Potassium nitrate

The chemical compound potassium nitrate KNO3 is a naturally occurring mineral source of nitrogen that constitutes a critical oxidising component of black powder gunpowder. In the past it was also used for burning fuse technologies including slow matches. It readily precipitates and was widely "harvested" since the Late Middle Ages and Early Modern era through the 19th century from urine from which it was forced to crystallise in various odorous ways. Its common names include saltpetre (from Medieval Latin sal petrae: "stone salt" or possibly "Salt of Petra"), American English saltpeter, Nitrate of potash and nitre. The name Chile saltpetre is also applied to sodium nitrate, which while related to explosives as well, is a very different compound.