industrial by-product
Slag (Industrial)
N/A (Anthropogenic Slag)
Hardness varies (generally 5-6), color is dark grey, brown, or black, often with a rusty appearance, dull to slightly shiny luster, amorphous structure, lacks cleavage, high specific gravity if iron-rich, often vesicular (contains holes or pores).
Identified More industrial by-product →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness varies (generally 5-6), color is dark grey, brown, or black, often with a rusty appearance, dull to slightly shiny luster, amorphous structure, lacks cleavage, high specific gravity if iron-rich, often vesicular (contains holes or pores).
Formation & geological history
Formed as a by-product of smelting ore to purify metals. It is the glassy mass left over after the desired metal has been separated from its raw ore.
Uses & applications
Used in construction, as aggregate in concrete, road base material, and sometimes in fertilizer.
Geological facts
Often mistaken for meteorites due to its dark color, high density, and melted appearance (vesicles). It is a common 'meteorwrong'.
Field identification & locations
Identify by the presence of vesicles (gas bubbles), irregular shape, lack of fusion crust typical of meteorites, and context of where it was found (often near old industrial sites or railroad tracks). Sometimes weakly magnetic.
More like this
Other industrial by-product specimens
Slag (Industrial By-product)
Anthropogenic Vitreous Silica/Iron Silicate
mineral
Slag (Industrial By-product)
Glassy silicate or metallic smelting residue
mineral-like (anthropogenic)
Opalite
Man-made glass (traditionally simulated Opal)
mineral
Flesh-colored Quartzite
Quartzite (SiO2)
metamorphic
Quartzite
Quartzite (composed primarily of SiO2)
metamorphic
N/A (Non-Geological Object)
N/A