Bismuth

Bismuth is a brittle, silvery metal with a pinkish tinge. Lab-grown crystals form stair-step shapes coated in a rainbow film of oxide. It was known to medieval miners but often confused with tin and lead; Claude François Geoffroy showed it was distinct in 1753. Most is a by-product of refining lead, copper and tungsten ores.

Unlike its neighbor lead, bismuth is barely toxic, so it increasingly replaces lead in plumbing fittings, fishing weights and low-melting solder. Its compounds settle upset stomachs and add pearly shimmer to cosmetics, and low-melting bismuth alloys trigger fire sprinklers. Bismuth is technically radioactive, but its half-life is more than a billion times the age of the universe.