Crystal structure of chlorinated mineral of cancrinite group with bystrite-type framework

The formula of chlorinated bystrite (rare mineral of cancrinite group) has been refined to Na7.22Ca0.92[Al6Si6O24](S5)0.94Cl1.01. The X-ray diffraction data on the contents of chlorine and sulfur in this mineral are confirmed by the results of chemical analysis. The bystrite cage is found to contain a (S5)2–cluster, which is elongated along the c axis and has a chain configuration. Different ways of aggregation of sulfur atoms lead to cis- and trans-configurations of chains. Columns of cancrinite cages contain–Ca–Cl–Ca–Cl–chains, which were observed previously in the structures of minerals of davyne subgroup, afghanite, and tounkite.