Project PO4 - AsO4 Uranyl

Researchers involved: Simon Philippo – Kim Totaro

Themes: palaeofluids / environmental mineralogy / home mining

In the mineral kingdom, around 230 species contain uranium as an essential structural component. Today, the crystal structure of fewer than 35% of natural uranium‑bearing minerals is known. Many data on their chemical composition, stability and paragenesis are still lacking. The main objective of this project is to carry out a complete mineralogical characterisation of uranyl arsenates and phosphates from the Lodève deposits (Occitanie, France) and Katanga (DRC), preserved in the mineralogical collections of the MNHNL. This research focuses primarily on the study of the chemical compositions, crystal structures and stability fields of these uranyl minerals. All these data are extremely useful for understanding the alteration processes of natural uraninite and for predicting the behaviour of nuclear waste stored in geological repositories.

This work was largely initiated by the doctoral research of Fabrice Dal Bo, entitled Crystal Chemistry of Uranyl Phosphates and Arsenates from the Lodève (France) and Katanga (DRC) Uranium Deposits.

Today, the project is carried out in collaboration with the expert Jakub Plášil. The systematic study of these collections has led to several publications and to the discovery of two new species: Lepersonnite‑(Nd) and Pendevilleite‑(Y). These new species were discovered in our collections, notably in the Virlet and Pendeville collections.

The study of these collections allows a drastic reduction in the number of samples required, as well as optimal conservation of exceptional specimens of this type of mineral species.

Publications :

+ DAL BO, F., HATERT, F. & PHILIPPO, S. (2017), A new uranyl phosphate sheet in the crystal structure of furongite. European Journal of Mineralogy, 29-3, 517-527.

+ DAL BO, F., HATERT, F. & PHILIPPO, S. (2017), New crystallographic data and formula revision of phuralumite, Al2[(UO2)3(PO4)2O(OH)](OH)3(H2O)9. Journal of Geosciences, 62, 87-95.

+ DAL BO, F., HATERT, F. & PHILIPPO, S. (2018), Supergene Uranyl Mineralization of the Rabejac Deposit, Lodève, France. Minerals, Section: Crystallography and Physical Chemistry of Minerals, Special Issue: Actinide Mineralogy and Crystallography, 8(414), pp. 22.

+ PLÁŠIL, J., KIEFER, B., GHAZISAEED, S. & PHILIPPO, S. (2020), Hydrogen bonding in the crystal structure of phurcalite, Ca2[(UO2)3O2(PO4)2]·7H2O: single-crystal X-ray study and TORQUE calculations. Acta Crystallographica, Section B: Structural Science 76(3).

+ PLÁŠIL, J., KAMPF, A.R., ŠKODA, R., PHILIPPO, S., GUENNOU, M. AND MEES, F. (2021) Lepersonnite-(Nd), IMA 2021-066. CNMNC Newsletter 64; Mineralogical Magazine, 85.

+ PLÁŠIL, J., STECIUK, G., ŠKODA, R., PHILIPPO, S. AND GUENNOU, M. (2022) Pendevilleite-(Y), IMA 2022-054. CNMNC Newsletter 70; Mineralogical Magazine, 86.