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Abstract

The Trembleur ultramafite in the Decar area in central British Columbia consists of several ultramafic protolith lithologies that are variably altered to serpentinite, ophicarbonate, soapstone and listwanite. Alteration minerals include brucite (Mg[OH]₂), which can be used to sequester atmospheric CO₂ and awaruite (Ni₃Fe), which is an economically attractive nickel alloy. These two minerals are formed during serpentinization and destroyed during carbonate alteration. This study examines the formation and preservation of these two minerals. The abundance, grain size and morphology of brucite and awaruite are variable, and the underlying controls on their distribution have been unclear. We use petrographic observations (textures, mineral assemblages), whole-rock and mineral major-element chemistry, and physical properties to characterize the formation, stability, and distribution of brucite and awaruite in order to optimize their utilization within the processing circuit should the deposit be mined. Brucite comprises up to ~13 wt.% of serpentinite and occurs as fine (