Durnor Ore (Sindarin: "Dark Fire") is an ore exclusively found in Mordor. It glows in the dark, though not too brightly, and can be mined for Durnor crystals. It has fiery properties, and in Mordor it is somewhat analogous to coal.
Upon mining Durnor ore, the player earns the achievement "Fires of the Deep".
Durnor Ore can be found in Mordor at roughly the same rates as iron would be found in most other biomes, albeit in veins as large as coal. It is the most common ore in Mordor, and cannot be found outside of the Black Land. It drops Durnor crystals when harvested.
The ore itself has not much use except for decoration purposes, when mined with a silken pickaxe. When mined with normal tools, it drops Durnor, which are quite useful in a number of recipes on the Morgul Crafting Table, as, in Mordor, it effectively replaces coal.