This huge repository hold not yet processed minerals. More developed storage can hold more minerals. Each new level of infrastructure development increases the storage capacity by 1%. If the repository is full, production is terminated. Minerals that don't fit into storage are lost at a rate of 2% per day when the overflow is up to 5%, and at a speed equal to the overflow percentage per day otherwise (with a maximum of 10%).
Storage capacity can be increased by hiring Officer Storekeeper. Facility capacity can be increased by the capacity of the fleet at the facility (if hired Storekeeper), and by the capacity of the Colony Ship (regardless of the presence of Storekeeper).