Morphotropism in fumarolic mineral-related anhydrous sulfates: novel representatives in A + 2 M 2+ (SO 4 ) 2 and A + 2 M 2+ 2 (SO 4 ) 3 series

• Published in: Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials
• Main Authors: Siidra, Oleg, I, Nekrasova, Diana, Blatova, Olga, Colmont, Marie, Mentré, Olivier, Charkin, Dmitri
• Other Authors: St Petersburg State University (SPbU), Kola Science Center of Russian Academy of Sciences, Unité de Catalyse et Chimie du Solide - UMR 8181 (UCCS), Université d'Artois (UA)-Centrale Lille-Institut de Chimie - CNRS Chimie (INC-CNRS)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Samara State Technical University, Lomonosov Moscow State University (MSU)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2022
• Subjects: morphotropism; copper; cobalt; caesium; anhydrous sulfates; fumarolic minerals; crystal structure; [CHIM.INOR]Chemical Sciences/Inorganic chemistry; [CHIM.CRIS]Chemical Sciences/Cristallography; Tolbachik; Kamchatka
• Online Access: https://hal.science/hal-03870080; https://hal.science/hal-03870080/document; https://hal.science/hal-03870080/file/Doc14.pdf; https://doi.org/10.1107/s2052520622000919

International audience The discovery of numerous endemic anhydrous sulfate minerals in fumaroles of the Tolbachik volcano (Kamchatka, Russia) has revived interest in the whole family of anhydrous sulfates. Herein is reported the crystal structure of Cs 2 Cu(SO 4) 2 which adds important data on the 'final' contributor with the largest A + cation to the A 2 [Cu(SO 4) 2 ] morphotropic series (A = Na, K, Rb, Cs), the 'initial' structurally characterized representative of this family being saranchinaite Na 2 Cu(SO 4) 2. With increasing ionic radius of the alkali metal cation(s), embedded in the [Cu(SO 4) 2 ] 2À framework, symmetry-breaking transformations occur. Cs 2 Cu(SO 4) 2 , which is here designated as the "-phase, has a layered structure. Cs 2 Co 2 (SO 4) 3 is a new representative of another morphotropic series of the orthorhombic A 2 [M 2+ 2 (SO 4) 3 ] family, being also the first anhydrous Cs-Co sulfate. Structural relationships in A + 2 M 2+ (SO 4) 2 and A + 2 M 2+ 2 (SO 4) 3 morphotropic series are discussed in detail.