Glossary

Bismuth is a brittle, silvery-white metal with a pinkish tint that sits on the periodic table as element 83 (Bi). It’s classified as a post-transition metal, and it is well known for its low melting point, unusual rainbow-oxide colors, and its tendency to form geometric, hopper-shaped crystals.

Bismuth is one of the heaviest naturally occurring elements that is not significantly radioactive. It’s extremely dense—heavier than lead—but is considered much safer and less toxic, which is why it has replaced lead in many modern alloys.

Industrially, bismuth is valued because it melts easily and expands slightly when it solidifies. This makes it useful in fusible alloys, which melt at low temperatures for safety devices like sprinkler heads and fusible plugs. It also appears in pharmaceuticals (like Pepto-Bismol), cosmetics, low-melting solders, precision casting alloys, and fire-detection devices.

In pure form it has very low thermal conductivity (one of the lowest among metals), is diamagnetic (repelled by magnetic fields), and forms striking iridescent oxide layers. Bismuth is typically produced as a byproduct of lead, copper, tin, silver, and tungsten mining, making it relatively rare but industrially valuable.