To use rectangular coordinates in which the malar ratios Na2O/SiO2,Sio2/Al2O3,H2O/ Na2O are used as coordinates. Typical diagrams shown in Fig. 4.6 for the Na2O-Al2O3-SiO2-H2O system at 25, 100 and 120-150 oC illustrate the correlation between gel composition and the zeolite produced.