Raman spectroscopy study of selected uranophanes

Abstract

Uranyl silicates are understood as common constituents of the oxidized parts of uranium deposits. They form as alteration phases during hydration-oxidation weathering of uraninite, and also as alteration phases of uranium dioxide and spent nuclear fuel in the series of paragenetic sequences [1-3]. It is possible that uranyl minerals including uranyl silicates (such as uranophane) will incorporate environmentally important radionucleides (e. g. 135Cs and 90Sr) and other actinides (e. g. Np(V) and Np(VI)) in their structures [4-8]. Burns presented recent advances in the understanding of uranyl mineral structures and the crystal chemistry of hexavalent uranium [8, 9]. Uranophane, Ca(UO2SiO3OH)2.5H2O is the most common uranyl mineral and possibly the most common uranium mineral after uraninite. Uranophane precipitates from near neutral to alkaline ground waters that contain sufficient concentration of dissolved Si and Ca [10]. It is imperative to have methodology to characterize these minerals. This methodology must be able to be used at a distance from the mineral deposit.