Changes

The Coal Mine is the main source of Coal [[File:icon coal.png|16px]], which can be sent for processing at a [[Toolworks]] to become Coal Tokens [[File:token coal.png|16px]] or it can be combined with Iron Ore [[File:icon iron ore.png|16px]] at a [[Foundry]] to create Iron [[File:icon iron.png|16px]] and Coal Tokens [[File:token coal.png|16px]]. In 4th era coal is being used as fuel to produce steel [[File:Icon_steel.png|16px]] in steelworks and from 5th era on it is needed as fuel in Coal Power Plant to generate electricity. Thus coal mining becomes critical throughout the whole game.