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The radioactive decay of uranium was first discovered by Antoine Henri Becquerel in 1896. The Paris physician accidentally discovered that photographic plates wrapped in dark paper were blackened by invisible radiation was capable of discharging an electroscope. In 1898, a France couple, Marie and Pierre Curie, discovered the radioactive elements radium and polonium. Marie Curie also discovered the radioactive element thorium..

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A sneak peek into some of the rarest elements on Earth. Some elements only have less than 50g of it on this planet at one given time!