Cordylite-(Ce)
- Author(s)
- Gerald Giester, Yunxiang Ni, Dietmar Jarosch, John M. Hughes, Jørn Rønsbo, Zhuming Yang, Josef Zemann
- Abstract
Six cordylites from the four known localities [Narssarssuk (Greenland), Mont St. Hilaire (Canada), Bayan Obo (China), and Kola Peninsula (Russia)] were investigated by electron microprobe and X-ray single-crystal structure determination, and a seventh sample was investegated by X-ray methods only. The material studied included type cordylite. The idealized formula for cordylite is redefined as (Na1-xCax/2)BaCe2(CO3)4F, 0 < x < 1, with Ce for the sum of REE; the SrO content may reach about 5.7%. All of our structure refinements (P63/mmc; a ≅ 5.10, c ≅ 23.10 Å ) agree very well among themselves and with the published structures of ‘‘baiyuneboite-(Ce)’’ and unnamed (Ca0.5⃞0.5)BaCe2(CO3)4F. Cordylite has a sheet structure formed of (001) layers of [Ba] [CO3] [Ce,CO3] [Na,F] [Ce,CO3] [CO3] [Ba] stacked along [001]. The interatomic distances are as expected, with the exception of unshielded Na-F distances of 2.94Ä; unlike the carbonate groups in basnäsite and synchysite, the carbonate groups in cordylite-(Ce) are parallel (001). Investigation of type cordylite showed that the formula proposed by Flink, i.e., BaCe2(CO3)3F2, is to be modified to that given above, with x ≅ 0 for Flink’s material. Baiyuneboite-(Ce), a mineral previously approved by the IMA CNMMN but later withdrawn because of potential similarities with cordylite, is confirmed here as being essentially identical to type cordylite.
- Organisation(s)
- Department of Mineralogy and Crystallography
- External organisation(s)
- Miami University, Danish Geological Survey, Chinese Academy of Sciences (CAS)
- Journal
- American Mineralogist: an international journal of earth and planetary materials
- Volume
- 83
- Pages
- 178-184
- No. of pages
- 7
- ISSN
- 0003-004X
- DOI
- https://doi.org/10.2138/am-1998-1-219
- Publication date
- 02-1998
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 105113 Crystallography, 105116 Mineralogy
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/cordylitece(327f6f04-d04e-4071-bccd-2c9e9611ec55).html