Marimaca Aligns Its Leadership for a US$587 Million Copper Mine Build

• Marimaca Copper promoted Peter Garner-Winship to Chief Financial Officer (CFO) on October 8, 2026, after he joined the company as Vice President, Finance in March 2026.
• Garner-Winship spent 17 years at Anglo American, including serving as Financial Controller for the US$5.5 billion Quellaveco copper project in Peru, from construction through the transition to operations.
• José Antonio Merino has handed over CFO responsibilities and remains Managing Director (Chile), focused on in-country development, permitting and growth strategy.
• Project Director Josh Watson brings more than 20 years of experience on multi-billion-dollar mining projects, and the board includes Zenon Wozniak, who delivered copper mine construction, including Cobre Panama.
• A separate exploration team runs Pampa Medina drilling, while financing, construction contracts, and the company's financial controls remain to be completed.

From Study Team to Build Team

Marimaca Copper (TSX: MARI | ASX: MC2 | OTCQX: MARIF) is preparing to build the Marimaca Oxide Deposit (MOD) in Chile's Antofagasta region. The 2025 definitive feasibility study (DFS) outlines an open-pit, heap leach, and solvent extraction-electrowinning (SX-EW) operation producing 50,000 tonnes per year of copper cathode at steady state over a 13-year mine life, with initial capital of US$587 million. A globally recognized engineering, procurement and construction management (EPCM) firm has been selected as lead engineer and is working alongside the Marimaca owner's team on detailed engineering. The company is targeting award of the Dry Area (crushing plant) and Wet Area (heap leaching and SX-EW) packages in the first half of 2027.

A company at the study stage is staffed around geology, metallurgy, and permitting. A company approaching construction also has to manage contracts, track spending against budget, and report to lenders, and those tasks fall on the owner's team regardless of how much work is outsourced to an engineering firm. The October 8 leadership change directly addresses that requirement.

Garner-Winship's appointment is an internal promotion. He joined in March 2026 as Vice President, Finance, and his elevation to Chief Financial Officer (CFO) moves finance responsibilities away from José Antonio Merino, who keeps the role of Managing Director (Chile). After the change, finance, in-country development, project delivery and exploration each report through a separate lead.

Financial Controls & the Quellaveco Precedent

Garner-Winship spent 17 years at Anglo American in senior roles covering corporate finance, strategic planning and capital allocation, and recently served as Head of Integrated Planning. His most directly relevant assignment was as Financial Controller for the US$5.5 billion Quellaveco copper project in Peru, where he helped build the project organization and finance function through construction and the transition into operations.

Chief Executive Officer (CEO) and Director of Marimaca Copper, Hayden Locke, connected that experience to the systems Marimaca now has to put in place:

"Peter was heavily involved in the set-up of the finance function for the successful Quellaveco construction in Peru and will leverage this experience to develop our own financial controls and systems. He also brings broad experience in financial reporting, capital allocation and risk management from his time at Anglo American."

The spending those controls will track extends well beyond the initial build. The DFS lists US$587 million in initial capital, US$77 million in expansion capital, and US$529 million in sustaining capital.  The MOD is a smaller project than Quellaveco in terms of budget, but the controller's task follows the same sequence: establish cost controls during construction, then carry them into the operating business. Marimaca's own controls and systems are still to be developed, so the appointment supplies relevant experience, and the systems themselves are the next deliverable.

In-Country Development Under a Single Remit

Merino has been part of Marimaca's management team since 2022 and brings 15 years of international and in-country experience in finance and mergers and acquisitions (M&A) in the natural resources sector, including serving as General Manager of Business Development and M&A at SQM.

Locke credited Merino's team with the permitting and commercial groundwork completed to date:

"José Antonio has been an integral member of the Marimaca management team since 2022, leading the team that delivered numerous de-risking milestones, including our environmental permits, securing water supply, power connections and commercial negotiations, our self-produced sulphuric acid strategy and other commercial initiatives."

With CFO duties transferred, Merino's remit covers all in-country aspects of MOD development and the company's broader operational, permitting and growth strategy in Chile. The open items on that list are concrete. As of October 1, 2026, Marimaca expected further permits to enable full construction to be granted in early October; site early works are scheduled to begin in the fourth quarter of 2026 with contractor packages out for tender, and upgrades to the primary access road from Ruta B-12 are targeted for completion by the end of 2026. The acid strategy his team developed has moved to a conceptual engineering study for the Dos Amigos acid plant, under a non-binding memorandum of understanding with a local acid producer. Marimaca is assessing the plant as a self-supply option to reduce exposure to sulfuric acid price volatility.

Project Delivery & Board Oversight

Josh Watson, Marimaca's Project Director, leads project delivery and has more than 20 years of experience delivering complex, multi-billion-dollar mining projects at Teck, Barrick, Vale, and Rio Tinto. His background includes leading project portfolios through studies, execution, sustaining capital, and operational readiness, which corresponds to the phases the MOD will pass through after a construction decision. Marimaca retains an owner's team working alongside its EPCM firm.

Construction experience is also present at board level. Non-Executive Director Zenon Wozniak has more than 40 years of experience leading multi-billion-dollar global mining projects and has delivered major copper mine construction, including Cobre Panama. The board also includes Non-Executive Chairman Giancarlo Bruno, a former CEO of Mantos Copper, and directors with leadership experience at Codelco, Antofagasta Minerals and Assore International Holdings. Locke has described the board as strengthened.

Marimaca has not yet awarded its main processing packages. Early works contracts, scheduled to start in the fourth quarter of 2026, and the Dry Area and Wet Area awards, targeted for the first half of 2027, will reflect the project team's procurement and contracting decisions.

Ring-Fencing Exploration From the Build

Pampa Medina, about 25 kilometers from the planned MOD processing plant, is the company's main growth asset. A 30,000 meters step-out and delineation drilling program is underway to test the extent of an oxide and sulfide sediment-hosted copper system. Vice President of Exploration Sergio Rivera, credited with several large copper discoveries including the Marimaca deposit, leads that work.

Locke described how the company has organized exploration alongside development:

"We have the luxury of running a parallel exploration strategy because we separated the teams: Sergio focuses exclusively on exploration, while a separate team focuses entirely on development. When entering construction, we will be prudent so we don't risk running short of funds, but we will continue drilling to demonstrate upside."

The separation extends to engineering scope. Before finalizing the MOD scope, Marimaca assessed the limiting factors if a significant oxide discovery were to share MOD infrastructure and identified power and water availability as key constraints. The company then sized its water pipeline to support up to 100,000 tonnes of cathode per year, and Locke has stated that MOD plant design is proceeding as planned. Pampa Medina oxides can later use MOD infrastructure, while the sulfide opportunity will take extensive drilling to understand and is not a short-term decision. Exploration is proceeding separately while the MOD design advances as planned.

What the Team Has Yet to Prove

The financing process is the first test of the new finance structure. 3 finalist groups of traditional senior secured lenders are in due diligence, with technical due diligence as the final component before Marimaca selects 1 group for exclusivity. Marimaca is targeting legal due diligence and long-form documentation through mid-2027, and the company is targeting full construction in 2027. Management has stated a relatively conservative debt-to-equity approach and an aim not to hedge.

Marimaca held US$ 140.0 million in cash and no debt as of June 30, 2026, against initial capital of US$ 587 million. The split between debt and equity for the remaining funding has not been disclosed, and Locke's commitment to prudent cash management during construction applies directly to the CFO's mandate.

The measurable tests for this team are specific: closing the debt package and long-form documents; securing the remaining construction permits and starting early works; awarding the Dry Area and Wet Area packages; and holding the MOD scope steady while Pampa Medina drilling continues. Each outcome will show whether the relevant experience translates into delivery on this project.

The Investment Thesis for Marimaca Copper

• Marimaca Copper promoted Peter Garner-Winship to Chief Financial Officer on October 8, 2026, and he previously helped set up the finance function as Financial Controller for the US$5.5 billion Quellaveco copper build in Peru.
• Finance, in-country development, project delivery and exploration now each have a dedicated lead, after José Antonio Merino handed over chief financial officer responsibilities to focus on development, permitting and growth strategy in Chile.
• Project Director Josh Watson has more than 20 years of experience on multi-billion-dollar mining projects at Teck, Barrick, Vale and Rio Tinto, and the board includes Zenon Wozniak, who delivered copper mine construction including Cobre Panama.
• The Marimaca Oxide Deposit requires US$587 million in Initial Capital. Under the 2025 Definitive Feasibility Study, the company held US$ 140.0 million in cash with no debt as of June 30, 2026, while 3 senior secured lender groups complete due diligence.
• A separate exploration team led by Sergio Rivera runs Pampa Medina drilling, and the water pipeline was oversized to deliver up to 100,000 tonnes per year of cathode in case a significant oxide discovery shares the same infrastructure.

Marimaca has placed finance, in-country development and project delivery under leaders with prior experience in each area, and it has kept exploration outside the development team's scope. Lender selection, early works contracts in the fourth quarter of 2026 and the Dry Area and Wet Area awards in the first half of 2027 will provide the first evidence of how that experience translates into delivery on the MOD.

TL;DR

Marimaca promoted Peter Garner-Winship to Chief Financial Officer on October 8, 2026. Garner-Winship previously served as Financial Controller on the US$5.5 billion Quellaveco copper project. José Antonio Merino retains his role as Managing Director (Chile), with a narrower focus on in-country responsibilities.

The leadership structure supports the US$587 million MOD development. Project Director Josh Watson leads delivery, while Zenon Wozniak brings construction experience to the board. A separate team manages exploration. Next steps include securing financing, awarding contracts, and demonstrating the effectiveness of Marimaca’s project controls in 2027.

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