Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample in Jáchymov.
While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive.
In July 1898 while studying pitchblende they isolated an element similar to bismuth which turned out to be polonium.
They then isolated a radioactive mixture consisting mostly of two components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before.
The Curies found the radioactive compounds to be very similar to the barium compounds, except that they were less soluble.
This made it possible for the Curies to isolate the radioactive compounds and discover a new element in them.
The Curies announced their discovery to the French Academy of Sciences on 26 December 1898.
The naming of radium dates to about 1899, from the French word radium, formed in Modern Latin from radius (ray): this was in recognition of radium's power of emitting energy in the form of rays.

On September 1910, Marie Curie and André-Louis Debierne announced that they had isolated radium as a pure metal through the electrolysis of a pure radium chloride (RaCl₂) solution using a mercury cathode, producing a radium–mercury amalgam.
This amalgam was then heated in an atmosphere of hydrogen gas to remove the mercury, leaving pure radium metal.
Later that same year, E. Eoler isolated radium by thermal decomposition of its azide, Ra(N₃)₂. Radium metal was first industrially produced in the beginning of the 20th century by Biraco, a subsidiary company of Union Minière du Haut Katanga (UMHK) in its Olen plant in Belgium.

The common historical unit for radioactivity, the curie, is based on the radioactivity of ²²⁶Ra.
Radium was discovered by Marie Sklodowska-Curie and her husband Pierre Curie on 21 December 1898, in a uraninite (pitchblende) sample in Jáchymov. While studying the mineral earlier, the Curies removed uranium from it and found that the remaining material was still radioactive. In July 1898 while studying pitchblende they isolated an element similar to bismuth which turned out to be polonium. They then isolated a radioactive mixture consisting mostly of two components: compounds of barium, which gave a brilliant green flame color, and unknown radioactive compounds which gave carmine spectral lines that had never been documented before. The Curies found the radioactive compounds to be very similar to the barium compounds, except that they were less soluble. This made it possible for the Curies to isolate the radioactive compounds and discover a new element in them. The Curies announced their discovery to the French Academy of Sciences on 26 December 1898. The naming of radium dates to about 1899, from the French word radium, formed in Modern Latin from radius (ray): this was in recognition of radium's power of emitting energy in the form of rays.
On September 1910, Marie Curie and André-Louis Debierne announced that they had isolated radium as a pure metal through the electrolysis of a pure radium chloride (RaCl₂) solution using a mercury cathode, producing a radium–mercury amalgam. This amalgam was then heated in an atmosphere of hydrogen gas to remove the mercury, leaving pure radium metal. Later that same year, E. Eoler isolated radium by thermal decomposition of its azide, Ra(N₃)₂. Radium metal was first industrially produced in the beginning of the 20th century by Biraco, a subsidiary company of Union Minière du Haut Katanga (UMHK) in its Olen plant in Belgium.
The common historical unit for radioactivity, the curie, is based on the radioactivity of ²²⁶Ra.
Radium