Mr. Hayden Locke reports

MARIMACA SECURES MOD GRID CONNECTION AUTHORIZATION AND AGREES KEY COMMERCIAL TERMS FOR POWER SUPPLY; PROVIDES PROJECT UPDATE

Marimaca Copper Corp. has discussed various development activities at the Marimaca oxide deposit (MOD), including the receipt of the grid connection authorization for the MOD and the key commercial terms for a power purchase agreement (PPA) framework. Marimaca has also received an overall A rating in its 2025 independent Digbee sustainability assessment, its third consecutive A rating.

Hayden Locke, chief executive officer and director of Marimaca Copper, commented:

"The approval of our grid connection is an important derisking milestone for the Marimaca oxide deposit. Together with the preliminary power purchase agreement framework, it provides a clear pathway to securing 100-per-cent renewable power at a cost closely aligned with our definitive feasibility study (DFS) assumptions. Importantly, the proposed commercial structure provides the flexibility required during commissioning and ramp-up.

"More broadly, we continue to make steady progress towards construction readiness. Access-road upgrades are advancing, early works packages are out for tender, key permits remain on track and detailed engineering is progressing well.

"Our third consecutive 'A' rating from Digbee, achieved under the more rigorous development phase framework, further reinforces the MOD's strong sustainability credentials. These achievements reflect the team's disciplined approach to planning and commercial execution as we advance the MOD."

Key project updates

• Power/electrical connection:
  • On Sept. 22, 2026, following a review and challenge period, the Panel of Experts upheld the National Electric Coordinator's (CEN) approval of Marimaca's application to connect to the 110-kilovolt El Lince Line, located approximately 13 kilometres from the MOD project area.
  • Additionally, Marimaca has signed a preliminary PPA framework agreement with a well-known energy provider in Chile to supply the MOD with 100-per-cent renewable energy from the national grid.
    • Agreed to long-term energy pricing resulting in an estimated all-in cost closely aligned with the energy cost provided in the MOD DFS ($93 (U.S.)/MWh).
    • Contract structured with flexibility to achieve commercial production with a ramp-up period that does not include any take-or-pay provisions.
    • Initial five-year term after the ramp-up period, postcompletion of the MOD construction.
• Detailed engineering and site early works
  • Upgrades to the primary MOD access road, which spurs from Ruta B-12, a paved national highway, are progressing well and are expected to be completed by the end of 2026.
  • Site early works are on schedule to commence in Q4, with contractor packages currently out for tender.
    • Activities will focus on establishing key facilities, roads and utilities to accommodate full-scale construction activities.
    • An additional workstream is planned to bring forward preparatory work for the seawater pipeline route to enable construction commencement in 2027.
  • Permitting workstreams progressing according to plan, with further key permits to enable full construction expected in early October.
  • Detailed engineering is continuing, with a globally recognized EPCM firm selected as lead engineer, working alongside the Marimaca owner's team.
    • Priority focus is site-layout optimization from the DFS and progressing detailed engineering for core project areas.
    • Key engineering procurement packages, including the dry area (crushing plant) and wet area (heap leaching and SX-EW plant), are expected to be awarded in H1 2027.
• Sulphuric acid
  • Further to the announcement on May 20, 2026, Marimaca is pleased to announce that as part of the non-binding memorandum of understanding (MOU) with a leading local acid producer, it has commenced the conceptual engineering study to define the optimal development pathway of the Dos Amigos acid plant (PADA plant).
  • The engineering study will focus on evaluating the optimal approach to developing the PADA plant to support the MOD via a self-produced acid option, which has the potential to reduce exposure to acid price volatility.

2025 Digbee assessment

• The company is pleased to announce the completion of its fifth independent ESG (environmental, social and governance) performance assessment via the Digbee ESG reporting framework.
• First assessment completed under the development phase framework, reflecting the company's progression on the MOD following the release of the DFS in 2025.
  • Development phase framework includes a more rigorous disclosure standard than prior submissions, including a focus on closure planning, community development commitments, work force planning and water management.
• Third consecutive year of achieving an A rating highlights the MOD's industry-leading ESG credentials:
  • Very favourable access to regional infrastructure given the MOD's location within 25 km of the Port of Mejillones;
  • No impact on local water supply -- recycled seawater secured from the Port of Mejillones for life of mine water requirements;
  • A pathway to securing 100-per-cent renewable energy from Chile's national grid, supported by the approved grid connection and PPA framework;
  • Use of leaching processing method removes the requirement of a wet tailings storage facility (TSF);
  • Production of copper cathode through SX/EW removes the Scope 3 emissions generated from smelting and refining of copper concentrates.
• The full report is available on the Marimaca Copper website.

About Marimaca Copper Corp.

Marimaca is a Toronto Stock Exchange- (MARI) and Australian Securities Exchange- (MC2) listed copper company focused on the development of high-quality copper assets in northern Chile. The company's flagship asset is the Marimaca oxide deposit project (MOD), located in Chile's prolific Antofagasta region. It is one of the few globally significant greenfield copper discoveries made in the last decade and represents a low-risk development opportunity, given the proximity to the city of Antofagasta and port of Mejillones, with substantial exploration upside. The company also controls additional exploration properties at Pampa Medina and Madrugador within the Sierra de Medina region, located 30 kilometres from the MOD, where recent drilling has identified both oxide extensions and high-grade sulphide mineralization at depth.

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