Crystal Structure of Alloriite

摘要

The cancrinite-sodalite group includes about 30 minerals, which are being studied in depth owing to their adsorption and ion-exchange properties. The minerals consist of a framework of Si and Al tetrahedra combined into six-membered rings. The rings of the same level along - are linked not to each other but to rings of neighbor levels shifted by 1/3 along x and y. The succession of alternation of rings is designated byrnletters A, B, and C, where A designates the rings around the axis [2/3 1/3 z]; B, around [1/3 2/3 z]; and C, around [0 0 z]. Minerals with 2 to 28 layers, which correspond to parameters with c ～5-74 A, are known in this group. The channels and cages within the framework are occupied by large cations and anions (mono- and/or multia-tom), while some minerals also include the water molecules.