Composition and formation conditions of nephrite, Nyrdvomenshor deposit, Polar Urals

Research subject. Nephrite and related rocks from the Nyrdvomenshor deposit in Polar Urals were studied. The is located exocontact of Rai-Iz ultramafic massif, confined to Main Ural Fault. was developed process geological exploration; a license has been issued for part deposit. Aim. To study nephrite alluvial deposit, formulate model its origin. Methods. Qualitative characteristics assessed visually using binocular microscope special flashlight. chemical composition determined by X-ray fluorescence method. contents trace elements ICP-MS analysis. mineral studied on scanning electron with an energy dispersive microanalysis system. Measurements isotopic oxygen carried out. Results. In addition vesuvianite rodingite, hydrogarnet rodingite found be common at substandard. Tremolite predominates nephrite, diopside forms relic grains. Uvarovite widespread, forming both idiomorphic grains, sometimes sheath, less often elongated xenomorphic, replacing chromite. Omphacite overgrows grains chromite uvarovite. Grains Fe-dominant shuiskite group are noted. Conclusions. formed through metamorphic metasomatic processes. Serpentinite replaced diopside, which then nephrite. Metamorphism enhanced metasomatism serpentinite melange provided cryptocrystalline tangled fibrous structure Then metamorphism led formation omphacite cracking reduced quality. As these processes progressed, contribution crustal fluid increased, confirmed results studying other