This paper reports the results of experiments on ultra fine layered silicates Na-fluorotaeniolite and Na-fluorotetrasilicic mica synthesis in the melts prepared from reaction blends based on synthetic silicate raw material, namely synthetic magnesium silicate dihydrate (MSDH, MgO.SiO2.2H(2)O). The MSDH-Na2SiF6-LiF, MSDH-Na2SiF6-MgF2 and MSDH-Na2SiF6-NaF blends, whose compositions are close to the stoichiometry of the Na-fluorotaeniolite (NaMg2Li[Si4O10]F-2) and Na-fluorotetrasilicic mica (NaMg2.5[Si4O10]F-2) were studied in the temperature range 1080-1225 degrees C. Magnesium silicate dihydrate, the phase composition of synthesis products and layered silicates (Na-fluorotaeniolite and Na-fluorotetrasilicic mica) were examined using the crystal optical, X-ray diffraction at room and high temperatures, differential thermal and chemical analyses. It has been shown that studied blends possessed a high reactivity, owing to which the layered silicates were synthesized at lower temperatures (similar to 180-300 degrees C) and the duration of the synthesis was shortened severalfold. The maximal yield of the Na-fluorotetrasilicic mica was observed in the reaction blend with the Na2SiF6 and NaF as halogen-containing compounds. The specific effects of MSDH on the physicochemical processes proceeded during heat treatment of the reaction blends were described. (C) Koninklijke Brill NV, Leiden, 2010