The present invention relates to a process for producing a surface-reacted calcium carbonate, wherein a calcium carbonate-comprising material is treated with at least one inorganic acid and carbon dioxide in an aqueous medium to form an aqueous suspension of surface-reacted calcium carbonate, wherein the at least one water-soluble, inorganic magnesium salt is added before, during and/or after the treatment step. Furthermore, the present invention relates to a surface-reacted calcium carbonate obtained from said process and its use.