Author name: John R. Bargar

Biogenic uraninite is of interest to geoscientists for its importance to bioremediation strategies, remarkably small particle size, and biological origin. Recent studies have begun to illuminate the chemical/structural complexities of this important natural nanomaterial. Intriguingly, in spite of its incredibly diminutive size, the molecular-scale structure, energetics, and surfacearea-normalized dissolution rates of hydrated biogenic uraninite appear to be similar to those of coarser-particle, abiotic, stoichiometric UO2. These findings have important implications for the role of size as a moderator of nanoparticle aqueous reactivity and for the bioremediation of subsurface U (VI) contamination.