@Article{, title={URANIUM IN THE IRAQI PHOSPHORITES}, author={Khaldoun S. Al-Bassam}, journal={Iraqi Bulletin of Geology and Mining مجلة الجيولوجيا والتعدين العراقية}, volume={3}, number={2}, pages={13-31}, year={2007}, abstract={The radioactivity of the marine sedimentary phosphorites of Iraq is investigated and found to be due to uranium. The Late Cretaceous – Early Tertiary phosphorite deposits are generally poor in uranium relative to other Tethyan deposits; they generally contain (20 – 50) ppm U and up to 100 ppm U in the francolite concentrates. Strong positive correlation exists between uranium with P2O5 and F. Most of uranium is believed to be present in the francolite structure as U4+ substituting for Ca2+. Uranium in the Iraqi phosphorties seems to be generally in equilibrium with its daughter products with minor scattering around the equilibrium line. Secondary uranium minerals are found as metatyuyamunite in phosphorite and limestone, and as carnotite in shale. It seems that the source of uranium is terrigenous, supplied by U-rich sandstones of older rock units and transported by rivers to shallow marine environments. Geochemical affinity of U towards phosphates and reducing conditions facilitated uranium incorporation in the francolite structure in the early stages of crystallization. The radioactivity of phosphorties provides excellent tool for surface and subsurface prospecting and exploration. But, the presence of uranium in the phosphate fertilizers represents an environmental hazard.

} }