Mr. Jason Barnard reports

RIO GRANDE RESOURCES COMPLETES 2025 FIELD PROGRAM AND ADVANCES DRILL TARGETING AT THE WINSTON GOLD-SILVER PROJECT

Rio Grande Resources Ltd. has successfully completed its 2025 geological field program at the Winston gold-silver project, located in the Black Range Mountains of Sierra county, New Mexico. The field program was carried out by Dahrouge Geological Consulting USA Ltd. and included a comprehensive site visit conducted from Dec. 2 to Dec. 8, 2025. The program focused on detailed geological mapping, targeted surface sampling and the compilation of historic mine workings to advance the company's understanding of the Winston epithermal gold-silver system and to refine priority areas for follow-up exploration and drill targeting.

Jason Barnard, president and chief executive officer of Rio Grande Resources, commented: "The completion of the 2025 field program at Winston marks an important step in advancing the project through a systematic, data-driven approach. Dahrouge's work has confirmed the presence of a well-developed epithermal gold-silver system with multiple mineralized vein trends and clear geological indicators that support continued exploration. We are now focused on integrating this work into an updated geological model to guide the next phase of exploration and drill targeting."

Exploration highlights

Field mapping confirmed that mineralization at Winston is hosted within a low-sulphidation epithermal gold-silver vein system, characterized by fissure-filling quartz veins and classic epithermal textures, including bladed quartz, comb quartz, colloform banding, vugs and amethyst, indicative of boiling zones associated with precious metal deposition.

A total of 72 samples were collected during the program, including channel and rock-chip samples, and 52 mineralized vein outcrops were mapped across the project area.

Fifty-eight historic mine workings, including shafts, adits, pits and trenches, were identified and documented, many of which were not previously captured in modern data sets.

Multiple mineralized vein trends and vein intersections were mapped, supporting the interpretation that Winston hosts a district-scale epithermal system with several prospective target areas rather than isolated structures.

Several areas, including the Ivanhoe-Emporia area, Little granite mine area and the Poverty Creek area of the Winston project, were identified as priorities for follow-up work based on structural complexity, vein density and historic development.

Geological interpretation

Observations from the 2025 field program confirm that the Winston project hosts a well-developed epithermal vein system with geological characteristics consistent with preserved precious metal mineralization. The presence of multiple vein orientations, intersecting structures and extensive historic works suggest that mineralization is structurally controlled and may occur in stacked or plunging shoots.

Mapping results indicate that vein continuity extends for hundreds of metres to over one kilometre along strike in several areas, and that the mineralized system remains open both along strike and at depth. These findings provide a strong geological framework to guide continued exploration and drill planning.

Next steps

The company plans to conduct additional work including the integration of mapping and sampling results into an updated geological and structural model, evaluation of additional geophysical surveys such as magnetic, gravity, and induced polarization methods to better define structures and alteration associated with mineralization, and improved access to certain portions of the project to support expanded sampling and mapping. This work is expected to support targeted drill planning focused on vein intersections, areas proximal to historic workings and zones exhibiting strong epithermal vein textures. Rio Grande expects to provide further updates as additional technical work is completed and exploration plans are refined.

Qualified person

The scientific and technical information contained in this news release has been reviewed and approved by Jacob Anderson CPG, MAusIMM, a qualified person as defined under National Instrument 43-101. Mr. Anderson is independent of Rio Grande Resources.

Historical results referenced in this news release have not been verified by a qualified person and should not be relied upon as indicative of mineral resources or reserves. The qualified person has reviewed the sampling and mapping data disclosed herein but has not independently verified the data. Verification included a review of field procedures, sample locations and consistency with historical records.

About Rio Grande Resources Ltd.

Rio Grande Resources is a burgeoning mineral exploration company focused on unlocking the high-grade gold and silver potential within its 3,000-acre drill-ready property in the Black Range of Sierra county, New Mexico. The company holds 100-per-cent interest in the Winston project group, which includes the two patented historic Ivanhoe and Emporia claims, and Little Granite mines, all known for their past production of high-grade precious metals. Rio Grande Resources is led by a team of experienced professionals with expertise in mineral exploration and development, who are targeting large-scale precious metal discoveries within the property's well-documented low-sulphidation epithermal setting.

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