MINERALOGICAL CHARACTERIZATION AND MICROPROBE ANALYSIS OF TELLURIUM MINERALS FROM THE PERSEVERANCE VMS, QUEBEC, CANADA

Tellurium is a metalloid element critical to manufacturing of advanced photovoltaic panels. Production of tellurium is mainly from anode slimes produced during the electrorefining of porphyry copper ore. Volcanogenic massive sulfide (VMS) deposits are an important additional source of tellurium, with deposits in the Ural Mountains of Russia, and Kankberg in the Paleoproterozoic Skellefte district of Sweden collectively producing ~17% of global tellurium annually. The processes of tellurium enrichment in black smoker systems and the mineralogical sequestration of this element in the massive sulfides are currently poorly understood. To address this, this study focuses on the telluride mineralogy of the Perseverance VMS deposit in the Matagami camp of Quebec, Canada. Although the deposits of this camp are known for their high tellurium contents, this element has not been produced as a byproduct in any of the mines. Perseverance is one of the most significant deposits in the camp and was mined between 2008 and 2013, with pre-mining reserves of 5.1 Mt of ore grading at 15.8% Zn, 1.24% Cu, 29.4 g/t Ag, and 0.4 g/t Au.

Thin sections from various ore and alteration zones of the Perseverance deposit were analyzed to identify and locate telluride minerals via scanning electron microscopy-based automated mineralogy. Identified Te phases include altaite, hessite, mattagamite, melonite, and others. Micro-textural relationships were studied by reflected light microscopy and field emission scanning electron microscopy. Frequently, these phases form as multi-mineral grains of up to four distinct telluride phases, commonly as inclusions in the highly recrystallized major ore minerals and along grain boundaries. The textural evidence indicates that the formation of telluride phases was a consequence of the recrystallization and associated purge of trace elements by the main sulfide minerals, primarily pyrite and sphalerite, caused as a result of regional greenschist to amphibolite facies metamorphism and structural deformation of the deposit. In a next step, all identified telluride phases from Perseverance will be analyzed using electron probe microanalysis. This new research will give insights into the composition of telluride phases in VMS deposits, as well as provide information important to mineral processing.