Uranium: Mineralogy, Geochemistry and the Environment

Recent Research:

Wyartite: Crystallographic Evidence for the First Pentavalent-Uranium Mineral

Wolsendorfite: A Masterpiece of Structural Complexity

 

Uranium Mineralogy

Uranyl minerals are important constituents of the oxidized portions of many uranium deposits. These minerals also form due to the oxidation of uranium mine tailings, thus they impact upon the release rates of uranium and lead into the environment. In addition, uranyl minerals form when spent nuclear fuel is corroded in an oxidizing environment, such as at the proposed Yucca Mountain geological repository. The direct disposal of spent fuel in a geological repository requires a knowledge of the behavior of spent fuel as a waste form. Experiments have shown that spent fuel, which is mainly UO2, is unstable under oxidizing conditions, and alteration rates are appreciable. The alteration phases, most of which are uranyl minerals, may impact upon the release rates of radionuclides from the repository into the biosphere, especially where incorporation of radionuclides into the uranyl minerals occurs. Ongoing research in the mineralogy/crystallography laboratory involves many aspects of uranyl minerals, including their crystal structures, structure energetics, hierarchy of structures, paragenetic sequences, thermodynamic stabilities, and ability to incorporate radionuclides within their structures. Research goals include an understanding of the occurrences and crystal chemistries of uranyl minerals in nature, with applications to predicting the behavior of spent nuclear fuel in a geological repository.

Crystal-Chemistry of Low-Temperature Minerals 

The weathered portions of ore deposits are mineralogically very diverse, and the complex paragenetic sequences of low-temperature minerals contained therein challenges our current understanding of mineralogy. The paragenetic sequences of minerals in such complex environments should be related to the crystal structures of the minerals. This is one area where the discipline of structural mineralogy has much to offer the Earth Sciences: an understanding of the relationship between the paragenetic sequences of minerals and their corresponding crystal structures may be realized, and is the key to understanding such complex mineral occurrences. Such an approach is now possible for low-temperature minerals owing to recent advances in X-ray area detectors that have facilitated the determination of crystal structures for very small mineral crystals. The Mineralogy group is researching the relationships between mineral structures, thermodynamic stabilities, and paragenetic sequences for a broad spectrum of low-temperature minerals, with specific emphasis on borate, copper oxysalt, uranyl, tellurate, selenate and mercury minerals.
 
 

Recent Publications

2000

Burns, P.C., Olson, R.A., Finch, R.J., Hanchar, J.M. and Thibault, Y. (2000): KNa3(UO2)2(Si4O10)2(H2O)4, a new compound formed during vapor hydration of an actinide-bearing borosilicate waste glass. Journal of Nuclear Material (in press).

Burns, P.C., Pluth, J.J., Smith, J.V., Eng, P., Steele, I. & Housley, R.M. (2000): Quetzalcoatlite: New octahedral-tetrahedral structure from 5-micrometer crystal at the Advanced Photon Source-GSE-CARS facility.  American Mineralogist (in press).

Burns, P.C., Smith, J.V. & Steele, I. (2000): Arizona porphyry copper/hydrothermal deposits I. The structure of chenevixite and luetheite.  Mineralogical Magazine (in press).

Chen, Fanrong, Burns, P.C. & Ewing, R.C. (2000): Near-field behavior of 99Tc during the oxidative alteration of spent nuclear fuel. Journal of Nuclear Materials (in press).
 

1999

Burns, P.C. (1999): The crystal chemistry of uranium. Reviews in Mineralogy 38, 23-90.

Burns, P.C. (1999): Cs boltwoodite obtained by ion exchange from single crystals: Implications for radionuclide release in a nuclear repository. Journal of Nuclear Materials 265, 218-223.

Burns, P.C. & Finch, R.J. (1999): Wyartite: crystallographic evidence for the first pentavalent-uranium mineral. American Mineralogist 84, 1456-1460.

Burns, P.C. (1999): A new sheet complex of uranyl polyhedra in the structure of wölsendorfite.  American Mineralogist 84, 1661-1673.

Chen, Fanrong, Burns, P.C. & Ewing, R.C. (1999): 79Se: Geochemical and crystallo-chemical retardation mechanisms. Journal of Nuclear Materials 275, 81-94.

Burns, P.C. (1999): The crystal structure of edoylerite determined from a microcrystal. Canadian Mineralogist 37, 113-118.

Grice, J.D., Burns, P.C. & Hawthorne, F.C. (1998): Borate minerals II: A hierarchy of structures based upon the borate fundamental building block.  Canadian Mineralogist, 37, 731-762.

Hill, F.C. & Burns, P.C. (1999): Structure of a synthetic Cs uranyl oxide hydrate and its relationship to compreignacite. Canadian Mineralogist 37, 1283-1288.

Burns, P.C. & Hanchar, J.M. (1999): The structure of masuyite, Pb[(UO2)3O3(OH)2](H2O)3, and its relationship to protasite. Canadian Mineralogist 37 (in press).

Burns, P.C. & Hill, F.C. (1999): A new uranyl sheet in K5[(UO2)10O8(OH)9](H2O): New insights into sheet anion-topologies.  Canadian Mineralogist 37 (in press).

Fayek, M., Burns, P.C., Guo, Y.X. & Ewing, R.C. (1999): Micro-structures associated with uraninite alteration. Journal of Nuclear Materials (in press).

Fouke, B.W., Farmer, J.D., Des Marais, D.J., Pratt, L., Sturchio, N.C., Burns, P.C. & Discipulo, M.K. (1999): Depositional facies and aqueous-solid geochemistry of travertine-depositing hot springs (Angel Terrace, Mammoth Hot Springs, Yellowstone National Park, USA). Journal of Sedimentary Research (in press).
 

1998

Burns, P.C. (1998): CCD X-ray area detectors applied to the analysis of mineral structures. Canadian Mineralogist 36, 847-853.

Burns, P.C. (1998): The structure of boltwoodite and implications of solid-solution towards sodium boltwoodite. Canadian Mineralogist 36, 1069-1075.

Burns, P.C. (1998): The structure of compreignacite, K2[(UO2)3O2(OH)3]2(H2O)7. Canadian Mineralogist 36, 1061-1067.

Burns, P.C. (1998): The structure of richetite, a rare lead uranyl oxide hydrate. Canadian Mineralogist 36, 187-199.

Burns, P.C., Roberts, A.C. & Nikischer, A.J. (1998): The crystal structure of Ca[Zn8(SO4)2(OH)12Cl2](H2O)9, a new phase from slag dumps at Val Varenna, Italy. European Journal of Mineralogy 10, 923-930.

Burns, P.C. (1998):  The crystal structure of szenicsite, Cu3MoO4(OH)4.  Mineralogical Magazine 62 461-469.

Novak, M., Burns, P.C. & Morgan, G.B. VI (1998): Fluorine variations in hambergite from granitic pegmatites. Canadian Mineralogist 36, 441-446.

Mitchell, R.H., Choi, J.B., Hawthorne, F.C., McCammon, C.A. & Burns, P.C. (1998): Latrappite: A re-investigation.  Canadian Mineralogist 36, 107-116.
 

1997

Burns, P.C. (1997): A new uranyl oxide hydrate sheet in the structure of vandendriesscheite: Implications for mineral paragenesis and the corrosion of spent nuclear fuel. American Mineralogist 82, 1176-1186.

Burns, P.C., Ewing, R.C. & Hawthorne, F.C. (1997): The crystal chemistry of hexavalent uranium: Polyhedral geometries, bond-valence parameters, and polymerization of polyhedra. Canadian Mineralogist 35, 1551-1570.

Burns, P.C., Ewing, R.C. & Miller, M.L. (1997): Incorporation mechanisms of actinide elements into the structures of U6+ phases formed during the oxidation of spent nuclear fuel.  Journal of Nuclear Materials 245, 1-9.

Burns, P.C., Finch, R.J., Hawthorne, F.C., Miller, M.L., & Ewing, R.C. (1997): The crystal structure of ianthinite, [U4+2 (UO2)4O6(OH)4(H2O)4](H2O)5: A possible phase for Pu4+ incorporation during the oxidation of spent nuclear fuel. Journal of Nuclear Materials 249, 199-206.

Burns, P.C. & Carpenter, M.A. (1997): Phase transitions in the series boracite-trembathite-congolite: An infrared spectroscopic study. Canadian Mineralogist 35, 189-202.

Burns, P.C., Hawthorne, F.C., Libowitsky, E., Bordes, N. & Ewing, R.C. (1997): Donathite discredited: a mixture of two spinels.  Neues Jahrbuch für Mineralogie Monatshefte, 163-174.

Hawthorne, F.C. & Burns, P.C. (1997): The crystal structure of jørgensenite.  Canadian Mineralogist 35, 1509-1514.

Pauly, H., Hawthorne, F.C., Burns, P.C. & Della Ventura, G. (1997): Jørgensenite: Na2(Sr,Ba)14Na2Al12F64(OH,F)4, a new aluminofluoride mineral from Ivigtut, Greenland. Canadian  Mineralogist 35, 175-179.

1996

Burns, P.C., Miller, M.L. & Ewing, R.C. (1996): U6+ minerals and inorganic phases: a comparison and hierarchy of structures. Canadian Mineralogist 34, 845-880.

Burns, P.C. & Carpenter, M.A. (1996): Phase transitions in the series boracite-trembathite-congolite: phase relations. Canadian Mineralogist 34, 881-892.

Burns, P.C., Hawthorne, F.C., Hofmeister, A.M. & Moret, S.L. (1996): A structural phase-transition in  K(Mg1-xCux)F3 perovskite. Physics and Chemistry of Minerals 23, 141-150.

Burns, P.C. & Hawthorne, F.C. (1996): Static and dynamic Jahn-Teller effects in Cu2+ oxysalts.  Canadian Mineralogist 34, 1089-1105.

Hawthorne, F.C., Burns, P.C. & Grice, J.D. (1996): The crystal chemistry of boron. Mineralogical Society of America Reviews in Mineralogy 33, 41-115.

Miller, M.L., Finch, R.J., Burns, P.C., & Ewing, R.C. (1996): Description and classification of uranium oxide hydrate sheet topologies. Journal of Materials Research 11, 3048-3056.