Bauxite is the most precious ore of Al which consists 30−60%Al2O3, the remaining is a mixture of SiO2,Fe2O3 and TiO2 When powdered form of bauxite is reacted wth concentratedNaOH, it mainly forms Al2O3 and SiO2 whereas other oxidesremain insoluble in the solution. Therefore, the pair of oxides which can be leached out areAl2O3 and SiO2