In $$ terms the Fairymount success is worth between $2.3m - $4.0m. This is according to a recent ABN Amro report on MOS. They value MOS at 22c.
It is an interesting read..if anyone is interested:
http://www.mosaicoil.com/PDF/Library/MOS80206.pdf
P.S Armstrong Freneau is the largest reward. Worth between $71m - $176m. Many other wells with significant rewards for MOS as shown in the report.
Cheers
OZ