Pure phase, high activity ZSM-48 crystals having a SiO2/Al2O3
ratio of less than about 150/1, substantially free from ZSM-50 and Kenyaite, and
fibrous morphology crystals. The crystals may further have a specific cross morphology.
A method for making such crystals using heterostructural, zeolite seeds, other
than ZSM-48 and ZSM-50 seeds.