Gallstones:
http://ferrethealth.org/archive/SG15408
http://ferrethealth.org/archive/SG15406
http://ferrethealth.org/archive/SG15387

Using search terms
gallbladder and stone:
http://ferrethealth.org/archive/YPG1050

Using search terms
bile and stone:
http://ferrethealth.org/archive/SG15350
http://ferrethealth.org/archive/SG6476

and there are certainly others but these seemed to possibly be the best
fits for your needs.

It is more typical to hear of uroliths (urinary tract stones).

Sukie (not a vet)

Recommended ferret health links:
http://pets.groups.yahoo.com/group/ferrethealth/
http://ferrethealth.org/archive/
http://www.afip.org/ferrets/index.html
http://www.miamiferret.org/fhc/
http://www.ferretcongress.org/
http://www.trifl.org/index.shtml
http://homepage.mac.com/sukie/sukiesferretlinks.html

[Posted in FML 5810]