The preparations, precipitations and recrystallisations of magnesium and calcium aluminosilicate hydrates, from aqueous suspensions of microcrystalline silica, aluminium hydroxide (and oxohydroxide) and magnesium (calcium) hydroxides at ambient temperatures to 400 °C, are surveyed. The phases reported in systems of different Mg(Ca)/(Al + Si) and Al/(Al + Si) composition ratios are tabulated and precipitation and recrystallisation mechanisms are proposed.