Going platinum: PGE and chalcophile elements from the mantle to mineral deposits

Metals such as cobalt and the platinum-group elements (PGE) are essential to the development of sustainable technology – from batteries and fuel cells, to resist ors in electronics and even in the production of 5G infrastructure. These metals are also classified as critical raw materials due to concerns over security of supply, as they are produced from only a handful of deposits in a few countries. Many of these elements, including platinum (Pt), palladium (Pd), rhodium (Rh), ruthenium (Ru), iridium (Ir), cobalt (Co), nickel (Ni), copper (Cu) and gold (Au) have an affinity for sulphur (they are chalcophile) and therefore the most fertile source of these elements comes from the Earth’s core and mantle. In the mantle, these important metals are largely hosted at trace concentrations by base metal sulphides (BMS) and in percentage concentrations in tiny platinum-group minerals (PGM).

To be mineralised and concentrated into ore deposits, we must consider how to mobilise these minerals and their precious metal cargo into the Earth’s crust. During partial melting of the mantle, sulphides release a portion of their metal budget into the magma generated, but it remains difficult to fully quantify this process given the diversity of sulphide compositions, let alone understand how PGM become mobilised. And yet, identifying how metals are mobilised out of the mantle into the crust may have some big implications for the fertility of magma, including exotic low degree partial melts such as carbonatites, lamprophyres and kimberlites, and with it some important consequences for mineral exploration. This talk will discuss a range of topics, from the uses and economics of the PGE and other chalcophile critical elements, to metallogenesis and how these metals end up in ore deposits.