Copper Ore is an ore that can be found quite readily (including at the surface) and is the most abundant ore in Galacticraft. It can be smelted into Copper Ingots, which can be used in many crafting recipes or compressed to make Compressed Copper.
Its generation in The Overworld can be disabled in the Galacticraft configuration files.
Copper Ore can be found anywhere between the layers of Y=0 and Y=75 with a frequency of 24 clumps within every chunk. It is generated in clumps of 7 blocks on average.