Vancouver, British Columbia--(Newsfile Corp. - June 9, 2026) - Riverside Resources Inc.  (TSXV: RRI) (OTCQB: RVSDF) (FSE: 5YY) ("Riverside" or the "Company"), is pleased to announce that the Second Phase drill program has commenced at the Union Project in northwest Sonora, Mexico. This work is being carried out by the Company operating in partnership with Questcorp Mining Inc. (CSE: QQQ), which is earning into the project through an option agreement from Riverside (press release, May 6, 2025).

Program Highlights

• Fully Funded Program Underway: A ~1,500-metre diamond drill program across 8 to 10 holes, each averaging 180 metres in depth, is fully funded and requires no near-term dilutive financing.

• Expanding Phase 1 Discoveries: Drilling is designed to expand zones of mineralization, including those intercepted during the Phase 1 program with results announced in January 2026, and to test new areas developed during the winter 2026 field program.

• District-Scale Target Testing: The program tests new targets and explores areas surrounding multiple historical mine workings across the 25 km² La Union project area.

• Two Mineralization Styles: Holes will test both the sediment-hosted gold mineralization identified in Phase 1 and carbonate-hosted replacement deposit (CRD) gold-silver-zinc mineralization, where gold is associated with mantos, chimneys, and structural zones.

• Structurally Targeted Drilling: Angled holes are oriented to intersect stratigraphic and structural targets at high angles, as is typical in CRD systems. Structural features interpreted as potential mineralizing conduits are a key focus of the program for high grade gold and zinc.

• Advanced Target De-Risking: Final drill positioning integrates property-wide structural mapping, 248 line-km of drone aeromagnetic coverage, and a recently completed property-wide induced polarization (IP) survey.

• Geological Analog: La Union's CRD and sediment-hosted gold systems share geological characteristics with significant deposits in northern Mexico and the southwestern United States.

• Continuous News Flow: Exploration is coordinated with partner Questcorp Mining Inc. (CSE: QQQ), supporting milestone-driven news flow through summer 2026.

The exploration work over the past four months by Riverside has improved the understanding of the structural geology and stratigraphy of the project. The Union district lies along the flanks of this range with host stratigraphy that has now been studied for target layers that can host large bulk tonnage gold potential as found in Paleozoic sedimentary host units in Nevada and similarly in Sonora, Mexico. The improved mapping and detailed sampling underground delivered a better understanding of the chimney and manto aspects which include the structural feeder zones and post mineral faults. The exploration target focus is for a large potential gold discovery that expands from previous smaller scale mine operations on the property. Phase 2 drilling is intended to test the new concepts and expand beyond these past mining sites.

"We are exceptionally well-positioned to move ahead with this second phase of drilling, deploying 1 to 2 high-impact holes per target area to evaluate the deep root potentials of these sediment-hosted and CRD targets well beyond legacy past-mining boundaries," said John-Mark Staude, CEO of Riverside Resources. "Advanced structural synthesis led by Riverside's Alejandro Gracida has successfully pinned down the primary northwest-trending fault structures, which are interpreted to act as the primary structural plumbing and corridors for wide zones of high-grade feeder gold mineralization. The comprehensive IP Survey completed last week feeds directly into our real-time targeting models, and the program is advancing with rapid operational efficiency."

"Today marks a transformative milestone for Questcorp as we transition from a successful target generation phase into aggressive discovery drilling," said Saf Dhillon, President & CEO of Questcorp Mining. "Over the past several months, our integrated technical teams alongside our partners at Riverside have unlocked the true scale of the La Union district. Every layer of new data, from structural mapping to our newly completed IP geophysics, points toward a vast, interconnected mineralized system that remains largely untouched at depth."

The drill program covers more than five target areas. It begins with follow-up at the Union Mine, where prior drilling resolved key stratigraphic and orientation questions, allowing this round to step out into ground adjacent to past mining. Underground work identified large-scale alteration and indications of a mineralized system, making this one of several priority areas. The high-grade gold-silver chip channel samples taken underground at the Union Mine will now be followed up with drilling.

The second phase of drilling will follow up on Phase 1 results and on the broader targets developed through the spring 2026 field exploration program. Phase 2 will consist of one to three holes per area, primarily for orientation and to expand on the Phase 1 drilling. Follow-up drilling beyond Phase 2 is planned and can be expanded based on results and on the geophysics completed over the past several months. The detailed stratigraphy, lithology, and structural framework developed by the Riverside geological team specifically targets high-grade, favorable horizons for sediment-hosted gold mineralization and CRD. The five target areas outside of the Union Mine are as follows:

• Union Main Mine - Jales Area - The program will use targeted drill holes to test limestone and other carbonate stratigraphic hosts within the Clemente Formation, with the potential to reach the underlying Caborca Formation. These units are considered the primary hosts for replacement-style mineralization and have gold, silver and zinc in oxide mineralization in the mine and could be potentially extensive.

• North Union Mine - Negra Area - The initial focus of the program will be on testing structural interpretations of NW fault feeder zones. The new Negra zone has provided gold mineralization in samples and now can be a new drill area which has never been tested.

• Luis Hill- Alej Hill Area - The upper part of the Clemente Formation revealed sediment hosted gold in Phase 1 drilling allowing the follow up work to potentially expand upon that. The geology team has carefully mapped the stratigraphy and structure geology northward for over 2 kilometers and this target could have vast potential. Careful structural mapping has found some critical cross feeder structures which the team will now target during this phase.

• Cobre Mine Area - The Clemente Formation is the primary host unit, and structural features combined with areas of past mining provide multiple target zones that can now be followed up after Phase 1 drilling. The careful 1:1000 mapping by Gracida across the NW features, along with detailed alteration mapping, gives Questcorp the best chances for success from their investment through Riverside in this work.

• Jabali Area - The primary targets are NW-striking structural veins, with 200 m of strike length identified to date and a surface width of 30 m across a series of low-sulfidation epithermal quartz veins. High-grade assays of over 5 g/t Au have been returned from this area. Drilling at Jabali during this phase will focus on two holes: one testing the vein target and one testing the source target. Detailed maps and cross-sections for each target have been prepared ahead of drilling to best define the conceptual targets.

General Overview of La Union Project

The Project is summarized in a recently published NI 43-101 Technical Report and, more briefly, on the Riverside website. Riverside initially acquired the Project and subsequently consolidated additional inlier mineral claims to build a strong land position. The company then advanced the Project through surface access agreements and drill permitting, making it a turnkey exploration opportunity for the Optionee.

The Project was originally identified through Riverside's exploration work in the western Sonora Gold Belt, conducted in collaboration with AngloGold Ashanti Limited, Centerra Gold Inc., and Hochschild Mining Plc. Earlier PhD research by Riverside founder John-Mark Staude also contributed to recognizing the district's potential. Initial work by members of the Riverside team, drawing on more than two decades of geological compilation and analysis, further confirmed the region as highly prospective.

At the Project, historical mining by Peñoles targeted chimney and manto-style replacement bodies within the upper oxide zones. As a result, the underlying sulfide zones represent immediate drill targets for further exploration.

The Project features favorable limestone host rocks, an extensive alteration footprint, and multiple small-scale historical workings, with mineralization styles similar to those at the Hermosa Project in southern Arizona. At Hermosa, South32 is advancing mine development after acquiring the project from Arizona Mining for over $400 million, and Hermosa is now considered one of Arizona's most promising upcoming mining operations.

At La Union, immediate drill targets offer the potential for significant-scale discoveries. The Project is well positioned for near-term exploration results, with targets that include both oxide and deeper sulfide mineralization.

Figure 1. Geologic map with the tenure of the Union with the updated field mapping work done for the entire project. The drill program will focus on the targets shown. 

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Figure 2. Drill sites and geology planned for Phase 2 with the detailed recently updated stratigraphy to focus on CRD style and sediment hosted gold type discoveries.

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https://images.newsfilecorp.com/files/6101/300648_905cef9e6451d90e_003full.jpg

Figure 3. Cross Section of the Union Mine target area where the first 2 drill holes are planned with the first one more northward already underway and intersecting limestones and mineralization indicators as expected near this past mine operation.

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Qualified Person & QA/QC

The scientific and technical data contained in this news release pertaining to the Project was reviewed and approved by Freeman Smith, P.Geo, a non-independent qualified person to Riverside Resources Inc., who is responsible for ensuring that the information provided in this news release is accurate and who acts as a "qualified person" under National Instrument 43-101 Standards of Disclosure for Mineral Projects.

Rock samples from previous exploration programs discussed above at the Project were taken to the SGS Laboratory in Hermosillo, Mexico for fire assaying for gold and ICP-ES for the multi-element package. The rejects remained with Riverside offices in Hermosillo. The ICP/ES analysis using 4-acid digestion methods has been used consistently for the program. A QA/QC program is continued as part of the sampling procedures for the exploration program. Standards were randomly inserted into the sample stream prior to being sent to the laboratory. Blanks and duplicates are run systematically with the QA-QC procedure in the sample stream.

About Riverside Resources Inc.

Riverside is a well-funded exploration company driven by value generation and discovery. The Company has a solid balance sheet with no debt and 93M shares outstanding with a strong portfolio of gold-silver and copper assets and royalties in North America. Riverside has extensive experience and knowledge operating in Mexico and Canada and leverages its large database to generate a portfolio of prospective mineral properties. Riverside has properties available for option, with information available on the Company's website at www.rivres.com.

ON BEHALF OF RIVERSIDE RESOURCES INC.

"John-Mark Staude"

Dr. John-Mark Staude, President & CEO

For additional information contact:

Certain statements in this press release may be considered forward-looking information. These statements can be identified by the use of forward-looking terminology (e.g., "expect"," estimates", "intends", "anticipates", "believes", "plans"). Such information involves known and unknown risks -- including the risk that the Transaction will not be completed as contemplates, or at all, availability of funds, the results of financing and exploration activities, the interpretation of exploration results and other geological data, or unanticipated costs and expenses and other risks identified by Riverside in its public securities filings that may cause actual events to differ materially from current expectations. Readers are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date of this press release.

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To view the source version of this press release, please visit https://www.newsfilecorp.com/release/300648