This page offers a guide on how to get Copper Ore in My Time at Sandrock.
How to Mine Copper Ore
Copper Ore is the most abundant ore in the Abandoned Ruins mines. Before you can access the Abandoned Ruins, you’ll need to complete the main quest, Picking Up the Slack, in which you build a Crane Lift.
Once you’ve got access to the Abandoned Ruins, Copper can be found on every level of the mines - including the first level meaning you can get a bunch in no time at all. You’ll get the most Copper Ore from mining big Copper Crystals found in the mines, but you’ll also get some ore from clearing the blue-brown debris that blocks your path.
Purchasing Copper Ore
As well as being mined, Copper Ore can also be purchased from Eufaula Salvage Shop for around 4 Gols each. This price will fluctuate as the cost of goods frequently change in Sandrock.