Evolution of Pyrite Trace Element Compositions from Porphyry-Style and Epithermal Conditions at the Lihir Gold Deposit: Implications for Ore Genesis and Mineral Processing

Abstract

Gold commonly occurs in pyrite (FeS2) as "invisible" or refractory gold, as is the case at the giant Lihir (i.e., Ladolam) hybrid alkali-type gold deposit in Papua New Guinea. The Lihir gold deposit is also unique as it the exemplar of a telescoped ore deposit, whereby volcanic sector collapse led to superimposition of shallow-level gold-rich epithermal mineralization upon preexisting, but genetically related, porphyry-style alteration. While this superimposition led to a giant 56 Moz gold resource, it also created complications with regards to ore processing, specifically with regards to the difficulties in mineral processing of the refractory gold-rich pyritic ore.