This paper reports the description of the reaction path taking place during the firing of cement-asbestos slates followed using different experimental techniques (optical microscopy, SEM, TEM , quali- quantitative X-Ray powder diffraction, FTIR). It will be demonstrated that only an interplay of different experimental techniques (mainly diffraction end electron microscopy) can lead to a safe verification of the yield of thermal transformation of asbestos minerals. The understanding of the complex temperature induced reaction path is of paramount importance for the optimization of industrial heating processes to yield a safe transformed product to be eventually recycled.