Investigations have been carried out for a number of cobalt deposits in Australia including three from the Mt Isa Block in Queensland, several deposits in New South Wales, and one deposit each in the Northern Territory and South Australia, with respect to the identification of cobalt-bearing mineralisation and possible modes of formation. The deposits studied cover a range of deposit and mineralisation types including hydrothermal (e.g., cobaltite, Esperanza, Queensland; arsenopyrite, Dome Rock, South Australia) and sedimentary (secondary mineralisation such as the manganese wads at Bungonia, New South Wales). Deposits that were studied previously by the author (MSc thesis) in the Mt Isa Block have been used for comparison of mineralisation and temperatures of formation. The determination of the temperatures of formation of mineralisation, in particular with respect to cobaltite and arsenopyrite, by means of the application of the FeAsSCoAsS-NiAsS ternary phase diagram and the arsenopyrite geothermometer, has helped lead to deductions concerning the modes of deposition. Other deposit features such as structural constraints and associated mineralisation aided in the formalisation of conclusions. Many of the deposits are hydrothermal in nature and contain high temperature phases including molybdenite and uraninite. The latter represent geochemical and mineralogical clues which show that many of the ores were emplaced by igneous processes associated with granites. The findings of this study suggest that despite high percentages of substituting species in arsenopyrite, derived temperatures, from the application of the binary and ternary geothermometers, are comparable. It was noted that the presence of pyrrhotite and/or löllingite to act as buffers in the system is an important constraint on the comparability of derived temperatures. Potential processing applications for the extraction of cobalt from ores are briefly discussed, with respect to the type and cobalt content of mineralisation identified. The Esperanza and the Selwyn copper-gold deposits show the greatest potential for economic cobalt recovery. / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:ADTP/235504 |
| Date | January 2006 |
| Creators | Munro-Smith, Vera, University of Western Sydney, College of Health and Science, School of Natural Sciences |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
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