Onyx Gold Returns 194 m of 1.8 g/t Au at Argus North, Including 28 m of 3.0 g/t Au and 24.1 m of 3.7 g/t AuDown-dip Follow-up Demonstrates Excellent Continuity and Consistency Between Drill Holes MC25-232 and MC25-233Vancouver, British Columbia--(Newsfile Corp. - December 16, 2025) - Onyx Gold Corp. (TSXV: ONYX) (OTCQX: ONXGF) ("Onyx" or the "Company") is pleased to additional drill results from Company's ongoing drill program (the "Program") at its 100%-owned Munro-Croesus Project ("Munro-Croesus" or the "Project"), located 75 km east of Timmins, Ontario. Results reported today include those from two (2) drill holes completed at the Argus North Zone ("Argus North") and seven (7) drill holes targeting the Argus Main Zone ("Argus Main"), located 100 meters ("m") south and up to 300 m east of Argus North. Key results include those from drill hole MC25-233, which was drilled 30 m below and on-section with previously reported drill hole MC25-232 which returned 208 m grading 2.3 grams per tonne gold ("g/t gold") (see Company news release dated November 17, 2025). Holes MC25-232 and MC25-233 are part of a series of planned northwest oriented holes designed to drill perpendicular to a recently defined northeast-trending structural corridor beneath the key Argus North outcrop exposed by mechanical stripping earlier this year. This developing concept of a strong northeast-southwest structural control on higher-grade gold distribution within Argus North is based on detailed geological mapping, surface channel sampling and 3D modeling by the Company's technical team.The assay results from hole MC25-233 returned 194.0 m grading 1.8 g/t Au, followed by a second lower interval that returned 60.7 m grading 1.3 g/t Au. These results reinforce the concept of the northeast-southwest structural controls on higher-grade gold mineralization at Argus North and have successfully extended the gold mineralization intersected in hole MC24-233 to depth. HighlightsDrilling at Argus North returned 194.0 m grading 1.8 g/t Au, in drill hole MC25-233, including 28.0 m grading 3.0 g/t Au, including2.0 m grading 9.1 g/t Au, and24.1 m grading 3.7 g/t Au, including2.0 m grading 9.0 g/t AuFollowed by a second lower interval that returned 60.7 m grading 1.3 g/t Au, in drill hole MC25-233, including18.2 m grading 2.7 g/t Au, including7.1 m grading 3.7 g/t AuDrilling at Argus Main returned broad near-surface mineralization over 200 m strike, with high-grade sub-intervals up to 10.5 g/t AuOngoing step-out drilling at the Argus North, Main and West discoveries has now defined broad zones of gold mineralization over a total strike length of 900 m and from surface to ~400 m verticallyAll of the Argus Zones (North, Main and East) remain open along strike, down-dip, and down-plungeThe Company has completed 100 drill holes to date, totalling >36,000 m as part of its 75,000 m Phase I/II/III drill program. Assays have been announced for 53 holesWith ~$30 M in the treasury, the Company remains fully funded to advance its 2026 exploration programs"These impressive results reinforce the strength of mineralization at Argus North and continue to validate our evolving geological model," said Brock Colterjohn, President & CEO of Onyx Gold. "With mineralization now traced from surface to over 400 m depth and remaining open in several directions, Argus North continues to grow in scale and significance with each phase of drilling.""At Argus Main, the latest drilling continues to demonstrate the broad footprint and near-surface continuity of gold mineralization along the Pipestone Fault corridor. These results confirm the presence of consistent gold grades over meaningful widths and highlight the potential for higher-grade structural controls within a shallow, large, bulk-tonnage system."Discussion of 2025 Argus North Drill ResultsThe 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. The discovery hole at Argus North, MC24-163, was reported earlier this year, and 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). 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. The higher-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 cut by dominant steeply dipping, northeast-trending faults and associated fractures. This combination of alteration and structural preparation is interpreted to be a key control on gold deposition. Results reported today include hole MC25-233, which was drilled 30 meters below and on-section w