Radium
A radioactive alkaline earth metal with atomic number 88, discovered by Marie and Pierre Curie in pitchblende in 1898.
Marie Curie's notebooks remain in lead-lined boxes 90+ years after her death — still dangerously radioactive. Soaked in radium and polonium she handled bare-handed, readers must sign a waiver and wear protective gear. Radium's half-life is 1,600 years.
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