FIG. 15. A. Plot of Pd (ppm) vs. Ir/Pd for samples from the southern Roby, Twilight, and High-Grade zones compared to other PGE deposits. Note that the Lac des Iles data plots along the general trend of other orthomagmatic deposits. B. Plot of Pd (ppm) vs. Pt/Pd for rocks from the Lac des Iles deposit. Note that the majority of the melanocratic rocks show comparable Pt/Pd ratios, but samples from the High-Grade zone have higher Pd and therefore low Pt/Pd. The scatter is most likely due to a nugget effect of coarse-grained platinum group minerals. Data sources: Komatite-hosted deposits (Picard et al., 1995); Marathon deposit in the Coldwell Complex, Ontario (Good and Crocket, 1994); Duluth Complex (Theriault et al., 1997); J-M reef (J-M: Naldrett, 1981); Merensky reef, Bushveld Complex (M: Naldrett, 1981).