In the production and development of building materials, burned clays are the center of major interest, particularly in the building industry. Henceforth, in order to analyze the effect of heat treatment on illite-rich natural clay samples from Turkey samples were exposed to heat at various temperatures between 350-650 oC. The results of the heat treatment on the structure of the samples were followed by Fourier transform infrared (FT-IR), solid state magic angle spinning nuclear magnetic resonance (MAS NMR) thermogravimetric (TG) and differential thermal (DTA) analyses techniques and all the findings were explained and discussed