You have found what Guthjon was looking for, and, as promsied, he will tell you a certain trade secret.

Requirements

This quest is available if you have completed the quest A Convenient Distraction.

Starting the Quest

Talk to Guthjon in Amh Araeng to begin the quest.

Speak with Guthjon

Go east to where the orange arrow is pointing in the minimap. Talk to Guthjon to proceed. There will be a cutscene.

Obtain the Smoke Bombs

Go to the quest icon on the map and check on the sparkling Pile of Supplies.

Place the Smoke Bombs at the Designated Locations

Go northwest to the northern entrance to the mines and go to the northeast part of the orange circle there. Dismount and target , and then you can either examine or target the sparkling Crevice and use the Smoke Bomb on it from the Key Items section of your inventory, or you can target it and use the icon to the right of the quest name in your list of active quests.

Go southeast to go back outside, then go south until you can go southwest into the southern tunnel. Go to the center of the eastern orange circle and use a Smoke Bomb on the crevice as before.

Go west to the final orange circle on the map and go west into the cave in the center of the orange circle. Use a Smoke Bomb on the crevice as before.

Inspect the Rubble

Go west to the northwest part of the southwest orange circle and check on the Rubble. Kill the Wandering Knocker that attacks, then kill the second Wandering Knocker that attacks.

Go southeast to the southeast part of the southwest orange circle and check on the Rubble. Kill the three Wandering Knockers that attack, then kill the fourth Wandering Knocker that attacks.

Go east and then northwest to the northeast edge of the southwest orange circle and check on the Rubble. Kill the Wandering Knocker that attacks, then kill the second Wandering Knocker that attacks.

Go southeast to the west edge of the southern orange circle. Check on the Rubble and kill the two Wandering Knockers that attack, then kill the third Wandering Knocker that attacks.

Go east to the east edge of the southern orange circle. Check on the Rubble and kill the three Wandering Knockers that attack, then kill the fourth Wandering Knocker that attacks.

Go east to go outside, then go north until you can go northwest through the northern tunnel into the mines. Go to the eastern edge of the orange circle and check on the Rubble. Kill the two Wandering Knockers that attack, then kill the third Wandering Knocker that attacks.

Go west to the western edge of the orange circle and check on the Rubble, then kill the two Wandering Knockers that attack, then kill the third Wandering Knocker that attacks.

Deliver the Glittering Rocks

Go east to where the orange arrow is pointing in the minimap and talk to Guthjon to hand over the Glittering Rocks and complete the quest. There will be a cutscene. This one is important, so it is recommended to watch it either now or via the Unending Journey in an inn room.

Aether Current Quest

With the completion of this quest, you can now start the blue quest "A Vein Pursuit" in Amh Araeng. Completing that quest will attune you to an Aether Current in this area.

Next Main Scenario Quest

After you complete the quest, talk to Guthjon to accept the next quest: Have a Heart.