Uranium glass is glass which has had uranium, usually in oxide diuranate form, added to a glass mix prior to melting. The proportion usually varies from trace levels to about 2% by weight uranium, although some 19th-century pieces were made with up to 25% uranium.
Uranium glass was once made into tableware and household items, but fell out of widespread use when the availability of uranium to most industries was sharply curtailed during the Cold War. Most such objects are now considered antiques or retro-era collectibles, although there has been a minor revival in art glassware. Otherwise, modern uranium glass is now mainly limited to small objects like beads or marbles as scientific or decorative novelties.
"Vaseline glass" is now frequently used as a synonym for any uranium glass, especially in the United States, but this usage is not universal. The term is sometimes carelessly applied to other types of glass based on certain aspects of their superficial appearance in normal light, regardless of actual uranium content which requires a blacklight test to verify the characteristic green fluorescence.
In England and Australia, the term "vaseline glass" can be used to refer to any type of translucent glass. Even within the United States, the "vaseline" description is sometimes applied to any type of translucent glass with a greasy-looking surface lustre.
However, like "vaseline", the terms "custard" and "jad(e)ite" are often applied on the basis of superficial appearance rather than uranium content. Similarly, Depression glass is also a general description for any piece of glassware manufactured during the Great Depression regardless of appearance or formula.
By the 1840s many other glassworks throughout Europe began to produce uranium glass items, including new varieties of uranium glass. The Baccarat glassworks of France created an opaque green uranium glass which they named chrysoprase, for its similarity to the green form of chalcedony with that name.
At the end of the 19th century, it was discovered that uranium glass with certain additional minerals could be tempered at high temperature to partially crystallise, changing from its normal transparent yellow or yellow-green with increasing opacity to, ultimately, opaque white. This material, technically a glass-ceramic, inspired the name "vaseline glass" due to its similar appearance to petroleum jelly.
Barrie Skelcher's research into Uranium Glass see