4 minute read - Published 09:30 AM EST, Monday September 30
This article was authored by Peyton Baird of witan nook.
The Munro-Croesus Gold Project, fully owned by Onyx Gold, stands as one of Ontario’s most promising gold exploration ventures. Located about 75 kilometres east of Timmins, Ontario, along Highway 101, the site occupies a strategic position within a well-known geological structure that has a storied history of gold production. The Munro-Croesus Project boasts a rich legacy, high potential, and prime proximity to significant gold-producing zones, making it a key target in the highly productive Timmins Gold Camp.
Onyx Gold Team Reviewing Land Claims via Helicopter | Onyx Gold Corp.
Historical Significance: The Croesus Mine
At the heart of the Munro-Croesus Project is the historic Croesus Mine, once celebrated for its exceptionally high-grade gold production. Between 1915 and 1936, the mine produced approximately 14,859 ounces of gold from 5,333 short tons of ore, with an average grade of 2.78 ounces per ton (95.3 g/t). What sets the Croesus Mine apart is its legendary status for 'bonanza-grade' gold. Five specimens mined from Croesus are currently held at the Royal Ontario Museum in Toronto, weighing 85 pounds and containing 480.7 ounces of gold. This equates to a staggering grade of 11,310 ounces per short ton, or 387,771 grams per tonne—a testament to the mine’s unique high-grade nature.
The Croesus Mine property had remained largely in private hands since its discovery in 1914, with limited involvement by publicly traded companies. In 2007, Constantine Metal Resources acquired a 100% interest in the property, including 13 patented mining claims, two Crown mineral leases, and two unpatented mining claims. This acquisition included the Croesus Mine itself, which had long been under private ownership until Constantine’s purchase. The gold assets were later spun out to HighGold Mining and eventually to Onyx Gold, where the project now resides under full control.
Geology and Exploration Potential
The Munro-Croesus Project benefits from its location within a highly prospective geological setting. The project lies close to the Porcupine-Destor Deformation Fault Zone, a major gold-bearing structural break in northern Ontario and Quebec that has collectively produced more than 110 million ounces of gold. The project also sits just three kilometres northwest of Mayfair Gold’s multi-million-ounce Fenn-Gib deposit and near STLLR Gold's Tower Gold Project.
The property is underlain by sedimentary rocks of the Porcupine assemblage to the south and by mafic and ultramafic volcanic rocks of the Upper Kidd-Munro assemblage to the northeast. Gold mineralization is predominantly structurally controlled, occurring in orogenic deposits within the Archean greenstone belts that define much of the Timmins region. These deposits, often associated with quartz-carbonate veins, are located along crustal-scale fault zones within deformed greenstone terranes. The known gold occurrences within the Munro-Croesus project are associated with an eight-kilometres segment of the Pipestone Fault, a splay of the Porcupine-Destor Fault Zone, enhancing the property’s prospectivity.
Onyx Gold's Munro-Croesus Gold Project's Regional Cartographical Claims | Onyx Gold Corp.
Strategic Location within a Gold-Rich Region
The Timmins Gold Camp is known for its wealth of bulk-tonnage gold deposits, typically containing low-grade but large volumes of gold. The Munro-Croesus Project is surrounded by numerous high-profile deposits, including the aforementioned Mayfair Gold Fenn-Gib project and STLLR Gold Tower Gold Project. These neighbouring deposits contain millions of ounces of gold, typically in deposits with grades under 1 g/t. Furthermore, McEwen Mining’s Black Fox underground gold mine is located just 1.5 kilometres southwest of the Munro-Croesus property, further highlighting the significance of the area.
Onyx Gold’s Munro-Croesus Project benefits from proximity to these deposits, and the company has pursued an aggressive land consolidation strategy in recent years. Between 2020 and 2024, Onyx Gold and its predecessors acquired over 25 additional land parcels, expanding the Munro-Croesus land package by over 200%. In 2024, Onyx added the Lalonde Property, increasing the total landholdings to 9,235 hectares. This acquisition increased the size of the Munro-Croesus Project by 32% and added further exploration potential, as the Lalonde Property contains high-grade gold occurrences.
Recent Exploration Activities
Onyx Gold is in the midst of the first significant exploration program at Munro-Croesus in nearly 90 years. The exploration strategy includes geophysical surveys, data compilation, prospecting, and extensive rock and soil sampling. In 2022, a ground direct current induced polarization (DCIP) and magnetic survey covering 63 line-kilometres was conducted over core target areas and key structures.
The 2024 spring drilling program is a major component of the exploration efforts, with 25 holes drilled, totalling 3,311 meters. Drilling primarily targeted the newly identified GM vein and the Argus Zone, two key areas of interest on the property. The GM vein, located near the surface, showed encouraging signs of high-grade mineralization. Five of the six holes drilled at the Argus Zone intersected significant gold mineralization, including a notable result of 0.99 g/t gold over 63 meters, which included a 17.4-meter section grading 2.18 g/t gold. The Argus Zone is characterized by silicified mafic variolitic volcanics and pyritic veinlets within a broader halo of carbonate alteration, pointing to its potential as a significant gold-bearing zone.
Future Outlook for Onyx Gold
With the ongoing drilling success and strategic acquisitions, the Munro-Croesus Gold Project is positioned as a key asset in Onyx Gold’s portfolio. The historic bonanza grades of the Croesus Mine, combined with modern exploration techniques, suggest that the project may yet hold significant untapped potential. As the company continues its exploration program and expands its land package, the Munro-Croesus Project will be one to watch in Ontario’s gold mining sector.
Onyx Gold’s focus on this high-grade historic mine, combined with its aggressive exploration strategy, gives the company a solid foundation to unlock further value in one of Canada’s most famous gold-producing regions. The Munro-Croesus Project, with its prime geological location, rich history, and ongoing exploration, may once again contribute to the long-standing gold legacy of the Timmins Gold Camp.
This article was authored by Peyton Baird of witan nook.
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