Amorphous aluminosilicate, sodium A zeolite and hydroxysodalite were obtained by treating Hadong-kaolin （halloysite） with 1N aqueous sodium hydroxide solution for one to five hours and with temperature range from 60 to 100 ℃. The reaction mechanism was observed as first order consecutive reaction as follows:
halloysite ⇬（k1）→ amorphous aluminosilicate ⇬(k2)→ sodium A zeolite ⇬(k3)→ hydroxysodalite By applying the above reaction mechanism, rate constants and activation energies were measured. The activation energies of the reactions from halloysite to amorphous aluminosilicate, from amorphous aluminosilicate to sodium A zeolite, and from sodium A zeolite to hydroxysodalite were 10 kcal/mol, 16 kcal/mol, and 7 kcal/mol, respectively.