The mechanism of CaCO 3 growth inhibition by additive Ca 2+ ions can be explained with changes in BET specific surface area (SSA) of the particles. As shown in Figure , increasing the concentration of additive Ca 2+ ions increases the BET SSA for all C P when β = 1. Each data point presented in Figure has a corresponding SEM micrograph in Figure . For each condition of C P in Figure , the SSA increased by a factor of ∼2.5 when C S increased from 5 to 15 mM. This suggests the particles become more porous as C S is increased. A close examination of the micrographs reveal the presence of pits and/or pores on the calcite particles.