Iron

Iron is required for upgrading higher-level buildings. It is also required for training higher-level troops, research, healing and some Maester expeditions. It can be produced using mine plots at your Keep, prayed for at the shrine, dropped by creatures or gathered in the following quantities: Iron can also be purchased in the store at a cost of:
 * Level 1 - 480
 * Level 2 - 660
 * Level 3 - 1,300
 * Level 4 - 2,300
 * Level 5 - 3,600
 * Level 6 - 5,400
 * 800 Iron = 45 Gold
 * 4K Iron = 200 Gold
 * 40K Iron = 1,500 Gold
 * 100K Iron = 3,500 Gold