Copper ore is a crafting component introduced in the Blood and Wine expansion that can be dismantled into unrefined copper ore and is needed to craft copper ingot.
Crafting Requirements 
It can be crafted, found as random loot, or purchased from the following merchants:
- Armorer in Hauteville
- Blacksmith at Ardaiso Quarry
- Blacksmith in Belgaard Manor, after he is rescued
- Lazare Lafargue in his workshop
- Trentin in his workshop in Hauteville
Copper ore can also be obtained by dismantling Blood and Wine junk items that have "copper" in their names, copper ingot, and many craftable swords.