Carnotite resources of Club Mesa, Montrose County, Colorado

Abstract

Club Mesa is 1 mile west of Uravan, Montrose County, Colo. About 200,000 short tons of carnotite ore containing an estimated 0.45 percent U 3 O 8 and 2.1 percent V 2 O 5 has been mined from the mesa. This production represents about one-fifth of the carnotite ore mined from the Colorado Plateau. All the principal deposits on the mesa are in the main ore-bearing sandstone which is in the top part of the Salt Wash sandstone member of the Jurassic Morrison formation. The deposits are in tabular masses of uneven thickness lying more or less parallel to the enclosing strata. The ore consists mainly of sandstone impregnated with carnotite and vanadiferous clay minerals. The sandstone near the deposits is generally over 30 feet in thickness, contains noticeable quantities of carbon, and vivid patches of limonite (?) stain. Also near ore deposits, the mudstone in contact with the sandstone is altered from red to gray or green through a thickness of 3 or 4 feet. Certain linear features of the ore bodies and of favorable parts of the main ore-bearing sandstone offer clues by their orientation to extensions of known ore bodies and of favorable ground. These features on Club Mesa trend mostly east to northeast. Between March 6, 1948, and January 22, 1952, the U.S. Geological Survey drilled 651 holes for a total of 167,495 feet. As a result of this drilling, 18 deposits were discovered and partly outlined. These range in size from 200 to 55,000 short tons of indicated ore reserves and are in layers 1 foot or more thick containing 0.10 percent or more U 3 O 8 or 1.0 percent or more V 2 O 5 . About 85 percent of this ore is in public land; the remainder is in claims owned by the United States Vanadium Co. Reserves in deposits known from drill holes or exposures are classed as indicated or inferred, and those in deposits that are predicted solely on geologic evidence are classed as potential. The tons of indicated and inferred reserves and the pounds of contained U 3 O 8 and V 2 O 5 are summarized in table 1. These reserves are subdivided also by thickness and grade cutoffs. At the higher grade cutoff, reserve figures express approximately the tonnage and grade of material that might actually be mined from these deposits under 1951 conditions. Indicated and inferred reserves of this type total 198,000 short tons, averaging 0.35 percent U 3 O 8 and 1.8 percent V 2 O 5, and contain 1,1,372,000 pounds of U 3 O 8 and 7,260,000 pounds of V 2 O 5. These reserves are based on Geological Survey drilling. Potential reserves are predicted to total about 40,000 short tons, averaging about 0.35 percent U 3 O 8 and 1.9 percent V 2 O 5 . No additional exploration on Club Mesa is planned by the Geological Survey, but exploration by private companies is recommended.