Rio Tinto has put fresh money behind one of the most contested copper projects in the country. The Northern Miner first reported that Rio Tinto’s board approved $144 million in additional spending at Resolution Copper, the proposed underground mine near Superior, Arizona, days after the long-fought land exchange that unlocked the project cleared its final legal hurdle.
- The approval: Rio Tinto approved $144 million in new spending at Resolution Copper, a joint venture it owns 55 percent alongside BHP’s 45 percent stake. Rio Tinto’s own share of the new spending is $79 million.
- What it funds: feasibility studies, final design engineering, equipment for the project’s two deep shafts, new water treatment facilities, continued exploration drilling, and long-lead electrical equipment.
- The jobs: roughly 50 new positions across mining, geotechnical, geological, engineering, and project-services work.
- The scale claim: Rio Tinto says Resolution Copper could eventually supply up to 25 percent of U.S. copper demand, a projection tied to a mine that has not reached a final construction decision.
- The legal backdrop: the spending follows the March 2026 completion of a federal land exchange that the U.S. Supreme Court let stand in 2025 over San Carlos Apache Tribe objections.
What did Rio Tinto just approve?
The $144 million adds to roughly $500 million in preliminary spending Rio Tinto announced in March 2026, when the land exchange for the project first closed. Engineering & Mining Journal reported that the new money advances engineering and underground development at a site that sits 5,000 to 7,000 feet below the surface near Superior, east of Phoenix. Rio Tinto Copper chief executive Katie Jackson said the spending accelerates underground development and positions the project for its next investment decision, language that signals Resolution Copper is still years from an actual construction commitment.
Why does Oak Flat remain contested?
The land at the center of this deal, known to the San Carlos Apache Tribe as Chi’chil Bildagoteel or Oak Flat, is a sacred site the tribe and allied groups fought for years to keep out of Resolution Copper’s hands. The Apache Stronghold coalition took its case to the U.S. Supreme Court, which declined to block the land transfer in 2025, and the exchange closed in March 2026. That ruling ended the litigation but did not end the opposition: the tribe and conservation allies continue to object on cultural and environmental grounds, even as Rio Tinto says it is working toward an outside resolution with affected tribes. Any Pulse reader following this project should treat the land exchange as legally final and the underlying conflict as still unresolved.
What is the $144 million actually funding?
None of this money builds a producing mine yet. It pays for feasibility studies and final design engineering, for installing development and production-level equipment in both of the project’s shafts, for new water treatment infrastructure, and for exploration drilling that refines the resource ahead of a later investment decision. Resolution Copper uses block-cave mining, a method that lets gravity help break and collect ore thousands of feet underground, which is part of why the shaft work and engineering studies matter before any ore reaches the surface at scale.
Why does this matter for America’s copper supply?
Arizona already produces most of the nation’s copper, and our Arizona state report tracks the state’s working mines alongside projects still years from production. Resolution Copper is often described as one of the largest untapped copper deposits in North America, and Rio Tinto frames it as a future source of a meaningful share of U.S. supply. That framing is still aspirational. The company has not announced a production timeline, and the project needs at least one more major investment decision before shafts built for exploration become shafts that move ore. What is real today is $144 million in approved spending, about 50 new jobs, and a legal path that, however contested on moral grounds, is no longer blocked in court.