OrigamiRobot and I are playing through the Sea of Flame II, and we can't find any iron. We got about 15 from the rotten caves, but that's not nearly enough.
Where can we find more iron?
The iron on the map is under the mossy citadel below the large sky shadow. The citadel is separated in three parts: the main building, the yard and the dungeons below. You pretty much have to clear the top two parts before getting to the dungeon.