The venture is currently developing a modern underground mine at the site. Rio Tinto owns 55% of the project, with BHP holding the balance. 

The Magma Copper Co mined and processsed ore at the site between 1910 and 1996, including smelting operations until 1971.

Resolution Copper has performed reclamation work since 2005, which included more than a decade of soil clean-up, placing a cover with soil and vegetation over the historic tailings, restoring and establishing drainage for the conveyance of stormwater, reshaping and vegetating development rock piles, removing the old concentrator complex and smelter structures.

The Arizona Department of Environmental Quality (ADEQ) has approved the work, and Resolution will continue post-closure monitoring for the next three decades, including groundwater monitoring, surface water monitoring, regular inspection of all facilities and monitoring of the vegetative cover.

Resolution Copper recently completed a US$200 million project to deepen Mine Shaft 9, originally constructed in 1971. It has been sunk a further 2,000 feet to over 6,800 feet underground. It now connects to the newer Shaft 10 in two places, improves ventilation, and increases safety by providing a second exit for workers.

The venture will now focus on the maintenance of Shaft 9 and 10 and continuing the underground characterization study to increase ore-body knowledge, as the project continues to progress through a multi-year federal, state and county permitting process.