Diffusion coefficients for Pb in fluorapatite at 900 to 1250C were obtained by measuring diffusional uptake profiles of the element in the margins of gem-quality crystals. The crystals were immersed in synthetic melts enriched in the trace element and presaturated in apatite. The resulting diffusion gradients were characterized by electron microprobe analysis. The results were erratic, probably because extremely Pb-rich melts were used for some of the experiments. Data which were believed to be reliable were described by:

D(cm2/s) = 0.035 exp[-70000/RT]

E.B.Watson, T.M.Harrison, F.J.Ryerson: Geochimica et Cosmochimica Acta, 1985, 49[8], 1813-23