Crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)–Ca2Al2VSi3O12(OH)

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Marco E. Ciriotti
Messaggi: 25463
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)–Ca2Al2VSi3O12(OH)

Messaggio da Marco E. Ciriotti » dom 15 lug, 2018 15:07

Prossima pubblicazione.

Referenza:
▪ Nagashima, M., Nishio-Hamane, D., Nakano, N., Kawasaki, T. (2018): Synthesis and crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)–Ca2Al2VSi3O12(OH). Physics and Chemistry of Minerals, 45, (in press).

Abstract:
This is the first report of the crystal structure of mukhinite, V-analogue clinozoisite, on the join Ca2Al3Si3O12(OH)–Ca2Al2V3+Si3O12(OH) synthesized at 1.5 GPa and 800 °C. The study was performed to clarify the distribution of V3+ among structurally independent octahedral M1, M2, and M3 sites, and the effect of V3+ on the crystal structure. Mukhinite and V3+-bearing clinozoisite in all run products are associated with zoisite, and also coexist with V-bearing phases such as vanadomalayaite, goldmanite, V-oxides, and unidentified Ca–Al-bearing vanadates. Mukhinite and V3+-bearing clinozoisite crystallized in the Run 20 product show a compositional gap between 0.33 and 0.74 V atoms per formula unit (apfu), and the V content attains 1.14 apfu. The coexistence of low V3+- and high V3+-clinozoisites indicates the presence of a miscibility gap at 1.5 GPa and 800 °C. Two mukhinite crystals with 0.75 and 0.83 V3+ apfu were used for X-ray single-crystal structure analysis. The unit-cell parameters are a = 8.8995(2), b = 5.6299(1), c = 10.1532(2) Å, β = 115.327(1)°, and V = 459.81(2) Å3 for the former, and a = 8.8999(1), b = 5.6357(1), c = 10.1499(1) Å, β = 115.306(1)°, and V = 460.24(2) Å3 for the latter. The resulting V3+ occupancies among the octahedral sites are M1(Al0.894(6)V0.106)M2(Al0.976(6)V0.024)M3(V0.621(6)Al0.379) for the former and M1(Al0.868(4)V0.132)M2(Al0.957(4)V0.043)M3(V0.652(2)Al0.348) for the latter. Site preference of V3+ at the octahedral sites is M3 > M1 > M2 as that of Fe3+ and Mn3+. The intracrystalline partition coefficient of V3+ and Al3+ between the M1 and M3 sites, KD = (V3+/Al)M1/(V3+/Al)M3, is 0.07–0.08, which is greater than those of Fe3+ and Al3+ (0.03–0.05) and of Mn3+ and Al3+ (0.04–0.06). Variations of the unit-cell parameters are strongly related to the variations of the M3−Oi and M1−Oi distances.
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: 25463
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
Contatta:

Re: Crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)–Ca2Al2VSi3O12(OH)

Messaggio da Marco E. Ciriotti » sab 23 feb, 2019 10:49

Pubblicazione effettuata.

Referenza:
▪ Nagashima, M., Nishio-Hamane, D., Nakano, N., Kawasaki, T. (2018): Synthesis and crystal chemistry of mukhinite, V-analogue of clinozoisite on the join Ca2Al3Si3O12(OH)–Ca2Al2VSi3O12(OH). Physics and Chemistry of Minerals, 45, 63–76.
Marco E. Ciriotti

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

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