The Fort Worth Press - Rio Grande Resources Advances District-Scale Gold-Silver Target Definition at its Winston Project Through Structural Mapping of Multiple Vein Corridor Systems

VANCOUVER, BC / ACCESS Newswire / May 21, 2026 / Rio Grande Resources Ltd. (CSE:RGR)(OTCQB:RGRLF) ("Rio Grande" or "RIO" the "Company"), is pleased to announce completion of its Phase 2 field sampling and structural mapping program at the Winston Gold-Silver Project ("Winston" or the "Project"), located in the Black Range Mountains of Sierra County, New Mexico. The program was completed by Dahrouge Geological Consulting USA Ltd. ("Dahrouge") and included extensive structural mapping and surface sampling designed to refine the Company's geological understanding of mineralized vein trends across the property ahead of its planned Phase 1 drill program.

During the seven-day program conducted the second week of May 2026 (see News release May 06, 2026), Dahrouge collected 75 rock chip samples and 5 channel samples, representing an additional 16 individual samples, for a total of 91 individual samples submitted for analysis. The program's extensive structural mapping, represented by 307 new data points, has significantly enhanced the Company's understanding of mineralized vein trends and interpreted corridors throughout the Winston claim block. The structural dataset includes mapped vein orientations, mineralization characteristics, textural observations, and structural measurements are expected to play an important role in refining and prioritizing drill targets for the Company's planned Phase 1 drill program.

Highlights include:

• 91 individual samples collected, including rock chip and channel samples

• 307 new structural data points collected across multiple target areas

• Multiple steeply dipping vein corridors and structural intersections identified

• Mapping supports continuity of interpreted mineralized trends between Poverty Creek, Highway 59, Ivanhoe-Emporia, and Little Granite.

• Epithermal quartz textures observed across several target areas, including bladed quartz, drusy quartz, comb quartz, amethyst, colloform banding, and vuggy textures

Jason Barnard, CEO of Rio Grande Resources, commented: "This second phase field program has significantly advanced our understanding of the Winston Project and further strengthened our confidence in the scale of the mineralized system. The structural data collected by Dahrouge has helped identify and refine several priority target corridors that we believe have strong potential. We are particularly encouraged by the increasing evidence that Winston may represent a larger district-scale epithermal system and look forward to integrating the pending assay results into our evolving drill targeting model in advance of our planned Phase 1 drill program, as we continue advancing the Winston Project for the benefit of our Company and its shareholders."

The Company believes the completed field program has materially advanced its geological model for the Winston Project. Multiple vein corridors appear to extend through key target areas, including Poverty Creek, north of Highway 59, Ivanhoe-Emporia, and the Little Granite area. The recognition of these potential continuities, combined with the newly collected structural dataset, is expected to help refine targets where future drilling may test for vein intersections, continuity along strike, and mineralization at depth (see Figure 1).

Figure 1: Property map showing 2026 sample points and vein trends. Vein lines are created using field data from December 2025 and May 2026 field programs

District Scale Potential Further Supported

Mapping completed to date increasingly supports the interpretation that Winston may represent a connected, district-scale low-sulfidation epithermal gold-silver system rather than a series of isolated vein occurrences. Multiple steeply dipping vein corridors, including vein swarms with several structural intersection points were identified in this program. In low-sulfidation epithermal systems, these structural intersections can represent favorable zones for enhanced hydrothermal fluid flow, a key geological process associated with precious-metal deposition.

Throughout the property, textures typical of a low-sulfidation epithermal system, including bladed quartz, drusy quartz, comb quartz, amethyst, colloform banding, and vuggy textures, were identified within structurally controlled vein systems (see pictures 1 and 2). These observations are consistent with the geological characteristics identified during the Company's December 2025 field program and further support the interpretation of a large-scale epithermal gold-silver system at Winston (See news release December 12, 2025).

In the Poverty Creek region, mapping identified a broad swarm of structurally controlled veins extending from the northern portion of the claim block through Highway 59 and into the Poverty Creek corridor. Several of these vein trends appear continuous across multiple target areas and are associated with historical workings and previously identified mineralized structures (see Figure 2).

Figure 2: Structural trends of the Poverty Creek area with 2026 sample points. Vein lines are created using field data from December 2025 and May 2026 field programs

Structural measurements collected during the program also improved the Company's understanding of vein orientations and controls on mineralization within the Ivanhoe-Emporia region.

Next Steps

Assay results from the completed sampling program are currently pending. Upon receipt, the Company plans to integrate the assay results with the newly collected structural mapping data, previously reported surface sampling results, and airborne geophysical interpretations to refine and prioritize high-confidence drill targets ahead of the planned Phase 1 drill program.

Picture 3: In Situ quartz vein exposure exhibiting classic epithermal textures and mineral banding. Sample WIN-051226-14

The Company expects this integrated dataset to support drill targeting focused on structurally favorable areas, including vein intersections, interpreted mineralized corridors, and zones demonstrating strong epithermal textures (see picture 3) and structural continuity across the Winston Project.

Corporate Secretary Appointment

Rio Grande Resources is also pleased to announce the appointment of Andrew Brown as Corporate Secretary, effective May 25, 2026. Mr. Brown has over thirteen years of experience in the public markets and has served as an executive officer of both TSX Venture Exchange and Canadian Securities Exchange listed issuers. Mr. Brown is the founder of Ardent Corporate Services Inc. and has served as President of a Vancouver-based corporate services firm. He previously served as Vice President, Corporate Affairs and Corporate Secretary of a TSX Venture Exchange listed issuer. His areas of specialization include business development, corporate governance, executive management, project management, and public company administration. Rio looks forward to benefiting from Mr. Brown's extensive experience and leadership as he assumes the role.

Qualified Person

The scientific and technical information contained in this news release has been reviewed and approved by Mr. Jacob Anderson CPG, MAusIMM, a Qualified Person as defined under National Instrument 43-101. Mr. Anderson 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

Rio Grande Resources (CSE:RGR) (OTCQB: RGRLF) 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% interest in the Winston project group, which includes the 2 patented historic Ivanhoe & 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-sulfidation epithermal setting.

To view the company fact sheet and corporate presentation, please visit our website at www.riogranderesources.ca

Contact and Information

Company
Jason Barnard, CEO and Director
(604) 767-6598
[email protected]

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Forward-Looking Statements

Except for the statements of historical fact contained herein, the information presented in this news release and oral statements made from time to time by representatives of the Company are or may constitute "forward-looking statements" as such term is used in applicable United States and Canadian laws and including, without limitation, within the meaning of the Private Securities Litigation Reform Act of 1995, for which the Company claims the protection of the safe harbor for forward-looking statements. Such forward-looking statements and forward-looking information include, but are not limited to, the proposed benefits of the Arrangement. These statements relate to analyses and other information that are based on forecasts of future results, estimates of amounts not yet determinable and assumptions of management. Any other statements that express or involve discussions with respect to predictions, expectations, beliefs, plans, projections, objectives, assumptions or future events or performance (often, but not always, using words or phrases such as "expects" or "does not expect," "is expected," "anticipates" or "does not anticipate," "plans," "estimates" or "intends," or stating that certain actions, events or results "may," "could," "would," "might" or "will" be taken, occur or be achieved) are not statements of historical fact and should be viewed as forward-looking statements. The Company cautions that the identification of structural features or geophysical anomalies does not necessarily indicate the presence of economic mineralization, and there can be no assurance that the Company's geological interpretation or exploration objectives will result in a discovery. Such forward-looking statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any future results, performance or achievements expressed or implied by such forward-looking statements. Such risks and other factors include, among others, the availability of capital to fund programs and the resulting dilution caused by the raising of capital through the sale of shares, continuity of agreements with third parties, the satisfaction of the conditions to the Arrangement, risks and uncertainties associated with the environment and delays in obtaining governmental approvals, permits or financing. Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in forward-looking statements, there may be other factors that cause actions, events or results not to be as anticipated, estimated or intended. There can be no assurance that such statements will prove to be accurate as actual results and future events could differ materially from those anticipated in such statements. Although the Company believes that the expectations reflected in such forward-looking statements are based upon reasonable assumptions, it can give no assurance that its expectations will be achieved. Forward-looking information is subject to certain risks, trends and uncertainties that could cause actual results to differ materially from those projected. Many of these factors are beyond the Company's ability to control or predict. Important factors that may cause actual results to differ materially and that could impact the Company and the statements contained in this news release can be found in the Company's filings on SEDAR+. The Company assumes no obligation to update or supplement any forward-looking statements whether as a result of new information, future events or otherwise. Accordingly, readers should not place undue reliance on forward-looking statements contained in this news release and in any document referred to in this news release. This news release shall not constitute an offer to sell or the solicitation of an offer to buy securities. Please refer to the Company's most recent filings under its profile on SEDAR+ at www.sedarplus.ca for further information respecting the risks affecting the Company and its business.

The CSE has neither approved nor disapproved the contents of this news release and accepts no responsibility for the adequacy or accuracy hereof.

SOURCE: Rio Grande Resources

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J.P.Estrada--TFWP