Alluaudite-group phosphate and arsenate minerals

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Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Alluaudite-group phosphate and arsenate minerals

Messaggio da Marco E. Ciriotti » gio 27 mag, 2021 10:52

Prossima pubblicazione.

Referenza:
▪ Tait, K.T., Hawthorne, F.C., Halden, N.M. (2021): Alluaudite-Group Phosphate and Arsenate Minerals. Canadian Mineralogist, 59, (in press).

Abstract:
A systematic study of alluaudite, hagendorfite, and varulite was done using single-crystal X-ray diffraction, powder diffraction, and electron probe microanalysis of samples from 12 separate localities. The crystal structures of the representative alluaudite and hagendorfite samples were refined to R1 indices of 3.7 and 1.8%, respectively, using a Siemens P4 automated four-circle diffractometer equipped with a graphite monochromator and MoKα X-radiation. These samples and several others were analyzed with an electron microprobe to study variations in chemical composition. For the single-crystal analyses, the resulting unit formulae are (Na0.11□0.89)(Na0.59Mn0.27Ca0.14)Mn1.00(Fe3+1.64Al0.24Mg0.13)(PO4)3 for alluaudite, (Na0.79□0.21)(Na0.81Mn2+0.19)(Mn0.70Fe2+0.30)(Fe2+1.72Mg0.27Al0.01)(PO4)3 for hagendorfite, and (Na0.84□0.16)(Na0.71Ca0.23□0.06)Mn1.00(Fe3+0.89Fe2+0.68Mn0.42Mg0.01)(PO4)3 for varulite.
Originally, a nomenclature scheme was proposed for the alluaudite-group minerals that was based on sequentially distributing the cations in the cell according to increasing polyhedron size, matching that size with increasing ionic radii of the cations. For alluaudite, the structural formula was written as X(2)4X(1)4M(1)4M(2)8(PO4)12, with the sites ordered in decreasing size of the discrete polyhedra. Later, the formula [A(2)A(2)'A(2)”2][A(1)A(1)'A(1)”2]M(1)M(2)2(PO4)3 was proposed, which takes into account the distinct crystallographic sites in the channels of the structure. More recently there has been a revision to the nomenclature of the group. The simplified structural formula for the alluaudite-type is now A(2)'A(1)M(1)M(2)2(TO4)3; the new nomenclature scheme has been adopted by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA-CNMNC), based on the contents of the M(1) and M(2) octahedral sites, and the results are reviewed here.
Compounds belonging to the alluaudite structural family have been the focus of synthetic mineral studies for decades owing to the open-framework architecture and their unique physical properties. Improvements in synthesis methods have allowed researchers to substitute a wide range of elements into the alluaudite structure.
Marco E. Ciriotti

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

Avatar utente
Marco E. Ciriotti
Messaggi: 31675
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Alluaudite-group phosphate and arsenate minerals

Messaggio da Marco E. Ciriotti » ven 02 lug, 2021 12:27

Pubblicazione effettuata.

Referenza:
▪ Tait, K.T., Hawthorne, F.C., Halden, N.M. (2021): Alluaudite-Group Phosphate and Arsenate Minerals. Canadian Mineralogist, 59, 243-263.
Marco E. Ciriotti

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

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