Publication Summary
Issue ID: P2014-01-08
Title: Platinum-group mineralogy of the Giant Mascot Ni-Cu-PGE deposit, Hope, B.C.
Author(s): Manor, M.J., Scoates, J.S., Nixon, G.T., Ames, D.E.
Series Name: Paper
Publication Year: 2014
Larger Work Citation: in Geological Fieldwork 2013, B.C. Ministry of Energy and Mines, Paper 2014-01
NTS Map Sheet(s): 092H/05 06, 11, 12
Place Keyword(s): British Columbia, Hope
Lat/Long (NSWE): 49.48, 49.44, -121.54, -121.48
Theme Keyword(s): Giant Mascot, platinum-group minerals, Ni-Cu-PGE mineralization, ultramafic, magmatic sulphide
The Giant Mascot Ni-Cu-PGE deposit is British Columbia’s only past-producing nickel mine (1958-1974), having yielded ~ 4.2 Mt of ore grading 0.77% Ni and 0.34% Cu with minor Co, Ag and Au. Intrusive ultramafic rocks (olivine-orthopyroxene ± hornblende ± clinopyroxene cumulates) host the Ni-Cu sulphide mineralization. Field mapping and petrographic study have revealed primary magmatic cumulus textures and minimal alteration of the ultramafic rocks. Platinum-group minerals (PGM) determined by microbeam techniques are predominantly bismuthotellurides, primarily moncheite [(Pt,Pd)(Te,Bi)2], merenskyite [Pd(Te,Bi)2], and palladian melonite [(Ni,Pd)(Te,Bi)2]. Other precious-metal minerals include sperrylite (PtAs2), hessite (Ag2Te) and altaite (PbTe). Pt-, Pd- and Ni-bismuthotellurides are in or at the margins of base metal sulphides, predominantly pentlandite, or in fractures; precious-metal minerals are mostly along fractures in silicate minerals. Textures are consistent with an orthomagmatic origin for sulphides and PGM involving exsolution from base metal sulphides during cooling. Locally abundant fractures filled by chalcopyrite and platinum-rich moncheite are evidence for relatively late-stage mobilization of residual Cu-rich sulphide melts. PGE-enriched sulphides containing identifiable PGM and associated precious-metal minerals in the Giant Mascot intrusion indicate that ‘orogenic’ Ni-Cu mineralization in the Canadian Cordillera and elsewhere may provide significant exploration targets for economic Ni-Cu-PGE deposits.