Riverside Resources Expands Porphyry Copper Targets at Ariel Project, Sonora, Mexico

26.02.2026  |  Newsfile

Vancouver, February 26, 2026 - Riverside Resources Inc. (TSXV: RRI) (OTCQB: RVSDF) (FSE: 5YY0) ("Riverside" or the "Company"), is pleased to announce early 2026 assay and porphyry Cu exploration results at the 100%-owned Ariel Copper Project (the "Ariel Project" or "Ariel") in Sonora, Mexico. Ariel is a drill-permitted, district-scale porphyry copper-gold set of targets located approximately 18 km east-southeast of the La Caridad copper mining complex in the highly productive Laramide-age Arizona-Sonora copper mining belt.

2026 Exploration Highlights

• High-grade base metals with 5.4% Pb, 320 g/t Ag in veins both as targets and high-level, lateral indicators for the Ariel Porphyry Cu target

• Sampling of veins in the north as shown on maps and cross section below link for the upgrade porphyry Cu target linking Maria Luisa and Ariel targets

• Age dating at Ariel provides similar age to La Caridad and Cananea Mine host rocks further linking the geologic comparisons for the project to major copper districts

• Applying spectral mineral analysis (near-infrared/short-wave infrared methods) to map alteration minerals commonly associated with porphyry and high-sulphidation systems, including advanced argillic assemblages and breccia-related alteration styles documented at Ariel.

• Integrating mapping, alteration interpretation, and regional geophysical datasets to prioritize drill collars within permitted areas with full drive-up easy access.

• Riverside sees the project ready for partnering and moving ahead as it has multiple partnerships with diverse companies on the Riverside portfolio, Ariel is now ready for partnering and drilling toward making a major copper discovery.

Building on Riverside's consolidation of the Ariel Project through acquisition of the adjacent Maria Luisa concessions, the Company has now conducted expanded early 2026 field work and has received high grade silver and lead samples from veins, porphyry style alterations, and turquoise mines that are all part of the advancing target definition work with detailed mapping, sampling, alteration mineral studies summarized in the graphics below. These high grades are significant because they are comparable to those seen in other major Arizona-Sonora mining camps, where early mining of silver veins later evolved into major copper discoveries at more than a dozen large mines, including Cananea, La Caridad, Bisbee, Resolution, Morenci, and Ray, to name a few.

"Riverside early 2026 field program at the Ariel and Maria Luisa mineral concessions now consolidated into a single, fully permitted drill-ready project area found high grade precious and base metals typical of the major copper mines in the region and now the targets at Ariel continue to improve as the Company derisks the project with systematic fieldwork to sharpen targeting and prepare it for partnering and immediate drilling," said John-Mark Staude, CEO of Riverside Resources. "The combination of geologic mapping, geochemistry, alteration mineral studies, and integrated geophysics is providing stronger vectors into the most prospective zones. Ariel remains a compelling, undrilled copper district target in a premier belt, with excellent access, safety and infrastructure. The recent geochemistry continues to enhance the porphyry Cu target potential at Ariel."

Exploration Work and Targeting Progress

Riverside has full mineral title for the Ariel property and has advanced copper exploration through database compilations, field mapping, sampling, remote sensing, mineral concession consolidation and regional geophysical data interpretation, leading to the definition of two principal porphyry target areas (Ariel and Maria Luisa). The project has seen limited to no historical drilling to Riverside's knowledge, and the Company considers Ariel a high-quality, drill-stage copper district target with extensive exposed targets and additional areas masked by shallow post-mineral cover. The Project is available for partnership per the Company's business model of project generation; however, the Company could choose to drill the project given the quality exploration district.

Project Highlights

• District-scale, consolidated footprint: Ariel totals 1,640 hectares (16 km²) across five fully titled concessions in good standing, including the Maria Luisa area, providing multiple priority target zones for drill testing.

• Two priority target styles defined: Ongoing work continues to refine (1) a porphyry copper target with near surface copper sulphides and oxides, and (2) an epithermal arget interpreted as the upper portion of a porphyry system, consistent with alteration, veining and breccia styles with walk up safe, easy access on private ranch land.

• Modern scientific exploration tools improving vectoring: Riverside is applying portable geochemical and mineralogical tools (including portable XRF and short-wave/infrared spectral mineral scanning) to distinguish vein and alteration assemblages and prioritize drill-ready areas.

• Strategically located in the Sonora, Mexico Laramide copper belt and less than 20km from the La Caridad Cu-Mo porphyry mining complex, with additional regional porphyry prospects in the district.

• Ariel is underlain by Late Cretaceous volcanic rocks of the Tarahumara Formation intruded by Paleocene (ca. 57 Ma) porphyritic intrusions comparable in age to regional porphyry mineralization events similar to many of the mines in the Arizona- Sonora Belt which includes over 10 significant copper operations.

2026 Sampling North Area - "Maria Luisa" Epithermal Target

New exploration geochemistry results from the early 2026 program for the Maria Luisa part of the Ariel Project have high grade Ag and Pb typical of lateral expressions of porphyry copper like those in Arizona at Resolution, Globe-Miami and Bingham in Utah. Here, silver values reach up to >10 oz/t Ag and Pb values reach up to 5.4%, along with gold anomalies of up to 0.4 g/t Au, as shown in the Table, Summary Map, and Cross Section figures in this news release. The sampling showed multiple sets of parallel veining consistent with what is common in major copper districts. Chip samples ranging from 0.5 to 1.5 m were taken by cutting the veins perpendicularly. Some select sample results include:

Table 1. Highlights of rock sampling in the northern zone of the Ariel project at Maria Luisa target with high silver and lead typical of the Arizona Sonora major copper operating districts by Riverside.

Figure 1. Drone photo looking NNE up the cross-section line from Ariel porphyry in the south toward the yellow loop and the Maria Luisa epithermal shown in blue loop in the north with epithermal Ag-Pb veins and overall distal parts of the drill ready porphyry target.

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/6101/285478_b6adfa66842e181f_002full.jpg

Figure 2: Map of the rock chip assays and sampling locations of recent results and other Riverside assay exploration data with expanded area showing some detail of the Maria Luisa high grade veins. Rock chip geochemical samples collected in 2026 (red) and similar results from previous sampling (yellow) part of epithermal target in the north and porphyry copper target of Ariel in the south.

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/6101/285478_b6adfa66842e181f_003full.jpg

Figure 3. Schematic section showing copper porphyry in red and epithermal in yellow cross hatch color to the north and over top with assays of >5% Pb and >130 gpt Ag typical for the high sulfidation veins potentially emanating from a related porphyry copper

To view an enhanced version of this graphic, please visit:
https://images.newsfilecorp.com/files/6101/285478_b6adfa66842e181f_004full.jpg

QA - QC, Sampling Management

Rock chip sampling at Ariel was taken generally of 1.5m chip channel and select pieces of rock materials from outcrops. Samples were then shipped for analysis by ACT Labs in Zacatecas, Mexico. Samples were analyzed for by gold fire assay, with pulps analyzed with Inductively Coupled Plasma-Mas Spectrometry ("ICP-MS") following four-acid digestion to determine silver, base metals, and pathfinders. Samples were maintained in chain of custody being delivered to the laboratory in sealed bags. Standards and blanks were inserted every 20 samples and the laboratory also did duplicates every 20 samples as additional check on the quality control. The QA/QC was analyzed with a check for any variations in the standards beyond 2 standard deviations and the standards passed. Historic samples were analyzed using the same procedures with samples delivered to Bureau Veritas (Hermosillo, Sonora) for gold fire assay, with pulps forwarded to Vancouver, Canada for Inductively Coupled Plasma-Mas Spectrometry ("ICP-MS") following four-acid digestion to determine silver, base metals, and pathfinders.

Qualified Person

The technical content of the 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.

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

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 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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