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Onyx Gold hits new High-Grade discovery at Munro-Croesus Project, Timmins

Dec 6, 2023

Onyx Gold Corp. is pleased to announce initial exploration results from its 2023 Fall drill program in the Timmins gold camp. The first assay results have been returned for drill hole MC23-132, which tested a prospective area 350m (1,148 feet) northwest of the former Croesus Gold Mine. The Croesus Gold Mine is famous for yielding some of the highest-grade gold mined in Ontario. 

The completed program included ~4,000 meters ("m") of diamond drilling with one drill rig and focused on targets proximal to the historic high-grade Croesus Gold Mine, and on the new bulk-tonnage-style Argus Zone discovered in 2022. 

Highlight Assay Results for Drill Hole MC23-132 include:

  • 121.8 grams per tonne ("g/t") (3.55 ounces per ton "opt") gold ("Au") over 0.9m (true width), including 

    • 363.0 g/t (10.59 opt) Au over 0.3m (true width) 

The drill hole intersected a 30-centimeter-wide quartz vein containing abundant visible gold that returned 363 g/t (10.59 opt) Au over 0.3m, representing the single highest assay in the Company's drill hole database for the project. The high-grade vein occurs within a broader zone of mineralization averaging 121.8 g/t (3.55 opt) Au over 0.9m and was intersected approximately 60 m vertically below surface. This new vein discovery represents an entirely new high-grade quartz vein in a geological setting comparable to the mined-out, bonanza-grade Croesus vein.

"The intersection of multi-ounce gold grades within a completely new vein system parallel to the renowned Croesus Vein is a direct validation of the team's recent advancements in geological and structural modeling in the area," said Brock Colterjohn, President & CEO. "The historic Croesus Gold Mine produced some of the highest-grade gold ever mined in Ontario, with an average head grade of 95.3 g/t (2.78 opt) gold. This new vein underscores the opportunity for additional discoveries within an established high-grade gold environment. It is an excellent start to Onyx Gold's inaugural drill program in Ontario." 

"The Timmins camp is one of the most prolific gold-producing regions in the world with multiple operating mines and excess milling capacity. Onyx Gold has established one of the largest land positions in the camp not owned by a producer. Much of this land package is in prime high-potential geology with little or no work completed for decades. Our land tenure represents particularly attractive opportunities for discoveries such as this. This new vein remains open in all directions, and we look forward to further expanding this high-grade discovery in a winter drill campaign. We are also looking forward to results from the rest of our fall program which will be reported in due course."

Discussion of Results

A total of five (5) holes (MC23-130 to MC23-134) totaling 872m were completed by the Company in late October/early November to follow-up north and south of drillhole MC22-92 drilled by the previous operator, HighGold Mining Inc., which intersected a narrow quartz vein that returned 14.0 g/t Au over 0.6 meters in a broader interval grading 3.4 g/t Au over 2.6m (See HighGold Mining Inc. press release from March 30, 2022). The area was targeted for its similar geological setting to the Croesus Gold Mine - specifically, the occurrence of a parallel vein to the Croesus Vein within a particular basalt flow unit that is locally brecciated and enriched in sulfides (the "Croesus Flow"). The Croesus Flow is interpreted to play an important role in the deposition of exceptionally high concentrations of gold within the Croesus Vein.

Results have been returned from hole MC23-132, a 25-meter step-out south of MC23-92, which intersected what is believed to be a new vein in a parallel orientation to the Croesus Vein within the upper portion of the Croesus Flow. The quartz vein was intersected from 83.0-83.3 meters downhole within sulfidic pillowed Croesus Flow and returned the highest-grade interval on the property to date of 363.0 g/t Au over 0.3m (true width) within a broader structural zone averaging 121.8 g/t Au over 0.9m (true width). The quartz vein is characterized by massive, white-grey quartz with abundant fine-grained aggregates of visible gold throughout and in and along the margins of pyrite grains. The quartz contains coarse, disseminated, and fracture-filling pyrite and trace, fine-grained sphalerite, and arsenopyrite as shown in Plate 1. The 363.0 g/t Au assay was obtained by gold gravimetric analysis (Au-GRA22) at the ALS Canada lab in North Vancouver. A gold screen analysis (Au-SCR21) was also performed and returned a total gold value of 342.0 g/t Au. 

Between 1915 and 1936, the Croesus Mine, produced 14,854 ounces of gold mined from 5,333 tons with an average grade of 2.78 opt Au (95.3 g/t Au) as reported by the Ontario Department of Mines in 1951. Note - this production number did not include the ore that was mined and shipped in packing crates directly to the Royal Canadian Mint. Five (5) gold samples purchased by the Ontario Bureau of Mines for exhibition purposes and now in possession of the Royal Ontario Museum in Toronto, Ontario weigh 85 pounds collectively and contain 480.7 ounces of gold or 11,310 oz gold per ton (387,727 g/tonne). The Croesus Vein and the new vein are parallel northeast-striking, east-southeast-dipping shear veins that contain abundant visible gold where they intersect the permissive host lithology (Croesus Flow). This highlights the opportunity to discover additional parallel high-grade veins within the Croesus Flow.

Drill hole locations for the holes reported herein are shown in Figures 2 and 3.  Assay results for the other four holes to test the target area are currently pending. 

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 (Figure 1). 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.

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