FIG. 20. Temporal evolution of palladium mineralization at the southern Roby and Twilight zones, Lac des Iles mine. The concentrations of MgO (wt %) and Pd (ppb) are shown by box-whisker plots where a box is defined by the 1^st and 3^rd quartile values. The total ranges of values are shown as lines and the median values of rock types are connected by the thick line. Note the increased MgO and Pd concentrations associated with the sulfide-bearing melanocratic rocks. The numbers on the left side of the diagram correspond to the rock types: 1a = leucogabbro and/or anorthosite, 1b = varitextured gabbro, 1c = medium-grained light gray gabbro, 1d = medium-grained gabbro, 2a = matrix of melanogabbro breccia, 2b = clinopyroxenite, 2c = dark gabbro, 3a = late clinopyroxenite, and 3b = late gabbro.