Riverside Resources Reports Positive Results from Union Project Drilling Campaign

VANCOUVER, British Columbia, Sept. 09, 2026 /CourierPR/ -- Riverside Resources Inc., a company exploring mineral deposits in northwest Sonora, Mexico, has announced positive results from its Phase 2A summer 2026 drilling campaign at the Union Project. The campaign, carried out in partnership with Questcorp Mining Inc., has intersected gold and base metals, expanding upon the carbonate hosted replacement deposits (CRD) associated with past mining while identifying new targets for further exploration.

The drill program, which included seven holes, confirmed the presence of near-surface gold and base metal mineralization at the Union Norte and Union Mine targets. The results from the Union Norte target, located 1.5 km north of the Union Mine, showed significant mineralization. Specifically, hole UND26-015 returned 14.60 meters of 0.45 grams per tonne (g/t) gold equivalent (Au Eq) from 1.0 meters, with a higher-grade subset of 7.60 meters grading 0.80 g/t Au Eq and 4.60 meters of 1.09 g/t Au Eq from 8.00 meters. This hole successfully crossed an interpreted NNW-trending feeder structure, which showed anomalous gold, lead, and zinc values from near-surface depths.

Another hole, UND26-014, intersected the same structure, returning 9.10 meters of 0.76 g/t Au Eq from 1.90 meters, including a higher-grade subset of 1.5 meters grading 3.38 g/t Au Eq from 9.50 meters. These findings support the potential for a larger mineralized system, with the structure and host Clemente Formation indicating proximity to the replacement body. The company noted that some high-angle, cross-cutting feeder structures, or "chimneys," could be projected northward toward the La Negra target, where untested surface sampling and mineral evidence suggest hydrothermal activity.

At the Union Mine target, hole UND26-013 was successful in finding lead and zinc mineralization, intersecting the replacement body south of known artisanal workings. Anomalous lead (>36 ppm) and zinc (0.1-0.7%) values confirm the proximity to the CRD replacement body. The company emphasized the need for deeper drilling to intersect the interpreted main feeder structure beneath the Union Mine, where the highest-grade results on the project were obtained.

The Induced Polarization (IP) survey at Luis Hill delineated a large chargeability anomaly extending over 1 km in strike, interpreted to be associated with sediment-hosted gold mineralization. The anomaly remains open along strike and at depth, significantly expanding the exploration footprint for this target. Another hole, UND26-18, was drilled above the anomaly but terminated before reaching the planned 150-meter target depth due to complications.

Riverside Resources Inc. plans to continue drilling at these areas, along with additional targets outlined in the exploration program. The company stated, "These results are encouraging, with grades similar to those at nearby operations near Union. Consistent near-surface intercepts are a positive sign, and we look forward to further drilling once the rainy season ends." The company also mentioned that it is actively evaluating a reverse-circulation contractor for Phase 2B drilling to improve drilling efficiency in the area's ground conditions.

The Union Project, which features favorable limestone host rocks, an extensive alteration footprint, and multiple small-scale historical workings, is well positioned for near-term exploration results. The company believes that the immediate drill targets offer the potential for significant-scale discoveries and is optimistic about the upcoming drilling campaign.