Polished slabs of apatite, oriented normal or parallel to c, were implanted with 100keV 3He to a dose of 5 x 1015/cm2. The 3He distributions were measured via nuclear reaction analysis using  3He(d,p)4He. The Arrhenius relationship at 148 to 449C, for diffusion normal to c, was:

D(m2/s) = 2.10 x 10-6exp[-117(kJ/mol)/RT]

There was little evidence of anisotropy.

D.J.Cherniak, E.B.Watson, J.B.Thomas: Chemical Geology, 2009, 268[1-2], 155-66