An Examination of Platinum-Group Element Thiospinels

Abstract

Abstract A review and discussion of platinum-group element thiospinels is presented, the context of which is a proposal accepted by the Commission of New Minerals, Nomenclature and Classification (voting proposal 17-H) made for the redefinition of cuproiridsite (ideally CuIr2S4), cuprorhodsite (ideally CuRh2S4), and malanite (ideally CuPt2S4), along with the discreditation of ferrorhodsite (ideally FeRh2S4) by Bosi et al. (2019). We review the literature in the context of the broader proposals by Bosi et al. (2019), highlight errors within them to conclude that all four proposals for redefinition and discreditation should have been rejected if the full facts had been consulted and IMA-established guidelines had been adhered to. It is agreed that dayingite should remain as a discredited mineral, while xingzhongite, redefined by Bosi et al. (2019) as Pb2+Ir3+2S4, is argued to be of questionable status and should be considered for discreditation.