Find someone who is interested in these goblin things
Speak with Glibnox at ( 132, -164, -768 ) /waypoint 132, -164, -768 in Twark
Go back to the Abandoned Mine Tunnel (near Grunt's Pass at ( -318, 48, 604 ) /waypoint -318, 48, 604) then enter.
Exit to Fens of Nathsar by following the tracks to the end and turning left ( -270, 57, -2017 ) /waypoint -270.33, 57.07, -2017.22)
Watch out for Greshdak during my travels. This NPC is not in this zone or the cave, but found at the end of the final sub-quest for Brappa.
Enter the tunnel and follow the rails until you reach the end, where you zone into Fens of Nathsar
Complete the all of the sub-quests from the 3 goblins (Irontooth, Rumbletum, and Brappa) at the Nurgan Mining Camp. A Potion of Progress can make this fairly painless. Get a quest from all three goblins and gather the required items. The items from the next quests will be in the same places. Use the Potion of Progress just before starting the first craft, and if you're quick gathering for the other quests, it should last for all of them.