Determination of rare earth elements in recent and fossil shells by radiochemical neutron activation analysis

Seven rare earth elements (La, Ce, Sm, Eu, Tb, Yb and Lu) in marine shell samples were determined by neutron activation analysis. In order to measure gamma-ray using a Ge(Li) detector without serious interference from the intense Compton background from Na-24, a simple radiochemical separation was performed by a co-precipitation method with hydrated iron(UI) oxide. The chemical yields for shell samples (91-99%) were determined by a re-activation technique for Gd and Yb. The interference from the U-235(n, fission) reaction was corrected for determination of La and Ce. The data obtained in this study showed the behavior of rare earth elements in shells during the process of fossilization.