There must be one heck of a tailing pile out at that huge old gold mine called Homestead...? Think it’s Homestead, in maybe South Dakota. Try a google earth flyover, that is a major big hole! As I understand there are layers and layers of tunnels too. Would take a long long time to sift through all of that.
Coal wash plants back in the 50s and 60s were unable to capture the minus quarter inch fine coal. Dozens of ponds full of fine coal were left behind in southern and central Illinois. In the 1980s, many of these ponds were reprocessed and the coal fines were recovered and sold.
Yep, Homestead is in Lead, SD. Now shut down. It was loosely the storyline basis for the HBO Series Deadwood and kept producing gold until a few years ago.
There are so many tailings piles to re-process, Homestead being just one of them.