Zeolites crystallise from amorphous alkaline aluminosilicates under the action of heat and pressure. When an alkaline silicate solution and a specific concentration of alkaline aluminate solution are mixed, a white amorphous precipitate or colloid normally forms, the amount of colloid depending onAl and Si concentrations and the time of formation. It is possible to produce aluminosilicate solutions that remain clear for times varying fromfive minutes to several days before eventually the particles aggregate into threedimensional networks and form coagulate colloids. This work obviously has shown that the sol formation time strongly depends on the Al concentration and the temperature, while the amount of the colloidal phase depends on the Si and the alkalinity of the solution. The Âcolloid formation timeÂ is defined as the time from mixing to the point when some colloid particles appeared in the solution, as judged visually and these times are listed.