Mineral associations in the uranium deposits of the Colorado Plateau and adjacent regions with special emphasis on those in the Shinarump Formation. Part III, Annual report July 1, 1951, to June 30, 1952

Abstract

Part III of our Annual Report deals with the mineral associations in deposits most of which were actually visited by us during several field seasons. The very large number of specimens we collected has been studied in some detail though much remains to be done. The following pages list the identifications and occurrences in such a manner that a comparison of the deposits and districts becomes possible and profitable. A distinct pattern of associations and parageneses begins to emerge from the wealth of data. Most deposits listed are in the Shinarump formation. Lately there have been significant finds in the formations above the Todilto in New Mexico. These seem to have a somewhat different mineralization from the well-known deposits in the Salt Wash formation. For this reason they were studied when the deposits in the Todilto formation near Grants were examined. An inclusion of the uranium minerals found in them up to the present will help in giving us a more complete picture of the problems that still face all the workers in the field and laboratory. A word of caution may be in order with regard to "oxidized" and "unoxidized" deposits. The latter contain uraninite and a new black mineral which the United States Geological Survey has tentatively called coffinite (identified at the Denise #1 Claim, Bow Knot Area and Small Spot Mine near Uravan, Colorado, in this report). "Unoxidized" is not synonymous with "hydrothermal" as some geologists would like to believe. Carbonaceous matter or hydrocarbons are "unoxidized". They possess the power to reduce uranyl solutions or minerals to uranous ones, though obviously igneous activity has no part in this process. Reduction could have occurred at any stage of geologic history whenever uranyl ions reached this favorable environment.