Crystal chemistry of globular layered silicates of the Troitsko-Bainovskoye fre-clay deposit (Middle Urals)

Research subject. The composition and crystal chemistry of glauconite from the open deposits (K2cn-cp) of the Poldnevskaya area of the Troitsko-Bainovskoye deposit of fire clays.Materials and methods. An analysis of the mineralogical and crystallochemical properties of glauconite was carried out using a set of modern analytical methods (“Geonauka” Centre for Collective Use, IG FRC Komi SC UB RAS): X-ray diffractometry, IR-spectroscopy, scanning electron microscopy, modeling of diffraction profiles.Results and conclusions. The crystal-chemical features of glauconite were determined. Two main glauconite varieties (green and light green) in the rocks of the Zaikovskaya suite were distinguished and their differences and degree of maturity have been established. It was found that dark green globules are close to glauconite and represent a more “mature” variety, while the light green ones are a disordered mixed-layer mineral of the mica (glauconite) – smectite series and are a product of incomplete replacement of the original smectite by glauconite. Phase heterogeneity of glauconite globules was revealed. It has been established that the rocks of the Troitsko-Bainovskoe deposit are exposed to intensive transformation under the influence of acidic surface and technogenic waters, which result in the destruction of the initial minerals and the appearance of secondary mineralization. Clay minerals of the glauconite-bearing rocks are represented by disordered mixed-layer phases of predominantly illite/smectite type.