Uranium Town: Uravan, Colorado
The town of Uravan, Colorado, shows up on maps and road signs. You might think it is a physical town. It sits north of Naturita (pronounced natter reeta), CO, on Hwy 141 about 15 miles up the narrow San Miguel River valley. If you look at it’s Wikipedia page, you’ll see a picture of a bare area of ground. Today all that remains at the surface is a ball field and picnic tables. Every bit of the town and the mill has been demolished, shredded and buried within the confines of a Superfund site. Even contaminated bulldozer blades were buried on-site. Also remaining is a Umetco commercial building. Umetco, a Dow Chemical subsidiary, was responsible for managing the reclamation of the site which lasted from 1987 to 2007.
Main uranium deposits in the US (DoE Office of Legacy Management, 2015)
The local topography consists of sandstone canyons and mesas. The map below (north is up) shows a large area of land west of the valley mill site and up above on Club Mesa. This is the location of buried mill tailings and other contaminated materials. The major radiological contaminant is Radium-226 and its daughter products. Radium is a common and troublesome constituent in uranium-bearing ore.
As an aside, I would recommend taking Colorado Hwy 141 from Naturita north through Gateway enroute to Grand Junction if you’re in the area. Truthfully, Uravan isn’t along the route to somewhere most people would want to go except for locals. This stretch of road is called the Unaweep-Tabeguache Scenic Byway and is absolutely gorgeous. Just like in nearby Arches and Canyonlands National Parks, red sandstone is the dominant country rock in that part of the Colorado Plateau. You’ll drive through breathtaking canyons of red sandstone along the Dolores River, south of Gateway.
During its post-WWII heyday, the company town of Uravan, CO, was one of a number of thriving yellowcake boomtowns in Wyoming, Utah, Colorado, and New Mexico. Overall, there were over 900 uranium mines in operation. The name “Uravan” comes from the URAnium-VANadium ore that was processed there. Uravan was one cog in a large wheel of uranium production first for the Manhattan Project then for the Atomic Energy Commission..
Uravan produced concentrate which was was trucked to Grand Junction, CO, to the Climax Uranium Mill for further processing. Activity at the Climax site began in 1943 for uranium procurement and processing of vanadium mill tailings for uranium.
An excellent timeline of uranium history in western Colorado can be found at the Museums of Western Colorado web site.
Uravan Mineral Belt (Wikipedia)
The earliest mining activity at what became Uravan was for radium recovery beginning in 1912 and falling off by 1923. By 1935 the mill was expanded for vanadium recovery and from 1940 to 1984 the mill was used to process uranium and vanadium.
The predominant ore that was processed at Uravan was Carnotite with a nominal composition of K2(UO2)2(VO4)2·3H2O with variable waters of hydration. Elemental uranium is a dense silvery metal that oxidizes in air, reacts with water and dissolves in oxidizing acids. It has two important oxidation states: the +4 uranous oxidation state which is green and the +6 uranyl oxidation state, UO22+, which is yellow. The uranous form is found in the UO2 mineral Uraninite and the uranium silicate Coffinite. The uranyl vanadate form is found with potassium cation in Carnotite, with cesium in Margaritasite, and with calcium in Tyuyamunite.
Yellow carnotite ore (Colorado Geological Survey)
Uranium-vanadium rich sandstone is found in Club Mesa to the west and just above the town of Uravan. This occurrance is part of the larger Uravan Mineral Belt which encompasses local commercial grade uranium ore. The mesa covers 6 sq miles and is bounded by the San Miguel River, the Dolores River, Saucer Basin and Hieroglyphic Canyon. According to the United States Geological Survey (USGS), the average grade of the ore ranged from 0.25 to1.5 % U3O8 and 1.5 to 5.0 % V2O5 (ref 1).
From an extensive drilling study by the USGS, the Salt Wash member of the Morrison formation sandstone of the late Jurassic age was found to be the host for most of the commercial-grade (in 1957) uranium-vanadium in the Club Mesa area.
Beginning in 1936, the mill site was owned by US Vanadium Corporation and built up to process vanadium ore. An entire town was constructed on site to accommodate workers. It also produced a uranium oxide side-stream as a yellow pigment. Then along came the nuclear age.
References
(1) Results of US Geological Survey Exploration for Uranium-Vanadium Deposits in the Club Mesa Area, Uravan District, Montrose County, Colorado, Boardman, Litsey, and Bowers, May, 1957, Trace Elements Memorandum Report 979.