Daily Archives: December 3, 2011

And now for something truly different

And now for something a bit intriguing. In the middle of November, the Czarina and I took our niece Emily to the annual Dallas Gem & Mineral Society Gem, Mineral, Fossil, Bead & Jewelry Show (*gasp for breath*) for a quick recce. The Czarina is always looking for new stones and beads for her jewelry, and I was looking for intriguing rock and slag glass samples for saikei arrangements. The big surprise wasn’t just in glass, but what kind of glass we found.

Uranium glass slab

Ray Thorpe of the Horseshoe Bend Knappers comes out to the Gem & Mineral Show as often as he can, and he regularly demonstrates his skills at knapping flint, obsidian, and slag glass for very appreciative audiences. Ray also sells slabs of knapping stone, and I was already drooling over some of the chunks of obsidian and chert that he had available. Out in front, though, were these slabs of custardy glass that really weren’t all that impressive, until a fellow dealer came over with a high-power UV LED flashlight intended for phosphorescent mineral hunting and ran it over a slab.

Most people are unfamiliar these days with uranium glass, but uranium used to be used as an additive to glasses to produce particularly vibrant colors. The main side effect is that both clear or “vaseline” and opaque or “custard” uranium glasses fluoresce under UV light. I’ve been collecting vaseline glass since I was in high school (the Czarina even found a beautiful vaseline glass juicer that she gave me for my birthday a few years back), but I’d never once seen any uranium slag glass. Ray got his from a collector in West Virginia who took advantage of the dumped slag from a long-defunct uranium glassworks, cut it into slabs, and used the more uniform slabs for knapping. (And boy howdy, you need to see knife blades and arrowheads made from uranium glass to believe them.) The rest he sold, and I promptly bought out his current stock for experimentation.

Now here’s where things get even more interesting. My day job is in a venue with some VERY interesting characters, and one of my co-workers is a former nuclear reactor tech from the US Navy. He still dabbles with various related projects, such as Geiger counters the size of keychain fobs (since the tube is so small, it’s not incredibly sensitive, but it can detect beta and gamma particle sources), so he dragged in his professional Geiger counter to see exactly how much radiation these slabs were emitting. It turned out that custard uranium glass is a slight alpha particle emitter, meaning that its only danger would come from ingesting or inhaling fragments (one reason why I don’t plan to use that vaseline glass juicer any time soon), but its radiation emissions were otherwise negligible. Another one of my co-workers is a glassworker in his spare time, so he naturally asked “Do you have a piece to spare?”

Several years back, the Czarina started lampwork training in order to make her own glass beads, and as with flintknapping, I picked up just enough knowledge to be dangerous. One of the things I learned was that different glass compositions have differing expansion and contraction rates when heated and cooled, and mixing incompatible glasses means that the final product cracks or shatters when it cools to room temperature. Mike was very familiar with these incompatibilities, and initial tests suggested that he had glass that could be miscible with the custard glass slabs. A final test to incorporate it into a paperweight, though…not so much.

Custard uranium glass paperweight

As can be told by the extensive cracks, that custard glass wasn’t quite compatible. However, Mike plans to use another piece and convert it into frit, and try again. In the meantime, this paperweight could theoretically come apart at any time, and I have plans for the fragments as part of a moonlight garden project when it does. And the rest of the custard glass? Keep an eye open at the Czarina’s next show, because she has some ideas for club-friendly pendants.