Formula [Al1,94Fe0,7Mg0,5][Si7,5Al0,5]O20(OH)4Ca1,56Na0,32K0,154 Molecular weight 791,711 g Density 2,75 g/cm3 BET specific area (Nitrogen) 60 m2/g Methylene Blue specific area 520 m2/g Total pore volume 143,9.10-03 cm3/g Average particle diameter 140 µm Elemental mass of grain 40.10-6 g

Table 1: Textural characterization of raw clay.