Process for the preparation of crystalline (metallo) silicates and/or derivatives thereof from a silica source, an organic cation source, a source of water and optionally an alkali(ne earth) metal and/or an aluminium and/or a further metal source wherein a crystalline (metallo) silicate is produced under synthesis conditions from a solution or a gel wherein at least 30%, on an atomic basis, of the silicon in said solution or gel originates from one or more crystalliz­ed quaternary ammonium or phosphonium double n-ring (metallo) silicate clathrates wherein n is 3, 4 or 5. Crystalline (metallo) silicates which can be suit­ably prepared according to the present process comprise SCS-1, SCS-2, SCS-4, dodecasil-3C, TMA-zeolite T, TMA-sodalite, ZSM-12, zeolite beta and zeolite L.