Within the building industry, the term “pozzolana” covers all the materials that react with lime in the presence of water, giving to calcium silicate and aluminate hydrates with cementing properties. As a consequence, all pozzolans have to be rich in reactive silica or alumina (Massazza 2003). Any pozzolanic compound or source of silica and alumina that is readily dissolved in an alkaline solution will suffice as a geopolymer precursor and thus natural pozzolans condensed with sodium silicate and geopolymerises in a highly alkaline environment lend themselves to geopolymerization