I first learned of the copper pits in high school when I took Michigan History. It's part of the curriculum to teach us about the copper pits and mysterious miners. I was always intrigued by it.
Never saw this article before but it has most of my info in it so it proves I'm not bullshitting anyone.
The Bronze Age is a period in Western European history typified by the usage of… bronze. The Bronze Age may be a term used daily in schools across the world, but there is one major issue that is seldom debated: where did the required components, tin and copper, originate from? Indeed, though it is undoubtedly the case that Europe had a "Bronze Age", archaeologists have accepted that much more copper was used than what they have been able to attribute to European mines. So where did an extremely large part of the copper come from? The answer, as bizarre as it may sound, could be America. It is known that during the European Bronze Age, large quantities of copper were mined in North America. However, no-one is able to answer as to what became of the copper that was mined there. If we were to add the two problems together, do we have the solution? Of course, the answer for the accepted scientific dogma is "no", as it argues that there were no transoceanic contacts in the Bronze Age, and hence copper could not have been traded from the New to the Old World. But perhaps there is sufficient scientific evidence available that will alter the assumptions of the scientists. --http://www.philipcoppens.com/copper.html