New Data on the Isomorphism in Eudialyte-Group Minerals. V: Crystal Structure of an Intermediate Member of the Manganoeudialyte−Ilyukhinite Isomorphous Series
Abstract
The crystal structure of a high-symmetry representative of the eudialyte group from the Norra Kärr massif (Sweden) has been investigated by X-ray diffraction analysis and IR spectroscopy. The trigonal unit-cell parameters are found to be a = 14.1767(4) Å, c = 30.286(1) Å, and V = 5271.3 (3) Å3; sp. gr. Rm. The crystal structure is refined to the final reliability factor R = 6.4% in the anisotropic approximation of atomic displacements using 1071 reflections with F > 3σ(F). The idealized formula of the mineral (Z = 3) is [(Na,H3O)13.5REE1.5]Ca6Mn2Zr3[Si25.5O73.5]Cl . H2O. The problems of hydrolysis and central symmetry of minerals with eudialyte-type structure are discussed.
- Publication:
-
Crystallography Reports
- Pub Date:
- March 2020
- DOI:
- 10.1134/S1063774520010204
- Bibcode:
- 2020CryRp..65...27R