Dr. John-Mark Staude reports

RIVERSIDE RESOURCES ANNOUNCES COMPLETION OF PHASE ONE DRILLING AT UNION PROJECT AND NOW AWAITS DRILL ASSAY RESULTS

Riverside Resources Inc. has completed the first phase of drilling at the Union project in Sonora, Mexico. Twelve diamond core holes were completed for a total of just over 1,600 metres across six priority targets. The work is being advanced with funding through partner Questcorp Mining Inc. under the option agreement announced earlier in 2025 with Riverside as operator and managing the exploration program.

Program highlights

• 12 core holes completed totalling greater than 1,600 m;
• Six targets drilled: Union mine, Union Norte, Cobre, Luis, Famosa and Famosa Mag;
• Three past-producing mine areas tested adjacent to historic workings to evaluate continuity;
• Greater than 700 half-core samples shipped; assays pending;
• Holes oriented as angle and near-vertical to cut stratigraphy and structures typical of carbonate replacement deposit-type (CRD) systems, with focus beneath oxidized horizons generally less than 150 m depth.

"This first exploration phase accomplished initial drill holes into six target areas. We tested multiple shallow gold and base metals targets, confirmed the key carbonate host units recognized by historic mining at Union and Famosa, and gathered the structural and alteration data to further progress efficient mineral exploration," said Dr. John-Mark Staude, president and chief executive officer of Riverside Resources. "This historically mined CRD district, validated by new drilling and improved data sets, advances our geologic model and supports the potential for a large-scale discovery. With six targets advanced and more than 700 samples at the lab, once results are received, we will scope the next exploration program and focus on the most prospective trends indicated by assay results, stratigraphy, structure and geophysics."

Drilling update by area

Union mine: Three holes at the Union mine targeted manto horizons and chimney/feeder structures adjacent to historic underground workings. This reconnaissance drilling was designed to evaluate stratigraphy, alteration and mineralization continuity typical of CRD systems.

Famosa mine area: Four core holes tested a west-dipping dolomite manto target and adjacent structures. Logging noted intrusive dikes and breccias; no geochronology has been completed. Historical small-scale mining left surface dumps reported with gold grades of greater than 0.5 oz/t Au (greater than 15 g/t) in an independent National Instrument 43-101 report filed on SEDAR+, May 7, 2025, by Questcorp. An inclined shaft dipping approximately 70 degrees to the west parallels the favourable horizon. Holes were drilled at angles toward the east to intersect the target as close to perpendicular as practical and to evaluate continuity of alteration and mineralization.

Union Norte: Two initial holes tested the manto horizon within dolomitic carbonate strata to evaluate continuity and geometry along favourable trends mapped near historic workings. This phase targeted the westward extension. Follow-up work, including possible stepouts to the east, will be considered after assays and geological interpretation.

Cobre and Luis: Each target was tested to assess style, structure and controls on mineralization. Results to date show sulphides, mineralization types and intrusions aligned with a carbonate-hosted metals system.

Sampling and assays

Core was logged, saw-cut and half-core samples were shipped for analysis. Samples from the first eight holes were delivered to Bureau Veritas (Hermosillo, Sonora) for gold fire assay, with pulps forwarded to Vancouver, Canada, for inductively coupled plasma-mass spectrometry (ICP-MS) following four-acid digestion to determine silver, base metals and pathfinders. Samples from the final four holes were shipped to ACT Labs Zacatecas, where preparation, gold assay and multielement ICP are completed in Mexico. Remaining half cores are retained for reference. The final four holes of the program were shipped to ACT Labs where they were similarly assayed using the same processing methods but with their initial preparation and assaying completed in Zacatecas, Mexico, using the same ICP and gold fire assay methods.

Next steps

After assays are received, the company plans to announce results and begin work to integrate the full exploration results including the assays, core logging, geophysics, advance detailed multielement geochemistry and updated structural mapping to refine the CRD model and scope for a phase 2 exploration campaign. The phase 2 campaign will likely include more extensive drilling and other exploration work as this phase 1 was only an initial sampling into some of the targets at Union. This next expanded drill program could take place in H1 2026 as all permits and access are in good standing and with the new data targets will be ready to explore.

Qualified person and QA/QC (quality assurance/quality control)

The scientific and technical data contained in this news release pertaining to the project was reviewed and approved by Freeman Smith, PGeo, a non-independent qualified person to Riverside Resources, 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.

About Riverside Resources Inc.

Riverside is a well-financed exploration company driven by value generation and discovery. The company has a solid balance sheet with no debt and less than 75 million 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.

We seek Safe Harbor.