Promethium is a general term for any form of fuel in the Imperium.
The term also commonly refers to the substance used as fuel for Imperial flamer weapons, a highly volatile incendiary gel which immediately ignites on contact with oxygen. It reaches super hot temperatures. Similar to napalm, the gel sticks to an individual, continuing to burn on its own accord, even underwater and in space. It also fuels most spacecraft and vehicles, both military and civilian.
In addition to this, Promethium is used to create an array of everyday necessities, ranging from dyes and plastics to pharmaceuticals and synthetic protein bars.
Promethium is extracted and refined in a number of different ways. Some of the most common methods are extracting it from the atmospheres of gas giants, the mining of ancient organic material deposits, and the processing of certain rare ices that are only found on ice worlds.
- 1: Codex: Imperial Guard (3rd Edition, 2nd Codex), pg. 62
- 2: Caves of Ice (Novel) - Ciaphas Cain: Hero of the Imperium (Omnibus) by Sandy Mitchell. Editorial Note after Chapter Two, pp. 317-318