Camping lanterns once glowed with radioactive thorium. ☢️ . . . Carl Auer von Welsbach perfected his mantle in 1891 and brought it to market in 1892. Its ash-like fabric was commonly about 99% thorium dioxide and 1% cerium dioxide, producing brilliant white light when heated. The brighter the mantle burned, the more radioactive dust it could shed.
Source
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