Onyx Gold’s Argus system: depth extensions and resource lens for mine planners
Reviewed by Tom Sullivan
First reported on MINING.com
30 Second Briefing
Drill results at Onyx Gold’s Munro-Croesus project in Ontario extend the Argus gold system at depth, with hole MC26-274A at Argus North cutting 28.1 metres grading 3.5 g/t from 380 metres, including 17.8 metres at 5.3 g/t, and MC26-324 at Argus Main returning 93 metres at 1 g/t from 316 metres, including 20 metres at 2 g/t. Argus North has now been intersected below 700 metres vertically and remains open, hosted in broad altered volcanic units with steeply plunging high-grade shoots. Onyx has completed 75,000 metres of a planned 110,000-metre, fully funded programme across 188 holes, targeting an initial resource beyond the historic Croesus mine, which averaged 93.5 g/t gold between 1908 and 1936.
Technical Brief
- Hole MC26-271 at Argus North cut 19 m at 3.5 g/t from 409 m, including 6.6 m at 8.3 g/t.
- Argus North intersections now extend beyond 700 m vertical depth and remain open down-plunge.
- Deeper drilling continues to encounter broad altered and mineralised volcanic units consistent with shallower Argus North geology.
- Argus gold system geometry combines steeply plunging high-grade shoots with disseminated low- to moderate-grade envelopes.
- Munro-Croesus lies 75 km east of Timmins and ~540 km north of Toronto, within the Abitibi belt.
- Historic Croesus mine on the property averaged 93.5 g/t Au between 1908 and 1936, indicating very high-grade potential.
- Current campaign totals 75,000 m across 188 holes, within a fully funded 110,000 m programme.
Our Take
Onyx Gold’s Argus results sit in the more technically advanced end of our gold project coverage, with 188 holes over two years of drilling placing Munro-Croesus among the better-constrained Abitibi exploration plays rather than early-stage ‘first-pass’ prospects.
The association with Hitachi Machinery and Pronto in this piece echoes a separate MoU between Hitachi Construction Machinery and Pronto on OEM-agnostic mine automation, signalling that any future underground or bulk-tonnage development at Munro-Croesus could be a candidate testbed for retrofit autonomous haulage once a resource is defined.
Depths beyond 700 m at Argus North, combined with multi-decade historic ultra-high grades at the nearby Croesus mine, suggest that if continuity is demonstrated, the project is more likely to evolve toward an underground, high-margin mine concept than a shallow open-pit scenario, which has implications for future capex profile and required shaft or ramp infrastructure in northern Ontario.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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