Abstract The present study about ternary diagrams of SiO 2 -Al 2 O 3 -K 2 O has been conducted from the determination of two possible optimal clay mixtures through hydrometric tests of a company dedicated to the manufacture of masonry products for construction in the North region of Santander in Colombia; this work is the continuation of others carried out previously. In this raw material (clay) the dominant minerals are silica, alumina, iron, potassium, among others, which provide the plasticity and adequate granulometric distribution. Two optimal m7 and m8 mixtures were selected from 5 samples (M1, M2, M3, M4 and M5) of clays from different points of the company’s mine, these mixtures were analyzed by Fluorescence and X-ray diffraction tests with the purpose of determining the chemical elements in their maximum percentage and to be able to graph them in ternary diagrams with the help of FACTSAGE software and finally determine their cooking behavior. The results of the investigation showed that the physical characterization of the clays provides a broad view on the technological behavior of the raw material and consequently the quality of the final product.