Limestone

Limestone is a common resource found in the world. It is mainly used to produce Concrete, an essential material in factory construction.

Obtaining
Limestone may be located using the Resource Scanner after completing the tier 0 milestone "Hub Upgrade 2". It can be mined by hand or by using any of the miners.

There are currently 75 Limestone Resource nodes in-game; 6 impure, 46 normal, and 23 pure. This means the upper limit of harvest rate is 47340 Limestone/min (Mk.3 miners, 250% overclock, Mk.6 belt).