Five mixtures (M1 to M5) of silica-alumina geomaterials and two varieties of alumina (A_P and A_R) were used for the elaboration of mullite refractory materials between 1500℃ and 1600℃. An X-ray diffraction (XRD) analysis showed that the refractory samples are composed of mullite, corundum and silica. The length of the mullite crystals was measured by a method of image analysis of scanning electron microscopy (SEM). Chemical and mechanical properties of these materials were investigated and correlated with their microstructure. Resistance towards Acid Attack test showed that the refractory samples present good resistance, as well as, the alumina powder A_R obtained from waste of silica-alumina bricks proves to be efficient for an eventual use.