- a white powder, BN, formed by heating boron in nitrogen. In its ordinary form, it has a structure of stacked layers of hexagonal rings, very similar to that of graphite, and is used as a refractory electrical insulator.
- a white inert crystalline solid existing both in a graphite-like form and in an extremely hard diamond-like form (borazon). It is used as a refractory, high temperature lubricant and insulator, and heat shield. Formula: BN
