Report discussing the identification of hydrothermal uranothorite from fluorite breccias in Colorado and its comparison/contrasting with other uranothorites and thorites. A description of thorium halos in fluorite is given.

This report discusses the results of an exploration made for uranium sources at the Caribou Mine in Boulder County, Colorado.

A report regarding the geology and uranium deposits of the Caribou Area, in Bouler County, Colorado. This report concerns work done on behalf of the Division of Raw Materials of the U.S. Atomic Energy Commission.

Abstract: Several radioactive deposits were found as a result of reconnaissance in the Gold Hill mining area, Boulder County, Colo. The ore deposits of the area have been worked chiefly for gold. All ore shipped has come from fissure veins, most of which are gold telluride veins. There are, however, some important sulfide veins which show a vague zonal distribution of pyritic gold ores and silverlead ores. The results of this reconnaissance suggest a possible relationship of the radioactive deposits to this indistinct sulfide zoning; however, the zoning is so obscure that its practical application to prospecting for uranium is of doubtful value at the present time. Pitchblende, torbernite, metatorbernite, and schroeckingerite have been identified in specimens from the area; however, no uranium minerals have yet been identified from most of the radioactive deposits, and the uraniferous material present is probably in disseminated small particles. Although selected samples from several localities assay 0.10 percent uranium or more, the known deposits are small and probably are not of immediate economic importance