Uranium in the environment resulting in workers exposed to high levels of radiation. Conventional uranium ore treatment mills create radioactive waste in the form of tailings, which contain uranium, radium, and polonium. Consequently, uranium mining results in "the unavoidable radioactive contamination of the environment by solid, liquid and gaseous wastes". Inhalation of radon gas caused sharp increases in lung cancers among underground uranium miners employed in the 1940s and 1950s. In the 1940s and 1950s, uranium mill tailings were released with impunity into water sources, and the radium leached from these tailings contaminated thousands of miles of the Colorado River system. Between 1966 and
Uranium mining in Colorado granite. Although the zinc skarn and the pitchblende vein are exposed in the same workings, the pitchblende appears to have been deposited much later. Other vein-type uranium mines in the Front Range were the Fairday A. M. mine near Jamestown in Boulder County, and the Wright Lease mine near Ideledale in Jefferson County. The 70 mile long Uravan mineral belt is an arcuate zone of uranium-vanadium deposits in San Miguel, Montrose, and Mesa counties, Colorado, and Grand County, Utah. It was the area most productive of uranium in the United States in the early 20th century. The mineral belt includes