Heatstone

Heatstone was a mineral mined by the dwarves of the Dwarf Kingdom.

Description
The dwarves used this curious metal like coal, and their refineries and smithies consumed vast quantities of them. Thus, one could say that heatstones were a central part of dwarven life. Due to the lack of wood heatsones served the subterranean race in all manners. It was mined primarily as a heating source, illumination, cooking etc. as an alternative substitute to using wood and coal.

Abilities
Heatstones were a special kind of metal. If one struck them with a very hard metal — mithril, at the barest minimum — they would produce intense heat.