How Does Precipitated Calcium Carbonate Differ From Ground Calcium Carbonate (GCC)?
In chemical composition, they are the same. PCC is purer than the limestone from which it is made, and is lower in silica and lead. PCCs shape and size are different from that of ground calcium carbonate (GCC). Under high magnification, GCC is seen to be irregularly rhombohedral in shape. The PCC crystal shape depends on the product, and the particles are more uniform and regular. The distribution of particle sizes in a GCC is much broader than for a PCC of the same sizethat is, there are many more large particles and many more small particles than in a PCC, and the size of the largest of the particles (the “top size”) is much greater for a GCC than for a PCC. The lower top size of a PCC gives better impact resistance in plastics than with a GCC. The narrower particle size distribution allows the generation of high oil absorptions, useful in certain applications. These differences can be quickly seen in these photos of a PCC and a GCC of the same median particle size, 0.7 microns. Spec
