HOW DID OSMIUM-187 GET INTO TERRESTRIAL MOLYBDENITES?
When attacking Re-Os dating, Woodmorappe ignores another critical issue. How did 187Re rapidly decay to 187Os in rocks whose mineralogy and chemistry indicate that they were NEVER hotter than 1000C? Although Re and Os have similar chemical properties, Re tends to concentrate more in crystallizing molybdenite (MoS2) ores than Os (Dalrymple, 1991, p. 98; also see Pearson et al., 1995, p. 959). Grain relationships and other textural and chemical data clearly indicate that molybdenites grow in igneous or hydrothermal rocks (for example, Jebrak and Doucet, 2002). For example, the following photograph shows silvery molybdenite crystals embedded in a pegmatite. The coarseness of the crystals indicates that they grew deep within the Earth and were not the product of molybdenite falling from the sky and into lava pools. Typical intimate cross-cutting relationships between molybdenites and surrounding minerals are discussed at this website. In another photograph, molybdenite crystals are embedde
