Abstract Intercalation of organic guest species into layered silicates is a way to construct clay mineral–polymer nanocomposites. An example is magadiite Na 2 Si 14 O 29 ·9H 2 O which like smectites intercalates organic species. Using hydrous silica precipitated from water glass with dilute HCl in aqueous dispersions of NaOH and Na 2 CO 3 , well-crystallized magadiite as a single phase was synthesized at 150 °C for 24 h or 170 °C for 9 h.