Arizona Breccia Pipe Uranium Mineralization - Geology

Geology

Collapse breccia pipes are vertical cylindrical bodies of broken sedimentary rock (breccia), down-dropped into caverns in underlying massive limestone. Uraninite, a reduced uranium ore mineral, accumulated within the permeable column of broken rock, forming a cylindrical and vertical (and stationary) rather than tabular and sub-horizontal (and migrating) uranium roll front deposit. Apparent mineralizing fluid flow direction was upward. As in roll front deposits, disseminated and massive sulfides are found on the downstream side of breccia pipe uranium accumulations (above the breccia pipe uranium ore).

The surface disturbance of collapse breccia pipe uranium mining has historically been remarkably small because of the high-grade, compact nature of the mineralization and use of underground waste rock back-fill procedures during breccia pipe mine development work. See Figures 6 through 9 of http://www.libertystaruranium.com/sub.asp?sub_id=36&section_id=8 for photographs of reclaimed breccia pipe uranium mine sites. The same reference written by Dr. Karen Wenrich states, “Although these uranium grades are dwarfed by those of the Athabasca Basin unconformity deposits in Canada, it is significant that (1) the breccia pipe mining costs are significantly less for the Arizona deposits, and (2) these ore grades of 0.4-1% are as high or higher than any other global uranium-deposit type.”