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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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