The crystal structure of "jixianite": a potential new member of the pyrochlore supergroup

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Marco E. Ciriotti
Messaggi: 24834
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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The crystal structure of "jixianite": a potential new member of the pyrochlore supergroup

Messaggio da Marco E. Ciriotti » mar 14 ago, 2018 12:59

Referenza:
▪ Li, G., Xue, Y., Yang, G. (2018): The crystal structure of the "jixianite". IMA2018 Abstract book. Poster presentations. Mineralogical crystallography, 464.

Abstract:
“Jixianite” is a new mineral that was found in Nanhe tungsten deposit in Jixian County, Hebei, China, in 1979. It is an oxide containing of W, Pb
components, and was approved by the IMA-CNMMN at that time. However, because of the mineral’s tiny crystal size, the structure data for this material were not gotten. According to the powder diffraction data, the diffraction characteristics was similar to that of pyrochlore supergroup minerals, so it was classified as the pyrochlore group mineral containing W and Pb. In 2010, based on the proposed new scheme of nomenclature for the pyrochlore supergroup, approved by the IMA -CNMNC, “jixianite” was discredited. Recently we’ve got the typical material specimens. A 1.2 kw high power microfocus rotating anode X-ray source and a hybrid pixel array detector single crystal diffractometer were using for the structure investigation, and the single crystal diffraction data were obtained with a small crystal which is less than 10 micron. The research results show that the mineral has a cubic system, the lattice parameters a=10.3421(5) Å, space group Fd-3m, Z=8. The crystal structure belongs to the pyrochlore type structure (R = 0.02). W is [6]-coordinated (site 16c), located at the center of octahedron, with a W-O bond length of 1.941 Å. Pb as a large cation is [8]-coordinated (site 16d), distributed in the channel, and the Pb-O bond length is 2.239 Å. Some H2O occupies the site of Pb while the others occupies the Y site (site 8b). So “jixianite” is still a pyrochlore supergroup mineral. The ideal endmember formula is (H2O,Pb)2(W,Fe)2O6(H2O) by the crystal structure. It belongs to the elsmoreite group mineral of pyrochlore supergroup, and this new mineral can be renamed as “hydroplumboelsmoreite”.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 24834
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Re: The crystal structure of "jixianite": a potential new member of the pyrochlore supergroup

Messaggio da Marco E. Ciriotti » mar 14 ago, 2018 16:03

Nel database appena aggiornato trovate la "jixianite" come specie questionabile: viewtopic.php?f=2&t=4216&start=270
Poiché avevo ritenuto la fase potenzialmente valida mi ero limitato a declassificarla come questionabile (status Q) in luogo del discredito.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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