Publication details
Nollmotzite, Mg[U-V((UO2)-O-VI)(2)O4F3]center dot 4H(2)O, the first natural uranium oxide containing fluorine
| Authors | |
|---|---|
| Year of publication | 2018 |
| Type | Article in Periodical |
| Magazine / Source | ACTA CRYSTALLOGRAPHICA SECTION B-STRUCTURAL SCIENCE CRYSTAL ENGINEERING AND MATERIALS |
| MU Faculty or unit | |
| Citation | |
| Web | http://dx.doi.org/10.1107/S2052520618007321 |
| Doi | http://dx.doi.org/10.1107/S2052520618007321 |
| Keywords | nollmotzite; new mineral; uranium oxide fluoride; pentavalent uranium |
| Description | Nollmotzite (IMA2017-100), Mg[U-V((UO2)-O-VI)(2)F3O4](H2O)(4), is a new uranium oxide fluoride mineral found in the Clara mine, Black Forest Mountains, Germany. Electron microprobe analysis provided the empirical formula (Mg1.06CU0.02)(Sigma 1.08)[U-V((UO2)-O-VI)(2)O-3.85 F-3.15][(H2O)(3.69)(OH)(0.31)](Sigma 4.00) based on three U and 15 O + F atoms per formula unit. Nollmotzite is monoclinic, space group Cm, with a = 7.1015 (12) angstrom, b = 11.7489 (17) angstrom, c = 8.1954 (14) angstrom, beta = 98.087 (14)degrees, V = 676.98 (19) angstrom(3) and Z = 2. The crystal structure [twinned by reticular merohedry; refined to R = 0.0369 with GoF = 1.09 for 1527 unique observed reflections, I > 3 sigma (I)] is based upon [U-V((UO2)-O-V-O-I)(2)F3O4](2- )sheets of, beta - U3O8 topology and contains an interlayer with MgF2(H2O)(4) octahedra. Adjacent sheets are linked through F-Mg-F bonds, as well as via hydrogen bonds. The presence of fluorine and pentavalent uranium in the structure of nollmotzite has potentially important implications for the safe disposal of nuclear waste. |