Radioactive waste also plays a significant role. Uranium tailings are waste by-product materials left over from the rough processing of uranium-bearing ore. They are not significantly radioactive. Mill tailings are sometimes referred to as 11(e)2 wastes, from the section of the Atomic Energy Act of 1946 that defines them. Uranium mill tailings typically also contain chemically hazardous heavy metal such as lead and arsenic. Vast mounds of uranium mill tailings are left at many old mining sites, especially in Colorado, New Mexico, and Utah. Although mill tailings are not very radioactive, they have long half-lives. Mill tailings often contain radium, thorium and
Uranium glass manufactured during the Great Depression regardless of appearance or formula. The use of uranium glass dates back to at least 79 AD, the date of a mosaic containing yellow glass with 1% uranium oxide found in a Roman villa on Cape Posillipo in the Bay of Naples, Italy by R. T. Gunther of the University of Oxford in 1912. Starting in the late Middle Ages, pitchblende was extracted from the Habsburg silver mines in Joachimsthal, Bohemia (now Jáchymov in the Czech Republic) and was used as a coloring agent in the local glassmaking industry. Martin Klaproth (1743–1817), who discovered uranium,