I think a lot of times copper will melt in the coals and run down into a pool in the ashes. Aluminum will too if the fire isn't quite hot enough.I believe a good wood stove or even a bonfire can reach over 2000 F at the bottom. Some guys here have said 2300 F, or just a bit less than natural gas or propane. So, an aluminum can will actually vaporize down to almost nothing. You can also melt copper.