QUEST: Goblin Ruins:
Items Needed: Nothing
Items Recomended: Torches
Lenght: Short (Just a bit of walking and exploring)
Reward: Diamonds, chainmail chestplate, torches, dirt, and a lot of other blocks not listed here.
The third quest of the Treasure Hunters Guild at Erebor , talk with a member of the guild, he will tell you that they found some information with the book you got in the previous quest , it talks about some forgotten goblin ruins near Erebor , head there, and take another book related with Aurum.
Go to the surface, there, put your render distance on far or normal, and look around, behind the Erebor Tower, there should be a little island at the Imperial Sea with some random placed mossy cobblestone, those are the ruins. Get inside and make your way to the bottom of the ruins, there you will find a chest with the book and your reward, then, just return to the surface and give the book to the guild to start the next quest.
For more quests, visit the quests article.