Abstract: A method for producing synthetic magadiite, including the step of: heating a liquid aqueous colloidal silica suspension, the liquid aqueous colloidal silica suspension having a mole ratio of sodium hydroxide to silica and a mole ratio of water to silica effective to produce a synthetic magadiite wherein more than fifty percent by weight of the synthetic magadiite is platy synthetic magadiite. The synthetic platy magadiite can be converted to the acid form and: (a) heated to produce quartz-like plates; or (b) alkylated to produce an organophilic material. A method for the production of platy sodium octasilicate and a method for preparing a liquid aqueous colloidal silica dispersion having a mole ratio of silica to sodium oxide of 3.5 to 10 are further disclosed.