The Metal Mine produces metal in comparison to the Gas Mine and the Crystal Mine, due to the fact it is used for nearly everything. The Metal Mine is used to produce metal, which can be used to upgrade buildings, build ships, research new technologies, and other. In addition, mining also takes energy, so you must upgrade your energy production too. Once the Metal Mine is upgraded, the amount of metal obtained per hour will increase. There is a description saying how much is produced per hour when clicked on the Metal Mine. The metal will continously keep increasing.