A Remarkable Discovery in Africa<\/strong><\/p>\n It began with the discovery of an anomaly in uranium ore from a mine near Oklo, Gabon. Perrin\u2019s team noticed that one sample of the material contained slightly less uranium-235 than would be expected in natural deposits.<\/p>\n The existing scientific information available to researchers at the time clearly detailed the constant ratio of radioactive uranium within ore. Yet the peculiar sample from the Oklo mine seemed to point to something else entirely.<\/p>\n \u201cThis cannot be possible,\u201d Perrin thought<\/a> at the time, pondering the odd discovery. Even a minuscule amount of missing uranium-235 seemed to indicate that some of the isotopes had been forced to divide, which, under modern conditions on Earth, can occur only one way: through a nuclear reaction<\/a>.<\/p>\n The implications were obvious, and meant one of two possibilities\u2014one of which was so remarkable that it, very much like the anomalous sample now in the possession of Perrin and his colleagues at a nuclear fuel processing plant in France, seemed impossible. Yet how could this be explained naturally, if all examples of natural uranium known to exist\u2014even those present on the lunar surface<\/a>, or in ancient meteorites<\/a>\u2014contain precisely 0.720% of this isotope?<\/p>\n Perrin and his colleagues were left to consider not only the possibility that the uranium ore had undergone artificial fission, but also how some natural version of the same process might work. With time and further analysis, the latter proved true, and Perrin and his team\u2019s conclusion revealed one of the most remarkable discoveries ever made in the natural world.<\/p>\n Fingerprints of Ancient Natural Fission<\/strong><\/p>\n In their findings, Perrin and his colleagues discovered evidence of fission products in the ore\u2014the veritable fingerprints of a natural sample of uranium ore that had undergone fission.<\/p>\n \u201cThere was no other explanation,\u201d said the noted French geologist Ludovic Ferri\u00e8re, curator of the meteorite collection and of the impactite collection at the Natural History Museum in Vienna, Austria, in a statement in 2019<\/a>.<\/p>\n \u201cAfter more studies, including on-site examinations,\u201d Ferri\u00e8re said, Perrin and his colleagues had proven that \u201cthe uranium ore had gone through fission on its own.\u201d But what did this all mean?<\/p>\n Fundamentally, the conditions required for this to occur meant that, at some point around two billion years ago, uranium deposits in western Africa near modern-day Gabon would have had to contain enough uranium-235 to achieve critical mass. Add to this another key component\u2014the presence of water<\/a>, which would have been needed as a cooling agent, slowing neutrons, allowing atom splitting to take place, and facilitating controlled fission.<\/p>\n Peter Woods, an Australian geoscientist who formerly led uranium production at the International Atomic Energy Agency (IAEA), compared the natural processes at Oklo two billion years ago to a modern, human-built light-water nuclear reactor.<\/p>\n \u201cThe water acted in Oklo as a moderator, absorbing the neutrons, controlling the chain reaction,\u201d said Woods, who is now an Environment Approvals Manager at OneSteel Mining in Adelaide, South Australia.<\/p>\n A Geological Enigma <\/strong><\/p>\n At the time the natural fission would have occurred, there would have been enough uranium to produce thick, large deposits that would have facilitated the process and preserved the ancient natural reactor. Having occurred once, it is possible that other natural reactors existed in various parts of the world under similar environmental conditions, although they were either destroyed over time or remain undiscovered.<\/p>\n \t\t
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Today, samples from the Oklo mine are preserved at the headquarters of the Orano renewable energy company in France and at Vienna\u2019s Natural History Museum. Standing within centimeters of one of the samples, the radiation emitted is comparable to the dose of cosmic radiation received by a passenger on an eight-hour flight.<\/p>\n For geologists like Ferri\u00e8re, studying ancient samples from Earth\u2019s geological past is comparable to reading a ledger detailing events from deep in the planet\u2019s prehistory.<\/p>\n \u201cRocks are like books,\u201d Ferri\u00e8re said in 2019. \u201cYou can look at the cover and get some basic information, but it\u2019s when you open them that you get the full story.\u201d<\/p>\n Woods also acknowledged the story the Oklo samples have managed to convey through time, calling it \u201cfascinating,\u201d and adding that the samples\u2014once an anomaly in the geological data\u2014are now understood as another example of nature\u2019s remarkable surprises.<\/p>\n \u201cThe detective story has been successfully solved,\u201d Woods said.<\/p>\n Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. A longtime reporter on science, defense, and technology with a focus on space and astronomy, he can be reached at<\/strong>\u00a0<\/strong>micah@thedebrief.org<\/strong><\/a>. Follow him on X\u00a0<\/strong>@MicahHanks<\/strong><\/a>, and at\u00a0<\/strong>micahhanks.com<\/strong><\/a>.<\/strong><\/p>\n \t\t\t\t\t\t\t\t\t![\"Oklo](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2026\/03\/Oklo.jpg\")
Above: Samples of deposits collected from the Oklo mine in Gabon, which were donated to Vienna\u2019s Natural History Museum in 2019 (Image Credit: Ludovic Ferri\u00e8re\/Natural History Museum\/IAEA)<\/p>\n![\"Ludovic](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2026\/03\/Ludovic-Ferriere.jpg\")
Ludovic Ferri\u00e8re, pictured in 2019 alongside Namibia\u2019s famous Hoba meteorite (Image Credit: Epigraphie12\/CC 4.0)<\/p>\n
\n\t\t\t\t![\"Galactic](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2026\/03\/composing-5126949_1280-120x120.jpg\")
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