Arizona Sonoran to Advance Cactus Copper Project Solo After Nuton Venture Talks End

CASA GRANDE, AZ – December 29, 2025 – Arizona Sonoran Copper Company (ASCU) has announced a significant strategic pivot for its flagship Cactus Project, signaling its intent to proceed on a standalone basis after mutually agreeing with Nuton, a technology venture of mining giant Rio Tinto, to discuss an early termination of their joint venture option agreement.

The announcement marks a decisive turn for the Arizona-based copper developer, which will now shoulder the full responsibility and potential rewards of developing what it terms a "generational open pit copper mine." The companies will begin formal discussions in January to amicably dissolve the agreement, which would have given Nuton the option to form a joint venture to develop the large-scale copper resource located near Casa Grande, Arizona.

While the termination of a potential partnership with a global industry leader like Rio Tinto could be perceived as a setback, ASCU is framing the move as a vote of confidence in the project's standalone viability. The company is moving forward with a clear and aggressive timeline, underscoring its belief in the robust economics of the Cactus Project.

A New Chapter and a Clear Path Forward

Rather than pausing to reassess, Arizona Sonoran Copper is accelerating its independent development plans. The company confirmed it will proceed directly with a Definitive Feasibility Study (DFS) for the Cactus Project, building on a positive Pre-Feasibility Study (PFS) completed recently. A DFS is a comprehensive and detailed technical and economic evaluation that serves as the final basis for a board to make a final investment decision (FID).

ASCU has set an ambitious target for this next phase, aiming to complete the standalone DFS in the second half of 2026. This would pave the way for a potential final investment decision on the mine’s construction as early as the fourth quarter of 2026. This timeline suggests that the company has a high degree of confidence in the project's fundamentals and its ability to secure the necessary project financing independently.

Alongside the critical feasibility study, the company will continue advancing related permitting amendments, project financing workstreams, and other early development activities. This parallel processing of key project milestones is a common strategy for developers looking to fast-track a project to production and minimize delays.

Company executives have indicated they do not intend to provide further updates on the discussions with Nuton until a definitive outcome is reached, a standard practice to avoid speculation during sensitive negotiations. The statement emphasizes that there is no certainty regarding the timeline or final terms of the termination, but the direction is clear: ASCU is preparing for a future where it retains 100% ownership and control of the Cactus Project.

Unpacking the "Generational" Cactus Mine

The confidence to proceed alone stems from the unique attributes of the Cactus Project itself. Located entirely on privately held land, the project is a "brownfield" site, meaning it is the location of a previous mining operation. This provides significant advantages over "greenfield" projects built from scratch. Brownfield sites typically benefit from a greater understanding of the local geology, established community relationships, and often, some level of existing infrastructure, which can substantially de-risk development and reduce initial capital costs.

ASCU highlights that the project is supported by in-place infrastructure, including nearby highways and rail lines, as well as onsite permitted water access—a critical and often contentious issue for any mining project in the arid Southwest. Furthermore, being on private land allows the project to proceed through a more streamlined state-led permitting process, avoiding some of the lengthy and complex federal reviews that can delay projects on public lands for years.

The project is centered on a large-scale porphyry copper resource. Porphyry deposits are the world's most significant source of copper and are known for their large size and long operational lifespans, which aligns with ASCU's description of Cactus as a "generational" asset. The company's objective is to develop Cactus into a mid-tier copper producer with low operating costs, capable of generating robust returns for investors while operating in a sustainable and responsible manner.

Copper's Critical Role and Market Dynamics

The strategic decision comes at a pivotal time for the global copper market. Copper is an indispensable metal for the world's transition to a green economy. It is a critical component in electric vehicles, wind turbines, solar panels, and the expanded electrical grids required to support them. This secular trend is projected to create a significant supply-demand gap in the coming years, placing a premium on new, stable sources of production.

Developing a major copper mine within the United States provides a strategic advantage, offering a secure domestic supply chain for a metal deemed critical for economic and national security. By advancing the Cactus Project independently, ASCU is positioning itself to capture the full upside of these powerful market tailwinds. While this path means the company will bear the full weight of financing and development risks, it also means it will not have to share the profits with a joint venture partner.

The company is led by an executive team and board with a stated track record of successful project delivery in North America. This experience will be put to the test as they navigate the complexities of project financing and development on their own. The market will be watching closely as ASCU works to turn its solo vision for the Cactus Project into a producing copper mine, a move that could establish it as a significant new player in the North American copper industry.