Crystal structure of turneaureite and its relationships with the arsenate apatites johnbaumite and svabite

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Marco E. Ciriotti
Messaggi: 23486
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Crystal structure of turneaureite and its relationships with the arsenate apatites johnbaumite and svabite

Messaggio da Marco E. Ciriotti » gio 22 giu, 2017 10:15

Prossima pubblicazione.

Referenza:
▪ Biagioni, C., Bosi, F., Hålenius, U., Pasero, M. (2017): The crystal structure of turneaureite, Ca5(AsO4)3Cl, the arsenate analogue of chlorapatite, and its relationships with the arsenate apatites johnbaumite and svabite. American Mineralogist, 102, (in press).
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: 23486
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Crystal structure of turneaureite and its relationships with the arsenate apatites johnbaumite and svabite

Messaggio da Marco E. Ciriotti » lun 02 ott, 2017 15:44

Pubblicazione effettuata.

Referenza:
▪ Biagioni, C., Bosi, F., Hålenius, U., Pasero, M. (2017): The crystal structure of turneaureite, Ca5(AsO4)3Cl, the arsenate analogue of chlorapatite, and its relationships with the arsenate apatites johnbaumite and svabite. American Mineralogist, 102, 1981-1986.

Abstract:
The crystal structure of turneaureite, ideally Ca5(AsO4)3Cl, was studied using a specimen from the Brattfors mine, Nordmark, Värmland, Sweden, by means of single-crystal X-ray diffraction data. The structure was refined to R1 = 0.017 on the basis of 716 unique reflections with Fo > 4σ(Fo) in the P63/m space group, with unit-cell parameters a = 9.9218(3), c = 6.8638(2) Å, V = 585.16(4) Å3. The chemical composition of the sample, determined by electron-microprobe analysis, is (in wt%; average of 10 spot analyses): SO3 0.22, P2O5 0.20, V2O5 0.01, As2O5 51.76, SiO2 0.06, CaO 41.39, MnO 1.89, SrO 0.12, BaO 0.52, PbO 0.10, Na2O 0.02, F 0.32, Cl 2.56, H2Ocalc 0.58, O(≡F+Cl) −0.71, total 99.04. On the basis of 13 anions per formula unit, the empirical formula corresponds to (Ca4.82Mn0.17Ba0.02Sr0.01)∑5.02 (As2.94P0.02S0.02Si0.01)∑2.99O12[Cl0.47(OH)0.42F0.11]∑1.00.
Turneaureite is topologically similar to the other members of the apatite supergroup: columns of face-sharing M1 polyhedra running along c are connected through TO4 tetrahedra with channels hosting M2 cations and X anions. Owing to its particular chemical composition, the studied turneaureite can be considered as a ternary calcium arsenate apatite; consequently it has several partially filled anion sites within the anion columns. Polarized single-crystal FTIR spectra of the studied sample indicate stronger hydrogen bonding and less diverse short-range atom arrangements around (OH) groups in turneaureite as compared to the related minerals johnbaumite and svabite. An accurate knowledge of the atomic arrangement of this apatite-remediation mineral represents an improvement in our understanding of minerals able to sequester and stabilize heavy metals such as arsenic in polluted areas.
Marco E. Ciriotti

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

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