Obsidian iron, where to take? (Assassin's Creed: Odyssey)

Now I'm wondering where to take so much iron, obsidian , resa need for improvement of gear, to every 2-3 LVL every LEGO to improve?
I am silent to resources lacked on the ship and on the improvement of gear, it is unreal, you have 24/7 to farm sink ships in the sea, not the plot and additional missions, for which their mother is given only nafig not need crystals for engravings I have that their whole bag is nowhere to go 500 pieces , although engrave all the new stuff, but need a resa is not present and is not enough! Where to take it? Sink ships or fortress to farm, duck end they..