Thallium is named from the Greek thallos, a green shoot or twig and was isolated in 1862. Thallium occurs in crooksite, lorandite and hutchinsonoite. It is also present in pyrites and is recovered from the roasting of this ore in connection with the production of sulfuric acid. It is also obtained from the smelting of lead and zinc ores. The metal is soft and malleable. Thallium sulfate has been widely used as a rodenticide and ant killer, but its use has been prohibited in the U.S. since 1975. Thallium is a highly toxic element with few commercial uses. It has been used to produce different types of glass with unique properties.