North Antelope to Black thunder: the ten biggest coal mines in .
WEBJul 16, 2014 · The Belle Ayr coal mine owned by Alpha Natural Resources and loed in the Powder River Basin, 18 miles southeast of Gillette, Wyoming, was estimated to hold around 350mt of proven and probable coal reserves by the end of 2013. Belle Ayr produced of coal in 2013, becoming the sixth highest producing coal mine in the country .