man-made silicate (anthropogenic glass)
Sea Glass (Uranium/Vaseline Glass variant)
Silicon Dioxide (SiO2) with trace Uranium Oxide (U3O8)
Hardness: 5.5-6.0 Mohs; Color: Lime green to yellow; Luster: Frosted/Vitreous; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal; Specific Gravity: 2.4-2.6. Fluoresces bright neon green under UV light.
- Hardness
- 5
- Color
- Lime green to yellow
- Luster
- Frosted/Vitreous
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Physical properties
Hardness: 5.5-6.0 Mohs; Color: Lime green to yellow; Luster: Frosted/Vitreous; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal; Specific Gravity: 2.4-2.6. Fluoresces bright neon green under UV light.
Formation & geological history
Formed from discarded glassware manufactured between the late 19th century and the mid-20th century. Over decades of tumbling in salt water with abrasive sand and rocks, the edges become rounded and the surface develops a characteristic frosted hydration patina.
Uses & applications
Used in jewelry making, beach-combing collections, and artisanal mosaics. Historically, uranium was used as a coloring agent for decorative table glass and vanity items.
Geological facts
Uranium glass (often called Vaseline glass) contains about 2% uranium by weight. It is famous for its radioactive property that causes it to glow intensely green under a blacklight. Despite the uranium content, it emits very low levels of radiation and is generally considered safe for handling as a specimen.
Field identification & locations
Identify in the field by looking for a translucent, frosted greenish-yellow pebble-like object with rounded edges and pitting. Collectors often use a portable UV flashlight at night on beaches to find these specific glowing shards. Common on beaches near old coastal dump sites or historical settlements.
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