Resolution Copper Oak Flat: Land Swap, Courts, Resource

Resolution Copper is a planned underground copper mine beneath Oak Flat, near Superior in Pinal County, Arizona. Rio Tinto owns 55% and operates it, and BHP owns 45% (Rio Tinto Annual Report, 2025). The congressionally ordered land exchange was completed on 16 March 2026 (Resolution Copper), but the project is not yet a mine. Rio Tinto still describes it as being in the permitting and study stage, and litigation continues. This page sets out the status, the court cases, the ownership and the resource figures from company filings, with sources on every number.

Terms used below. A Mineral Resource is a body of rock that a company reports with reasonable prospects of eventual economic extraction. It is not a Mineral Reserve, which has passed mining and economic tests. Indicated resources are known with moderate confidence and inferred resources with low confidence. Grade is the share of copper in the rock, written as % Cu. Panel caving is an underground method that lets the rock above the ore collapse in a controlled way. The FEIS is the final environmental impact statement and the ROD is the record of decision. A preliminary injunction is a court order that pauses an action while a case goes on. En banc means a rehearing by a larger group of judges of the same court. This page gives facts from filings, courts and agencies. It takes no side and is not legal or investment advice.

Where the Oak Flat land exchange stands

Congress ordered the exchange in December 2014. The Forest Service transferred 2,422 acres of Tonto National Forest land, which includes Oak Flat, to Resolution Copper in March 2026. In return the company handed over more than 5,000 acres of private land to the federal government. The company and BHP give 16 March 2026 as the completion date. Eos gave 13 March, which is the date of the Ninth Circuit ruling that cleared the way. The Forest Service record of decision, Resolution Copper, BHP and a KJZZ report of 16 March all place the transfer on Monday 16 March.

BHP says the exchange remains subject to ongoing litigation, and that the litigation is not currently affecting technical work (BHP Annual Report on Form 20-F, financial year 2026). The ownership change also did not close the site. Resolution Copper says it will keep the Oak Flat campground open to the public, run by 4Winds Contracting, a company owned by a San Carlos Apache Tribe member.

▶ A two-minute example from one survey in which most of the anomalous ground sat under a town, so land access rather than rock quality decided what could be mined. · 2:05

Who owns Resolution Copper

Resolution Copper Mining LLC is a joint venture formed in 2004, with Rio Tinto as operator and 55% owner and BHP as 45% owner (BHP Form 20-F, 2026). Rio Tinto’s subsidiary Kennecott Exploration entered the project in 2001 under an earn-in agreement and became operator in 2004, and the deposit itself was found in 1996 by a drill hole angled from the old Magma Mine workings (Rio Tinto, 2025). The Magma Mine worked the nearby Magma Vein until 1998.

Chart

Resolution resource tonnage, project and BHP share

Million tonnes; Rio Tinto at 31 December 2025, BHP at 30 June 2026

Ownership matters for the numbers. Rio Tinto reports Resolution on a full-project basis and shows its own 55% interest in a separate column. BHP reports only its 45% share. The two companies’ tables agree once you apply the percentage. Rio Tinto lists 724 Mt of indicated resource at 1.89% Cu, and BHP lists 326 Mt at the same grade, which is 45% of 724 Mt. The chart above shows both bases side by side.

Oak Flat timeline from discovery to rehearing denial

1. 1955. President Eisenhower’s order protects the Oak Flat area from mining, according to KJZZ and Agri-Pulse.
2. 1996. The Resolution deposit is found by a drill hole from the Magma Mine workings (Rio Tinto, 2025).
3. 2001 to 2004. Kennecott Exploration enters an earn-in agreement and becomes operator; the Resolution Copper joint venture follows (Rio Tinto and BHP filings).
4. December 2014. Congress passes the Southeast Arizona Land Exchange and Conservation Act as Section 3003 of the 2015 National Defense Authorization Act, Public Law 113-291 (Forest Service final EIS).
5. March 2016. Oak Flat is listed in the National Register of Historic Places as a traditional cultural place (final EIS).
6. August 2019. The Forest Service publishes the draft environmental impact statement (final EIS).
7. 15 January 2021. The first final EIS is published, and three plaintiff groups sue, including Apache Stronghold.
8. 1 March 2021. The US Department of Agriculture directs the Forest Service to withdraw the final EIS to review tribal and cultural concerns (final EIS).
9. March 2024. The full Ninth Circuit, sitting en banc, rules in Apache Stronghold v. United States that the land exchange did not burden the plaintiffs’ religious exercise (as described in the Ninth Circuit opinion, 2026).
10. 27 May 2025. The Supreme Court denies review of that case, with Justice Gorsuch, joined by Justice Thomas, dissenting (Supreme Court order, No. 24-291).
11. 20 June 2025. The Forest Service republishes the final EIS and draft record of decision, which restarts the 60-day clock in the Act for the land transfer.
12. June to August 2025. The district court denies injunctions on 6 June, 15 August and 17 August. On 18 August the Ninth Circuit enters an administrative stay that holds the transfer in place.
13. 6 October 2025. The Supreme Court denies Apache Stronghold’s petition for rehearing.
14. 7 January 2026. The Ninth Circuit hears oral argument on the appeals.
15. 13 March 2026. The Ninth Circuit panel affirms the denial of the injunctions and dissolves the stay.
16. 16 March 2026. The record of decision is signed and the land exchange is completed.
17. 19 March 2026. Justice Kagan denies an emergency application to halt the transfer.
18. April 2026. Opponents file an amended lawsuit in federal court.
19. 29 September 2026. The Ninth Circuit denies rehearing en banc (KJZZ).

The Oak Flat court cases explained

There are two groups of cases, and they are often mixed up. The first group is about religion. Apache Stronghold, a non-profit led by Apache members, argued that mining under Oak Flat would stop Apache worship there. It sued under the First Amendment and under the Religious Freedom Restoration Act. The en banc Ninth Circuit rejected the claim in March 2024, and the Supreme Court declined to hear it on 27 May 2025. Justice Gorsuch wrote that the Court should have taken the case, calling its refusal a “grievous mistake” (Eos).

The second group is about the process. The Arizona Mining Reform Coalition, the San Carlos Apache Tribe and a separate set of Apache plaintiffs (the Lopez plaintiffs) challenged the land appraisal, the environmental review under NEPA, tribal consultation under the National Historic Preservation Act and the Land Exchange Act, and religious freedom. The Ninth Circuit panel found that the plaintiffs had standing to sue. It then held that none was likely to win on the merits, so it affirmed the denial of a preliminary injunction.

What the March ruling decided, and what it did not

The ruling was about a preliminary injunction, not a final judgment. The panel applied the earlier en banc decision to the religion claims and said it was bound by it. It also wrote that the transfer will fundamentally alter the land, including sites sacred to the Tribe and the Lopez plaintiffs, and that Congress chose to transfer the land despite those harms. A note in the opinion says Judge Rawlinson would dissent on the appraisal question. The September 2026 rehearing denial does not necessarily end the litigation (Chamber Business News, 2026).

The rehearing denial and the dissents

On 29 September 2026 the Ninth Circuit declined to rehear the case. The request did not win enough support among the court’s active judges. Several judges dissented from that decision and argued that the court should reconsider how federal religious freedom law applies to the exchange. KJZZ reports that Chief Judge Mary Murguia wrote that the court missed a second chance to fix what she called a tragic error (KJZZ, 2 October 2026). Resolution Copper called the denial yet another ruling in its favour. No new Supreme Court petition against the March ruling had been reported in the sources we reviewed by 15 October 2026.

What can still be challenged

Owning the land does not give the company every permit. KJZZ reports that plaintiffs can still sue over new projects, such as a transmission line or a road, so development could be delayed on those fronts (KJZZ, 15 April 2026). The company also needs state and local permits, and Rio Tinto lists air quality and aquifer protection permits among those still required.

Resolution Copper resource figures from company filings

Rio Tinto’s 2025 Annual Report gives the resource as at 31 December 2025, on a full-project (100%) basis, as a dry in-situ weight. It lists no Ore Reserve for Resolution. The table below shows the figures. The second table shows BHP’s share, which BHP reported as at 30 June 2026. BHP says it declared a Mineral Resource for Resolution for the first time in its 2026 financial year.

Chart

Grade of measured and indicated copper resources, selected Rio Tinto projects

% Cu, 100% basis, as at 31 December 2025; Resolution shows its indicated category, the only measured-or-indicated one reported there

Our own arithmetic on those figures gives about 13.7 Mt of copper in the indicated category (724 Mt at 1.89%) and about 14.5 Mt in the inferred category (1,134 Mt at 1.28%), roughly 28 Mt in total. That is metal in the ground. It is not a production forecast, because mining and processing losses and cost cut-offs reduce what could be sold.

BHP states its estimate at the operator’s consensus prices, which include 421.08 US cents per pound of copper, and its tables are exclusive of reserves (BHP Form 20-F, 2026). The deposit is a porphyry copper and molybdenum system, which is the type that USGS describes as supplying about 60% of the world’s copper at an average of 0.44% Cu in mined ore (2008 figure). A grade of 1.5% to 1.9% Cu is several times that average. Grade alone does not make a mine, since depth, rock strength, water, permits and cost all matter, and this ore lies 4,500 to 7,000 feet below the surface.

Why you will see different tonnage numbers

Several figures circulate for the same deposit, and they measure different things. The final EIS cites an older estimate of 1.787 billion tonnes at an average 1.54% Cu. The Ninth Circuit opinion describes a deposit containing almost two billion metric tons. The mine plan that Resolution Copper proposed and the Forest Service reviewed, by contrast, removes about 1.4 billion tons of ore (the final EIS uses short tons) to produce 40 billion pounds of copper. That plan figure is smaller than the resource because a mine plan covers only the part of the rock that the company proposes to mine. Use the Rio Tinto and BHP tables for the resource and the final EIS for the plan.

Taking the plan’s numbers, 40 billion pounds is about 18.1 Mt of copper. Spread over the planned 41 years of operation, that is roughly 0.44 Mt a year (our arithmetic). The calculator on this page lets you try your own tonnage, grade, recovery and price.

What the final environmental impact statement projects

The Forest Service’s final EIS, republished in June 2025, is the main public description of the plan (Forest Service final EIS, volume 1). Its headline projections are below. They are projections from the review, not measurements.

• Method and depth. Underground panel caving at 4,500 to 7,000 feet, with ore processed at the old Magma Mine site in Superior.
• Schedule. About 10 years of construction, about 41 years of operation and 5 to 10 years of reclamation.
• Surface subsidence. A crater that starts to appear in year 6 of mining and ends up 800 to 1,115 feet deep and about 1.8 miles across at Oak Flat.
• Tailings. About 1.37 billion tons of tailings, which are the ground-up waste rock left after the copper is extracted. The Forest Service’s preferred option is the Skunk Camp site.
• Water. External water needs of 180,000 to 590,000 acre-feet over the life of the mine, depending on the alternative. An acre-foot is about 325,851 US gallons.
• Jobs. An average of about 2,100 people a year in Pinal County during operations and another 1,700 elsewhere.

The final EIS lists the loss of Oak Flat, which Native Americans hold as sacred, among the main areas of controversy, along with water use, public safety and air and water quality. It says the Forest Service looked at other mining methods to avoid subsidence and found them unreasonable. The company says the project could eventually supply up to 25% of US copper demand and generate up to US$61 billion in economic value for Arizona over its life. These are company estimates, and Chamber Business News reports them (Chamber Business News, 2026).

▶ Covers seven environmental impacts of mining in plain words, as a claymation with satellite maps and sourced numbers. · 2:31

Why Oak Flat copper matters for US supply

The US mined an estimated 1.0 million tonnes of copper in 2025, down 5% on 2024, and Arizona produced about 70% of it. Net import reliance was an estimated 57% of apparent consumption (USGS Mineral Commodity Summaries 2026, Copper). Apparent consumption of primary refined copper and copper from old scrap was an estimated 2.2 million tonnes. If the plan averages 0.44 Mt a year, that is about a fifth of 2025 US apparent consumption, though the company’s own “up to 25%” claim refers to its own basis.

Chart

US copper mine output and consumption, 2021 to 2025

Thousand tonnes of copper; 2025 values are USGS estimates; consumption is primary refined copper plus copper from old scrap

For wider copper context, see our guides to copper deposit types and top countries and to porphyry copper deposits and their grades.

▶ Explains why electric vehicles use more copper than petrol cars, how the giant Chilean pits work and how refined copper reaches a motor. · 6:03

What to watch next

• The Supreme Court. Opponents could ask the Court to review the March ruling. No such petition had been reported in the sources we reviewed by 15 October 2026.
• The district court cases. The suits filed in April 2026 and the original NEPA, appraisal and consultation cases can continue.
• Power line, road and pipeline. The record of decision also authorizes permits for related infrastructure, including a power line and pipeline (Agri-Pulse), and each piece can draw its own challenges.
• State and local permits. Rio Tinto lists air quality and aquifer protection permits as future requirements.
• Drilling and underground work. BHP says the exchange enables the next phase of technical work and development planning. The company’s general manager told KJZZ it plans to do more drilling in the future.
• The investment decision. The Rio Tinto and BHP filings we read give no decision date for construction or first production.

How satellite imagery fits a project like this

Public satellite images let anyone follow surface change at a site over time, such as new roads, drill pads, tailings corridors and, eventually, subsidence. They show what is on the surface and cannot show what is underground, so they never replace drilling, resource estimation or legal review. Farmonaut’s mining service works from a licence boundary you send as KML, KMZ or a polygon and returns satellite-derived exploration targets, which sit ahead of a resource estimate. It is not an environmental or social clearance. To check who holds a claim or licence before you map it, see our guide to mining cadastre portals.

Frequently asked questions

Who owns Resolution Copper?

Rio Tinto owns 55% and is the operator, and BHP owns 45%. Both companies state this in their latest filings (Rio Tinto Annual Report, 2025; BHP Form 20-F, 2026).

Is the Oak Flat land exchange complete?

Yes. Resolution Copper and BHP give 16 March 2026 as the completion date. The exchange still faces litigation, according to BHP.

How much copper is at Resolution Copper?

Rio Tinto reports 1,859 Mt of Mineral Resource at 1.52% Cu on a full-project basis as at 31 December 2025. That is 724 Mt indicated at 1.89% Cu and 1,134 Mt inferred at 1.28% Cu. BHP’s 45% share is 326 Mt indicated and 510 Mt inferred.

Is Resolution Copper a working mine yet?

No. Rio Tinto describes the project as being in the permitting and study stage, and BHP lists the property at exploration stage. The site has old workings from the Magma Mine and two existing shafts, but the Rio Tinto and BHP filings we read announce no construction decision or first-production date.

What did the Ninth Circuit decide in March?

A three-judge panel affirmed the denial of preliminary injunctions that would have blocked the exchange, and it dissolved the stay that held the transfer in place. It found the plaintiffs unlikely to win on their appraisal, NEPA, consultation and religion claims. It was not a final judgment on the whole case.

Did the Supreme Court hear the Oak Flat case?

No. On 27 May 2025 the Court denied review in Apache Stronghold v. United States, and on 6 October 2025 it denied rehearing. On 19 March 2026 Justice Kagan denied a separate emergency application. Justices Gorsuch and Thomas dissented from the May 2025 denial.

How many acres changed hands?

The Forest Service transferred 2,422 acres at Oak Flat. The final EIS says the company offered 5,460 acres of private land in return, and the company says the public received more than 5,400 acres. Reports of the acreage differ slightly, so quote the document you rely on.

How big will the crater be?

The final EIS projects a subsidence crater of 800 to 1,115 feet deep and about 1.8 miles wide, starting to appear in year 6 of mining and growing over about 40 years. It results from panel caving.

Why is Oak Flat important to Apache people?

Western Apaches regard Oak Flat, called Chí’chil Biłdagoteel, as sacred. The Supreme Court dissent describes it as a direct corridor to the Creator and a place for ceremonies that cannot be held elsewhere. The National Register of Historic Places listed it as a traditional cultural place in 2016.

Is the Resolution Copper resource the same as a reserve?

No. A Mineral Resource has reasonable prospects of eventual economic extraction but has not passed the tests for a reserve. Rio Tinto lists no Ore Reserve for Resolution, and about 61% of the total tonnage is in the lower-confidence inferred category.

Where is Oak Flat?

It is in Pinal County, Arizona, about 60 miles east of Phoenix near the town of Superior, inside the area that was the Tonto National Forest before the exchange.