This quest is unlockable in the moment we step the Town of the Bolmus Populi. We just have to fly to a tower past the market and talk with Adolphus, which will doubt your trading abilities. To prove him wrong we will have to trade an apple for a Gold Nugget.

Fast-travel to the Capilli Village, step right and enter the second building. There you will give the apple to a white bearded teacher and he'll give you a shovel in return.

Fast-travel to the Old Monastery and fly left close to the ground. In a moment you'll encounter a carriage and a gravedigger. Talk to him and he'll give you a lantern in exchange for the shovel.

Fast-travel to the Bolmus Populi Town and fly right until you see Magna's face. Then follow the images.



There you'll exchange the lantern for the gold nugget.

Get back to Adolphus and talk with him. He wont teach you anything, that part was fake, but what he gives you, sure is worth the trade :D