Riverside Resources and Questcorp Complete Geophysics Programs and Continue Drilling at La Union Project

VANCOUVER, British Columbia, July 09, 2026 (GLOBE NEWSWIRE) — Riverside Resources Inc. (“Riverside” or the “Company”) (TSX-V: RRI) (OTCQB: RVSDF) (FSE: 5YY0) is pleased to announce, with partner Questcorp Mining Inc. (CSE: QQQ) (OTCQB: QQCMF) (FSE: D910) (“Questcorp”), the completion of expanded geophysical programs linked to the current drilling at the La Union Project, Sonora, Mexico.

The programs included an aeromagnetic drone survey and an Induced Polarization (“IP”) ground geophysics survey. The aeromagnetic survey has been completed, and the processed data has now been received and can be integrated into the ongoing summer core drilling program at La Union. The IP ground survey has also been completed, with processed results expected soon; this data will build on current drill targets and is anticipated to identify expansions and additional targets, consistent with the robust H1 2026 exploration efforts at the project.

The geophysics can potentially be applied immediately to the active drill program, which has so far focused on three areas: Union, Union North, and Jabali. The IP data covering these areas is being used to interpret results from completed drilling and to expand targets, extending the potential for drilling along strike and at depth. Initial work had generally relied on surface mapping, geochemistry, and past mine activity as a guide. This more robust and expansive geophysical dataset helps place Union’s discovery potential in a larger regional context, similar to major deposits in Arizona and Sonora where these tools have proven effective at that scale.

Highlights

• IP program completed and extended over current drilling and into new mapped target areas
• Drilling completed at Union and Union North targets
• Actively drilling the Jabali target
• Aeromagnetic drone survey: The final report has been received for 145 flight lines totaling 193 km, plus 20 tie lines totaling 55 km, for 248 km of total drone coverage. The survey builds on the 2025 baseline dataset and was flown at 100 m line spacing for high-resolution definition, which now shows good targets
• Cross structures trending NE and NW potentially coincide with mapped feeder fault zones for the Carbonate Replacement Deposit (“CRD”) and sediment-hosted gold
• Relating the outcropping diorite bodies into a larger context for potential scale and their relationship to the known gold-zinc mineralized areas at Union
• Improved imaging of structures beneath post-mineral cover, including the new NW trending structures identified by spring 2026 field mapping as a potential ore control creates new targets which have never been drilled before.

“With the IP survey now complete, combined with the processed aeromagnetic data, we have a expanded view of the Union Project’s targets and structural framework, both at depth and along strike from current drilling,” said John-Mark Staude, President and CEO, Riverside Resources Inc. “Our teams are in the field continuing Phase 2 drilling, and this data is immediately helping us expand targeting and prioritize the project’s robust set of targets. The program is going well, and our teams are processing drill core and sending samples to the laboratory for assays. We’re also now using the new geophysics to put our surface geology observations into a mineralization targeting context, helping focus our efforts toward discovering high-grade gold and base metals similar to what was previously mined here, now with geophysics to help image potential source targets at depth.”

Geophysics Integration

The completed IP survey consists of 5 lines, shown in red in Figure 1, which integrate with the magnetic data to define both current drill targets and broader targets. The IP lines cross over the current drilling, providing context for how the drilling fits into the larger target framework and allowing for expansion. Similarly, the aeromagnetic data defines structures shown in the figure, with targets particularly common along the NE and NW-trending structures, where feeder fault zones are currently being drilled.

Figure 1: Map showing the integration of geophysics from the drone aeromagnetic survey and IP lines, along with assay data collected during Riverside’s Union exploration program.

Qualified Person and QA/QC
The technical content of this news release has been reviewed and approved by Freeman Smith, P.Geo. (British Columbia), a qualified person under National Instrument 43-101 who is non-independent and the Vice President Exploration for the Company.  

QA/QC for the surface geochemistry shown in Figure 1 involved rock samples shipped to ACT Labs in Zacatecas for preparation and analysis. Gold was analyzed using fire assay techniques. A 45-element ICP/EOS analysis using 4-acid digestion methods was used, similar to the earlier assay work on the Project. Samples were maintained in chain of custody and delivered to the laboratory in sealed bags. Standards were inserted into the sample stream by Riverside every 20 samples, and blanks were inserted every 100 samples. The laboratory also inserted duplicates every 20 samples as an additional check on quality control. The QA/QC data were analyzed with a check for any variations in the standards beyond 2 standard deviations, and the standards passed.

About the Union Project

The Union Project is located in northwestern Sonora and shows district-scale carbonate replacement deposit (CRD) mineralization. The project hosts historical mining areas and multiple exploration targets associated with gold, silver, zinc and lead mineralization within carbonates and structurally controlled settings. Riverside operates the project through its Mexican subsidiary while advancing exploration in partnership with Questcorp.

About Riverside Resources Inc.:
Riverside is a well-funded exploration company driven by value generation and discovery. The Company has a strong balance sheet with over C$5,000,000 cash, no debt and tight share structure with a strong portfolio of gold-silver, copper, and REE assets and royalties in North America. Further information about Riverside is 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

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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 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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A photo accompanying this announcement is available at https://www.globenewswire.com/NewsRoom/AttachmentNg/59e7b1ae-5668-4b34-a531-8bb69e6e2014