The exploration team for Riverside Resources Inc. (TSXV: RRI, OTCQB: RVSDF, FSE: 5YY0) released Phase 2 surface and underground sampling results from the La Union Project in Sonora, Mexico on May 5, 2026. The campaign focused on historical workings and district reconnaissance, returning several exceptional assays that sharpen drill targets. These findings, together with a property-wide structural reinterpretation and recent geophysical work, are being integrated to finalize hole locations for a planned summer 2026 drilling program.
The fieldwork concentrated on near-surface oxidized zones and underground exposures at classic carbonate replacement-style occurrences. Detailed channel and selective sampling produced very high-grade gold, silver and base metals that support both priority drilling at existing mines and follow-up on newly defined prospects. While some over-limit assays for silver remain pending, the announced results include multi-gram gold intervals and exceptionally high silver and zinc values that establish clear exploration priorities.
Table of Contents:
Phase 2 field results overview
Union Mine and Union Norte remain the most compelling immediate drilling targets. At the Union Mine, channel sampling produced a 2.9 m interval averaging 20 g/t gold and 1.83% zinc, which includes a narrow 0.6 m slice grading an extraordinary 91.7 g/t gold. A separate 0.3 m sample assayed 40% zinc. These selective underground exposures demonstrate high-grade continuity in oxidized zones and provide vectors for down-dip and along-strike drilling.
Union Norte and tonnage potential
The Union Norte work returned multiple, high-value underground samples. Notable results include a 1.0 m interval of 4.38 g/t gold, 1,413 g/t silver, 7.7% lead and 6.38% zinc, and a separate 1.0 m sample returning 4.25 g/t gold, 1,827 g/t silver and 6.89% zinc. The mineralization is hosted in breccia zones and vein arrays with steep dips and low-angle offsets, offering both high-grade shoot and broader tonnage targets for the upcoming drill program. Several silver assays exceeded routine lab limits and final over-limit values are still pending.
Additional prospects and district reconnaissance
Beyond the historical mines, Phase 2 mapping and sampling expanded the pipeline of targets. At Jabalí, interpreted low-sulfidation epithermal veins in carbonate host rocks produced multiple surface samples above 1 g/t gold and elevated silver and lead values; one sample reported multi-gram gold with strong silver. Creston returned selective outcrop assays including 10.03 g/t gold with greater than 100 g/t silver and 8.06% lead. Field reconnaissance also identified three new priority areas — Jabalí, La Negra and Ali Hill — which will be integrated into the Phase 2 drill plan.
Geological interpretation and geophysics
Riverside completed a district-wide structural reinterpretation to refine targets and is combining these results with an expanded aeromagnetic drone survey announced on April 1, 2026. The integrated dataset is being used to optimize drill hole placement, testing both high-grade shoots exposed in workings and potential deeper feeder systems that could host additional mineralization.
Quality assurance, permitting and next steps
All analytical work was conducted under a documented QA/QC program. Rock samples were shipped to ACT Labs in Zacatecas for preparation and analysis. Gold analyses used fire assay techniques and a 45-element ICP/4-acid digestion suite was applied for multi-element data. Riverside maintained chain of custody, inserted standards every 20 samples and blanks every 100 samples, and the laboratory added duplicates per its protocol. The program was reviewed by Freeman Smith, P.Geo., who acts as the company’s qualified person under National Instrument 43-101.
Operational readiness
With permits secured, site access established and a drill contractor and geophysical provider contracted, Riverside and partner Questcorp are positioned to commence drilling in summer 2026. The company emphasizes that these are exploration-stage results and that no mineral resource or reserve has been declared. Additional laboratory results from submitted samples are pending and will be released when available.
Riverside continues to operate La Union through its Mexican subsidiary while advancing the project collaboratively with Questcorp. The company reports a solid financial position with over C$5,000,000 cash and no debt, enabling the planned Phase 2 drill program and continued district-scale exploration across the La Union property.