Onyx Gold drills 60.8 m of 1.2 g/t Au at Munro-Croesus

Mr. Brock Colterjohn reports ONYX GOLD DEFINES GOLD MINERALIZATION RIGHT AT SURFACE AT ARGUS NORTH Onyx Gold Corp. has released surface channel sampling and drill results from the company's continuing 25,000-metre drill program at its 100-per-cent-owned Munro-Croesus project, located 75 kilometres east of Timmins, Ont. Results are reported today for four shallow stepout holes and a series of sawn channel samples of new outcrop exposed by mechanical stripping near previously reported drill hole MC25-180 (see the company's news release dated July 23, 2025), which returned 4.0 metres of 5.9 grams per tonne gold within 50.4 m of 1.9 g/t Au starting at 6.1 m downhole. Collectively, the new results outline a significant zone of gold mineralization that comes right to surface, located just two kilometres off Highway 101. Highlights: Drill holes: 60.8 m grading 1.2 g/t Au in drill hole MC25-200, including 3.0 m grading 5.9 g/t Au; 37.8 m grading 1.8 g/t Au in drill hole MC25-202, including 8.6 m grading 5.0 g/t Au; 37.5 m grading 1.2 g/t Au in drill hole MC25-204, including 10.2 m grading 2.4 g/t Au; Channel samples: 10.7 m grading 0.6 g/t Au, including 3.1 m grading 7.4 g/t Au, in Channel A; 8.9 m grading 0.9 g/t Au, including 2.8 m grading 1.6 g/t Au, in Channel B; 21.3 m grading 2.0 g/t Au, including 4.0 m grading 5.0 g/t Au, in Channel C; 15.5 m grading 1.6 g/t Au, including 6.5 m grading 2.8 g/t Au, in Channel D; 7.4 m grading 4.9 g/t Au, including 3.9 m grading 8.4 g/t Au, in Channel E; 3.4 m grading 1.8 g/t Au, including 1.0 m grading 4.0 g/t Au, in Channel F; 7.4 m grading 4.9 g/t Au, including 3.9 m grading 8.4 g/t Au, in Channel G; 15.4 m grading 2.2 g/t Au, including 2.0 m grading 8.4 g/t Au, in Channel H; Surface sampling and continuing stepout drilling at Argus North continues to demonstrate wide intervals of promising gold mineralization over greater than 100 metres of strike length and from surface to greater than 350 metres vertically; The company has completed 64 drill holes (assays announced for 18 holes to date) completing approximately 20,000 m (80 per cent) of the expanded 25,000-metre program. "Argus North continues to deliver wide intervals of gold mineralization right from surface, just two kilometres off the highway -- a rare and highly attractive combination in the Timmins camp," said Brock Colterjohn, president and chief executive officer of Onyx Gold. "These results reinforce the potential for Argus North to evolve into a significant, road-accessible gold system, and, with the majority of assays from our fully funded 25,000-metre program still pending, we are steadily building a clearer picture of the opportunity. With the recent closing of our $20-million bought deal financing and the upcoming close of our upsized $6.4-million non-brokered financing with strategic investors, Onyx is well financed to maintain strong news flow and advance exploration through 2026." Discussion of 2025 Argus North near-surface 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 the company's 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-metre-by-200-metre near-surface bulk-tonnage gold target (for example, 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 broad zones (50 m to over 100 m) of greater-than-one-gram-per-tonne-gold mineralization containing multiple continuous higher-grade subintervals. 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 greater-than-one-gram-per-tonne-gold mineralization, compare favourably 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 subintervals 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, traced from surface to over 350 metres depth, with the system remaining open along strike, down dip and down plunge. Mechanized stripping and power washing at Argus North over a 15-metre-by-80-metre area have now exposed an alternating stratigraphic sequence of massive, variolitic, fragmental and pillowed basalts intruded by two feldspar porphyry dikes. Mineralization is hosted primarily within fragmental basalt units, which represent the main lithology of the stripped area, and correlates well with observations from drill core. The mineralization is broadly disseminated pyrite within the fragmental basalts, with higher gold grades associated with 2 per cent and 5 per cent disseminated and stringer pyrite, strong albite alteration, and locally feldspar porphyry dikes. One hundred seventy-four individual channel samples averaging one m in length were collected in total from 11 channels crosscutting main structures and volcanic stratigraphy. Details of the channel sample lines reported in this news release are shown in Table 1. Details for drill hole assay reported in this news release are shown in Table 2. Results for a fourth hole, MC25-203, are still pending. The company has completed 64 drill holes (assays announced for 18 holes to date) completing approximately 20,000 m (80 per cent) of the expanded and fully financed $10-million, 25,000-metre program. 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. This large, 100-per-cent-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 to 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 square kilometres 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 Corp. Onyx Gold is an exploration company focused on well-established Canadian mining jurisdictions, with assets in Timmins, Ont., and Yukon. 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 140-square-kilometre Golden Mile property is located nine kilometres northeast of Newmont's multimillion-ounce Hoyle Pond deposit in Timmins. The 187-square-kilometre Timmins South 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, 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. Ian Cunningham-Dunlop, PEng, executive vice-president for Onyx Gold and a qualified person as defined by National Instrument 43-101, has reviewed and approved the technical information contained in this release. We seek Safe Harbor.