Diffusion of the rare earth elements in natural and synthetic fluorapatite was characterized under anhydrous conditions. In the case of in-diffusion experiments, apatite was immersed in reservoirs of synthetic REE apatite analogs of various compositions. At 800 to 1250C, the Arrhenius relationship for Dy for in-diffusion experiments using REE silicate oxyapatite sources was:

D(m2/s) = 9.7 x 10-7 exp[-340(kJ/mol)/RT]

D.J.Cherniak: Geochimica et Cosmochimica Acta, 2000, 64[22], 3871-85