Thermal reactions of ultrafine Mg(OH)(2) mixtures of ultrafine particles and kaolin mixtures were investigated to obtain cordierite at low temperatures. Magnesium hydroxide was precipitated from magnesium chloride (MgCl2) solution. Kaolin with three different chemical composition (K-l, K-S and K-K) was mixed with Mg(OH)(2) to form cordierite at different temperatures (900-1200degreesC). Mole ratio of mixtures were MgO:Al2O3:2SiO(2). To obtain dense cordierite, boron oxide in different quantities (in the form of magnesium borate 2MgO(.)B(2)O(3)) were added into mixtures of kaolin and Mg(OH)(2). After sintering, it was observed that, by increasing the amount of B2O3 in the mixture, the density was not changed significantly.