Robin Joudrie, BSc
R. Joudrie1, W.M. Bain1, F. de Waal2, D.J. Goudie3
1Department of Earth Sciences, Western University, London, Ontario, Canada
2School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
3Core Research Equipment and Instrument Training (CREAIT) Network, Memorial University of Newfoundland, St. Johns, Newfoundland, Canada
Cobalt (Co), nickel (Ni), and platinum-group elements (PGEs) are essential to low-carbon technologies, yet global supply chains for these metals are acutely vulnerable to disruption. Recent studies have identified significant Co–Ni–PGE enrichments in alkalic Cu–Au porphyry deposits of the Canadian Cordillera. Although analysis of ore-stage mineralogy suggests that these elements occur primarily as trace constituents within sulphide minerals, bulk geochemistry and mineral tenors suggest that PGEs and other critical elements may occur as discrete mineral phases.
This study evaluates the possible occurrence of discrete Co-, Ni-, and PGE-bearing mineral phases in the New Afton alkalic Cu–Au porphyry deposit via a detailed mineralogy and textural characterization of Co-, Ni-, and PGE-rich zones. This study unitizes combined Mineral Liberation Analysis (MLA) and targeted scanning electron microscopy (SEM) analysis to develop a high resolution, quantitative mineralogical and textural dataset that can be used to link Co–Ni–PGE enrichment to specific sulphide textures and alteration domains. When applied to a large deposit-wide sample sets, this technique can efficiently link mineralogical variation to observed variations in bulk geochemistry and help better understand the source of Co, Ni, and PGE enrichment observed in production assays.
Here we present data from PGE-, Ni-, and Co-rich zones within the New Afton and nearby Copper King deposits. Preliminary results indicate that PGE-minerals (PGMs; sperrylite, froodite, palladium arsenides) and cobaltite occur in primary sulphide-oxide-carbonate veins and are commonly hosted in or spatially associated with PGE-bearing pyrite and chalcopyrite. These PGMs are typically intergrown with ore-stage mineralogy and are texturally and paragenetically distinct from the sulfides with PGE-bearing growth zones identified in previous studies. Moreover, PGM also appear to be spatially, and possibly paragenetically associated with magnetite–apatite–sulphide veining and possibly later-stage carbonate–quartz veining. These observations suggest that PGE and Co enrichment occurred during multiple mineralizing events and may reflect shifts in redox conditions or the larger magmatic evolution of intrusions associated with the New Afton deposit.
These findings refine genetic models for alkalic porphyry deposits and support evaluation of Co–Ni–PGE by-product potential within existing Cu–Au operations, contributing to Canada’s critical mineral strategy.