In Tolkien's Middle-earth, mithril is extremely rare by the end of the Third Age, as it was now found only in Khazad-dûm. Once the Balrog destroyed Khazad-dûm, the kingdom of the Dwarves in Moria, the only source of new mithril ore was cut off. Before Moria was abandoned by the Dwarves, while it was still being actively mined, mithril was worth ten times its weight in gold. After the Dwarves abandoned Moria and production of new mithril stopped entirely, it became priceless.