Butte a big copper producer at one time.
The reason they quit mining up in the copper country is the difficulty of removing it. A lot of that copper is over 90% pure and they had to manually chip it apart to send it up to the top.
I think the largest mass was over 27 tons found in one of the old mines up there. A couple years ago, they found about a 17 ton mass on top of the ground on some guys land and its now on display in China. Can you imagine? 17 tons of nearly pure copper? They found another mass under the water in a lake up there and that one is on display at Michigan Tech. I have talked to divers who have seen entire walls of pure copper under the surface in Lake Superior.
Its all float copper and it came from Canada via the ice age. Simpley bulldozed all that stuff to the south shore I guess.
At $3.23/pound (today's spot price), that 17 ton boulder is worth... $109,820... and that's only if it is nearly 100% pure.
Nice, but the cost of transporting it... or worse, dragging it up from the depths of Lake Michigan... have to make it almost not worth the effort.
Copper's most recent highs and lows:
In 2011, it was $4.42.
In 2001, it was $0.62.
In 1988, it was $1.99.
In 1971, it was $0.50
WOW! Thanks for the info.