This is an actual nuclear reaction profile obtained by the Frankfurt group on a kimberlite-hosted megacryst olivine from Kaalvallei, South Africa. It shows a high concentration of 'water' on the surface of the crystal and a much lower internal OH content.
These results represent
the state of the art for our analyses of olivine. Near linear calibrations
are obtained with minerals with several 10's to a few 100's ppm hydrogen
(expressed as water) in the sample.
Reference: Bell DR, Rossman GR, Maldener J, Endisch D, Rauch F (2003). Hydroxide in olivine: A quantitative determinatin of the absolute amount and calibration of the IR spectrum. Journal of Geochemical Research, 108(B2), 2105, doi:10.1029/2001JB000679, 2003.