now im not a geo by any means, but i did some looking..
it seems it can vary drastically depending on the process used to recover, and by they type of mineralization.. different mines need different processes..
but i figure the safest bet... is to look at hbm's recovery %, and i believe that varries from 90-93%
altho im sure bamako will be nice enough to share the proper #'s we should be using :)