Drilling Confirms Vertical and Lateral Extensions of Argus North, Highlighting System Scale and Continuity

Onyx Gold Corp. (TSX-V: ONYX) (OTCQX: ONXGF)  is pleased to announce additional drill results from the Company’s ongoing 25,000 metre drill program at its 100% owned Munro-Croesus Project, located 75 km east of Timmins, Ontario.

Results are reported today for eight (8) step-out holes drilled on a cross-section located 50 metres west of the Argus North discovery section. This new drilling builds on results reported in June 2025, where four (4) holes included standout intercepts such as 91.0 m grading 1.8 g/t Au, including 32.0 m of 4.0 g/t Au in hole MC25-168 and 59.7 m grading 2.5 g/t Au including 18.7 m grading 5.2 g/t Au in drill hole MC25-171 (see Company news release dated June 26, 2025).

Highlights

• 91.0 m grading 1.1 g/t Au including 4.0 m grading 4.6 g/t Au, and a second deeper intersection of 103.4 m grading 1.1 g/t Au including 38.4 m grading 2.4 g/t Au, in drill hole MC25-177 for a total cumulative width of 194.4 meters of mineralization.

• 139.1 m grading 0.8 g/t Au including 6.9 m grading 4.3 g/t Au, in drill hole MC25-181, a 50 m down-dip step-out from drill hole MC25-177.

• 9.8 m grading 2.9 g/t Au including 2.2 m grading 11.8 g/t Au, in drill hole MC25-174, within the Argus Main Zone.

• 35.0 m grading 1.1 g/t Au including 7.0 m grading 3.4 g/t Au, in drill hole MC25-187A,

• Step-out drilling at Argus North continues to demonstrate wide intervals of promising gold mineralization over >100 meters of strike length (CS 50 W to CS 50 E) and from surface to >350 meters vertically.

• The Company has completed 48 drill holes (assays announced for 15 holes to date) completing approximately 15,000 m (60%) of the expanded 25,000 m Program.

• With approximately $10 M in cash, the Company remains fully funded for all its 2025 exploration programs.

• The Argus North Zone is open along strike, down-dip and down-plunge. Ongoing plans include step-out drilling along strike on 50-m to 100-m spaced cross-sections designed to extend the limits of the known gold mineralization.

“Our latest drilling at Argus North continues to demonstrate broad zones of gold mineralization with multiple higher-grade subintervals,” said Brock Colterjohn, President & CEO of Onyx Gold. “Intersecting nearly 200 metres of cumulative mineralization in a single hole underscores the scale of the system, while the presence of higher-grade sub-intervals within these broader envelopes highlights the strength of the gold system. Importantly, mineralization has now been traced from surface to over 300 metres depth and remains open along strike and down-plunge.”

“The Munro-Croesus project benefits from excellent infrastructure, with all reported gold results located beneath or adjacent to existing logging roads, less than 2 km away from Highway 101 and accessible year-round. With roughly half of our expanded 25,000-metre program still to come, we believe Argus North is only beginning to demonstrate its potential as the Timmins Camp’s newest gold discovery.”

Discussion of 2025 Argus North Results

The Argus North Zone is located on the western half of the Munro-Croesus Project, approximately 150 metres north of the regional Pipestone Fault, a major structural corridor that hosts several significant gold deposits in the Timmins camp. Discovery hole MC24-163, reported earlier this year, returned 69.6 m grading 3.4 g/t Au, including 34.5 m grading 5.4 g/t Au and 9.5 m grading 13.9 g/t Au (see Company news release dated April 10, 2025). Argus North lies roughly 100 metres north of the east-west trending Argus Main Zone, which represents a separate 750 m x 200 m near-surface bulk-tonnage gold target (e.g., 1.0 g/t Au over 63.3 m and 0.5 g/t Au over 136 m).

Gold mineralization at Argus North is distinguished by both broad zones (50 m to over 100 m) of +1 g/t Au mineralization containing multiple continuous higher-grade sub-intervals. Notable recent high-grade intercepts include 17.0 m grading 5.3 g/t Au in hole MC25-168, 18.7 m grading 5.2 g/t Au in MC25-171, 5.2 m grading 5.1 g/t Au and 6.6 m grading 4.2 g/t Au in MC25-178, 4.0 m grading 6.6 g/t Au in MC25-179, 4.0 m grading 5.9 g/t Au in MC25-180, and 4.0 m grading 4.6 g/t Au in MC25-177. For context, intercepts of this grade and thickness, in addition to the broad zones of +1 g/t Au mineralization, compare favorably with those reported from other major gold deposits in the Timmins camp, underscoring the potential significance of Argus North as a material new gold discovery in the district.

Geologically, the high-grade sub-intervals are closely associated with zones of strong albitization and silicification, pyritic stringers, and localized porphyritic intrusions within variolitic basalt and volcanic breccias. This combination of alteration and structural preparation is interpreted to be a key control on gold deposition. Drilling to date demonstrates excellent vertical continuity of mineralization, now traced from surface to over 350 meters depth, with the system remaining open along strike, down-dip and down-plunge.

The eight drill holes reported in this news release are all located within 25 m of the same north-south cross-section, situated 50 m west of previously reported drill holes MC24-163/168/171 (see Figure 1, Figure 2 and Figure 3) with approximate 50 m step-outs up-dip and down-dip. The drilling to date has continued to return encouraging results with drill holes MC25-177 and MC25-181 both intersecting plus 100-meter widths of consistent gold mineralization as reported below and in Table 1. The Argus North Zone remains open along strike, down-dip and down-plunge and ongoing plans will continue to see step-out drilling along strike on 50-m to 100-m spaced cross-sections to extend the limits of the known gold mineralization.

Argus North Zone

• 91.0 m grading 1.1 g/t Au, in hole MC25-177 (50 m west of drill hole MC25-163), including
  • 27.0 m grading 2.0 g/t Au, including
    • 4.0 m grading 4.6 g/t Au, AND

• 103.4 m grading 1.1 g/t Au, also in hole MC25-177, including
  • 38.4 m grading 2.4 g/t Au, including
    • 7.0 m grading 3.4 g/t Au

• 53.5 m grading 0.8 g/t Au, in hole MC25-181(50 m down-dip from MC25-177), including
  • 18.7 m grading 1.2 g/t Au, including
    • 4.8 m grading 2.2 g/t Au
• 139.1 m grading 0.8 g/t Au, also in hole MC25-181, including
  • 8.5 m grading 2.2 g/t Au, including
    • 4.9 m grading 3.1 g/t Au, AND
  • 23.5 m grading 1.7 g/t Au, including
    • 6.9 m grading 4.3 g/t Au
• 16.0 m grading 1.0 g/t Au, in hole MC25-176A (50 m up-dip from MC25-177), including
  • 4.5 m grading 2.5 g/t Au

• 35.0 m grading 1.1 g/t Au, in hole MC26-187A (25 m east and behind the cross-section), including
  • 7.0 m grading 3.4 g/t Au, in drill hole MC25-187A

Argus Main Zone

• 9.8 m grading 2.9 g/t Au, in hole MC25-174, including
  • 2.2 m grading 11.8 g/t Au

Note – Drill holes MC25-169 and MC25-170 returned no significant values at Argus North.

The Company has completed 48 drill holes (assays announced for 15 holes to date) completing approximately 15,000 m (60%) of the expanded and fully funded $10 M, 25,000 m Program.

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

Figure 2 – Longitudinal-Section Highlighting Drill Holes Reported in this Release – Looking North

 Figure 3 – Plan Map Highlighting Argus North Zone Drill Holes Reported in this Release

 Figure 4 – 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.

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 4). 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., and the Tower Gold Project being developed by STLLR Gold Inc.

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.