Natural occurrence of lanthanides, actinides, and superheavy elements
Natural occurrence of lanthanides, actinides, and superheavy elements While it is possible to synthesize transuranium elements up to proton number of Z = 105, only a small success can be reported on naturally occurring transuranium nuclides. Only extremely small quantities of primordial plutonium- 244, the longest-llved transuranium nuclide, have been detected in the cerium- rich Californian mineral bastnaesite, which means that plutonium must be considered as a naturally occurring and not as an artificial element. Promethium- 147, plutonium-239, and neptunium-237, detected in several minerals and identified by ucts. No other transuranium nuclides and no superheavy elements could be found in terrestrial, lunar, and meteoritic probes. Investigations on the anomalous isotopic composition of uranium in ores from Oklo./Gabon led to a scientific sensation: a prehistoric natural nuclear reactor, working about 10/sup 9/ years ago, which showed much similarity in comparison with modern nuclear power reactors. (GE)
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