Mineral Mapping through a Ni-Cu Deposit – Internship [Video]

Layered intrusions can host several ore deposit types, including magmatic Ni-Cu sulphide deposits. Exploration of these deposits can be difficult as they represent small targets with ore bodies that are usually confined to the base or within a small layer of the host intrusion. Subtle changes in mineral chemistries of the major silicate minerals, minor and trace minerals have the potential to track interactions with the sulphide melt. Therefore, the variability in mineral chemistries and in modal mineral abundances could potentially be used as a vectoring tool towards Ni-Cu sulphide ore horizons in layered intrusions. The Mirabela layered intrusion, located in NE Brazil, is the pilot case study for this research. The intrusion is host to the stratiform disseminated Ni-sulphide bearing Santa Rita orebody which is up to 180 m in thickness and lies just below the ultramafic-gabbro contact. Six drillholes from Mirabela have been sampled across, and where possible, above and below the orebody. These samples were analysed petrographically and using a Tescan integrated mineralogy analyser (TIMA). The TIMA data was processed to accurately identify and quantify the modal mineralogy and individual mineral chemistries throughout 43 samples. Other grain analyses were run including mineral associations, which revealed a link between the sulphides and the hydrous minerals. Finally, this data was evaluated using CSIRO’s XTMineral app to test for drillhole-scale mineral abundance gradients.

 

Bio: Lily is a CSIRO Mineral Resources – Dicovery intern student who has spent the last three months investigating automated mineralogy techniques and looking for mineral zonation in mafic intrusions under the supervision of Louise Schoneveld and Tobias Schlegel. For her PhD studies back in the UK (University of Leeds), she is researching cobalt mineralisation in the Rajapalot Au-Co deposit, Finland, using micro-geochemical and -structural techniques. Her passion lies with tying observations from hours looking down the microscope to deposit-scale processes.