fatwiggywiggles t1_jef7uls wrote
Reply to comment by SrTobi in A Timeline Of The Earths Average Temperature - Since The Last Ice Age Glaciation. by Ok_Satisfaction6810
It was just kinda lying around Lake Superior, not much digging or smelting required to get ahold of 99% pure copper
https://en.wikipedia.org/wiki/Old_Copper_complex
There's still a bunch of copper mines in the UP of Michigan
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