Originally, the work of Becquerel used pitchblende, a blackish colored ore containing uranium oxide or UO2. Pitchblende is rich in uranium, but much harder to find than other uranium bearing ores. As fate would have it, a French chemist by the name of Charles Poulot, who, unable to use a sample of ore from the mines of western Colorado for his copper chemistry experiments, gave it to his professor Charles Friedel. Friedel promptly determined it was an as yet unknown uranium and vanadium bearing ore. That ore is what we today know as carnotite.
The interesting thing about the name carnotite is no one really knows who gave it that name. Some authors claim it was Marie Curie herself, who on a trip to Colorado in 1899 named the ore after the French Inspector General of Mines, A. Carnot. Others say that it was in fact Charles Friedel, who after determining the ore was unnamed christened it carnotite after the same man. There is even a third story, where Marie Curie never visits Colorado, but names the ore carnotite after Monsieur Carnot anyways. Personally, I believe the third story is correct. In a 1921 article in the New York Times entitled "The Story of Radium," the writer never mentions that Curie visited Colorado during her trips to the United States.
Either way, carnotite was the name that stuck, and from 1898 until 1922 the radium business grew prosperous. In 1922, the Belgians discovered a large source of pitchblende in Belgian Congo (now the Democratic Republic of the Congo) and undercut their competition by selling radium at $70,000 (rather than upwards of $100,000) a gram. One of the radium mines in western Colorado that was shut down during this period was the Joe Junior Camp in western Montrose County. This site would sit dormant until 1936 when a subsidiary of Union Carbide, United States Vanadium (USV) would take over the town and rename it Uravan (uranium-vanadium). Uravan would in the ensuing decades become one of the centers of uranium mining and milling in the American West.