In high-temperature geochemistry and cosmochemistry, highly siderophile and strongly chalophile elements can be defined as strongly preferring metal or sulfide, respectively, relative to silicate or oxide phases. The highly siderophile elements (HSE) comprise Re, Os, Ir, Ru, Pt, Rh, Pd, and Au and are defined by their extreme partitioning (>104) into the metallic 

Распределение халькофильных элементов и элементов платиновой группы в ультраосновных породах комплекса Стиллуотер, Массачусетс, США - влияние на процессы обогащения слоев хромита Os, Ir, Ru и Rh

All of the rocks from the Ultramafic series of the Stillwater Complex are enriched in PGE relative to most mafic magmas. Furthermore, the chromite layers are particularly enriched in IPGE (Os, Ir, and Ru) and Rh. This enrichment appears to be a common characteristic of ultramafic rocks from many types of settings, layered intrusions, ophiolites, and zoned complexes.