mineraloid (man-made)

Green Glass Slag

Amorphous Silicon Dioxide (SiO2) with metal oxide impurities

Hardness: 5.5-6 (Mohs); Color: Translucent emerald green; Luster: Vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.4-2.8

Hardness: 5
Color: Translucent emerald green
Luster: Vitreous

Identified February 1, 2026More mineraloid (man-made) →

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Physical properties

Hardness: 5.5-6 (Mohs); Color: Translucent emerald green; Luster: Vitreous; Crystal Structure: Amorphous (non-crystalline); Cleavage: None (conchoidal fracture); Specific Gravity: 2.4-2.8

Formation & geological history

Formed as a byproduct of industrial smelting or glass manufacturing processes where silica is melted and cooled rapidly; typically modern or industrial age; found in industrial dumping sites or landscaping piles

Uses & applications

Used primarily for decorative landscaping, filler in construction, artistic glass projects, and as 'aquarium rock' or low-cost jewelry beads

Geological facts

While it resembles obsidian or emerald, it is a byproduct of human industry. It often contains trapped air bubbles which do not occur in natural obsidian. Deep green color is usually achieved through the addition of iron or chromium oxides during production.

Field identification & locations

Identify by looking for conchoidal (shell-like) fractures, lack of crystal faces, and spherical air bubbles. Common in regions with a history of iron/steel production or glass factories. Collectors should beware of it being mislabeled as natural green obsidian.

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