Xəbərlər

The present research is the first essential attempt of comparison parent structural minals and the activated complexes for finding-out crystal-chemistry features formations of minerals in the hydrothermal environment.

 

The method of comparative crystallochemistry has been used substantiate possible variants of tscharoite structure. It is supposed that tscharoite structure preserves structure element of miserite, where canasite radicals bind with double octahedral columns and form a structure block Ca₈(Si₁₂O₃₀)₂. Impossible variant chemical composition K₃NaCa₈(Si₁₂O₃₀)(Si₆O₁₅)(OH)₂×3H₂O, spatial group P2/m.

 

The system CaO-SiO₂-Al₂O₃-B₂O₃ was studied under hydrothermal conditions. Boratocancrinite (Na,Ca)2/Na₆(AlSiO₄)₆/BO₃2H₂O and sodium silicate - b - Na₂Si₂O₅ phases were synthesized and characterized using physicochemical methods. At about 700°C boratocancrinite converts to nepheline Na₈Al₈Si₈O₃₂. The main structural elements of these minerals are built of the same precursor structural minals. Then substantiated a structural mechanism for the boratocancrinite – to nepheline transformation.

 

As a result of autoclaved Na-zeolite in an aqueous solutions of NH₄NO₃ their NH₄ – form have been received. Parameters of a rhombic cell are improved: a=15.082 (4), в=16.428 (4), с=5.226 (2) A, z=4, space group Pbn2₁. On the basis of determined structure chemical composition of new phases have been improved and is (NH₄)₄Na₈Al1₂Si₁₂O₄₈×4H₂O.