IMA 2015-083 = vasilseverginite

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Marco E. Ciriotti
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IMA 2015-083 = vasilseverginite

Messaggio da Marco E. Ciriotti » mer 12 ago, 2020 11:02

Prossima pubblicazione.

Referenza:
▪ Pekov, I.V., Britvin, S.N., Krivovichev, S.V., Yapaskurt, V.O., Vigasina, M.F., Turchkova, A.G., Sidorov, E.G. (2021): Vasilseverginite, Cu9O4(AsO4)2(SO4)2, a new fumarolic mineral with a hybrid structure containing novel anion-centered tetrahedral structural units. American Mineralogist, 106, (in press).

Ndr: chemical and structural hybrid of dolerophanite, Cu2+2O(SO4), and popovite, [Cu2+5O2](AsO4)2. Un nuovo tipo di minerale: un ibrido! Due dolerophanite + una popovite = vasilseverginite.
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: 28029
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Re: IMA 2015-083 = vasilseverginite

Messaggio da Marco E. Ciriotti » mer 14 apr, 2021 8:47

Pubblicazione effettuata.

Referenza:
▪ Pekov, I.V., Britvin, S.N., Krivovichev, S.V., Yapaskurt, V.O., Vigasina, M.F., Turchkova, A.G., Sidorov, E.G. (2021): Vasilseverginite, Cu9O4(AsO4)2(SO4)2, a new fumarolic mineral with a hybrid structure containing novel anion-centered tetrahedral structural units. American Mineralogist, 106, 633–640.

Abstract:
The new mineral vasilseverginite, ideally Cu9O4(AsO4)2(SO4)2, was found in the Arsenatnaya fumarole at the second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with tenorite, lammerite, stranskiite, lammerite-b, langbeinite, dolerophanite, sanidine, hematite, and gahnite. Vasilseverginite occurs as prismatic crystals up to 0.02 × 0.02 × 0.06 mm3 combined in groups or interrupted crusts up to 1 × 2 cm2 in area and up to 0.1 mm thick. It is transparent, bright green, with vitreous luster. Dcalc is 4.41 g⋅cm–3. Vasilseverginite is optically biaxial (–), a 1.816(5), b 1.870(5), g 1.897(5), estimated 2V is 30(15)°. Chemical composition (wt%, electron-microprobe) is: CuO 64.03, ZnO 0.79, Fe2O3 0.25, P2O5 0.05, As2O5 20.83, SO3 14.92, total 100.87. The empirical formula calculated on O = 20 apfu is (Cu8.78Zn0.11Fe3+0.03)S8.92As1.98P0.01S2.03O20. Vasilseverginite is monoclinic, P21/n, a = 8.1131(4), b = 9.9182(4), c = 11.0225(5) Å, b = 110.855(2)°, V = 828.84(6) Å3, and Z = 2. The strongest reflections in the powder XRD pattern [d,Å(I)(hkl)] are: 7.13(41)(101), 5.99(70)(110, 111), 5.260(100)(101), 4.642(46)(111), 3.140(31)(031), 2.821(35)(023), 2.784(38)(132, 032), 2.597(35)(204), and 2.556(50)(231, 212). The crystal structure, solved using single-crystal X‑ray diffraction data, R1 = 0.025, is based upon complex [O4Cu9]10+ layers parallel to (101) that are composed of edge- and corner-sharing (OCu4) tetrahedra. The topology is unprecedented in inorganic structural chemistry. The crystal structure can be considered a hybrid of the structures of popovite Cu5O2(AsO4)2 and dolerophanite Cu2O(SO4) according to the scheme Cu9O4(AsO4)2(SO4)2 = Cu5O2(AsO4)2 + 2Cu2O(SO4). The chemical hybridization does not result in a significant increase in chemical complexity of vasilseverginite compared to the sum of those of popovite and dolerophanite, whereas the structural hybridization leads to the doubling of structural information per unit cell. The mineral is named in memory of the outstanding Russian mineralogist, geologist, and chemist Vasiliy Mikhailovich Severgin (1765–1826).
Marco E. Ciriotti

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