A large additional copper deposit is discovered deep underground, adjacent to an older mine near Superior, Arizona. Since 2004, indigenous and environmental groups have been resisting plans to construct a large copper mine. Not only would it destroy up to 6,000 hectares of public land, protected since 1955, it would also destroy the area of Oak Flat which is sacred to the San Carlos Apache tribe and other Native American tribes. Rio Tinto is the majority owner (55%, with BHP owning 45%) of Resolution Copper, the company managing the project. The proposed mine would use a controversial and technically problematic deep underground block cave mine 2,134 metres below the surface of Oak Flat. This would create a crater roughly 3,200 metres wide and 300 metres deep due to subsidence of the land.