Mineraloid

Cullet Glass (Man-made Glass Slag)

Amorphous Silica (SiO2) with chemical additives

Hardness: 5.5-6 on Mohs scale; Color: Vibrant green (due to iron or chromium additives); Luster: Vitreous (glassy); Structure: Amorphous (non-crystalline); Cleavage: None (exhibits conchoidal fracture); Specific Gravity: 2.4-2.8.

Hardness: 5
Color: Vibrant green (due to iron or chromium additives)
Luster: Vitreous (glassy)

Identified February 26, 2026More mineraloid →

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Physical properties

Formation & geological history

Formed as a byproduct of industrial glass manufacturing or as recycled waste material (cullet) that has been melted and cooled. It is not geological in origin and can be modern or decades old depending on the site of discovery.

Uses & applications

Used in decorative landscaping, aquarium gravel, recycled glass production, or sold as 'andara crystals' or 'sea glass' in the metaphysical and craft markets.

Geological facts

While often mistaken for minerals like emerald or peridot, this specimen is clearly glass due to its high transparency, conchoidal (shell-like) fracture patterns, and the presence of small internal gas bubbles which do not occur in natural crystals.

Field identification & locations

Identify in the field by looking for air bubbles, lack of crystal faces, and smooth, curved fracture surfaces. Commonly found near old factory sites, riverbeds, or beaches. It is a common 'leaverite' (leave it right there) for serious mineral collectors but popular for crafts.

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