Mr. Jason Barnard reports

RIO GRANDE RESOURCES SECURES HISTORICAL NORTH STAR AND LITTLE WONDER MINES AND CONFIRMS MINERALIZATION WITH RETURNED SAMPLES OF UP TO 35.9 G/T GOLD AND 248 G/T SILVER

Rio Grande Resources Ltd. has staked 26 additional lode mining claims covering approximately 537 acres at its 100-per-cent-owned Winston gold-silver project in Sierra county, New Mexico. The staking expands the company's claim block incorporating the historic North Star and Little Wonder mine areas and additional prospective ground along interpreted mineralized structural trends identified during Rio Grande's May, 2026, exploration program. The program has significantly advanced Rio Grande's understanding of the structural controls on mineralization at Winston and provided the company with new geological information from the North Star-Little Wonder area immediately west of the company's previous claim boundary.

"The results from Poverty Creek gave us a compelling reason to continue following the geology beyond our existing claim boundary," said Jason Barnard, chief executive officer of Rio Grande. "At Poverty Creek, we returned channel samples grading up to 46.3 g/t gold and 1,030 g/t silver, together with high-grade results across multiple interpreted mineralized vein corridors. As our understanding of that system developed, our work at the North Star and Little Wonder historical mines and area surrounding, it returned gold and silver mineralization in all samples collected. With our structural interpretation indicating these veins may form part of a broader network extending from Poverty Creek, securing this ground was an important next step. We now have a substantially larger area over which to test the extent and continuity of the mineralized system as we work to understand the potential scale of Winston and look forward to drill testing the potential of these samples and this area in our inaugural drill program."

Sampling results

The decision to increase the Winston claim block follows the company's phase 2 exploration program, which included surface sampling, rock chip sampling and structural mapping program (see press release dated May 6 and May 21, 2026) completed by Dahrouge Geological Consulting USA Ltd. Dahrouge identified vein trends and epithermal textures in the area, providing the geological basis for Rio Grande to secure the historical workings and surrounding prospective ground.

Seven samples collected in the phase 2 program from the North Star-Little Wonder area returned gold and silver mineralization, including 3.21 grams per tonne gold and 351 g/t silver, 2.69 g/t gold and 70.6 g/t silver, and 1.38 g/t gold and 317 g/t silver. Table 1 below provides full assay results, including samples from the company's 2020 exploration program (see news release dated Sept. 21, 2020) that includes never released sample results including 35.9 g/t gold and 248 g/t silver.

Field mapping identified vein and epithermal textures, including mapped vein trends extending from the North Star and Little Wonder historical workings. Together with the geological observations made by Dahrouge, the results provide the company with a modern geological basis to explore an area where historical miners undertook underground development more than a century ago. All samples collected from the North Star-Little Wonder area returned gold and silver mineralization.

Historical North Star-Little Wonder area

Historical records indicate that mining of the North Star area dates back to at least 1883, during the early development of the Black Range mining district. Reporting at that time in The Black Range newspaper described continuing work at the North Star and reported that the work was improving both the property and its "showing of mineral," with Governor Foster contemplating an additional 50 to 100 feet of development.

Building on the Poverty Creek exploration program

With Rio preparing for its phase 1 drill program, the expansion of the Winston claim block builds directly on Rio Grande's recent exploration results at Poverty Creek and the company's evolving interpretation of a potentially broader mineralized vein system at Winston. As reported on the July 6, 2026, news release, the phase 2 exploration program returned multiple high-grade gold and silver results across the Poverty Creek target area, including channel samples grading up to 46.3 g/t gold and 1,030 g/t silver, grab samples grading up to 67.1 g/t gold, and rock-chip samples grading up to 26.1 g/t gold and 348 g/t silver. Sampling and structural mapping defined multiple northeast-southeast-and southwest-trending mineralized structural corridors across Poverty Creek, with high-grade samples distributed across several interpreted vein systems.

The significance of Poverty Creek to Rio Grande is therefore not based solely on individual high-grade samples, but on the emerging scale and structural complexity of the mineralized system. Integration of the company's 2025 and 2026 exploration data significantly refined its interpretation of the orientation, geometry and potential continuity of the mapped veins, and provided increased confidence in the geological model being developed at Winston. Of particular interest to Rio Grande is the potential for mineralized structures identified at North Star and Little Wonder to extend beyond the historical workings. Combined with the strength and distribution of the Poverty Creek results, these observations provided a compelling exploration rationale for Rio Grande to secure the intervening and surrounding prospective ground.

The company's current structural interpretation indicates that mineralized veins identified in the North Star-Little Wonder area may form part of a broader structural network extending from the Poverty Creek area to the south. With North Star and Little Wonder now incorporated into the Winston claim block, Rio Grande can systematically evaluate a larger portion of the interpreted mineralized system as it works to establish the extent, continuity and potential scale of mineralization at Winston. The interpreted connection between these areas has not yet been established, and will require additional mapping, sampling and drilling to test.

Next steps

The results indicate the potential for mineralization to extend beyond the historical workings at North Star and Little Wonder. Rio Grande's next phase of work in the newly acquired area will focus on additional geological and structural mapping and systematic sampling to refine the company's understanding of the vein orientations, extent of mineralization and potential continuity toward the known mineralized structural trends in the Poverty Creek area. The North Star and Little Wonder historical workings, together with structural observations, vein orientations and sample locations collected during the May program, require a broader geological model for the Winston project. In parallel, Rio Grande continues to advance toward its inaugural phase 1 drill program at Winston. The expanded claim block provides the company with additional ground for systematic exploration while it continues advancing its highest-priority targets toward drilling.

Equity grants

The company also announces that it has granted a total of 30,000 stock options and 30,000 restricted share units collectively to a director of the company pursuant to the company's long-term incentive plan. The grants were approved by the board of directors on Sept. 30, 2026. The awards are intended to align the interests of management, directors, employees and consultants with those of shareholders while supporting the company's long-term growth strategy.

The options are exercisable at 33 cents subject to Canadian Securities Exchange approval and a have a term of five years. The options and RSUs are subject to vesting provisions. All awards are subject to a statutory hold period of four months and one day, and all awards are subject to the terms of the company's long-term incentive plan and applicable securities law hold periods.

Sampling, analytical methods and quality assurance/quality control

Dahrouge personnel collected channel and rock chip samples from exposed in situ veins and submitted them to ALS Laboratory in Tucson, Ariz. Channel samples, ranging from 0.45 metre to 4.42 metres, were collected perpendicular to vein strike and generally included left host rock, vein and right host rock intervals. Where insufficient host rock was exposed, representative rock chip samples were collected across the vein. Sample locations were photographed, tagged and recorded by GPS.

Samples were analyzed by 33-element four-acid ICP-MS, with gold determined by fire assay ICP-AES. Blanks were inserted at approximately one per 10 samples and returned gold and silver values at or near detection limits. No certified reference materials or duplicates were included due to the reconnaissance nature of the program. ALS Tucson is ISO/IEC 17025 accredited.

Qualified person

The scientific and technical information contained in this news release has been reviewed and approved by Gareth Flitton, a qualified person as defined under National Instrument 43-101. Mr. Flitton is independent of Rio Grande Resources. The qualified person has reviewed the sampling procedures, analytical methods and results disclosed herein and is satisfied that the information has been accurately presented. 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 approximately 3,500-acre drill-ready property in the Black Range of Sierra county, New Mexico. The company holds a 100-per-cent interest in the Winston project group, which includes the two patented historical Ivanhoe and Emporia claims, in addition to the Little Granite, North Star and Little Wonder 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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