Uranium Glass
The glass that glows — and yes, it's mildly radioactive.
What Is Uranium Glass?
Uranium glass is any glass that has had uranium dioxide or diuranate salts added to the molten glass mixture during production. The uranium gives the glass a distinctive yellow-green color in natural light, but the real party trick is what happens under ultraviolet light — it fluoresces a vivid, almost electric green.
The effect is caused by the uranium ions in the glass absorbing UV energy and re-emitting it as visible green light. It's the same basic principle behind fluorescent minerals, just trapped inside your grandmother's dessert bowl.
A Brief History
Uranium has been used as a glass colorant since at least the early 1800s, with some evidence of experimental use dating back even further. The heyday of uranium glass production ran from the 1830s through the 1940s, when manufacturers across Europe and the United States used it extensively for tableware, decorative pieces, and architectural elements.
Production slowed dramatically during World War II when governments restricted access to uranium for wartime use (yes, that kind of wartime use). After the war, some manufacturers resumed production, and a handful of artisan glassmakers still work with uranium today — though the heyday is long past.
Is It Safe?
This is the question everyone asks first. The short answer: yes, it's safe to collect and display. The amount of uranium in the glass is small — typically between 0.1% and 2% by weight — and the radiation it emits is extremely low-level. You'd get more radiation exposure from a long-haul flight or a few hours in the sun.
That said, most collectors avoid using uranium glass for food and drink as a common-sense precaution, especially with acidic foods that could theoretically leach trace amounts of uranium from the surface. But for display purposes? Completely fine. Your shelf is not a hazard zone.
How to Identify It
The easiest and most reliable method is a UV flashlight — also called a blacklight. Shine it on the glass in a dark or dim room. If it glows bright green, you've found uranium glass. A small UV flashlight is an essential tool for any glass collector and can be picked up for a few dollars online.
In natural light, uranium glass typically has a yellow-green, lime, or olive-tinted appearance, though the exact shade varies depending on the concentration of uranium and other additives in the formula. Not all green glass is uranium glass, and not all uranium glass looks green in daylight — the UV test is the definitive check.
Common Forms
Uranium glass shows up in an enormous range of forms. Some of the most commonly found pieces at thrift shops and antique malls include:
- Dessert bowls and plates (Depression-era pieces are especially common)
- Drinking glasses and goblets
- Vases and candlesticks
- Decorative figurines and paperweights
- Jewelry (beads, pendants, and brooches)
- Marbles
- Doorknobs and cabinet pulls
What Makes It Collectible?
Beyond the obvious cool factor of owning something that glows, uranium glass appeals to collectors for its rich history, wide variety of forms, and the thrill of the hunt. Pieces range from common Depression-era tableware that can be found for a few dollars to rare art glass that commands hundreds or more.
There's also a strong community aspect — uranium glass collectors love sharing their finds under UV light, and the visual effect never gets old. It's one of the few collectibles that's just as fun to show off to someone who's never seen it as it is to a fellow collector.
Notable Manufacturers
Many well-known glass manufacturers produced uranium glass at some point during their history. A few names to look for:
- Fenton Art Glass — produced uranium glass pieces across several decades
- Anchor Hocking — made uranium glass tableware during the Depression era
- Hazel-Atlas — another major Depression glass producer
- Mosser Glass — a smaller manufacturer that has produced uranium glass pieces
- Various Czech and Bohemian glassmakers — known for uranium glass beads and decorative items
Fun Facts
- The term "Vaseline glass" is sometimes used interchangeably with uranium glass, though it technically refers to a specific yellow-green shade that resembles petroleum jelly.
- Some marbles contain uranium glass — bring a UV light to your local antique mall's marble jar.
- The oldest known example of uranium glass dates to around 79 AD — a small mosaic tile found near Naples, Italy.
- A Geiger counter will pick up a reading from uranium glass, which makes for a fun demonstration but is not cause for concern.