Amethystium

Amethystium is a deep violet when extracted, and has lightning bouncing around inside - individuals holding it can feel the crackle. Forging with it is incredibly difficult, and most dwarves can only apply it to weapons as an enchantment - not as the blade itself. It is more than just forging the material, it's taming and focusing the lightning contained within. Amethystium is the prized material used in the forging of the weapons for the Amethyst Preservers.