I loaded a save after getting the battle tower, headed to the fjords, dropped the barrier, talked to Simeon and then headed to the spot you meet the traveling merchant (to buy his malachite gem) before going to the depleted ore mine (on my second reload there I got 2 malachite gems anyway).
Sending the gems to the battle tower does revert the status of the quest, but when I moved the gems out of the chest, the quest was also updated, and I could give 2 of them to Simeon to complete it.
