Cordylite-(Ce)
- Autor(en)
- Gerald Giester, Yunxiang Ni, Dietmar Jarosch, John M. Hughes, Jørn Rønsbo, Zhuming Yang, Josef Zemann
- Abstrakt
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 detn., and a seventh sample was investigated 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 .simeq. 5.10, c .simeq. 23.10 .ANG.) agree very well among themselves and with the published structures of "baiyuneboite-(Ce)" and unnamed (Ca0.5.box.0.5)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 interat. distances are as expected, with the exception of unshielded Na-F distances of 2.94 .ANG.; unlike the carbonate groups in bastnasite 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 .simeq. 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 Baiyuneboite-(Ce), a mineral previously approved by the IMA CNMMN but later withdrawn because of potential similarities with cordylite, is confirmed here as being essentially identical to type cordylite.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(en)
- Institut für Mineralogie und Kristallographie
- Externe Organisation(en)
- Miami University, Danish Geological Survey, Chinese Academy of Sciences (CAS)
- Journal
- American Mineralogist: an international journal of earth and planetary materials
- Band
- 83
- Seiten
- 178-184
- Anzahl der Seiten
- 7
- ISSN
- 0003-004X
- DOI
- https://doi.org/10.2138/am-1998-1-219
- Publikationsdatum
- 02-1998
- Peer-reviewed
- Ja
- ÖFOS 2012
- 105113 Kristallographie, 105116 Mineralogie
- Link zum Portal
- https://ucrisportal.univie.ac.at/de/publications/cordylitece(327f6f04-d04e-4071-bccd-2c9e9611ec55).html