Topic summary
Octiron
Extracted from the Wikipedia article Discworld (world).
Substances
The Disc contains magical substances. One such is octiron, a dense black metal that makes up much of Discworld's crust. Its melting point is above the range of metal forges. The gates of Unseen University are made out of it, as is Old Tom, the university's bell. It is used to make magic needles and bells. Octiron releases magical radiation, but if it becomes negatively polarised, it can be used to absorb the radiation. Octiron generates significant amounts of heat under pressure, accounting for most volcanic geological processes on Discworld. When struck, octiron briefly silences anything around it instead of producing sound.