Highly dispersed MgO center dot SiO(2) system was pptd. from aq. soln. of MgSO(4) and Na(2)SiO(3) (water glass) at room temp. for 5 h, dried under static conditions, spray-dried at 220 degrees C, and optionally heat-treated (calcined) at 1000 degrees C for 2 h, and studied for chem. compn., crystal structure, porosity, sp. surface and wettability. The calcined product consisted of grains with av. size 27.4 mu m, showed lowest absorption activity and H(2)O content, crystobalite structure and highest SiO(2)/MgO ratio.