We report results from experiments on the evaporative chemical evolution of synthetic J13 water, representative of water from well J13, a common reference water in the Yucca Mountain Project. Data include anion and cation analysis and qualitative mineral identification for a series of open system experiments, with and without crushed tuff present, conducted at sub-boiling temperatures. Ca and Mg precipitated readily as carbonates and anions Cl, F, NO{sub 3} and SO{sub 4} remained in solution in nearly identical ratios. The pH stabilized at about 10. After {approx} 1000x concentration, the minerals formed were amorphous silica, aragonite and calcite. The presence of tuff appears to have very little effect on the relative distribution of the anions in solution, except for possibly F, which had a relatively lower concentration ratio. The Si was lower in the solutions with tuff present suggesting that the tuff enhances SiO{sub 2} precipitation. Even though the tools to model highly-concentrated salt solutions are limited, we compare our experimental results with the results of geochemical models, with (perhaps) surprising good results. In response to different assumed CO{sub 2} levels, pH varied, but anion concentrations were not greatly affected.