Project Overview

The Resolution Copper deposit ranges from 5,000 to 7,000 ft (1,500 to 2,130 m) below the surface.

The deposit’s average grade is estimated at 1.5% copper ¹. The proposed underground mine is expected to become the largest copper mine in North America, supplying copper that’s critical to everyday life.

Our aim is that the mine will produce as much as 40 billion pounds of copper over 40 years.

History

The area around Superior, Arizona, has a long mining history dating back to the 1870s. The Magma Mine, located in the Town of Superior, started production in 1910 and operated until 1996.

The potential to develop a rich new copper deposit near Superior and reuse the already disturbed historic Magma Mine kept the site active and alive after closure. In 2004, Resolution Copper Mining assumed control of the Magma Mine site.

Resolution Copper began the U.S. permitting process in 2013, with the U.S. Forest Service (USFS) conducting a comprehensive independent review under the National Environmental Policy Act (NEPA). In April 2025, the USFS issued a 60-day notice of its intent to republish the Final Environmental Impact Statement (FEIS) and Draft Record of Decision (DROD), marking an important permitting milestone. A decade of construction will follow once final approvals are secured.

To date, project partners (55% by Rio Tinto and 45% by BHP) have spent over $2 billion to develop and permit the Resolution Copper project.

Permitting

There is no doubt that mining changes the landscape. We’re committed to protecting the land and surrounding area while we operate and after mining is complete.

To date, we have initiated a variety of land management and restoration programs to protect and balance the delicate interaction between critical environmental factors. Examples include cleanup of the historic Magma Mine site, Arizona hedgehog cactus preservation, and monarch habitat conservation.

We will continue to work with the community and our partners to progressively rehabilitate land during the life of our operations.

Federal state, and local approvals are required before construction can begin. As noted above, the U.S. Forest Service is managing the federal review under NEPA and recently signaled progress by issuing a 60-day notice to republish the FEIS and Draft ROD. This step builds on more than a decade of permitting activity and public engagement.

The Permitting Process

In 2013, Resolution Copper submitted a Mine Plan of Operations to the U.S. Forest Service (USFS), the federal agency in charge of the approval process. The document outlined our proposed plans to design, construct, operate, and close the mine. We also stated how we would reclaim and restore the area once mining is complete. The plan included baseline data about the water, air, and biology in and around the project and our plans to protect these valuable resources.

Next, the USFS formally announced its plan to develop a Draft Environment Impact Statement (EIS) for the project, which provided the public opportunity to comment on the proposed plan. What followed was years of community engagement in the review process.

In August 2019, the agency issued a Draft EIS. The Draft EIS included information about project impacts on the environment, how to mitigate or offset those impacts, and alternatives to the mine plan. After the public reviewed and commented on the draft EIS, the USFS and other agencies began conducting additional analysis of our plan. As a result, the agency may require us to change or refine our proposal.

In January 2021, the USFS published a Final EIS, but it was later withdrawn in March 2021 to allow for additional review and tribal consultation. On April 17, 2025, the USFS announced a 60-day notice of its intent to republish the FEIS and DROD. A federal land exchange will occur no sooner than 60 days following the official republication of the Final EIS

Once the republished Draft ROD is released, the public will have 45 days to submit objections. The USFS will then respond and address any concerns within 90 days. If that process is completed without further delay, the agency may issue a Final ROD and approve the project’s plan of operations.

Only after we receive final approval, and dozens of additional permits, can the Resolution Copper project move forward and begin producing copper.

Learn More

• Permitting process on the US Forest Service website
• Land Exchange parcels fact sheet (16mb PDF)

¹ This copper grade for the Resolution Mineral Resource was reported in accordance with the JORC Code and the ASX Listing Rules in Rio Tinto’s 2024 Annual Report released to the ASX on 20 February 2025. Rio Tinto confirms that it is not aware of any new information or data that materially affects the information included in the 2024 Annual Report, that all material assumptions and technical parameters underpinning the estimates in the 2024 Annual Report continue to apply and have not materially changed, and that the form and context in which the Competent Persons’ findings are presented have not been materially modified.