Abstract: Radioactive zones are present in the upper silty part of the pre-Cambrian Dripping Spring quartzite at the Red Bluff prospect, Gila County, Ariz. The prospect is in the SE 1/4 sec. 31, T. 5 N., R. 14 E., at the southern end of the Sierra Ancha area and 12 miles northeast of Roosevelt Dam. Stratigraphic control of the radioactive zones is indicated by the restriction of the zones to two layers, each about 20 feet thick.The zones are spatially associated in part with a diabase dike that occupies a fault, and in part with a thick diabase sill. The main uranium mineral disseminated through the rock in these zones has not been identified definitely, although minor quantities of secondary uranium minerals were observed. The results of scintillometer traverses and radiometric analyses indicate that the deposits probably contain an average of 0.026 percent uranium. Some black streaks and some fractures contain a higher percentage of uranium, but so far as is known the volume of such material is probably too small to affect the overall grade of the deposits.

Report discussing a reconnaissance study performed in September and October 1954 of the Bisbee district in Cochise County, Arizona. The purpose of the study was to determine the area's suitability for a detailed study of the relation between uranium and hypogene mineral zoning.