The Rainy Day mine in the Circle Cliffs area, Utah, is developed on a long slender pod of uranium ore. Ore is localized in siltstone of i the Moenkopi formation of Triassic age, on the south edge of a channel about 3*300 feet wide "by ko feet deep that is filled with sandstone of the Shinarump member of the Chinle formation of Triassic age. Shale of the Chinle rests directly on siltstone of the Moenkopi on either side of thfe channel. The pod of ore is of moderately high grade, measures if by k

more »

... feet in cross section, and is continuous for a mined distance of more than 1,800 feet. Sphalerite, chalcopyrite, pyrite, marcasite, and galena are associated with a black uranium mineral, which is probably uraninite. Semiquantitative spectrographic analyses show that lead, copper, nickel, cobalt, silver, molybdenum, zinc, yttrium, and ytterbium increase proportionately with uranium; the increase suggests that -these metals were introduced by the ore-forming fluid. 'T'he deposit is on the east Hank of the northwest-trending Circle Cliffs anticline. No major faults are near the mine, nor were any through-going joints noted in the deposit. Efforts to correlate the localization of the deposit with minor structures were unsuccessful.