mineraloid
Cullet Glass (Slag Glass)
Amorphous Silicon Dioxide (SiO2) with metallic oxide impurities
Hardness: 5.5-6 (Mohs); Color: Vivid pink to reddish-orange; Luster: Vitreous (glassy); Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific gravity: 2.4-2.8.
- Hardness
- 5
- Color
- Vivid pink to reddish-orange
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5.5-6 (Mohs); Color: Vivid pink to reddish-orange; 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 glass manufacturing or as leftover molten glass from a furnace. This material is modern and man-made rather than geological in age.
Uses & applications
Commonly used for landscaping, decorative garden stones, aquarium decor, and sometimes wire-wrapped jewelry or craft projects.
Geological facts
While it resembles natural obsidian or volcanic glass, the presence of air bubbles and the intense artificial color indicate its industrial origin. It is often sold at rock shows as 'Andara Crystal' or 'Strawberry Obsidian' despite being man-made glass.
Field identification & locations
Identify by looking for air bubbles (vacuoles), swirling color patterns, and a lack of true crystalline structure. It is commonly found near old glass factory sites or sold in decorative stone bins.
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