Massive copper mine tests Trump's push to slash regulation

Superior, Arizona

RIO Tinto's proposed Resolution Copper Mine in Arizona would tunnel 2.1 km underground, where rocks radiate heat from the earth's molten core. It would suck up enough water to supply a city and leave a crater 2.4 km wide and 305 metres deep.

Planned for more than a decade, the project would be a prototype for a looming era of more invasive US mines as companies run out of easy- to-reach deposits, geologists say.