The evaluation of the amount of amorphous form of silica is very important. For this purpose, there are some specific methods in the literature [24, 25]. One of them established that the degree of amorphous form of silica is estimated by the ‘silica activity index’, which is determined by calculating the percentage of valuable silica dissolved in an excess of boiling 4 M KOH in a 3-min extraction period [24]. This method was investigated for extracted silica and nanosilica, and the results were 99.7% and 99.9% amorphous form, respectively. For clarification, the XRD results were examined. Figures 4 and 5 show, from some samples of RHA prepared at different conditions and nanosilica present, a broad peak at 2θ = 22° associated with amorphous silica. The lack of sharp peaks indicates the absorbance of any ordered crystalline structure, confirming the results from the silica activity index and the lack of crystalline phase. Also, there are no peaks of carbon, porous or activated, which can be produced by heating RH at a relatively lower temperature when this phenomenon occurs due to the presence of potassium [26]. However, an acid treatment of the husk removed most of the potassium, and the ash became free of fixed carbon. The size of the particles was estimated by the half width of the peak (β) using Scherer's formula: