Luminescence of uranium and rare-earth elements in apatite of fossil fish teeth

Time-delayed laser-induced luminescence of uranium and rare-earth elements (REE) in apatite of fossil fish teeth from the phosphorites of the Senonian Mishash Formation, Israel, were investigated before and after thermal treatment. The unheated samples show luminescence of UO₂/²⁺. Luminescence of REE³⁺ (Sm, Eu, Pr) is observed only after heating the samples at 1100 K in air. The spectral properties indicate that UO₂/²⁺ in the unheated samples is located in two different positions, as aqua- complexes of uranyl-ions and associated with organic matter. The REE in the unheated samples are accommodated in non-luminescent form. After heating the REE³⁺ (Sm, Eu, Pr) are located in the Ca²⁺ II site presumably due to thermal diffusion.