TELLURIDE MINERALOGY OF THE GOLDEN MILE DEPOSIT, KALGOORLIE, WESTERN AUSTRALIA

The Golden Mile is a giant orogenic lode gold deposit located within the Norseman-Wiluna Belt in the Yilgarn Craton, Western Australia. It is a unique deposit because of its size (having produced greater than 1200 tonnes of Au) and in that telluride mineralization is responsible for 15 to 20% of gold production. Gold mineralization is hosted primarily by Archean-aged dolerites and basalts that have been metamorphosed to the greenschist facies. This mineralization occurs within hundreds of shear zones as auriferous and telluride-bearing lodes, which have been classified into three structural types based on orientation (main (trending NNW), caunter (trending NW) and cross lodes (trending NE)). Three distinct styles of mineralization are present within the area. The older Fimiston (characterized by main, caunter and cross lodes) and Oroya (vanadium and telluride rich cross lodes) styles are overprinted by younger Mount Charlotte (quartz vein stockwork) style mineralization. Native tellurium and sixteen tellurides (calaverite (AuTe₂), krennerite ((Au,Ag)Te₂), sylvanite ((Ag,Au)Te₄)), montbrayite ((Au,Sb)₂Te₃), petzite (Ag₃AuTe₂), coloradoite (HgTe), hessite (Ag₂Te), stuetzite (Ag_5-xTe₃), altaite (PbTe), tellurantimony (Sb₂Te₃), nagyagite (Au(Pb,Sb,Fe)₈(S,Te)₁₁), melonite (NiTe₂), weissite (Cu_2-xTe), tetradymite (Bi₂Te₂S), rickardite (Cu₄Te₃), and one poorly identified gold-arsenic telluride) occur in the Golden Mile. Calaverite, petzite, coloradoite, altaite, and native gold are commonly found throughout the Golden Mile. Tellurantimony, melonite, hessite, stuetzite, krennerite and sylvanite are rarely found in the main and caunter lodes. Additionally, hessite is found in trace amounts in the cross lodes and montbrayite is found in trace amounts in the main lodes. Krennerite is restricted to the central part of the deposit whereas montbrayite has been found only along the margins of the Golden Mile. First generation tellurides in the Fimiston and green leader ores formed at logfTe₂=-11.4 to –6.8 and logfS₂=-12.6 to –5.5, approximately (assuming a T of ore formation of 300^oC). Ultimately the results obtained from this study will be useful as potential guides to ore on mine, local, and regional scales.