Copper is one of the base metals added by Thermal Foundation. It can be obtained from Copper Ore. The metal is very common in modded Minecraft.
Copper Ore can also be processed in various ways in an Induction Smelter, with varying byproducts.
Like most base metals in the mod, Copper can be used to craft tools and armor. It is also a common ingredient for creating machines in Thermal Expansion. Furthermore, Copper can be combined with Tin to create Bronze, or combined with Silver and Destabilized Redstone to create Signalum.