mineral
Blue Obsidian (Cullet Glass)
Silicon Dioxide (Amorphous Glass)
Hardness of 5.5 on the Mohs scale, vibrant blue color, vitreous luster, amorphous crystal structure (no true crystal lattice), conchoidal fracture, specific gravity around 2.4-2.6
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Physical properties
Hardness of 5.5 on the Mohs scale, vibrant blue color, vitreous luster, amorphous crystal structure (no true crystal lattice), conchoidal fracture, specific gravity around 2.4-2.6
Formation & geological history
Formed artificially as a byproduct of industrial glass manufacturing (cullet glass), though natural volcanic glass (obsidian) forms from rapidly cooling lava
Uses & applications
Commonly sold to rockhounds, used in decorative lapidary work, wire-wrapping jewelry, and as a display specimen
Geological facts
While often sold to unsuspecting buyers as 'natural blue obsidian,' volcanic obsidian naturally occurs almost exclusively in black, dark brown, or grey. Brightly colored obsidian like this is almost always man-made cullet glass.
Field identification & locations
Easily identified by its glass-like conchoidal fractures, bubbles trapped inside the material, and vibrant unnatural hue. Found worldwide near glass manufacturing waste sites or rock shops
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