Mineral associations in the uranium deposits of the Colorado Plateau and adjacent regions: interim report

Abstract

This interim report describes the essential mineral associations in uranium deposits, most of which were examined by us during several field seasons. The listings of identifications and occurrences of the minerals make a comparison of the deposits and districts possible and profitable. The pattern of associations and parageneses shows the great similarity of the deposits, notwithstanding the preponderance of vanadium-bearing minerals in one category and sulfides in another. Most deposits listed are in the Shinarump (this includes such new designations as Mossback, Monitor Butte and others), and Chinle formations. In New Mexico the described deposits are in the Todilto and Morrison formations. "Black ores", that is unoxidized ones, have become very important lately. They contain uraninite--the term pitchblende being more or less synonymous with it should be dropped--and coffinite, a still problematic black mineral of uranium. The word "unoxidized" as used here is not synonymous with hydrothermal as some geologists interpret it. It simply means that carbonaceous matter and iron sulfides in the ore reduced the uranium or kept it reduced during deposition. This reduction could have occurred at any stage of geologic history regardless of whether uranium was of a syngenetic origin or was contributed by solutions of magmatic origin.