The carbon ingots acquired in Vinland can only be used in Vinland and their function here is different than in England. They are used as currency to buy gear from local traders. Although there are only 5 wealth points in Vinland, each one of them will yield two carbon ingots. This means that you can collect a total of 10 ingots, which (plus one that you receive as a quest reward) is the amount you need to buy all the items that are available.
Brúhamarr OutpostCarbon Ingot x2. The chest has two locks, so you need two keys.
One of the keys is located in a red tent across the canyon.
The second key is in a tent located west of the chest.
Hvallgrof Outpost #1Carbon Ingot x2. The chest is located in the red tent. To unlock it you need a key that the Woe-Bringer has.
Hvallgrof Outpost #2Carbon Ingot x2. Kill the Wolf-Stormr and loot his corpse.
Narfljot CampCarbon Ingot x2. The chest is in one of the tents in the camp and is locked in two locks. The keys are held by two soldiers who are in the camp.
Steinnhus CampCarbon Ingot x2. The chest stands at the foot of the wooden scaffold.
