Discovery of the Six Members of the Platinum Group and Their Mineralogical Characterization

The native platinum-group elements (PGE), namely, the light PGE (Ru, Rh, and Pd) and the heavy PGE (Os, Ir, and Pt), are important historically, scientifically, and industrially. The scientists who discovered and refined these metals in the 18th and early 19th centuries, besides being chemists, some were also physicians, but all were also knowledgeable of mineralogy. We cannot but be impressed by their achievements because of the complexity of the minerals they studied. The PGE alloys occurred as a fraction of the heavy minerals concentrated from alluvial deposits. Today we can understand why some details of their discovery and mineralogy have not been well understood because of a lack of modern mineralogical studies and misunderstandings of some of the early literature, especially for native palladium and platinum. Though reported widely, highlights of the historical discoveries are assembled in a single paper and discussed with respect to the mineralogy of the samples studied.