Sourcenatural - Hells, very rare - Gelugon Range

Tantulhor is a fiery red metal, about the weight of iron. It can be worked into a smooth finish and said to make a weapon unbreakable. Weapon blades fashioned of it will cut nearly anything they touch, except stone. In game terms, a tantulhor edged weapon scores +2 damage. This metal is found naturally only on worlds of the Hells system. When tantulhor is crafted in hellfire forges, it hardens greatly and gives items three times the hardness of iron and twice the durability.