The Whirlwind and other Beaver Mesa District uranium-vanadium deposits are typical of the Uravan Mineral Belt type. The Uravan Mineral Belt was defined as a curved, elongated area in southwestern Colorado where the uranium vanadium deposits in the Salt Wash Member of the Morrison Formation generally have closer spacing, larger size, and higher grade than those in adjacent areas and in the region as a whole (Fischer and Hilpert, 1952). The location and shape of mineralized deposits is largely controlled by the permeability and primary structures of the host sandstones (Cater, 1955). Most mineralization is in trends where Top Rim sandstones are thick, usually 40 feet or greater.

Most of the Mineral Belt area consists of oxidized sediments of the Morrison Formation, exhibiting red, hematite-rich rocks. Individual deposits are localized in areas of reduced, gray sandstone and gray or green mudstone. The Morrison sediments accumulated as oxidized detritus in the fluvial environment. However, there were isolated environments where reduced conditions existed, such as oxbow lakes and carbon-rich point bars. During early burial and diagenesis, the through-flowing ground water within the large, saturated pile of Salt Wash and Brushy Basin material remained oxidized, thereby transporting uranium in solution. When the uranium-rich waters encountered the zones of trapped reduced waters, the uranium precipitated at or near this interface. Vanadium may have been leached from the detrital iron-titanium mineral grains and subsequently deposited along with or prior to the uranium, similarly by reduction.

The exposed, remnant areas of mineralization in the old mines that have been examined show habits typical of the Uravan Mineral Belt deposits. Where the sandstone has thin, flat beds, the mineralization is usually tabular. In the more massive sandstone sections, it rolls across the bedding, reflecting the mixing of two waters and redox reactions at their boundary. This accounts for the fact that there are several horizons within the Top Rim that are mineralized. Very thin clay layers on cross beds appear to have retarded ground water flow which enhanced uranium precipitation. The beds immediately above ore horizons sometimes contain abundant carbonized plant material and green or gray clay galls. The mudstone beds adjacent to mineralized sandstone are reduced, but can grade to oxidized within a few feet. The deposits exposed in the limited workings of the Whirlwind Mine show these same characteristics. There are no significant differences between mineral depositional habits in the Top Rim and those in the Middle Rim sands.

The uranium and vanadium bearing minerals occur as fine grained coatings on the detrital grains, they fill pore spaces between the sand grains, and they replace carbonaceous material and some detrital grains.

The primary uranium mineral is uraninite (pitchblende) (UO2) with minor amounts of coffinite (USiO4OH). Montroseite (VOOH) is the primary vanadium mineral, along with vanadium clays and hydromica. Traces of metallic sulfides occur. In outcrops and shallow oxidized areas of the older mines, the weathered minerals now exposed are the calcium and potassium uranyl vanadates, tyuyamunite and carnotite.

The remnant deposits in the ribs and pillars of the old mines show a variety of oxidized minerals common in the Mineral Belt. These brightly-colored minerals result from the moist-air oxidation of the primary minerals. Minerals from several oxidation stages are seen in the Packrat Mine, including corvusite, rauvite, and pascoite. Undoubtedly, the excess vanadium forms other vanadium oxides depending on the availability of other cations and the pH of the oxidizing environment (Weeks et al., 1959). Exposures in the Whirlwind rarely show the colorful oxides because it was standing full of water until recently.

Some stopes in old mines are over 1,000 feet long and several hundred feet wide. More often they are 400-600 feet long and 100-200 feet wide. The Indicated Mineral Resources of the Whirlwind Mine are of similar size. Individual mineralized beds vary in thickness from several inches up to 4-5 feet. Locally, two or more mineralized horizons separated by thin waste layers will make a thick mineable zone of 15-18 feet.

Mining will be conducted by conventional rubbertired underground drill-blast-muck methods in a random room-and-pillar configuration (reflecting the geometry of the deposit as found during mining).

Samples of mineralized material were collected from the pillars and ribs of the Packrat Mine before the Whirlwind was dewatered. These were used along with samples from other mines in the region for preliminary testing of amenability to the proposed Pinon Ridge Mill leaching conditions. The samples were analyzed by J. E. Litz & Associates in October 2008 for grinding properties and process chemical consumption. Samples were ground to minus 28-mesh and leached for 24 hours at 85oC under strong sulfuric acid and oxidizing conditions. Leach tests of the Packrat samples showed U3O8 to be soluble up to 99.3% and V2O5 to be soluble up to 94.5% on a sample with head grades of 0.527% U3O8 and 2.11% V2O5. Settling tests were performed on leach slurries. A simulated raffinate was prepared and neutralized to 4.5 and 7.5 pH to determine the deportment of the soluble ions. These results and the historic milling of district ores suggest at this point that the Whirlwind deposit will present no unforeseen problems with either metallurgical testing or processing.