To improve mechanical properties of mullite, a mullite-Al2O3\mullite laminate composite was prepared. Lamination generates residual stresses within the structure, measured by piezospectroscopy. A preliminary and complete piezo-spectroscopic characterization of the Al2O3\mullite system was carried out. A method to determine the concentration of Al2O3 in the composite by Raman spectrum was proposed and used to assess the composition of the laminated structure along the cross section. The experimental results evidenced a gradual change of composition and residual stress state between the two layer.