Gehennite

Also known as Demon Star Crystal, Gehennite is used in the manufacture of many things, from heavy vehicles to certain weapons, and even the Stasis Pods that allow the resurrection of the Imperial High Council.

Properties
Gehennite is nearly unbreakable, save for very few tools. If any amount should enter the bloodstream, it will invariably kill within hours; this makes it ideal for use in poisons, however powdered Gehennite is strictly regulated as a Tier 4 highly dangerous substance.