However, most of that which had been produced by the Dwarves before the fall of Moria was gathered by the Orcs and paid as tribute to Sauron, who was said to covet it. The only way to obtain a Mithril object at the end of the Third Age was to either use heirloom Mithril weapons and armour that were produced before the fall of Moria, or to melt down these existing weapons to forge new ones. After the Dwarves abandoned Moria and production of new Mithril ore stopped entirely, it became priceless, as the presence of the Balrog prevented the Orcs in Moria from delving for it.
Before Moria was abandoned by the Dwarves Mithril was worth ten times its own weight in gold. Once the Balrog known as Durin's Bane destroyed the kingdom of the Dwarves at Khazad-dûm, Middle-earth's only source of new Mithril ore was cut off.
The Dwarves of Moria mined for Mithril too greedily and too deep and thus released the Balrog. Mithril was extremely rare by the end of the Third Age, as it was found only in Khazad-dûm.
