Chemical diffusion of the rare-earth element was measured in natural calcite

under anhydrous conditions, using rare-earth carbonate powders as the sources. Experiments were run in sealed silica capsules together with finely ground calcite to ensure stability of the single-crystal samples during diffusion anneals. Rutherford back-scattering spectroscopy was used to measure diffusion profiles. The Arrhenius relationship at 600 to 850C was:

D(m2/s) = 2.4 x 10-14 exp[-150(kJ/mol)/RT]

D.J.Cherniak: Earth and Planetary Science Letters, 1998, 160[3-4], 273-87