Industrially most important zeolite structures: A) LTA, B) X and Y (FAU topology), C) ZSM-5 (MFI topology), D) MOR, E) FER and F) *BEA. The symbols I, I′, II, II′, III, and III′ indicate exchangeable cation sites in LTA and FAU. The lines represent the O atoms; the corners Si or Al atoms. ZSM-5, MOR and FER are also known as pentasil zeolites.