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 Coalkylated to produce an organophilic material. In another aspect the instant invention is a method for the production of platy sodium octasilicate which includes the step of: heating a liquid aqueous colloidal silica dispersion containing silica, sodium oxide, and water, the mole ratio of the silica to the sodium oxide being in the range of from about 3.5 to about 10. In another aspect, the instant invention is a method for preparing a liquid aqueous colloidal silica dispersion, the dispersion having a mole ratio of silica to sodium oxide of from 3.5 to 10, which includes the step of: mixing a sufficient amount of liquid aqueous colloidal silica suspension with a liquid aqueous sodium silicate suspension to produce the liquid aqueous colloidal silica dispersion, the liquid aqueous colloidal silica suspension having a mole ratio of silica to sodium oxide of more than 20, the liquid aqueous sodium silicate suspension having a mole ratio of silica to sodium oxide of less than 3.5, the rate of mixing being effective to prevent the gelation or solidification of the liquid aqueous colloidal silica dispersion.