Primos Chemical Co. Vanadium Mine - San Miguel Co., CO  Photo: www.miningartifacts.org
At the beginning of the 20th century, the USA was the largest producer of radium. Uranium mining was concentrated in the mineral deposits called the Uravan belt. This is the area with uranium-vanadium deposits in San Miguel, Montrose and Mesa counties, Colorado and Grand County, Utah .
Uranium mining in Colorado started in 1898 when a miner dug up 10 ton of yellow ore which contained much uranium and vanadium. The ore was sent to France for testing, and M.C. Friedel and E. Cumange found a new mineral which they named Carnotite. Mainly vanadium was then extracted from this mineral for the steel industry, while uranium was at first a by-product.
Three years before, in 1889 Pierre and Marie Curie discovered the element radium in the mineral pitchblende (uranium oxide). In the tests in 1898 it was not discovered that also carnotite contained radium. In 1903, the suspicion arose that radium was present due to the unusually high radioactivity of the ore. In 1911, the laboratory of Marie Curie in Paris confirmed that carnotite contained a low concentration of radium. Because of the high demand for medical radium, the price rose rapidly to 100 US$ per milligram, making the radium in the carnotite ore more valuable that the vanadium or uranium. A rush on the mining area in the Uravan Belt followed. In 1913, the Standard Chemical Company opened a radium factory which became the largest producer in the world.
In 1921 Marie Curie visits the Radium factory in Canonsburg 
In the photo, Marie Curie is discussing with the factory director and the president of the Standard Chemical Company. During her visit to the USA, she is also received by President Harding who makes a donation of one gram of radium from the Canonsburg factory. The value of this radium was 100,000 US $.
Between 1910 and 1922, half of all the radium mined in the world came from the Uravan Belt in Colorado and Utah. The mines in this area were quickly closed however, when the price of radium fell due to cheaper production in the Belgian colony of Congo in West Africa, where a richer deposit of pitchblende had been found.