Definition: Grades of calcium carbonate (CaCO3) are used as fillers for plastics. They are obtained from naturally-occurring deposits as well as by chemical precipitation. The natural material is derived from natural chalk, limestone or dolomite, consisting of calcium carbonate with up to about 44% magnesium carbonate. The synthetic product is manufactured by a precipitation process in order to obtain a finer or more uniform panicle size range. Also known as aragonite, calcite, CHALK, LIMESTONE and WHITING.
