Abstract
Finchite (IMA2017-052), Sr(UO2)2(V2O8)·5H2O, is the first uranium mineral known to contain essential Sr. The new mineral occurs as yellow-green blades up to ~10 μm in length in surface outcrops of the calcrete-type uranium deposit at Sulfur Springs Draw, Martin County, Texas, U.S.A. Crystals of finchite were subsequently discovered underground in the Pandora mine, La Sal, San Juan County, Utah, U.S.A., as diamond-shaped golden-yellow crystals reaching up to 1 mm. The crystal structure of finchite from both localities was determined using single-crystal X‑ray diffraction and is orthorhombic, Pcan, with a = 10.363(6) Å, b = 8.498(5) Å, c = 16.250(9) Å, V = 1431.0(13) Å3, Z = 4 (R1 = 0.0555) from Sulfur Springs Draw; and a = 10.3898(16), b = 8.5326(14), c = 16.3765(3) Å, V = 1451.8(4) Å3, Z = 4 (R1 = 0.0600) from the Pandora mine. Electron-probe microanalysis provided the empirical formula (Sr0.88K0.17Ca0.10Mg0.07Al0.03Fe0.02)ς1.20(UO2)2(V2.08O8)·5H2O for crystals from Sulfur Springs Draw, and (Sr0.50Ca0.28Ba0.22K0.05)ς0.94(U0.99O2)2(V2.01O8)·5H2O for crystals from the Pandora mine, based on 17 O atoms per formula unit. The structure of finchite contains uranyl vanadate sheets based upon the francevillite topology. Finchite is a possible immobilization species for both uranium and the dangerous radionuclide 90Sr because of the relative insolubility of uranyl vanadate minerals in water.
Original language | English |
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Pages (from-to) | 383-388 |
Number of pages | 6 |
Journal | American Mineralogist |
Volume | 108 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 2023 |
Funding
The authors thank Ashley Shields and Andrew Miskowiec for helpful discussions and comments. Reviewers Giuseppina Balassone and Jakub K. PláŠil are also thanked for their constructive comments, which improved the manuscript. This work was supported by the Department of Energy, Basic Energy Sciences, Heavy Elements Program under grant number DE-FG02-07ER15880. Analyses were conducted at the ND Energy Materials Characterization Facility at the University of Notre Dame. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Funders | Funder number |
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Heavy Elements Program | DE-FG02-07ER15880 |
U.S. Department of Energy | |
Basic Energy Sciences |
Keywords
- Finchite
- carnotite
- curienite
- francevillite
- new minerals
- tyuyamunite
- uranyl vanadates