in not given heating of Al2O3 and SiO2 (>1:2);;

in water byproducts: hydralsite; High Pressure; hydrothermal treatment (50 MPa, 400°C, 480 or 1056 h, molar ratio K2O:kaolinite 10:90 or 50 MPa, 400°C, 1056 h molar ratio K2O:kaolinite 20:80); X-ray diffraction;