Bismuth has been known since the late Middle Ages, but for centuries it was confused with lead, tin and antimony and not clearly recognised as a distinct metal until Claude-Francois Geoffroy demonstrated its separateness in 1753. The origin of the name is uncertain, most likely from the German Wismut, perhaps meaning white mass or from a mining term. Bismuth is a brittle, silvery metal with a faint pink cast, famous for the vivid iridescence of its oxidised crystals and, medicinally, as the active ingredient of some stomach remedies. Unusually for a heavy metal bismuth is relatively non-toxic, which suits it to stomach medicines, cosmetics and, increasingly, to lead-free solders, alloys and shot, while its low-melting alloys are used in fire-safety devices and its compounds as catalysts and pigments.
Bismuth held the title of heaviest stable element for decades, but in 2003 French physicists showed that its only naturally occurring isotope, bismuth-209, is in fact very weakly radioactive, decaying with a half-life more than a billion times the current age of the universe, a finding that quietly moved lead back into the position of the heaviest truly stable element without changing anything about how bismuth behaves in practice. The pink stomach remedy long sold as Pepto-Bismol takes its name directly from bismuth subsalicylate, its active ingredient since the product's introduction in the early twentieth century.