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Crystallization of metastable monoclinic carnallite, KCl·MgCl 2 ·6H 2 O: missing structural link in the carnallite family
Author(s) -
Pannach Melanie,
Paschke Iris,
Schmidt Horst,
Freyer Daniela,
Voigt Wolfgang
Publication year - 2020
Publication title -
acta crystallographica section c
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 17
ISSN - 2053-2296
DOI - 10.1107/s2053229620005197
Subject(s) - monoclinic crystal system , orthorhombic crystal system , chemistry , potassium , crystallography , crystallization , magnesium , crystal structure , mineralogy , organic chemistry
During evaporation of natural and synthetic K–Mg–Cl brines, the formation of almost square plate‐like crystals of potassium carnallite (potassium chloride magnesium dichloride hexahydrate) was observed. A single‐crystal structure analysis revealed a monoclinic cell [ a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C 2/ c ]. The structure is isomorphous with other carnallite‐type compounds, such as NH 4 Cl·MgCl 2 ·6H 2 O. Until now, natural and synthetic carnallite, KCl·MgCl 2 ·6H 2 O, was only known in its orthorhombic form [ a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna ].