Comments on "Bermanec, V., Wegner, R., Kniewald, G., Rakvin, B., Palinkas, L.A., Rajic, M., Tomasic, N. Furic, K. (2005): The role of uranium(V) ion in the chemical composition of meta-autunite from pegmatites of Quintos de Baixo, Brazil". N. Jb. Miner. A
Locock, Andrew J.
published: Apr 21, 2006
ArtNo. ESP154018202010, Price: 29.00 €
On the basis of a chemical analysis and EPR data, Bermanec et al. (2005) reported considerable uranium vacancies and substantial pentavalent uranium in meta-autunite from Brazil. These controversial interpretations are at variance with the previous literature on meta-autunite, nominally Ca[(UO2)(PO4)]2(H2O)n, n ∼ 6–8, in which the uranium position was interpreted to be fully occupied and entirely hexavalent (e.g., Volborth 1959, Sowder et al. 2000). There is no doubt that the material investigated by Bermanec et al. (2005) is meta-autunite, as their reported cell dimensions agree with those in the literature to within 0.01 Å. As discussed below, it is likely that the chemical analysis presented by Bermanec et al. (2005) is inaccurate, and that the interpretations of considerable uranium vacancies and substantial pentavalent uranium in meta-autunite are not correct.