Polyester composition containing vaterite-type calcium carbonate

A polyester composition comprising a saturated polyester and 0.005-10 weight %, based on the polyester, of a particulate vaterite-type calcium carbonate having the following particle size and particle size distribution:

• 0.1 .mu.m.ltoreq.DS.ltoreq.2.0 .mu.m
• DP3/DS.ltoreq.1.25
• 1.0.ltoreq.DP2/DP 4.ltoreq.2.5
• 1.0.ltoreq.DP1/DP 5.ltoreq.4.0
• (DP2-DP4)/DP3.ltoreq.1.0
• wherein
• DS is the mean particle size in .mu.m,
• DP1 is the particle size in .mu.m for 10% by weight,
• DP2 is the particle size in .mu.m for 25% by weight,
• DP3 is the particle size in .mu.m for 50% by weight,
• DP4 is the particle size in .mu.m for 75% by weight of the particles, and
• DP5 is the particle size in .mu.m for 90% by weight of the particles, said particulate vaterite-type calcium carbonate having been prepared by the carbonation of a calcium compound in a mixed alcohol and water medium.