Finely divided calcium carbonate compositions

A finely divided, wet-ground, dispersant-free calcium carbonate composition in which the particle size distribution of calcium carbonate is such that:

• (a) the size of the calcium carbonate particles at the 50% point on a SediGraph particle size distribution curve representing the composition is from about 0.60 .mu.m to about 1.30 .mu.m in equivalent spherical diameter,
• (b) the size of the calcium carbonate particles at the 80% point on said distribution curve divided by the size of the calcium carbonate particles at the 50% point on said distribution curve gives a number of from about 1.40 to about 1.90,
• (c) the size of the calcium carbonate particles at the 20% point on said distribution curve is from about 0.80 .mu.m to about 0.30 .mu.m in equivalent spherical diameter, and the overall sizes of calcium carbonate particles present are such that:
• no more than about 2 weight percent of the particles present are larger than about 8 .mu.m in equivalent spherical diameter;
• at least about 98 weight percent of the particles present are less than about 8 .mu.m in equivalent spherical diameter;
• at least about 97 weight percent of the particles present are less than about 5 .mu.m in equivalent spherical diameter;
• at least about 90 weight percent of the particles present are less than about 3 .mu.m in equivalent spherical diameter;
• at least about 75 weight percent of the particles present are less than about 2 .mu.m in equivalent spherical diameter;
• at least about 35 weight percent of the particles present are less than about 1 .mu.m in equivalent spherical diameter, and
• no more than about 25 weight percent of the particles present are less than about 0.4 .mu.m in equivalent spherical diameter.