This whole copper thing has fascinated me for years. When I was a Kid I was taught that some WOG discovered it in his camp fire. Wilhelm Von Loon.
So I conducted an experiment, while working for a very large company that gave me little to do under slack supervision.
I built a furnace of refractory brick, several bricks stacked in a circle with a small opening on side. The crucible was a 6” steel cap.
I took some scrap copper and tossed into the pot and applied 3000 degree heat from an H2O2 torch. No melt after Eight hours.
Good thing these preliterate craftsmen weren’t relying on you, buster. ;’)