pores of the ZSM-8 and be cracked, said zeolite having an X-ray difiraction pattern as set forth in Table 4 and a composition, in terms of oxide mole ratios, as follows: 0910.2 M2/ O:A1g03:5100 SlO IZH O wherein M is a cation, n is the valance of said cation, and z is from 0 to 40.] 8.