This is a comparison of typical specifications between USA produced Ground
Calcium Carbonate (GCC) and USP Precipitated Calcium Carbonate (PCC).
Item GCC PCC

PCC has a higher calcium assay than GCC
CaCO3 96. 99+ typical, 98% guaranteed
MgCO3 1.0 1.0
Fe2O3 0.2 0.06
Moisture 0.5 0.2

PCC has more smaller particles than GCC
D90 10.0 9.0 micron
D50 4.0 1.9 micron
D10 1.0 0.2 micron

PCC has a higher brightness than GCC
Brightness 91 98

GCC density is higher than GCC for the same particle size
Loose density 40 18 lbs/cu ft
Tapped density 70 31

However, the density of PCC can be controlled over a very wide range

The particle shape of PCC can be controlled and even designed, while the
particle shape of GCC is usually blocky

The price of GCC is lower than the price of PCC
Price x-mill $0.1150/lb $0.2225/lb
As of Dec. 2001