CRYSTAL-FORMING FUNCTIONS OF GLIDE PLANES IN THE STRUCTURAL ORGANIZATION OF A NUMBER OF (PB, BI)-CONTAINING SULFIDES
S. V. Borisov, S. A. Magarill, N. V. Pervukhina
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: (Pb-Bi)-сульфиды, зальцбургит, эльдрагонит, изоклакеит, викингит, кристаллографический анализ, катионные и анионные подрешетки, плоскости скользящего отражения, эффект ВІбиенияВІ подрешеток, left-handed configurations, salzburgite, eldragonite, izoklakeite, vikingite, crystallographic analysis, cation and anion sublattices, glide planes, sublattice beat effect
Abstract
The reasons for the preference of glide planes in natural crystals are considered by studying the results of an X-ray crystallography analysis of the minerals salzburgite, eldragonite, izoklakeite, and vikingite. The glide planes organize the combination of right- of atomic fragments, which appear during crystallization, and contribute to a uniform distribution of atoms in complex compositions and a more dense and symmetrical packing. The fact that the structures have cation and anion sublattices with similar dimensions and orientations creates a situation similar to that of beats in oscillatory systems and, hence, modulates the intensity of X-ray reflections. The progressively increasing number of structures where individual atomic positions are occupied by two or more types of atoms suggests a stable geometry of the corresponding atomic sublattices with respect to compositional variations. Analysis of these “skeletal” sublattices is a key to understanding the solid-phase transformations, contact interactions, and dynamic processes in mineral associations.
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