Gulduril Ore is a mysterious ore that spawns only in Mordor, Dol Guldur, and Angmar. This green crystalline ore has many uses in Morgul-sorcery, all of them nefarious and unnatural. It is roughly as common as gold, and can generate either in Mordor Rock or stone. Its Mordor Rock variant can be found only in Mordor, while its stone variant appears in Angmar and Dol Guldur.
Mining Gulduril Ore for the first time gives the achievement "A Sickly Light".
Gulduril Ore gives off a sickly green light, somewhat like a corrupted version of glowstone, which makes it easy to make out in the deep caves where it can be found. When mined with an iron pickaxe or better, the ore drops Gulduril. It generates at the same rate as gold in all of the biomes in which is can be found, with the exception of Morgul Vale, in which it instead generates at the same rate as iron. Players looking for large amounts of Gulduril would do well to mine for it in Morgul Vale, where it can be found in vast quantities.
In the renewed version only, Gulduril can also spawn in groups of crystals underground. These drop one Gulduril when mined with an iron pickaxe or better and can be collected in crystal form with a Silk-touch pickaxe. These crystals also give off a moderate amount of light.
Gulduril Ore itself is useful only as a decorative block, but Gulduril, which it drops when mined, has many uses for evil players, including building Morgul Portals, crafting Morgul Torches, or coating bricks to make them glow. Gulduril can also be alloyed with Morgul Iron, which creates Morgul steel, a material used in crafting Morgul blades and armour. Morgul steel is stronger than Orc Steel, but not as strong as Mithril, or even Black Uruk Steel.