The Lord of the Rings: Shadow of the East
Pure mithril is in many ways like normal silver: shining white and very malleable — but it does not tarnish and alloys with other metals to produce unique enchanted metals of incomparable quality. It always appears polished.
There are many tales of the mithril from Númenor, but that Isle is no more, and Khazad-dûm may now be the only source of true-silver. It no doubt contributes to the vast wealth held by Durin’s Folk. Wherever one travels to lands where it is known, it is considered the richest of metals. Mithril is loved above all materials by the Dwarves and is also treasured by the Elves, the Dúnedain, and the dark forces of Morgoth.
Very little true-silver made its way westward to Nargothrond, and the samples which did were highly prized. Celebrimbor’s recommendations that the Noldor journey toward Eregion when he left Beleriand, in hope making contact with the Dwarves of Durin, and gaining access to true-silver, gives some idea of how highly the Eldar regarded the metal. Their eventual alliance brought more mithril into the hands of the Noldor than they imagined could have existed. From this true-silver many wondrous alloys emerged.
The famed mithril lode is but a single vein. Running northward from the Seventh Deep of Moria, it extends well under the mighty Redhorn.