After acid treatment and controlled combustion, 22.5% of RHA was produced. The percentage of pure silica in the RHA, extracted silica, and nanosilica were 90.469%, 96.529%, and 98.801%, respectively (Table 3). It is interesting to note that only MgO was detected in the extracted silica, and it was also present in a lower concentration in the nanosilica. Other impurities could be detected below the limit of quantification