First find of nephrite with accessory minerals of the platinum group

Abstract

The relic minerals of the platinum group (MPG) were found for the first time in nephrite of tremolite–diopside composition associated genetically with the boninite dike of the Gorlyk-Gol deposit. This latter is confined to a segment of the zone of serpentinite mélange in the southern part of the Ospinsko–Kitoi ultrabasite massif in the East Sayan ophiolite belt. The micro- and nanophases of MPG were identified: rutheniridosmine with Ni and Fe admixtures, ruthenium, rutheniridium, iridoarsenite, omeiite, and laurite. The MPG sources are chromium spinels from harzburgites and dunites of the Ospinsko–Kitoi massif subjected to deforming transformations in the zone of the serpentinite mélange.