The crystal structure of natural Fe-rich chevkinite-(Ce)
- Author(s)
- Zhuming Yang, Michel Fleck, Martin Smith, Kejie Tao, Renkui Song, Ping Zhang
- Abstract
Chemical composition and crystal structure of natural non-metamict Fe-rich chevkinite-(Ce) from the aegirine-alkali granite, Mianning, Sichuan Province, China, were investigated. Microprobe analyses indicated that FeO (total iron) content in Fe-rich chevkinite(Ce) ranges from 10.97% to 11.59% (wt.) and Ce2O3 from 23% to 25%. There are deficient A- and (B+C)-type cations in the formula. The crystal structure of Fe-rich chevkinite-(Ce) was refined from CCD data in the space-group type C2/m (R = 2.41%). Cell parameters are a = 13.456(3) A°, b = 5.728(1) A°, c = 11.083(2) A°, ß = 100.60(3)°, V = 839.7(3) A°3, Z = 2. The structure of Fe-rich chevkinite-(Ce) is made up of two kinds of sheets, one is a sheet of Si2O7 groups and B-octahedra, and the other is a sheet of C-octahedra, both parallel to the ab plane. The two kinds of sheets alternate along c axis and form a three dimensional framework. The rare earth ions lie between the disilicate groups and the sheets of octahedra to form (8+3)-coordinated A1-polyhedra and 10-coordinated A2-polyhedra. The Fe and Ti are partially ordered among the octahedral sites of B, C1, C2A and C2B. The Charge Distribution analysis confirms Fe3+/SFe = 0.61 and a mixture of Fe2+ and Fe3+ in the B site. The chemical formula for the natural Fe-rich chevkinite-(Ce) is (Ce3+1.76 La0.89 Ca0.46 Nd0.22 Pr0.18 Sm0.04 Th0.03 Ba0.01 ?0.37)S4.00 (Fe3+0.29 Ti0.21 Fe2+0.18 Mn2+0.13 Mg0.08 ?0.11)S1.00 (Ti2.16 Fe3+0.81 Fe2+0.52 Nb0.16 Al0.06 n0.08)S4.00 Si4O20.72 (OH)1.28.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Chinese Academy of Sciences (CAS), IEEE Computational Intelligence Society
- Journal
- European Journal of Mineralogy: an international journal of mineralogy, geochemistry and related sciences
- Volume
- 14
- Pages
- 969-975
- No. of pages
- 7
- ISSN
- 0935-1221
- Publication date
- 2002
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 1051 Geology, Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/8c74785c-33de-4ce8-b0fc-922b3ffa8223