Surface properties of illite-smectite minerals as detected by interactions with Rhodamine 6G dye

Interactions between smectite clay minerals and various organic dyes have been studied extensively, but little information has accumulated from dye interactions with mixed-layer illite-smectite (I-S) minerals, especially regarding relationships with clay layer expandability, layer charge, particle size/shape, and molecular aggregation of organic dye molecules. The purpose of this study was to investigate the surface interactions of a set of mixed-layer illite-smectites from different geological environments with Rhodamine 6G dye. The samples used have different amounts of expandable smectite interlayers, different particle size and/or shape, and different layer-charge density at the surface. Five smectites with differences in layer charge and some non-expandable layer silicates were also tested. The interactions detected by UV-vis spectroscopy show no reaction between R6G and non-expandable minerals (kaolinite, mica), and intense reactions forming H-aggregates and monomers with smectites and illite-smectites. The intensity of H-aggregate formation increases with increase in the layer charge of smectites. Mixed-layer illite-smectites interact with R6G more intensely than do smectites. H-aggregate and monomer formation increases with the illitization process for randomly ordered illite-smectites (R = 0) and decreases in the course of illitization for the ordered illite-smectites (R > 0)

Hydrothermal speleogenesis in carbonates and metasomatic silicites induced by subvolcanic intrusions: a case study from the Štiavnické vrchy Mountains, Slovakia

Several caves of hydrothermal origin in crystalline limestones and metasomatic silicites were investigated in the central zone of the Štiavnica stratovolcano, Štiavnické vrchy Mountains, central Slovakia. Evidence of hydrothermal origin includes irregular spherical cave morphology sculptured by ascending thermal water, occurrence of large calcite crystals and hydrothermal alteration of host rocks, including hydrothermal clays. The early phases of speleogenesis in the crystalline limestone near Sklené Teplice Spa were caused by post-magmatic dissolution linked either to the emplacement of subvolcanic granodiorite intrusions during Late Badenian time or to the spatially associated Late Sarmatian epithermal system. Speleogenesis in metasomatic silicites in the Šobov area is related to hydrothermal processes associated with the pre-caldera stage of the Štiavnica stratovolcano in Late Badenian. Both localities are remarkable examples of hydrothermal speleogenesis associated with Miocene volcanic and magmatic activity in the Western Carpathians

Particle properties of hydrothermal ammonium-bearing illite-smectite

Mixed-layer illite-smectite with high degree of ordering (rectorite-like clay) and with three types of interlayer cations - K, Na and NH , was detenrimed in the high-sulfide epithermal mineralization of the Western Carpathian Mountains. The tobelitic portion of the clay comprises 5-10%. Ammonium was detected both by chemical analysis and by Fourier transform infrared analysis. Some of the ammonium can be assigned to a poorly bound form, not fully fixed in the illitic interlayer. The finest size fraction separated from the samples behaves differently from the rest of the sample. It contains two layers of water molecules in the expandable interlayers as determined by X-ray diffraction, whereas coarser fractions have only one water layer in the interlayers