Now if Someone had not mined out all the copper in Michigan’s Upper Peninsula we’d all be rich now.
Today copper ore is about 3-4% copper. The mined out UP copper ore, all 250,000 tons (est.), was 99% pure.
Good news for the Arizona Copper Basin
“The mined out UP copper ore, all 250,000 tons (est.), was 99% pure.”
Not sure where you’re getting your numbers, but they are way off. From a history of copper mining in the UP, which took me about five minutes to find online:
“Most of the native copper production came from a 20 kilometer long belt between the towns of Houghton and Calumet, and was mined both from amygdaloidal zones in the tops of basalt lava flows and from interbedded conglomerates. During its productive period, from 1845 to 1977, the district produced 11.5 billion pounds of copper from over 300 million tonnes of ore. All of this production was from underground mines.”
This divides out to a grade of around 1.75% copper by weight. While the native copper itself was of very high purity, the miners had to extract a lot of rock containing the small pieces of pure copper. In fact, very large masses of native copper usually could not be removed economically, as blasting won’t work on them.
Anyway, grade alone is not the most important thing. A billion tons of ore at 0.3% copper contains 60 billion pounds of copper, far more than all of the native copper production from Michigan ever, and there are mines in Arizona with considerably more than that.