Onyx Gold intercepts 1.7 g/t Au over 67.0 m at Argus Main

Drilling Continues to Define Higher-Grade Plunging Mineralization within the 1.4-km-long Argus Gold System

Vancouver, British Columbia--(Newsfile Corp. - August 19, 2026) - Onyx Gold Corp. (TSXV: ONYX) (OTCQX: ONXGF) (" Onyx " or the " Company ") is pleased to report assay results from an additional nine (9) drill holes from the Argus Gold System (" Argus ") at its 100%-owned Munro-Croesus Project (" Munro-Croesus " or the " Project "), located 75 kilometers east of Timmins, Ontario. (Figure 4).

Results reported today are from the Argus Main and Argus West zones, two of several mineralized zones being explored within the broader Argus Gold System.

At Argus Main, drill hole MC26-340 returned one of the strongest higher-grade intersections drilled in the zone to date, grading 1.7 g/t gold (" Au ") over 67.0 meters (" m "), including 4.1 g/t Au over 24.5 m and 13.2 g/t Au over 6.0 m , including 73.4 g/t Au over 1.0 m associated with visible gold (Plate 1). Hole MC26-329, drilled approximately 150 m down-dip, returned a broad interval of 0.7 g/t Au over 144.5 m , including 1.1 g/t Au over 75.0 m and 2.1 g/t Au over 21.3 m .

The results further define a higher-grade plunging zone at Argus Main within a much broader envelope of gold mineralization. A similar relationship between broad mineralized envelopes and higher-grade plunging zones has been identified at Argus North, approximately 600 m to the west.

The Argus Gold System has now demonstrated gold mineralization across multiple zones over approximately 1.4 km of strike and more than 700 m vertically, while remaining open along strike, at depth and down-plunge. The Company's 110,000 m drill program is approximately 75% complete, with four drill rigs currently operating.

Highlights from Argus Main

Assay results reported today include two significant intersections at the Argus