Durnaur ore is an ore exclusively found in Mordor. The name is derived from the Elvish words "dur" (dark) and "naur" (fire).
Upon mining Durnaur ore, the player earns the achievement "Fires of the Deep".
The ore itself has not much use except for decoration purposes, when mined with a Silktouch pickaxe. When mined with normal tools, it drops Durnaur gems, which are quite useful in a number of recipes.