The metal lift clangs and rattles during its 10-minute journey down to “68 Level”, over 2km beneath the scrubland near the Arizona town of Superior.
Its passengers step out into what feels like warm rain, thanks to water in the area between 68 level and the surface. They wear hard hats, steel-capped boots and a one-piece suit with emergency breathing apparatus attached to it. “Stench”, a pungent gas, will be released into the complex as an evacuation signal in an emergency.
This is the deepest part of a huge complex in Arizona’s famous “copper triangle”, which has been mined since the 19th century. Resolution Copper, its owner, has spent more than $2bn to date on developing and permitting the site.