The Copper Discovery Hiding in Plain Sight at Marimaca

• The market prices Marimaca Copper's entire enterprise value below US$700 million, a figure that its Marimaca Oxide Deposit (MOD) alone covers.
• The MOD carries Proved and Probable Reserves of 179 million tonnes at 0.42% total copper and targets 50,000 tonnes per annum of cathode over a 13-year mine life.
• The MOD's post-tax net present value is US$709 million in the base case at US$4.30 per pound of copper and US$1.1 billion in the upside case at US$5.05 per pound of copper.
• Pampa Medina, the discovery the market is not pricing, spans management scenarios from 120 to 150 million tonnes to nearly half a billion tonnes of ore.
• Management is structuring the MOD financing to ring-fence the project and shield shareholder exposure to Pampa Medina from dilution. 

Marimaca's 2 Assets & Enterprise Value

Marimaca Copper (TSX: MARI | ASX: MC2) is priced by the market as a single enterprise value covering 2 very different assets. The first is the Marimaca Oxide Deposit (MOD), a defined copper project advancing toward a construction decision in Chile's Antofagasta region. The second is Pampa Medina, a sediment-hosted copper discovery approximately 28 kilometres to the east, still ahead of its first resource statement. 

In June 2026, the combined enterprise value sits below US$700 million. The company holds US$147.2 million in cash as of March 2026, and has no debt. With no debt on the balance sheet, that figure is effectively the market's combined price for the oxide mine, the discovery to its east, and the sulphide system beneath it.

If the defined oxide project alone can account for the entire enterprise value, then the discovery to its east is being carried at nothing. The 2 assets sit at opposite ends of the development curve, so a single enterprise value can fully reflect one and ignore the other.

Marimaca Oxide Deposit Reserves & Production Plan

The Marimaca Oxide Deposit carries Proved and Probable Reserves of 179 million tonnes at 0.42% total copper, for 748,000 tonnes of contained copper. From that base, the plan targets a cathode production rate of 50,000 tonnes per annum, averaging 48,000 tonnes per annum over the first 10 years of a 13-year mine life. Initial capital is set at US$587 million, with life-of-mine capital of US$1,198 million. On costs, the project has a C1 cash cost of US$1.45 per pound over the first 5 years, an all-in sustaining cost of US$1.97 per pound over the same period, and US$2.29 per pound over the life of mine. 

Beyond the reserve, Fitzroy reports Measured and Indicated Resources of 213 million tonnes at 0.40% total copper and Inferred Resources of 21 million tonnes at 0.29%, alongside total operating costs of US$12.3 per tonne processed over the first 5 years. The Measured and Indicated Resources of 854,000 tonnes of contained copper exceed the reserve of 748,000 tonnes, a base that stands independently of Pampa Medina. The base-case project economics assume a copper price of US$4.30 per pound, above the life-of-mine sustaining cost of US$2.29 per pound, so the operation's margin does not depend on elevated prices. Because the reserve and cost base are set by completed engineering, they hold regardless of the drilling still running at Pampa Medina. 

Copper Price Sensitivity in the Marimaca Oxide Deposit Economics 

A post-tax net present value at an 8% discount rate (NPV8%) of US$709 million for the Marimaca Oxide Deposit, based on a base-case copper price of US$4.30 per pound, with an internal rate of return (IRR) of 31%. Under an upside case of US$5.05 per pound, that figure rises to US$1.1 billion at a 39% IRR.

Set against an enterprise value below US$700 million, the base-case oxide valuation alone accounts for the market's pricing of the entire company. The upside case would place the oxide project's value at US$1.1 billion, above the sub-US$700 million enterprise value, before any credit for the discovery. The move from a 31% to a 39% IRR between the 2 price cases shows how directly the project's return scales with copper, without any change to the reserve or the cost base. 

Chief Executive Officer of Marimaca Copper, Hayden Locke, puts the comparison in plain terms:

"Let's assume $300 a tonne acid price and $5 a pound copper. If you just assume that those are run through our MOD model, it's worth more than our current share price today comfortably." 

On that basis, every element of the business other than the oxide project is carried at the market value of zero. The downside is covered by an asset the company has already modelled, and the upside, a discovery still being actively drilled, carries no cost in the current price. 

Pampa Medina as Unpriced Optionality

If the oxide project accounts for the enterprise value, Pampa Medina is the asset the market is not paying for, and its scale is not small. Drilling has confirmed economic widths and grades across more than 2 square kilometres within an initial area of interest of 3 kilometres by 1.5 kilometres, reported in the June 8, 2026, results. Grade delivery has held across the programme, with 36 of approximately 40 recent holes returning economic widths and grades. Across the high-grade corridor, 96% of holes exceeded 10% copper %-metres and 58% exceeded 20% copper %-metres.

Management's own scenarios show how quickly that translates to tonnage. In the June 10, 2026, interview, a 2-kilometre-by-2-kilometre area at a true thickness of 20 metres was estimated at 120 to 150 million tonnes of ore, while tripling that thickness to 60 metres would bring the figure to nearly half a billion tonnes of ore. The gap between those 2 scenarios is the scale of the asset that the market currently assigns no value. 

Locke frames the gap directly:

"You're effectively getting the oxide growth component, which we're very confident on, for free, and you're getting all of the sulphide component for free."

The oxide growth he refers to is a potential 25,000 to 30,000 tonnes per year of additional cathode from Pampa Medina's shallow oxide material, feeding the existing infrastructure. The deeper sulphide system, dominated by bornite and chalcocite, is a separate, longer-dated development that management describes as a completely different project with its own standalone footprint. Management frames the discovery as having tier-one potential, with the ultra-high-grade zone changing its view of the asset's quality and its capacity to deliver a strong return on invested capital. Because no resource has yet been declared, that tonnage falls outside any classified figure to which a valuation could attach, which is how a discovery of this scale reaches the market without a price.

Financing Structure & Dilution Exposure

An unpriced option holds value only if it survives to be recognised, and its main threat is dilution from funding the oxide project. Marimaca has a project financing process underway, supported by current market conditions and what the company describes as a high level of interest. It approaches the process debt-free, which widens the range of structures available to it.  

Management's stated intent is to fund the build without surrendering the discovery's upside. Locke is precise about the financing intent:  

"How do we structure our financing package so that we ring-fence the MOD and therefore preserve our shareholders' exposure to the upside of Pampa Medina, which we think is very significant. There are some very interesting proposals being made to us that allow us to do that."

A financing that isolates the oxide project would keep the discovery's value with existing shareholders rather than transferring it to new capital, protecting them in a downside scenario while the build proceeds.

Catalysts Toward a Re-Rating

Three sets of events could force the market to price the second asset. The first is Pampa Medina's maiden Mineral Resource Estimate (MRE), which follows the data cutoff at the completion of the 150 metre-spaced delineation campaign across the central area of interest. That first figure will carry an inferred classification and cover only a small subset of the prospective area, making it an entry point rather than a ceiling.  

The second is progress at the oxide project itself. The company sets 2026 milestones, including sectoral permits, securing long-lead items with delivery times beyond 50 weeks, and initiating site early works ahead of a Final Investment Decision (FID). Alongside the resource work, 2 rigs are targeting extensions of the mineralised horizon to the northeast and southwest, while geochemical and geophysical target generation continues in the Sierra Norte and Pampa Norte areas. The third is the acid-supply partnership, with the company arranging life-of-mine acid supply from a large-scale producer at a price targeted below US$300 per tonne, a direct input to the oxide project's operating cost. 

Locke is direct about what would draw a larger buyer:

"If you start to deliver a project that has 3 to 5 million tonnes of contained copper in Chile's low coastal belt, with access to infrastructure, that would grab the attention of just about every major mining company in the world. All of them are desperate for copper exposure."   

At the contained-copper threshold he describes, the discovery stops reading as exploration upside and starts reading as a second core asset within the portfolio. Each of these events converts part of the discovery from narrative into a figure that an analyst can put in a model, which is the route by which the valuation gap would close. 

The Investment Thesis for Marimaca Copper

• The market prices Marimaca Copper's entire enterprise value below US$700 million, a level that the Marimaca Oxide Deposit alone accounts for at a base-case post-tax net present value of US$709 million.
• The upside-case valuation of the Marimaca Oxide Deposit at US$1.1 billion places the defined oxide project above the market's pricing of the whole company. 
• The Pampa Medina discovery is carried at no value despite management scenarios spanning 120 to 150 million tonnes to nearly half a billion tonnes of ore.
• Management is structuring the oxide project financing to ring-fence it and preserve shareholder exposure to Pampa Medina from dilution.
• A maiden Mineral Resource Estimate, a Final Investment Decision for the oxide project, and a life-of-mine acid-supply partnership are the near-term events that could close the gap.
• A Pampa Medina resource of 3 to 5 million tonnes of contained copper would reposition the discovery as an acquisition-scale second asset rather than exploration upside.

The valuation case rests on a comparison that the company itself invites. On its own base-case economics, the Marimaca Oxide Deposit supports the entire enterprise value, leaving the market assigning nothing to a discovery whose scenarios alone reach nearly half a billion tonnes of ore. The open questions are real, since Pampa Medina has no declared resource, the optimal mining method is undecided, and the oxide project still has to clear permitting and a financing decision. What the company controls in the interim is dilution, and the stated financing strategy is built to keep the discovery's value with existing shareholders while the oxide project is funded toward a construction decision.  

TL;DR

Marimaca Copper is a Chilean copper developer whose enterprise value below US$700 million is covered in full by the Marimaca Oxide Deposit alone, on the company's own base-case economics at US$4.30 per pound copper. That leaves the Pampa Medina discovery, with management scenarios running from 120 to 150 million tonnes to nearly half a billion tonnes of ore, priced at zero. Management is arranging oxide-project financing designed to ring-fence the build and protect shareholder exposure to the discovery from dilution. The maiden MRE, the oxide-project investment decision, and a life-of-mine acid-supply partnership are the events that could force the second asset to be priced.

FAQs (AI-Generated)