Many vintage marbles have a curious feature that thrills children and adults alike: or another source of intense ultraviolet light), they fluoresce in an absolutely brilliant green color.
Why do some vintage marbles shine so brilliantly and some simply react to the presence of black light like any other glass? The secret lies in the composition of the glass: many vintage marbles were made from uranium-infused glass. Upon exposure to ultraviolet light, the glass emits an intense (and stereotypically "radioactive") green.
But why would anyone add uranium to glass marbles, however small it may be? It's especially strange to think that in the 1
The selling point was not the glow (which modern collectors love), but a much more subtle color scheme. Uranium-infused glass, commonly referred to as "vaseline glass" by collectors for its slightly cloudy appearance, has a special appearance when exposed to even the lower concentration of ultraviolet light that is sunk on us by the sun. Uranium-infused glass vases, bowls, prisms, and glass door panels received a beautiful, almost opalescent, emerald quality when sunlight hit them. Although the green tint was by far the most common, other variations were pale yellow and blue.
The use of uranium glass fell into disfavor in the late 1930s and 1940s when the United States government used all available uranium for nuclear research and development and weaponry purposes. A small handful of marble companies today still produce small quantities of marble with uranium glass, and even fewer glass craftsmen still make vases, bowls and decorative objects with the curious glass. If you are concerned about the safety of uranium jewelery, you should not do so. While some rare pieces have a higher uranium content than normal, the vast majority of uranium glass is considered negligible radioactive material and requires very sensitive equipment to detect even their radioactivity.