Gloom'rel

Gloom'rel can be found in the Summoners' Tomb of Blackrock Depths.

He offers the mining quest to learn how to smelt Dark Iron. Thus it is important to talk to Gloom'rel before speaking to Doom'rel, who will start of the event in which The Seven are killed. Dead dwarves make poor teachers.

Dark Iron Smelting
After you speak to Gloom'rel, a bowl will appear at his feet. Touching the bowl will give him his tribute:
 * 20 Gold Bar
 * 10 Truesilver Bar
 * 2 Star Ruby

Speak to him again, and he will teach you to smelt.

Quotes
"I am forever denied the touch of stone. I will never again know the glory of shaped iron..."