Westernmost hole returns 1.0 g/t Au over 27.6 Meters; Zone Remains Open

Onyx Gold Corp. (TSX-V: ONYX) (OTCQX: ONXGF) is pleased to announce the final exploration drill results from its 2023 Fall Drill Program at its Munro-Croesus Project in the Timmins gold camp, Ontario.

2023 Work Program Highlights:

• Drilling continues to define gold mineralization on 100-m step-outs at the Argus zone, successfully doubling the strike length to 525m and a width of 200m, which remains open in all directions.

• The Argus zone remains open for expansion, especially towards the west, where the zone likely converges with the Pipestone Fault, a key regional structure known to host material gold deposits, including Mayfair Gold’s 3.5 million-ounce Fenn-Gibb deposit located 3.5km to the southwest of the Argus Zone.

• The westernmost hole returned 1.0 grams per tonne gold “Au” over 27.6 meters, demonstrating the strength of the Argus mineralized system, highlighting the upside potential of further expanding the zone to the west.

• Drilling in an under-tested area of the Argus zone successfully intersected gold mineralization consistent with this zone, including 0.61 g/t Au over 47.6m and 0.66 g/t Au over 28.5m.

• Geological modeling of the Argus zone continues to define and refine controls to gold domains.

• Plans for a 2024 follow-up drill program at the Munro-Croesus property are expected to be announced in the coming weeks.

“We are very excited about the portfolio of properties we’ve accumulated in this world-renowned mining camp. With opportunities for continued discoveries of both high-grade vein and bulk tonnage gold systems, it stands to reason that Onyx could become the go-to explorer in this prolific region,” said Brock Colterjohn, President & CEO. “The fall drill program successfully doubled the strike length of the Argus zone to 525m, demonstrating the strength and continuity of the mineralized system. In addition, a new high-grade vein discovery was made at Croesus, returning 121.8 g/t Au over 0.9 m, including 363.0 g/t Au over 0.3m. This work validates our approach to exploration in the Timmins Camp, and we are excited to continue to test these zones and find new discoveries on our other properties on the belt. We look forward to outlining our targets and drill plans for 2024 in the coming weeks.”

The Company completed the Program in early December with 4,078 meters drilled in 19 holes. About half of the Program was focused on expansion drilling at the Argus Zone on the Property’s western side, with the remaining half focused on follow-up holes at targets near the historic high-grade Croesus Gold Mine. Initial results reported from the Program included a new quartz vein discovery 350 meters northwest of the historic Croesus Gold Mine, which returned 121.8 g/t Au over 0.9m, including 363.0 g/t Au over 0.3m, within a 30 cm wide quartz vein containing abundant visible gold in drill hole MC23-132 (See Company press release dated December 6, 2023).

Results reported today include eight (8) drill holes totaling 2,163.4 meters from the shallow, bulk-tonnage style Argus Zone located three kilometers west of the Croesus Gold Mine. The Program tested an area of low drill density to expand the Zone to the northwest and then stepped out in 100-meter increments to the southwest to test the convergence of the Argus Zone and the regional Pipestone Fault.

Highlight Assay Results

• 0.96 g/t Au over 27.6 m, in hole MC23-140, including
  • 3.86 g/t Au over 5.1 m, including
    • 8.57 g/t Au over 0.5 m
• 0.61 g/t Au over 47.6 m, in hole MC23-135, including
  • 1.69 g/t Au over 4.9 m
• 0.66 g/t Au over 28.5 m, in hole MC23-136, including
  • 2.09 g/t Au over 3.4 m
  • 1.29 g/t Au over 5.1 m
• 0.45 g/t Au over 21.2 m, in hole MC23-137
• 0.33 g/t Au over 24.0 m and 8.33 g/t Au over 0.6 m in hole MC23-138, and

• 0.43 g/t Au over 25.5 m, in hole MC23-139, including
  • 5.27 g/t Au over 0.7 m

The Argus Zone has now been defined over a strike length of 525 meters and a width of 200 meters and remains open in all directions. The results from hole MC23-140, the most westerly hole drilled by the Company, show the strength of the Argus mineralization system as it approaches the Pipestone Fault and highlight the potential to continue to drill further to the west.

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% 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 2020-2023 has unified the patchwork of patented and unpatented mining claims surrounding the Croesus Gold Mine into one coherent package (Figure 1) and enhanced the exploration potential of the Project. The Project covers 70 km² (27 mi²) 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. that contains an Indicated Resource of 3.38 Moz at 0.93 g/t Au and an Inferred Resource of 157 koz at 0.85 g/t Au, and the Tower Gold Project being developed by Moneta Gold Inc. that contains an open pit Indicated Resource of 4.46 Moz at 0.92 g/t Au and an Inferred Resource of 8.29 Moz at 1.09 g/t Au¹.

The Argus Zone is located three kilometers west-northwest of the past-producing Croesus Gold Mine and immediately north of the Pipestone Fault (Figure 2). It is a broad zone of near-surface gold mineralization within the influence of the regional gold-bearing Pipestone Fault. The Argus Zone is characterized by silicified mafic variolitic volcanics cut by northeast-trending pyritic veinlets within a broader halo of carbonate alteration and local development of specular hematite. Selective historical sampling during a small 1990s-era drill program yielded promising gold assays over narrow widths with large sections of core unsampled. Onyx’s recognition that mineralization may be more widespread provided the rationale to target the prospect, resulting in the discovery of shallow, bulk-tonnage style gold in 2022, highlighted by 62.8m at 0.79 g/t within 136.0 m at 0.54 g/t Au in MC22-110.

Discussion of Argus Zone Results

The Company completed 2,163.4m in eight drill holes in the Argus Zone area to expand on the known mineralization identified in 2022. Three holes, MC23-135/136/137, were drilled on the same drill hole cross-section through a little tested area of the zone; three holes, MC23-138/139/140, were drilled as 100-meter step-outs along the projected intersection of the Argus Zone with the Pipestone Fault; and two holes, MC23-141/142, tested new targets to the east of the Argus Zone within the same variolitic mafic volcanic flow below anomalous surface gold geochemistry (4.0 and 1.6 g/t Au).

Results from holes MC23-135/136/137 returned intercepts of 0.61 g/t Au over 47.6m in hole MC23-135, 0.66 g/t Au over 28.5m in hole MC23-136, and 0.45 g/t Au over 21.2m in hole MC23-137 (See Figures 2 and 3). The geological model for the Argus Zone has now been updated and shows an overall east-west trend to the mineralization, which bodes well for its ultimate convergence with the northwest-southeast-trending Pipestone Fault.

Holes MC23-138/139/140 were drilled in 100-meter step-outs along the Pipestone Fault, immediately southwest of the Argus Zone. All three holes collared in sediments of the Porcupine assemblage and were drilled north through the Pipestone Fault into the prospective mafic variolitic flow volcanics of the Kidd-Munro assemblage. All three holes intersected multiple zones of Argus-style mineralization within the mafic volcanics and returned 0.33 g/t Au over 24.0m and 8.33 g/t Au over 0.6m in hole MC23-138, 0.43 g/t Au over 25.5m in hole MC23-139, and 0.96 g/t Au over 27.6m in hole MC23-140 (Figure 4).

The Argus Zone has now been defined over a strike length of 525m and a width of 200m and remains open in all directions. The results from hole MC23-140, the most westerly hole drilled by the Company, highlight the continuation of the Argus mineralization system with encouraging 1.0 g/t Au grades as it approaches the Pipestone Fault. The Company is developing a follow-up drill plan with further holes planned to the west.

Drill hole locations for the holes reported herein are shown in Figures 2 and 3 and significant assay intersections are shown in Table 1.

Results from Remaining Holes Testing the Croesus Flow

Results from four additional holes, MC23-130/131/133/134, completed on the Brown-Munro Vein Extension target in the vicinity of previously reported hole MC23-132 have been returned and included 1.92 g/t Au over 0.6m, 25 meters down-dip the visible gold intercept in MC23-132. Due to the high variability in gold grades across the new vein discovery, follow-up work will prioritize drilling on closely spaced centers around hole MC23-132 to determine the orientation and potential plunge to the gold-rich zone.

Results from six short holes, MC23-124/125/126/127/128/129, completed on the northeast extension of the Backhoe Vein target, immediately northeast of the Croesus Gold Mine, returned narrow widths of gold mineralization associated with quartz veining with highs of 5.19 g/t Au over 0.8 m and 4.45 g/t Au over 0.4 m in hole MC23-125.

H1-2024 Ontario Drill Program

The Company is currently developing exploration budgets and programs for follow-up drilling at the Munro-Croesus project and other Timmins-area projects during 2024.

Figure 1 – Location of Munro-Croesus Gold Project, Ontario

Figure 2 – Plan Map of Argus Zone Drill Holes

Figure 3 – Cross-section of Argus Zone with Drill Holes MC23-135/136/137

Figure 4 – Cross-section of Argus Zone with Drill Hole MC23-140

Table 1 – Munro-Croesus Project – 2023 Drill Hole Results

About the Timmins Area Gold Properties

Onyx owns 100% of each of its three Timmins properties. The Munro-Croesus Gold Project is located approximately 75 kilometers (47 miles) east of Timmins, proximal to the Porcupine-Destor and Pipestone Faults, and approximately two kilometers (1.2 miles) northwest and along trend of Mayfair Gold Corp.’s multi-million-ounce Fenn-Gib gold deposit. Mining occurred intermittently at Munro-Croesus between 1915 and 1936. The Golden Mile 140 square kilometer (54 square miles) property is located nine kilometers (5.6 miles) northeast of Newmont’s multi-million-ounce Hoyle Pond deposit in Timmins. The Timmins South (Golden Perimeter) 187 square kilometers (72 square miles) property is located to the south and southeast of Timmins and surrounds the Shaw dome structure.

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. 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.

Qualified Person and Quality Assurance

Ian Cunningham-Dunlop, P.Eng., Executive Vice President for Onyx Gold Corp. and a qualified person as defined by Canadian National Instrument 43-101, has reviewed and approved the technical information contained in this release.