The Last Found in Nature, Named for France

Francium closed the era in which new elements were still being found occurring naturally; every element discovered afterwards was made in the laboratory. Perey, who had begun as Marie Curie's laboratory assistant and rose to become a distinguished scientist and the first woman elected to the French Academy of Sciences, named the element in patriotic tribute to France. So unstable is francium that no more than a few tens of grams are thought to exist in the entire crust of the Earth at any instant, and a visible sample has never been gathered.

The element has no ancient, mythological or alchemical association, being a twentieth-century discovery; its human interest lies in its discoverer's remarkable career and in its distinction as nature's final gift to the periodic table. Perey did not receive a doctorate for the very discovery that made her famous until 1946, seven years after her initial 1939 identification of francium, a delay that reflected the limited institutional recognition then available to a laboratory assistant without a formal science degree, and her election to the Academie des Sciences in 1962 came only after decades further of published research on francium's properties and on radioactivity more broadly.