-Systematic SAXS studies have been performed at the LURE Synchrotran, Orsay, using an intense beam of point like cross-section to obtain information about the sol wet gel dried gel silica glass transformation. The intensity curves have been analysed in term of power law in log-log plots, whose exponent is related to mass and surface fractal dimensions of the structure. It was found that almost all phases present fractal structures and for the case of basic gels, is of hierarchical nature. The aerogels are formed by a dense matrix, with a smooth surface and exhibit a very narrow auto-similarity range that gives a mass fractal dimension
