A series of crystalline alumino-silicate zeolites identified as UZM-12 have been synthesized. These UZM-12 compositions have the ERI topology, a Si/Al>5.5 and can be prepared as nanocrystallites having an average particle size of about 15 to about 50 nanometers and a spheroidal morphology. The UZM-12 composition can be treated to remove at least a fraction of the framework aluminum atoms thereby providing zeolites with a Si/Al>5.75 and identified as UZM-12HS. Both the UZM-12 and UZM-12HS can catalyze various hydrocarbon conversion processes.