The invention relates to a method for preparing a synthetic talc composition. According to said method, a kerolite composition is subjected to an anhydrous thermal treatment carried out at a pressure lower than 5 bar, from over a few hours up to over a few days, at a treatment temperature higher than 300° C. The invention also relates to a synthetic talc composition prepared in this way, the synthetic talc particles of the composition being exclusively of chemical formula —(Si4)Mg3O10(OH)2— and identifiable, during X-ray diffraction, by the presence of a characteristic diffraction peak located at a distance of between 9.40-9.68 and corresponding to a plane (001). Said synthetic talc particles also have a thermally stable crystalline structure of stacked laminae, which is very similar to that of a natural talc and has a particle size smaller than approximately ten micrometers.