Abstract: Compositions comprising calcium carbonate, methods of preparation thereof, and methods of use thereof are discussed. The particulate mineral may be prepared by a precipitation process and/or by a grinding process, for example. The composition may comprise a particulate mineral that comprises calcium carbonate and magnesium, wherein the particulate mineral comprises from about 7% to about 80% magnesium by weight, with respect to the total weight of the particulate mineral. The bulk chemical composition of the particulate mineral may have a magnesium content within 5% of the magnesium content of the surface of the particulate mineral, and/or the particulate mineral may have a steepness value ranging from about 20 to about 80.