The effect of different silicon sources - silica gel SiO2, tetraethylorthosilicate Si (OC2H5)4 and silicic acid H2Si2O5 - on the crystallization of cordierite were investigated. Aluminum chloride (AlCl3-6H2O) and magnesium chloride (MgCl2- 6H2O) were respectively used as sources of Aluminum and magnesium. The precursors of cordierite were prepared through the coprecipitation method. The different starting materials were mixed in an aqueous medium in stoichiometric proportions of the cordierite (2Al2O3, 2MgO, 5SiO2. Different experimental techniques (TGA, X-ray, IR, SEM and dilatometry) were used to characterize the prepared precursors. The obtained results indicated the presence of several crystalline phases such as mullite, spinel, corundum, enstatite, cristobalite at low temperature (1000 °C, 1100 °C) beside the amorphous phase. At 1200 °C, the crystallization of μ-cordierite was observed; this crystalline phase was transformed into α-cordierite (Indialite) at 1300 °C. By increasing the temperature up to 1400 °C the main phase obtained is α-cordierite with an amount of spinel that varies with the silicon sources. The morphological analysis showed that the shape and the size of grains of α-cordierite phase were influenced by the nature of silicon source. Keywords: cordierite, silicon, calcination, spinel, coprecipitation.