Uranium had no large scale application in the late 19th century and therefore no large uranium mines existed.
In the beginning the only large source for uranium ore was the silver mines in Jáchymov, Austria-Hungary (now Czech Republic).
The uranium ore was only a byproduct of the mining activities.

In the first extraction of radium, Curie used the residues after extraction of uranium from pitchblende.
The uranium had been extracted by dissolution in sulfuric acid leaving radium sulfate, which is similar to barium sulfate but even less soluble in the residues.
The residues also contained rather substantial amounts of barium sulfate which thus acted as a carrier for the radium sulfate.
The first steps of the radium extraction process involved boiling with sodium hydroxide, followed by hydrochloric acid treatment to minimize impurities of other compounds.
The remaining residue was then treated with sodium carbonate to convert the barium sulfate into barium carbonate (carrying the radium), thus making it soluble in hydrochloric acid.
After dissolution, the barium and radium were reprecipitated as sulfates; this was then repeated to further purify the mixed sulfate.
Some impurities that form insoluble sulfides were removed by treating the chloride solution with hydrogen sulfide, followed by filtering.
When the mixed sulfates were pure enough, they were once more converted to mixed chlorides; barium and radium thereafter were separated by fractional crystallisation while monitoring the progress using a spectroscope (radium gives characteristic red lines in contrast to the green barium lines), and the electroscope.

After the isolation of radium by Marie and Pierre Curie from uranium ore from Joachimsthal, several scientists started to isolate radium in small quantities.
Later, small companies purchased mine tailings from Joachimsthal mines and started isolating radium.
In 1904, the Austrian government nationalised the mines and stopped exporting raw ore.
For some time radium availability was low.

The formation of an Austrian monopoly and the strong urge of other countries to have access to radium led to a worldwide search for uranium ores.
The United States took over as leading producer in the early 1910s.
The Carnotite sands in Colorado provide some of the element, but richer ores are found in the Congo and the area of the Great Bear Lake and the Great Slave Lake of northwestern Canada.
Neither of the deposits is mined for radium but the uranium content makes mining profitable.

The Curies' process was still used for industrial radium extraction in 1940, but mixed bromides were then used for the fractionation.
If the barium content of the uranium ore is not high enough it is easy to add some to carry the radium.
These processes were applied to high grade uranium ores but may not work well with low grade ores.

Small amounts of radium were still extracted from uranium ore by this method of mixed precipitation and ion exchange as late as the 1990s, but today they are extracted only from spent nuclear fuel.
In 1954, the total worldwide supply of purified radium amounted to about 5 pounds (2.3 kg) and it is still in this range today, while the annual production of pure radium compounds is only about 100 g in total today.
The chief radium-producing countries are Belgium, Canada, the Czech Republic, Slovakia, the United Kingdom, and Russia.
The amounts of radium produced were and are always relatively small; for example, in 1918, 13.6 g of radium were produced in the United States.
The metal is isolated by reducing radium oxide with aluminium metal in a vacuum at 1200 °C.
Uranium had no large scale application in the late 19th century and therefore no large uranium mines existed. In the beginning the only large source for uranium ore was the silver mines in Jáchymov, Austria-Hungary (now Czech Republic). The uranium ore was only a byproduct of the mining activities.
In the first extraction of radium, Curie used the residues after extraction of uranium from pitchblende. The uranium had been extracted by dissolution in sulfuric acid leaving radium sulfate, which is similar to barium sulfate but even less soluble in the residues. The residues also contained rather substantial amounts of barium sulfate which thus acted as a carrier for the radium sulfate. The first steps of the radium extraction process involved boiling with sodium hydroxide, followed by hydrochloric acid treatment to minimize impurities of other compounds. The remaining residue was then treated with sodium carbonate to convert the barium sulfate into barium carbonate (carrying the radium), thus making it soluble in hydrochloric acid. After dissolution, the barium and radium were reprecipitated as sulfates; this was then repeated to further purify the mixed sulfate. Some impurities that form insoluble sulfides were removed by treating the chloride solution with hydrogen sulfide, followed by filtering. When the mixed sulfates were pure enough, they were once more converted to mixed chlorides; barium and radium thereafter were separated by fractional crystallisation while monitoring the progress using a spectroscope (radium gives characteristic red lines in contrast to the green barium lines), and the electroscope.
After the isolation of radium by Marie and Pierre Curie from uranium ore from Joachimsthal, several scientists started to isolate radium in small quantities. Later, small companies purchased mine tailings from Joachimsthal mines and started isolating radium. In 1904, the Austrian government nationalised the mines and stopped exporting raw ore. For some time radium availability was low.
The formation of an Austrian monopoly and the strong urge of other countries to have access to radium led to a worldwide search for uranium ores. The United States took over as leading producer in the early 1910s. The Carnotite sands in Colorado provide some of the element, but richer ores are found in the Congo and the area of the Great Bear Lake and the Great Slave Lake of northwestern Canada. Neither of the deposits is mined for radium but the uranium content makes mining profitable.
The Curies' process was still used for industrial radium extraction in 1940, but mixed bromides were then used for the fractionation. If the barium content of the uranium ore is not high enough it is easy to add some to carry the radium. These processes were applied to high grade uranium ores but may not work well with low grade ores.
Small amounts of radium were still extracted from uranium ore by this method of mixed precipitation and ion exchange as late as the 1990s, but today they are extracted only from spent nuclear fuel. In 1954, the total worldwide supply of purified radium amounted to about 5 pounds (2.3 kg) and it is still in this range today, while the annual production of pure radium compounds is only about 100 g in total today. The chief radium-producing countries are Belgium, Canada, the Czech Republic, Slovakia, the United Kingdom, and Russia. The amounts of radium produced were and are always relatively small; for example, in 1918, 13.6 g of radium were produced in the United States. The metal is isolated by reducing radium oxide with aluminium metal in a vacuum at 1200 °C.
Radium