A silicoaluminophosphate molecular sieve is disclosed that comprises first
and second intergrown phases of a CHA framework type and an AEI framework
type, wherein said first intergrown phase has an AEI/CHA ratio of from
about 5/95 to about 40/60 as determined by DIFFaX analysis, the second
intergrown phase has an AEI/CHA ratio of about 30/70 to about 55/45 as
determined by DIFFaX analysis and said molecular sieve has a silica to
alumina molar ratio (Si/Al.sub.2) from about 0.13 to about 0.24.