For the last few years I've been amassing a small collection of Uranium Glass, sometimes called Vaseline Glass (though technically, the Vaseline Glass is the pale yellow variety)
This stuff is fascinating, it was at its most popular between the 1880s and 1920s and is made by adding uranium salts to the silica in glass production. It stopped being produced during WWII, as the uranium was being used in explosives. It started to be produced again in the late 1950s, but never on the same scale as earlier.
The best part of this glass is its fabulous green glow under black light.
It also reads positive on a Geiger counter, but, as I don't have one, I've never been able to confirm that.
This odd looking bulbous piece is a sock darner, probably 1930s - very unusual.
I discovered three of my vintage marbles were Uranium Glass.
I also found a small selection amongst my old buttons.