Continuity of New Argus North Zone now demonstrated over 100 Vertical Meters

Onyx Gold Corp. (TSX-V: ONYX) (OTCQX: ONXGF)  is pleased to announce the first drill results of from the Company’s 10,000-meter spring drill program at the Argus North Zone, a newly identified gold zone located on its 100% owned Munro-Croesus Project, 75 km east of Timmins, Ontario.

Results are reported for two new step-out holes and the extension of two existing holes (Tables 1 and 2 and Figures 1 and 2). These holes followed up on discovery hole MC24-163, which defined a broad, continuous zone of strong gold mineralization, grading 3.4 grams per tonne gold over 69.6 meters (see Company news release dated April 10, 2025).

Highlights

• 91.0 m grading 1.8 g/t Au including 32.0 m grading 4.0 g/t Au and 17.0 m grading 5.3 g/t Au in drill hole MC25-168, a 50 m up-dip step-out from discovery hole MC24-163

• 59.7 m grading 2.5 g/t Au including 18.7 m grading 5.2 g/t Au in drill hole MC25-171, a 30 m up-dip step-out from hole MC25-168

• Three of four holes drilled so far at the Argus Zone have hit high-grade mineralization with a “grade thickness” of greater than 150 gram-meters – a strong indicator of potential

• Excellent continuity has been established between drill holes over 100 vertical meters, and the Argus North Zone remains open to expansion in all directions

• Wide sub-intervals (17 m to 34.5 m) of greater than 5 g/t Au have been intersected in multiple holes, all demonstrating remarkably consistent strong gold values throughout the reported sub-intervals (Table 2)

• 5,580 m have been drilled to date in 17 holes at the Argus North Zone as part of the fully funded, 10,000 m Phase 1 program (only four holes reported to date). Ongoing step-out drilling along strike will continue on 50-m spaced sections. Additional assay results will be reported on an ongoing basis once received and validated through its QA/QC protocols and interpreted for context.

“This is an outstanding start to our initial follow-up drilling at Argus North, where we’re quickly demonstrating the continuity of broad zones of high-grade gold mineralization,” said Brock Colterjohn, President & CEO. “Every hole is adding valuable insight into the scale and geometry of the system, with mineralization now confirmed along strike and up-dip from the discovery hole. With only half of our fully funded Phase 1 program complete and the zone still open in all directions, we’re just beginning to tap into the potential at Argus. We’re excited about what’s ahead and look forward to sharing more results as drilling advances.”

Discussion of 2025 Argus North Results

The Argus North Zone is located on the western half of the Munro-Croesus project, 150 m north of the regional Pipestone Fault, a major structural corridor known to host significant gold deposits. Hole MC24-163, the discovery drill hole at Argus North reported earlier this year, returned 69.6 m grading 3.4 g/t Au, including 34.5 m grading 5.4 g/t Au, including 9.5 m grading 13.9 g/t Au. The Argus North Zone is situated 100 m north of the east-west trending main Argus Zone, which is a separate 750 m x 200 m near-surface bulk tonnage target (e.g. 1.0 g/t Au over 63.3 m and 0.5 g/t Au over 136 m).

Mineralization at Argus North is hosted within a strongly brecciated structural zone with 3-10% fine-grained stringer and disseminated pyrite, and distinct pyritic stringers extending into the host mafic variolitic basalts (see Plate 1 and Plate 2). Halos of strong albitization, strong silicification, and locally moderate sericitization are associated with the mineralized zones, often intruded by 1 to 7 m thick mafic to intermediate dikes. Drilling to date indicates an east-southeast trend (or strike) and a steep southerly dip to the structural zone that is host to the mineralization at Argus North. The structural zone is sub-parallel to the regional-scale Pipestone Fault and may represent a splay off it. Gold mineralization at Argus North has been delineated between 100- and 200-meters vertical depth and remains open in all directions, including up-dip to surface.

The four drill holes reported today in this news release are all located on the same north-south cross-section as drill hole MC24-163 (see Figure 1 and Figure 2) with 20 m to 50 m step-outs up- and down-dip. The drilling to date has returned very encouraging results with holes MC25-168, MC25-171 and MC23-140-EXT all reporting wide intervals of gold mineralization as reported below and in Table 1:

• 91.0 m grading 1.8 g/t Au, in hole MC25-168 (50 m up-dip from MC24-163), including
  • 32.0 m grading 4.0 g/t Au, and including
  • 17.0 m grading 5.3 g/t Au
• 59.7 m grading 2.5 g/t Au, in hole MC25-171 (30 m up-dip from MC25-168), including
  • 18.7 m grading 5.2 g/t Au, and including
  • 2.1 m grading 9.6 g/t Au
• 43.8 m grading 0.9 g/t Au, in hole MC23-140-EXT (20 m down-dip from MC24-163), including
  • 2.4 m grading 4.1 g/t Au, and including
  • 2.2 m grading 5.5 g/t Au

Hole MC25-163-EXT, the 195 m re-entry and extension to hole MC25-163, fully defined the width of the Argus North mineralizing system and no additional zones of gold mineralization were intersected beyond those already reported in hole MC25-163.

Next Steps

The Company has completed 17 drill holes totalling 5,580 meters to date as part of its fully funded ~10,000-meter Phase 1 drill program at the Argus Zone. Ongoing plans will continue to see step-out drilling along strike on 50-m to 100-m spaced cross-sections designed to extend the zone up-dip to surface and down-dip to depth.

At a larger scale, historical and recent trenching and sampling by the Company in 2024 have demonstrated that the same key prospective mafic variolitic volcanic units extend to the west and east immediately north of the Pipestone Fault, suggesting multi-kilometer scale potential along a trend that is completely untested by any drilling to date.

Plate 1. Example of Argus North Mineralization Style with Strong Albite-Silica Alteration and Disseminated Pyrite in Mafic Breccia (Hole MC25-168)

 Plate 2. Example of Argus North Mineralization Style with Intense Silica-Albite Alteration and Pyrite Stringers in Variolitic Basalt Flow (Hole MC25-140-EXT)

 Figure 1 – Cross-Section Highlighting Drill Holes Reported in this Release – Looking East

 Figure 2 – Plan Map Highlighting Argus North Zone Drill Holes Reported in this Release

 Figure 3 – Location of the Munro-Croesus Gold Project, Ontario

Table 1 – Significant Assay Results from 2025 Drilling Completed at the Argus North Zone

*Intersections are reported as drilled width; true width is estimated to be 70-90% of drilled width.

Table 2 – Individual Assay Values from >5 g/t Subintervals in MC25-168 and MC25-171

The Munro-Croesus Project

The Munro-Croesus Project is located along Highway 101 in the heart of the Abitibi greenstone belt, Canada’s premier gold mining jurisdiction (Figure 3). This large, 100% owned land package includes the past-producing Croesus Gold Mine, which yielded some of the highest-grade gold ever mined in Ontario. Extensive land consolidation from 2020-2025 has unified the patchwork of patented and unpatented mining claims surrounding the Croesus Gold Mine into one coherent package and enhanced the project’s exploration potential.

The Project covers 109 km² of highly prospective geology within the influence of major gold-bearing structural breaks. Bulk-tonnage gold deposits located in the immediate region include the Fenn-Gib gold project being developed by Mayfair Gold Corp. that contains an Indicated Resource of 4.31 Moz at 0.74 g/t Au and an Inferred Resource of 141 koz at 0.49 g/t Au, and the Tower Gold Project being developed by STLLR Gold Inc. that contains an open pit Indicated Resource of 4.46 Moz at 0.92 g/t Au and an Inferred Resource of 8.29 Moz at 1.09 g/t Au¹.

About Onyx Gold

Onyx Gold is an exploration company focused on well-established Canadian mining jurisdictions, with assets in Timmins, Ontario, and Yukon Territory. The Company’s extensive portfolio of quality gold projects in the greater Timmins gold camp includes the Munro-Croesus Gold property, renowned for its high-grade mineralization, plus two additional earlier-stage large exploration properties, Golden Mile and Timmins South. The Golden Mile 140 km² property is located 9 km northeast of Newmont’s multi-million-ounce Hoyle Pond deposit in Timmins. The Timmins South 187 km² property is located to the south and southeast of Timmins and surrounds the Shaw dome structure.

Onyx Gold also controls four properties in the Selwyn Basin area of Yukon Territory, which is currently gaining significance due to recent discoveries in the area. Onyx Gold’s experienced board and senior management team are committed to creating shareholder value through the discovery process, careful allocation of capital, and environmentally/socially responsible mineral exploration.