Thursday, June 25, 2015

New report indicates massive increase in uranium potential in northwest Arizona

We released our new report yesterday “Partial database for breccia pipes and collapse features on the Colorado Plateau, northwestern Arizona” ( that found concentrations of breccia pipes 10 to 100 times higher than previously known, in two test study areas.  Breccia pipes are primary targets for uranium and other minerals.   We believe that same density of pipes extends across the entire region, which would make the area one of the largest and richest uranium districts in the world.  

I interviewed lead author Jon Spencer on our video magazine Arizona Mining Review which was webcast yesterday and is online at

We will be sharing this report with our congressional members to help them make informed decisions about the proposed Grand Canyon Watershed National Monument.

A 1989 USGS study mapped 1294 breccia pipes in the region.  Subsequent USGS maps and new investigations by AZGS identified at least 1,000 additional features in just two small study areas (outlined in red in map above).  It appears from this work that the number of likely breccia pipes is one to two orders of magnitude greater than previously recognized. The study raises the possibility that the higher concentration of breccia pipes extends across the entire region.

Mineralized breccia pipes—pipe-like masses of broken rock—may contain high-grade uranium ore and variable amounts of copper, gold, silver, vanadium and other mineral ore. More than 71 mineralized breccia pipes have been discovered in the region, and as of 2010, nine of these pipes yielded more than 10,500 metric tons of uranium.

Breccia pipes are vertical formations, typically a few tens to hundreds of feet across and hundreds to thousands of feet in vertical extent. The pipes formed more than 200 million years ago within Paleozoic and Triassic rocks over a broad area around Grand Canyon. The pipes formed as groundwater, flowing through Redwall Limestone dissolution breccias and along fracture zones, dissolved more limestone, causing collapse of overlying rocks and possibly creating sink holes.

This new map is accompanied by an Excel Workbook database with three datasets. The datasets are drawn from geologic maps produced by the U.S. Geological Survey and from mapping by geologic consultant and co-author Karen Wenrich. The datasets include point locations and comments on features identified as 1) breccia pipes, 2) collapse structures that might be breccia pipes, and 3) circular features that might be collapse features or breccia pipes.

Some features occur in more than one dataset, so the total number of features is less than the 3,286 features comprising the three datasets. GIS data as ArcGIS shapefiles built from the three datasets are included with this publication.

US Geological Survey geoscientists estimated that roughly 8% of breccia pipes contain some mineralization (Wenrich and Sutphin, 1988). A fraction of those are likely to host economic concentrations of minerals. 

In 2012, the U.S. Department of the Interior withdrew from mining 1,006,545 acres of federal lands in northern Arizona for a 20-year period to prevent further exploration or development of uranium on those lands. Withdrawal curtails new exploration of breccia pipes and limits production to those pipes with valid existing mineral rights.

Spencer J.E., Wenrich, K. and Cole, T., 2015, Partial database for breccia pipes and collapse features on the Colorado Plateau, northwestern Arizona. Arizona Geological Survey Digital Information, DI-42, 5 p., 1 map plate, shapefiles, and Excel Workbook.

Wenrich, K.J. and Sutphin, H.B., 1988, Recognition of Breccia Pipes in Northern Arizona. Arizona Bureau of Geology and Mineral Technology, Fieldnotes, v18, #1, p1-5.

1 comment:

  1. Lee, It was disappointing to see you quote the USGS citation of Wenrich and Sutphin, 1988 in your post regarding the 8% of breccia pipes as being mineralized and then a fraction of those being economical.

    This has been thoroughly disproven and shown to be entirely and grossly inaccurate. One need only analyze the Hack-Pinenut control area to see that this proposition is untrue.

    I will provide my analysis of this issue if you would consider posting on your blog.

    Truthfully, a several increase in magnitude of breccia pipes or possible pipes matters little if you apply the 8% cut and then a further cut for being economical.

    The Grand Canyon EIS stated that 85% the endowment calculated by Circular 1051 was low grade ore. Mathematically, this leads to the conclusion that all breccia pipes have a very large low grade ore body in the 900 to 1800 ft zone in the breccia pipe. There is no other conclusion that can be drawn. However, this conclusion finds no observed geologic support.