Forest Service Clears South32's Hermosa Mine Plan in Arizona
A federal land agency has signed off on the mine plan for South32's Hermosa project in Arizona, clearing a key hurdle for a zinc, battery-grade manganese and copper development.
The US Forest Service has approved the mine plan of operations for South32's Hermosa project in Arizona, which hosts one of the world's largest undeveloped zinc deposits, a battery-grade manganese deposit and the emerging Peak copper discovery.
The US Forest Service has approved the mine plan of operations for South32's Hermosa project in southern Arizona, removing one of the largest single obstacles standing between a well-drilled orebody and an operating American zinc and manganese mine.
Hermosa is not an ordinary base-metals property. It hosts what is described as one of the world's largest undeveloped zinc deposits, sits alongside a battery-grade manganese resource, and includes the emerging Peak copper discovery — three distinct mineral systems on one land package, two of which sit squarely on the list of materials Washington has spent years trying to source outside China. The Forest Service decision, reported by Mining.com, is the federal land-management step that governs surface disturbance on national forest land: roads, portals, waste rock placement, water handling and the shape of the operation as it is actually built.
What a mine plan approval actually unlocks
A mine plan of operations is the document that translates a resource estimate into a physical footprint. Until a land agency accepts it, a developer can drill and study but cannot build the surface infrastructure a mine requires on federal ground. Approval does not by itself start construction — state permits, water-quality authorisations and a final corporate investment decision typically sit behind it — but it converts the largest category of permitting risk, the one investors discount most heavily, from open-ended to closed.
For a project of Hermosa's scale, the practical consequences are sequencing consequences. Long-lead items can be ordered against a defined layout. Earthworks contracts can be scoped. Engineering that had been carried at study level can be firmed up, which in turn tightens the capital cost estimate rather than leaving it as a range. Each of those steps compresses the gap between approval and first production, and each is difficult to take while a federal sign-off is still pending.
Why zinc and manganese make this a policy story
Zinc is the workhorse metal of galvanised steel — the coating that keeps bridges, transmission towers, guardrails and building frames from rusting. It is not glamorous, and it is not typically discussed in the same breath as lithium or rare earths, but new large-scale zinc supply has been thin for years as older mines have depleted. A genuinely large undeveloped deposit inside the United States is a rare thing.
Manganese is the part of Hermosa that connects it to the energy transition. Battery-grade manganese sulphate is a feedstock for lithium-ion cathode chemistries, and the refining capacity for it has historically sat almost entirely outside North America. Domestic supply of a battery-grade product, rather than raw ore shipped overseas and bought back as chemical, is precisely the gap US industrial policy has been trying to close. A permitted deposit in Arizona is a different proposition to one still at the drawing-board stage.
The Peak copper discovery is the wildcard. Copper carries its own demand story — grid buildout, electrification, data-centre power infrastructure — and an early-stage discovery adjacent to already-permitted ground is worth considerably more than the same geology in isolation, because much of the access, water and workforce logic is already resolved.
Where the shares stand
South32's US-traded depositary receipts (SOUHY) last changed hands at 18.40 in the most recent session, up 0.16% from the prior close of 18.37, having traded between 18.34 and 18.59 across the day, as of 20:00 GMT on 2 September 2026. The market is closed; that is the last trade, not a live quote.
The move is essentially flat, and that is itself informative. Permitting milestones at large diversified miners tend not to reprice the equity on the day, because the project is one asset among many and the market has usually been assigning it some probability-weighted value already. The benchmarks were mildly firm in the same session: the S&P 500 tracker closed at $765.16, up 0.44%, the Nasdaq 100 tracker at $709.24, up 0.23%, and the Dow tracker at $530.62, up 0.54%. On an illustrative basis, SOUHY's 0.16% gain trailed each of the three, meaning the day's tape offers no evidence of a re-rating tied to the approval.
The benchmarks were mildly firm in the same session: the S&P 500 tracker closed at $765.
The re-rating question, if there is one, tends to arrive later — with a capital cost number, a construction decision, or an offtake agreement that puts a buyer's name against the manganese output.
What to watch from here
Three things will tell investors whether the approval translates into a mine.
- The capital number. A defined layout should produce a firmer capex estimate. Whether that estimate holds against the cost inflation that has plagued mine construction across the industry is the first test.
- The manganese route. Battery-grade means chemical processing, not just mining. How South32 intends to produce a saleable battery-grade product — and who has agreed to buy it — determines whether the manganese is a strategic asset or a stranded one.
- Peak's drill results. An emerging copper discovery on permitted ground can change the economics of the whole package. Continued drilling, and any resource statement that follows, is the cheapest optionality in the portfolio.
There is also a legal dimension worth flagging in general terms. Federal approvals for mines on public land in the American West are routinely tested in court by environmental and tribal groups, and a signed decision is not always a final one. Nothing in the reported facts indicates a challenge here, but the pattern is common enough that the calendar between approval and construction rarely runs unimpeded.
The wider supply picture
The United States has spent the better part of a decade discovering that a critical-minerals strategy built on demand incentives runs into a permitting bottleneck on the supply side. Projects that clear that bottleneck therefore carry weight beyond their own economics — they become reference points for how long the process takes and what it takes to finish it.
Hermosa's particular value is that it is three commodities, not one. Zinc gives it a conventional industrial-metals base case that does not depend on battery demand materialising on schedule. Manganese gives it exposure to cathode supply chains if that demand does arrive. Copper, through Peak, gives it an exploration lever. Few single land packages in the US offer that combination, and fewer still now have a federal mine plan behind them.
Key facts
- Approval: US Forest Service signed off on the Hermosa mine plan of operations, Arizona
- Deposits: One of the world's largest undeveloped zinc deposits, battery-grade manganese, plus the Peak copper discovery
- SOUHY last trade: 18.40, +0.16% vs prior close 18.37, as of 20:00 GMT 2 Sep 2026
- Day range: 18.34–18.59 in the most recent session
Frequently asked questions
What did the US Forest Service approve?
The Forest Service approved the mine plan of operations for South32's Hermosa project in Arizona. A mine plan of operations governs surface disturbance on federal land — roads, portals, waste rock placement and water handling. Approval sets the physical footprint of the operation and removes the principal federal land-management hurdle, though other permits and a corporate investment decision typically remain.
What metals does Hermosa contain?
Hermosa hosts three distinct mineral systems: one of the world's largest undeveloped zinc deposits, a battery-grade manganese deposit, and the emerging Peak copper discovery. Zinc is used chiefly for galvanising steel, manganese is a cathode feedstock for lithium-ion batteries, and copper serves grid, electrification and data-centre infrastructure demand.
Does approval mean construction starts immediately?
No. A mine plan approval clears the federal land-use pathway but does not by itself begin construction. State permits, water-quality authorisations and a final company investment decision generally follow. What approval does deliver is a defined layout, which allows engineering to be firmed up, long-lead equipment to be ordered and capital cost estimates to be tightened.
How did South32's US-listed shares react?
South32's US depositary receipts under the symbol SOUHY last traded at 18.40, up 0.16% from a prior close of 18.37, with a session range of 18.34 to 18.59, as of 20:00 GMT on 2 September 2026. That is essentially flat and trailed the day's gains in the S&P 500, Nasdaq 100 and Dow tracking funds.
Why does battery-grade manganese matter for US supply chains?
Battery-grade manganese sulphate is a feedstock for several lithium-ion cathode chemistries, and the refining capacity to produce it has historically sat largely outside North America. A domestic deposit capable of yielding a battery-grade product, rather than ore exported for processing abroad, addresses a specific gap that US critical-minerals policy has targeted.
What are the main risks from here?
The chief risks are cost inflation pushing the capital estimate higher, uncertainty over how and where battery-grade manganese chemical would be produced and sold, and the possibility of legal challenge. Federal mine approvals on public land in the American West are frequently contested in court, which can extend the timeline between sign-off and construction.
Sources
Photo: Danilo Tic from Slovenska Bistrica, Slovenia · BY-SA 2.0 — source
