This data matrix contains the codebook vectors for a 82 x 50 neuron Emergent Self-Organizing Map which describes the multivariate topology of reservoir temperature and geochemical data for 190 samples of produced and geothermal waters from across the United States. Variables included are coordinates derived from reservoir temperature and concentration of Sc, Nd, Pr, Tb, Lu, Gd, Tm, Ce, Yb, Sm, Ho, Er, Eu, Dy, F, alkalinity as bicarbonate, Si, B, Br, Li, Ba, Sr, sulfate, H (derived from pH), K, Mg, Ca, Cl, and Na converted to units of proportion. The concentration data were converted to isometric log-ratio coordinates (following Hron et al., 2010), where the first ratio is Sc serving as the denominator to the geometric mean of all of the remaining elements (Nd to Na), the second ratio is Nd serving as the denominator by the geometric mean of all of the remaining elements (Pr to Na), and so on, until the final ratio is Na to Cl. Both the temperature and log-ratio coordinates of the concentration data were normalized to a mean of zero and a sample standard deviation of one. The original source data all come from the U.S. Department of Energy Resources Geothermal Data Repository and are detailed in Engle (2018).