The Iron Mine produces iron for your base. Its first plot requires Base level 9. More mine plots and higher mine levels are separate construction projects, each with its own requirements.
How iron production works
A level 1 mine produces 1,440 iron per hour. Output reaches 11,520 at level 10, 23,040 at level 20 and 33,840 at level 30. Each value is the rate for that building level.
Production must be collected. The game's resource-capacity reminder appears when base production is full; it is not a notification that a building upgrade has finished. Collecting resources and completing an upgrade are separate actions.
Iron supply and protection
The Iron Warehouse increases protected iron quantity. It does not produce the iron shown in the mine's hourly output.
Food is also required by many upgrades, but the Food Factory supplies it separately. A construction project with both costs needs both resources, even when one production building is much further ahead than the other.
