Guilleminite 
Ba(UO2)3(Se4+O3)2O2 • 3H2O [CNMNC approved formula]
Named for French Claude Guillemin (1923-1994), founder of the National Geological Service of the BRGM.
| IMA status : | Approved Species 1965 () |
| CLASSIFICATION | |
| Dana (8th edition) : |
34.07.03.01 |
| (34) Selenites - Tellurites - Sulfites | |
| (34.07) | |
| (34.07.03) | |
| Nickel-Strunz (10th edition) : |
04.JJ.10 |
| (04) Oxides and Hydroxides | |
| (04.J) Arsenites, Antimonites, Bismuthites, Sulfites, | |
| (04.JJ) Selenites with additional anions, with H2O | |
| Crystal system: | Orthorhombic System |
| Point group (H-M): | mm2 — pyramidal |
| Other Properties: | Radioactive. |
| Comments: | Radioactive. |