Antropogenic (Man-made glass byproduct)
Blue Slag Glass
Amorphous Silica (Industrial byproduct)
Hardness: 5.5-6.5 (Mohs scale); Color: Vibrant blue; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: ~2.4-2.8
- Hardness
- 5
- Color
- Vibrant blue
- Luster
- Vitreous/Glassy
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5.5-6.5 (Mohs scale); Color: Vibrant blue; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Fracture: Conchoidal; Specific Gravity: ~2.4-2.8
Formation & geological history
Formed as a byproduct of iron smelting or glass manufacturing processes. Molten waste cools rapidly, preventing crystal formation and creating a glass-like solid. Often found in historical industrial sites.
Uses & applications
Historical specimens are used by collectors, as aquarium decor, or tumbled for jewelry making. In the past, crushed slag was used for road ballast or railroad beds.
Geological facts
While not a natural mineral, slag glass is a popular 'found' geological specimen. The blue color often comes from cobalt or copper additives used in the smelting process or the glass batch.
Field identification & locations
Identify by its conchoidal (curved) fracture, presence of tiny air bubbles (vesicles) trapped inside, and unnatural 'electric' colors not common in local geology. Often found near old furnace sites or riverbeds near historical industrial areas.
More like this
Other antropogenic (man-made glass byproduct) specimens
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (Industrial Byproduct)
mineraloid
Cullet (Slag Glass)
Amorphous Silica (SiO2) with various metal oxide colorants
mineraloid / anthropogenic
Aluminum Slag
Anthropogenic Aluminum (Al)
mineral
Blue Slag Glass
Amorphous Silica (Byproduct of smelting)
Antropogenic (Man-made)
Slag (Industrial Byproduct)
Artificial silicate/iron byproduct
Mineral description (Anthropogenic material)
Slag
Anthropogenic glassy silicate
Mineral-like byproduct