Vaesite (NiS2): the first finding in carbonatites

Information is given on the morphology, chemical composition and structure of crystals of rare nickel disulfide - vaesite (NiS2), first discovered in carbonatites. Prior to this, vaesite was found in rocks confined to ultrabasic and basic masiffs, or to hydrothermal veins. Vaesite was met in the form of single grains. The crystals, like other accessory minerals (phlogopite, tremolite, muscovite, pyrite, ruby, tourmaline), had an idiomorphic faceting, located in isolation from each other, or toward the growth zones of large calcite crystals. Most likely, all these minerals were crystallized from carbonate magma, which formed carbonatite dikes. The mineral from carbonatites differed from vaesite from other sites by a noticeable amount of Cu (about 9 wt.%), a small content of Fe (2-5 wt.%), and the absence of Co. X-ray diffraction characteristics of vaesite corresponded to its typical samples. The main rock-forming minerals (calcite and dolomite) and the main part of accessories (phlogopite, tremolite, muscovite, pyrite, tourmaline, ruby and vaesite) were formed simultaneously. A later association was represented by native sulfur, quartz, and fluorite, performing miarola cavities. The weathering crust on carbonatites containing nickel sulfides can serve as a source of nickel for silicate ores.