French chemist · 1874–1949
André-Louis Debierne
André-Louis Debierne discovered actinium in 1899, working on the same pitchblende residues that had given the Curies polonium and radium.
How Actinium was found
Debierne followed the radioactivity through the fractions of rare earths and iron separated from the ore and found a new active substance. He named it actinium, from the Greek aktis, “ray”.
Friedrich Giesel found the same element independently in 1902. Actinium gave its name to the actinide series that Seaborg proposed 45 years later.
Life and career
Born 1874 · Died 1949
Debierne was born in Paris and was a close collaborator and friend of the Curies. In 1910 he and Marie Curie isolated radium as a pure metal.
After Marie Curie’s death in 1934 he succeeded her as director of the Radium Institute’s laboratory.
Discovered in the same era
Other elements identified within ten years of 1899.