Diamond accessory minerals in the Rassolninskoe and Volynka deposits (Perm' Oblast, Russia)

Crystallographic and geochemical features of the platinum group minerals (P GM), Sold, garnet, and chromespinellids-diamond accessory minerals from the Rassolninskoe and Volynka bedrock xenoeffusive (visherite) diamond-bearing deposits are characterized. The scanning electronic microscope JSM-6400 wi th the energy-dispersing adapter Link ISIS-300 was used for the research. T he PGM and gold crystallomorphology and composition were characterized for the first time. The following features of accessory minerals were revealed: perfect crystallographic morphology (chromespinellids, isoferroplatinum, a nd osmium), primary xenomorphic crystal habit (ilmenite and gold), and trac es of mantle etching and solution (resorbed surfaces of andradite-knorringi te-pyrope and chrome-spinellids). Compositions of the major part of garnets and chromespinellids correspond to ultrabasic and eclogite diamond assembl ages of the diamond-pyrope facies. The majority of grains of accessory mine rals and gold do not have evidences of mechanical wear and prolonged presen ce in alluvial flow. This testifies to their close occurrence in proximity to their bedrock source. It is possible that visherites possessing cutting contacts with country sedimentary rocks served as a source-carrier of diamo nds and their accessory minerals derived from depths. It is also probable t hat some of the studied minerals were formed in diamond-bearing rocks in th e process of their hydrothermal-metasomatic transformation (gold, monazite, rutile, anatase, pyrite, marcasite, and hoethite). Taking into account the prospecting for diamond primary sources carried out in the Urals and Timan s, the obtained results can be of interest.