Publication details
Crystal structure of synthetic “magnesiorietveldite”, Raman spectroscopy data and bond-valence approach to the svornostite group of minerals
| Authors | |
|---|---|
| Year of publication | 2025 |
| Type | Peer-reviewed scientific article |
| Magazine / Source | JOURNAL OF GEOSCIENCES |
| MU Faculty or unit | |
| Citation | |
| web | https://www.jgeosci.org/detail/jgeosci.0047.25/affiliations |
| Doi | https://doi.org/10.3190/jgeosci.0047.25 |
| Keywords | magnesiorietveldite; svornostite group; uranyl sulfate; crystal structure; Raman spectroscopy |
| Description | The new synthetic counterpart of a potentially new member of the svornostite group of minerals, "magnesiorietveldite", ideally Mg(UO2)(SO4)(2)(H2O)(5), is orthorhombic, space group Pmn2(1), a = 12.7950(9), b = 8.3288(4), c = 11.2962(4) & Aring;, V = 1203.80(11) & Aring;(3) and Z = 2. The crystal structure (R-1 = 0.0168 for 3113 I > 3 sigma I reflections) contains uranyl-sulfate chains that are linked into sheets by M1O(2)(H2O)(4 )and M2O(2)(H2O)(4) octahedra, where Mg is a dominant cation over Zn at both sites. The structure is well known and has already been described for other members of the svornostite group; the fundamental building unit - an infinite [(UO2)(SO4)(2)(H2O)](2-) chain - is common in several uranyl minerals and synthetic compounds. Synthetic "magnesiorietveldite" was obtained after treatment of a specimen containing pitchblende with sulfuric acid. Electron microprobe analyses yielded the empirical formula (Mg0.63Zn0.22Cu0.09Fe0.05)(& sum;0.99)(UO2)(SO4)2 & centerdot;5H(2)O, confirming the predominance of Mg over the other divalent cations. Infrared and Raman spectroscopy confirmed the presence of structurally non-equivalent molecular H2O and sulfate tetrahedra. We append an extensive discussion on the role of molecular H2O in the svornostite-group of minerals based on the bond-valence approach. |
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