to:          Rob Ripperdan

Dear Rob,

We refer a lot to a paper by I. Friedman and J.R. O'Neil:
"Compilation of Stable Isotope Fractionation Factors of
Geochemical Interest". It is referred to in Ihsan Al-Aasm's
paper. The fractionation factor for rhodochrosite at 25 deg.C
is given there. If you can't get it let me know. I can fax you
the critical page. Ihsan's paper is very useful for reaction
rates.

Natalie Morisset