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- Title
Modular Structure of a Sodium-Rich Analogue of Eudialyte with the Doubled c-Parameter and the R3 Symmetry.
- Authors
Rastsvetaeva, R. K.; Khomyakov, A. P.
- Abstract
The structure of a new sodium-rich representative of the eudialyte group with the ideal formula (Na, Sr,K)[sub 35]Ca[sub 12]Fe[sub 3]Zr[sub 6]TiSi[sub 51]O[sub 144](O,OH,H[sub 2]O)[sub 9]C[sub 13] was established by the X-ray diffraction analysis (R = 0.054 based on 3503 F). The unit-cell parameters are a = 14.239(1), c = 60.733(7) Å, V = 10663.9 ų, sp. gr. R3. The mineral structure is characterized by in-layer order of cations resulting in doubling of the c-parameter and the formation of two modules, the composition and the structure of one of which corresponds to eudialyte (with an impurity of kentbrooksite), the prototype of the second module is alluaivite. Lowering of the symmetry is caused by ordering of Ca atoms and the Ca-replacing elements in the alluaivite module and by the displacements of the alkali cations from the m plane.
- Subjects
MODULAR construction; X-ray diffraction; CRYSTALLOGRAPHY; INORGANIC compounds; EUDIALYTE
- Publication
Crystallography Reports, 2001, Vol 46, Issue 5, p752
- ISSN
1063-7745
- Publication type
Article
- DOI
10.1134/1.1405861