tsuwm's wwftd, schistaceous,= fissile reminded me of having
a learned clergyman tell me that a theological "split" was a "schism" pronounced "sizzm" But all the medical words I know that start with "schiz- " are pronounced "sk=" and the ones with "schisto-" are pronounced "sh-".
And I think "fissile" will make most people think of
atomic energy fuels.

AHD4 accepts both pronunciations.

True, but the "in" pronunication fifty years ago was "sizzm.