The new K, Pb-bearing uranyl-oxide mineral kroupaite: Crystal-chemical implications for the structures of uranyl-oxide hydroxy-hydrates
| Authors | |
|---|---|
| Year of publication | 2020 |
| Type | Article in Periodical |
| Magazine / Source | American Mineralogist |
| MU Faculty or unit | |
| Citation | |
| Web | https://doi.org/10.2138/am-2020-7311 |
| Doi | http://dx.doi.org/10.2138/am-2020-7311 |
| Keywords | Kroupaite; new mineral species; uranyl-oxide hydroxy-hydrate; crystal structure; Voronoi-Dirichlet polyhedral; Cs-135; Sr-90; Jachymov |
| Description | Kroupaite (IMA 2017-031), ideally KPb0.5[(UO2)(8)O-4(OH)(10)]center dot 10H(2)O, is a new uranyl-oxide hydroxylhydrate mineral found underground in the Svornost mine, Jachymov, Czechia. Electron-probe micro-analysis (WDS) provided the empirical formula (K(1.2)8Na(0.07))Sigma(1.35)(Pb0.23Cu0.14Ca0.05Bi0.03Co0.02Al0.01)(Sigma 0.48) [(UO2)(7.90)(SO4)(0.04)O-4.04(OH)(10.00)]center dot 10H(2)O, on the basis of 40 O atoms apfu. Sheets in the crystal structure of kroupaite adopt the fourmarierite anion topology, and therefore kroupaite belongs to the schoepite-family of minerals with related structures differing in the interlayer composition and arrangement, and charge of the sheets. Uptake of dangerous radionuclides (Sr-90 or Cs-135) into the structure of kroupaite and other uranyl-oxide hydroxy-hydrate is evaluated based on crystal-chemical considerations and Voronoi-Dirichlet polyhedra measures. These calculations show the importance of these phases for the safe disposal of nuclear waste. |
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