Pseudobrookite group: Crystal chemical features of the armalcolite Fe2+ analogue

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Marco E. Ciriotti
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Iscritto il: ven 25 giu, 2004 11:31
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Pseudobrookite group: Crystal chemical features of the armalcolite Fe2+ analogue

Messaggio da Marco E. Ciriotti » gio 06 mag, 2021 16:21

Referenza:
▪ Kazheva, O.N., Zubkova, N.V., Schäfer, Ch., Chukanov, N.V., Pekov, I., Britvin, S.N., Pushcharovsky, D. (2021): The Pseudobrookite Group: Crystal Chemical Features of the Armalcolite Fe2+ Analogue. Doklady Earth Sciences, 497, 305-309.

Abstract:
The crystal structure of a potentially new mineral, the Fe2+-dominant analogue of armalcolite with the idealized formula Fe2+Ti2O5 has been solved. The sample studied originates from a pneumatolytic association related to the lamproite complex of SE Spain. The mineral is orthorhombic, space group Cmcm, the unit-cell parameters are a = 3.7325(1) Å, b = 9.7649(4) Å, c = 9.9902(3) Å, V = 364.12(2) Å3. The crystal-chemical formula M1(Mg0.19Fe2+0.25Fe3+0.26Ti0.30)2.86+[M2(Ti0.65Fe3+0.27Fe2+0.08)3.57+]2O5 (Z = 4) is in good agreement with the chemical composition of the mineral.

NdR: general formula of the pseudobrookite group: M(1)M(2)2O5, the M cations (Mg2+, Fe2+, Fe3+, and Ti4+) occupy two independent positions M(1) and M(2) (Wykoff positions 4c and 8f, respectively) [5, 7]. These cations have octahedral coordination.
Marco E. Ciriotti

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