Electron diffraction study of 1M illites with interstratified trans- and cis-vacant 2 : 1 layers

Abstract

Illites from the volcanogenic Zn-Au-Ag sulfide deposit Galkinskoe (Northern Urals) have been investigated using oblique texture electron diffraction patterns in combination with the simulation of diffrac tion effects. Along with single phase tv/cv1M illites, the structures of which are formed by statistically inter stratified dioctahedral 2 : 1 layers with vacant trans or cis octahedra, illites in the form of a mixture of two interstratified tv/cv1M phases, with the dominance of tv or cv layers, are identified. It is shown that in the latter case the diffraction pattern can also be interpreted within the single phase tv/cv model, provided that the tv and cv layers are distributed with some tendency to segregate. The structural features indicating the preference of the two phase model are analyzed.

Noble Metal Speciations in Hydrothermal Sulphides

“…Locally semi-massive and massive sulphide ore forms thin (up to 1 m) lenses in interlayers of carboniferous fineclastic sedimentary rocks. The abundant veinlet-impregnated ores are hosted by argillic (illite/smectite-sericite-quartz and kaolinite) alteration, formed after cement of rhyodacitic breccia [82]. The ores are almost unaffected by any metamorphism, so colloform structures, and fine-grained textures of ores, are widespread, and sulphides carry a high proportion of invisible gold [15].…”