From introduction: A rapid appraisal of the carnotite resources of the Salt Wash sandstone member of the Morrison formation in the Carrizo Mountains area was undertaken by the U. S. Geological Survey late in 1951 in connection with its current project of geologic mapping of the area. Though brief and preliminary, this report provides a summary of production trends and estimated reserves in the area and indicates as far as possible the total potential of the area as a source of uranium. This information may be helpful in planning new milling facilities or other measures to encourage a higher rate of production.

Although uranium gas first discovered in the Carrizo Mountains area in 1918, the ores were not developed until 1942. They have, however, been mined continuously since that time. Formations in the area range from the Pernian Cutler through the Cretaceous Mancos shale, and all are intruded by a dioritic laccolith and its related dikes. The older structures, which include the Defiance Uplift, the San Juan Basin, and the Four Corners Platform are somewhat disrupted by the effects of the intrusion. A number of mines are described and mineralogical and geochemical studies made are outlined. The primary uranium mineral is unknown, but the chief uranium ore-mineral is the secondary mineral, tyuyamunite. It is concluded that there is at least minor structural control of the ore bodies along sedimentary trends and joints, and that all ore bodies of 500 tons or more are on the Defiance monocline or its extensions. The uranium may have been syngenetic in the sediments, and redistributed by solutions or, more likely, that it rose vertically in hydrothermal solutions from the local intrusive bodies.

From Purpose, Scope, and Methods: The objective of this study was an evaluation of resources of the Carrizo Mountains area. Four factors: distribution of ore bodies, relation of uranium to the host rock, relation of ore to structure, and circumstances that might precipitate uranium were studied in search of data bearing on manner of distribution of ore, the time and causes of deposition, and the probable source of the uranium-bearing solutions.

Report documenting work to map in detail the Roy Mesa and Enos Johnson claim areas so that ore guides could be determined and the areas could be evaluated for drilling and to complete a general reconnasaince of the favorable Mesozoic.

Discussing a uranium reconnaissance program undertaken to evaluate formations that were producing uranium and vanadium ore in the Sanastee area.