Crystal structure of a novel analogue of eudialyte with the R3 symmetry

The X-ray diffraction study of a new representative of the eudialyte group (R = 4.2% for 1809 unique reflections) has revealed a number of specific st ructural features associated with the chemical composition unusual for eudi alytes, namely, calcium deficiency and high manganese content. It is found that the ordering of Ca and Mn at the centers of octahedra in the six-membe red rings results in the lowering of the symmetry of the structure to R3.