Mineral-like byproduct (often mistaken for igneous rock or meteorite)
Aluminum Slag
Anthropogenic Aluminum (Al)
mineral
Silver (Native Element)
Ag (Argentum)
mineral