Process for producing chain structured corpuscular calcium carbonate

In a process for producing chain structured corpuscular calcium carbonate, an improvement which comprises a first carbonation of calcium hydroxide in a form of an aqueous suspension containing 0.1 to 20 wt. parts of a chelating agent for CaOH per 100 wt. parts of calcium hydroxide to form a viscous colloidal suspension and a second carbonation of the resulting viscous colloidal suspension containing 0.0001 to 0.5 mole of a water soluble metal salt which forms a water insoluble precipitate in an aqueous suspension of calcium hydroxide per 1 mole of calcium hydroxide as the starting material, carrying out the carbonation to be pH of 7 to 8 at the temperature of the aqueous suspension of 0.degree. to 30.degree. C. during the first and second carbonations, whereby chain-structured corpuscular calcium carbonate having an aspect ratio of length to diameter of from 5 to 50 and a primary particle average diameter of 0.01 to 0.1.mu. is produced.