According to the _Manual_of_Exotic_Pets_ 1991, (Published by the British
Small Animal Veterinary Association) they can be crossed:
 
Under the paragraph on fur ranching (P. 97) it states:
"It is the practice of some ranches to breed male mink with female ferrets
in order to obtain two litters per year compared with the female mink's one
litter.  The offspring are infertile hybrids with a better quality fur than
the pure ferret."
 
-Ilena Ayala=
[Posted in FML issue 2359]