Onyx Gold begins phase 3 drilling at Munro-Croesus

Mr. Brock Colterjohn reports ONYX GOLD COMMENCES 50,000 M PHASE THREE DRILL PROGRAM AND ADDS THIRD RIG AT THE MUNRO-CROESUS GOLD PROJECT, ONTARIO Onyx Gold Corp. has commenced a fully financed 50,000-metre (m) phase 3 expansion to the diamond drill program at its 100-per-cent-owned Munro-Croesus project, located 75 kilometres east of Timmins, Ont. The new 50,000 m program, budgeted at $11-million and utilizing three drill rigs, follows a successfully completed 25,000 m campaign (81 holes -- 36 reported to date). This marks the largest drill program in the property's history and one of the most significant continuing exploration programs in the Timmins gold camp. With a strong cash position of approximately $31.4-million, Onyx is well positioned to continue unlocking the exceptional district-scale potential of the Munro-Croesus project. Summary of corporate and exploration activities completed to date: Raised $41.6-million in 2025, through a combination of non-brokered and bought deal private placements (see the company's news releases dated May 22, 2025, June 6, 2025, Oct. 2, 2025, and Oct. 15, 2025; Two diamond drill rigs have been active since early May at the Argus North zone, on the large 109-square-kilometre (km) Munro-Croesus project, approximately two km north of Highway 101; Successfully completed the previously announced 25,000 m drill program, totalling 81 holes (see the company's news release dated July 23, 2025). Results from 45 drill holes remain pending. Reported assay results for 36 drill holes to date (see the company's news releases dated June 26, 2025, July 23, 2025, Sept. 3, 2025, Oct. 7, 2025, and Oct. 22, 2205) and significant highlights include: 69.6 m grading 3.4 grams per tonne (g/t) gold (Au), in discovery hole MC24-163, including 34.5 m grading 5.4 g/t Au and 9.5 m grading 13.9 g/t Au; 91.0 m grading 1.8 g/t Au, in hole MC25-168, including 32.0 m grading 4.0 g/t Au and 17.0 m grading 5.3 g/t Au; 59.7 m grading 2.5 g/t Au, in hole MC25-171, including 18.7 m grading 5.2 g/t Au; 52.2 m grading 2.2 g/t Au, in hole MC25-178, including 5.2 m grading 5.1 g/t Au, and 61.3 m grading 1.5 g/t Au, in hole MC25-178, including 6.6 m grading 4.2 g/t Au; 66.8 m grading 1.4 g/t Au, in hole MC25-179, including 4.0 m grading 6.6 g/t Au; 50.4 m grading 1.9 g/t Au, starting at 6.1 m downhole, in hole MC25-180, including 4.0 m grading 5.9 g/t Au; 91.0 m grading 1.1 g/t Au, in hole MC25-177, including 4.0 m grading 4.6 g/t Au, and 103.4 m grading 1.1 g/t Au, in hole MC25-177, including 38.4 m grading 2.4 g/t Au; 139.1 m grading 0.8 g/t Au, in hole MC25-181, including 6.9 m grading 4.3 g/t Au; 99.5 m grading 1.5 g/t Au, in hole MC25-195, including 17.0 m grading 3.3 g/t Au; 71.0 m grading 1.3 g/t Au, in hole MC25-197, including 8.3 m grading 3.9 g/t Au; 60.8 m grading 1.2 g/t Au, in hole MC25-200, including 3.0 m grading 5.9 g/t Au; Stepout drilling at Argus North continues to deliver broad zones of strong gold mineralization -- 50 to over 100 m thick, averaging more than one g/t Au, with consistent higher-grade intervals. Drilling has now traced the zone for over 100 m along strike and from surface to depths exceeding 350 m, with mineralization remaining open in all directions, highlighting significant expansion potential; These broad gold intercepts, combined with strong high-grade cores, compare favourably with other major deposits in the Timmins camp, underscoring Argus North's potential as a material new gold discovery in the district; The exploration team is using advanced tools to analyze drill core in real time -- studying rock structures and geochemistry to better understand how the gold is oriented and where higher-grade zones may extend; In July/August, the company completed a mechanical stripping and sampling program near the collar of hole MC25-180 to expose the Argus North mineralization at surface. Continuous channel sampling returned strong results including 21.2 m grading 2.0 g/t Au and 15.4 m grading 2.2 g/t Au (see the company's news release dated Oct. 7, 2025). "This 50,000-metre program marks an important milestone for Onyx and underscores the exceptional potential we see at Munro-Croesus," said Brock Colterjohn, president and chief executive officer of Onyx Gold. "Argus North has consistently delivered wide, continuous zones of gold mineralization that compare favourably to the best emerging discoveries in the Abitibi. With three rigs turning and more than $31-million in the treasury, we can execute this expanded program without dilution while maintaining flexibility to scale further as results warrant. This next phase will deepen our understanding of Argus North, test multiple kilometres of the underexplored Pipestone fault and advance several high-priority targets across the very large property. We believe Munro-Croesus has the potential to become a cornerstone gold project within one of Canada's most prolific mining districts." Summary of exploration activities planned for the remainder of Q4 (fourth quarter) 2025 and H2 (second half) 2026: With approximately $31.4-million in cash, Onyx remains fully financed for all 2025-2026 exploration programs. Stepout drilling, detailed trench mapping and surface sampling completed at Argus North since May, 2025, have resulted in a clearer understanding of the potential controls on gold mineralization, including: The importance of the permissive mafic variolitic volcanic stratigraphy, proximal to the regional, camp-wide Pipestone fault; The use of topographic and magnetic data to predict disruption, to that host horizon; The identification of key northeast-trending structures and structural geophysical-geochemical corridors; The presence of feldspar porphyry intrusions acting as fluid barriers and a minor host to gold mineralization; And, most importantly, the recognition of a variety of breccias (hyaloclastic, crackle, jigsaw and polylithic), which provide permeability for fluid migration and gold accumulation. The new phase 3 50,000 m program at Munro-Croesus will utilize three drill rigs allocated as follows: Approximately 36,000 m allocated to testing a three km trend of underexplored mafic variolitic basalts -- the same unit that hosts the Argus Main and Argus North zones. Key objectives of this drilling include: Expand Argus North along strike and plunge; Test fault-offset blocks west of Argus North; Drill along the Pipestone fault for new high-grade plunge zones and bulk targets, including targets across quartz-feldspar porphyry intrusions in Porcupine sediments similar to neighbouring deposits such as Fenn-Gib; Drill test Argus West; Drill southeast of Argus Main on anomalous stratigraphy; Evaluate and expand mineralization in Porcupine sediments along key structures; Approximately 4,500 m will focus on extending GM vein and Croesus Flow shoots onto the newly acquired Munro mine ground; Approximately 1,500 m testing Lalonde quartz-carbonate vein targets with known gold showings; Approximately 2,5000 m will focus on testing the Flipper zone, where historical drilling returned broad zones of mineralization hosted within the Porcupine sediments, including 42.6 m grading 1.0 g/t and 28.8 m grading 1.3 g/t Au, including 1.5 m grading 10.8 g/t Au. Stock options granted The company announces the issuance of 300,000 stock options with an exercise price of $1.18 per share for the purchase of up to 300,000 shares of the company. A 100,000-option portion of the stock options were granted to Chad Levesque Consulting, pursuant to the terms of an investor relations consulting agreement announced by the company on June 24, 2015. 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 km 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 a Canadian exploration company focused on unlocking district-scale gold opportunities in two of the country's most prolific and proven mining jurisdictions -- Timmins, Ont., and Yukon. In the Timmins gold camp, Onyx controls an extensive portfolio anchored by the Munro-Croesus property, host to the historic high-grade Croesus mine and site of the company's recent Argus North discovery -- one of the most exciting new gold zones emerging in the camp. Complementing Munro-Croesus are two large, early-stage projects -- Golden Mile, a 140 square km property situated just nine km from Newmont's multimillion-ounce Hoyle Pond mine, and Timmins South, a 187 square km land package strategically positioned around the Shaw Dome structure, offering exceptional discovery potential. Beyond Ontario, Onyx holds a commanding land position across four properties in Yukon's Selwyn basin, an area rapidly gaining recognition for new gold discoveries and growing exploration investment. The company's King Tut property sits approximately 50 km south of Snowline Gold's Valley discovery and adjacent to Fireweed Metals's MacPass property. Led by an experienced team with a strong record of discovery, development and value creation, Onyx Gold is well financed and committed to delivering shareholder value through disciplined exploration, strategic growth and responsible resource development. Additional notes The company maintains a robust QA/QC (quality assurance/quality control) program that includes the collection and analysis of duplicate samples and the insertion of blanks and standards (certified reference material). Ian Cunningham-Dunlop, PEng, executive vice-president for Onyx Gold and a qualified person (QP) as defined by Canadian National Instrument 43-101, has reviewed and approved the technical information contained in this news release. We seek Safe Harbor.