Copper had to be processed to make bronze, but it was also (like bronze, which looked a lot like gold) used in its own right as jewelry and other adornment.
The Copper Age (3500 – 2300 BC)
http://www.iceman.it/en/copperage
I was curious about the level of metallurgical sophistication these smelters had. Different ores require different processes. Oxides vs. sulfides
I read an article years ago about a treasure find of gold ingots in the Southwest. They were found to be about 60% copper, some silver and gold.