The phase separation process changes as the solution concentration increases. This movie shows cluster formation and growth under three increasing concentration conditions. In dilute solution (low supersaturation) clusters grow in the presence of a free energy barrier (nucleation) and coarsen through single particle additions. At high supersaturation growth proceeds spontaneously (spinodal decomposition) and coarsening occurs mostly by cluster aggregation. This video relates to a paper that appeared in the 23 August, 2013, issue of Science, published by AAAS. The paper, by Adam F. Wallace at the Lawrence Berkeley National Laboratory in Berkeley, CA, and colleagues was titled, "Microscopic Evidence for Liquid-Liquid Separation in Supersaturated CaCO3 Solutions."