Uranium Glass Coaster - Glowing Yooperlite Rocks Sold Separately

Uranium glass is glass that has had uranium, usually in oxide diuranate form, added to a glass mix before melting for colouration. The proportion usually varies from trace levels to about 2% uranium by weight, although some 20th-century pieces were made with up to 25% uranium.  Uranium glass glows under black light; this particular glass glows green.