you can also get cobalt at cedar wood starting at around lvl 25. cobalt will be about 15% of you take and iron will be around 75% the rest will be brimstone raw spinal and raw turquoise. Once you hit 35 go to iron lake to mine. I dont know what lvl your miner is so i gave you advice starting at lvl 25

edit: if you cant mine and dont have gil to buy mats then just do leves