Illite is a kind of mica clay minerals with rich potassium silicate, It is also named as water white mica. Formula as K0.75 Al1.75 (R) Si3.5 Al0.5 O10 (OH) 2, R=metal ions, mainly for the bivalent magnesium, ferrous iron. It is showed as irregular scaly under the electron microscope . Hardness 1-2, no swelling and no plasticity. Chemical composition SiO2 Al2O3 Fe2O3 TiO2 CaO MgO k2O Na2O 46.27 34.81 0.28 0.66 0.42 0.18 8.94 0.99 Physicial Whiteness Moisture(%) PH Bulk density (g/cm 3 ) Size 78-80 0.5max 7-7.5 2.6-2.9 800-2000 mesh