mineraloid
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (Industrial Man-made)
Hardness: 5.5-6.5 (Mohs scale); Color: Pale green to translucent; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.4-2.8
- Hardness
- 5
- Color
- Pale green to translucent
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5.5-6.5 (Mohs scale); Color: Pale green to translucent; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.4-2.8
Formation & geological history
Formed as a byproduct of industrial smelting or glass manufacturing processes. It is man-made molten material that has cooled rapidly, capturing air bubbles and gas pockets (vesicles) as it solidifies.
Uses & applications
Used primarily for landscaping, decorative garden stones, and occasionally tumbled for inexpensive jewelry or aquarium decor. Often collected by enthusiasts as 'found' artifacts.
Geological facts
While it looks like volcanic obsidian or green beryl, its bubbly texture and presence near old industrial sites confirm its man-made origin. It is often mistaken for rare gemstones by amateur collectors.
Field identification & locations
Identify in the field by looking for conchoidal (shell-like) fractures, trapped air bubbles, and a lack of crystalline structure. Frequently found near old railroad beds, iron furnaces, or factory sites.
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