Geology of carnotite-bearing sandstone in the Uravan and Gateway districts, Montrose and Mesa counties, Colorado, and Grand County, Utah

Most of the caraotite deposits in the Uravan and Gateway mining districts ate in the persistent upper sandstone stratum of the Salt Wash sandstone member of the Morrison formation, Areas In which this stratum is predominantly lenticular have been delimited from areas in which this stratum is predominantly nonlenticularar. Ground most favorable for carnotite deposits is in areas of lenticular sandstone where the stratum is underlain by green-gray altered mudstone.
Ore is localized in scour-and-fill bedded sandstones within favorable areas of lenticular sandstone. Regional control of the movement of ore-bearing solutions in the persistent ore-bearing sandstone stratum is indicated by; 1. A concave arcuate belt of partly altered mudstone transitional between areas of unaltered
mudstone to the west and areas of altered mudstone to the east; 2. An increase in size, grade, and number of ore deposits from areas of partly altered to altered mudstone.