From pitchblende to polonium and radium

Pitchblende remained unusually active after uranium was removed. Marie and Pierre Curie followed that clue through repeated measurements and chemical separations. In July 1898, they reported a new substance they named polonium; in December, they and Gustave Bémont reported evidence for radium.

Identifying the elements was only an early step. Isolating radium in a form pure enough to study required years of processing large quantities of ore. Their work joined physical measurement with demanding chemical analysis.

Historical note: This is a modern summary of the research, not a text written by the Curies.