Carbon mineralization is recognized as one of the safest and most permanent methods for storing anthropogenic CO2. Combining CO2 capture and storage eliminates energy-intensive sorbent regeneration and uncertainties associated with geological sequestration of CO2. Carbonation of Mg(OH)(2) in a gassolid system has been investigated, but both the reaction kinetics and the overall conversion were limited. Derived from silicate minerals or industrial wastes, a Mg(OH)(2) slurry can react with dissolved CO2 to form a variety of magnesium carbonate phases with differing amounts of hydroxide and crystallized H2O incorporated within the carbonate crystal. In this study, slurry-phase Mg(OH)(2) carbonation was investigated at moderate temperatures and CO2 pressures (up to 200 degrees C and 15 atm). Mg(OH)(2) carbonation in the slurry phase involved heterogeneous dissolution of Mg(OH)(2) and CO2, in addition to homogeneous precipitation of magnesium carbonates. The reaction conditions responsible for hydrated and anhydrous carbonate product phases were evaluated, and the carbonate formation kinetics were investigated. Solid and liquid analyses by TGA, XRD, ICP-OES, and carbon analysis allowed for qualitative and quantitative compositional characterizations of the reacted slurry samples. Reaction temperature was found to be the dominant parameter driving the formation of specific carbonate phases, although solution additives showed potential for bypassing the effects of temperature.