Sample records for melanovanadite

  1. Duttonite, a new quadrivalent vanadium oxide from the Peanut mine, Montrose County, Colorado (United States)

    Thompson, Mary Eleanor; Roach, Carl Houston; Meyrowitz, Robert


    Duttonite, a new quadrivalent vanadium oxide from the Peanut mine, Montrose County, Colo., has the formula VO(OH)2. The mineral occurs as crusts and coatings of pale-brown transparent platy crystals, as one of the first oxidation products of montroseite ore. It is associated with melanovanadite and abundant crystals of hexagonal native selenium. Duttonite is biaxial positive, 2V is about 60°, dispersion is r v, moderate; X = a, pale pinkish brown; Y = c, pale yellow-brown; Z = b, pale brown; α = 1.810 ± 0.003, β = 1.900 ± 0.003, γ > 2.01. The hardness is about 2.5; the calculated specific gravity is 3.24. The chemical analysis shows, in percent: V2o3 2.6, V2O4 75.3, FeO 0.4, H2O 18.1, insoluble 4.2, total 100.6. Duttonite is monoclinic, ao = 8.80 ± 0.02A, bo - 3.95 ± 0.01A, co - 5.96 ± 0.02A, β = 90°401 ± 51. The space group is I2/c, (C62h); the cell contents are 4[VO(OH)2]. The crystals are strongly pseudo-orthorhombic, and the structure departs only slightly from the space group Imcm. Duttonite is named for Captain Clarence Edward Dutton (1841-1912). A detailed study of the geology, geochemistry, and mineralogy of the vanadium-uranium ore at the Peanut mine, Montrose County, Colo., was begun early in 1954 by Carl H. Roach of the U. S. Geological Survey. A number of rare and new minerals were found in the ore and the study of these samples was undertaken by Mary E. Thompson. Duttonite is the first new vanadium mineral to be described from the Peanut mine. It is named for Captain Clarence Edward Dutton (1841-1912), who was one of the first geologists to work in the Colorado Plateau region and who was a member of the U. s. Geological Survey from 1879-91. We are indebted to the following members of the Geological Surbey: K. E. Valentine for spectrographic analyses of duttonite, and M. E. Mrose and H. T. Evans, Jr., for measurement of the unit cell constants. This work is part of a program being conducted by the U. S. Geological Survey on behalf of the

  2. Summary of the mineralogy of the Colorado Plateau uranium ores (United States)

    Weeks, Alice D.; Coleman, Robert Griffin; Thompson, Mary E.


    In the Colorado Plateau uranium has been produced chiefly from very shallow mines in carnotite ores (oxidized vanadiferous uranium ores) until recent deeper mining penetrated black unoxidized ores in water-saturated rocks and extensive exploration has discovered many deposits of low to nonvanadiferous ores. The uranium ores include a wide range from highly vanadiferous and from as much as one percent to a trace of copper, and contain a small amount of iron and traces of lead, zinc, molybdenum, cobalt, nickel, silver, manganese, and other metals. Recent investigation indicates that the carnotite ores have been derived by progressive oxidation of primary (unoxidized) black ores that contain low-valent uranium and vanadium oxides and silicates. The uranium minerals, uraninite and coffinite, are associated with coalified wood or other carbonaceous material. The vanadium minerals, chiefly montroseite, roscoelite, and other vanadium silicates, occur in the interstices of the sandstone and in siltstone and clay pellets as well as associated with fossil wood. Calcite, dolomite, barite and minor amounts of sulfides, arsenides, and selenides occur in the unoxidized ore. Partially oxidized vanadiferous ore is blue black, purplish brown, or greenish black in contrast to the black or dark gray unoxidized ore. Vanadium combines with uranium to form rauvite. The excess vanadium is present in corvusite, fernandinite, melanovanadite and many other quadrivalent and quinquevalent vanadium minerals as well as in vanadium silicates. Pyrite and part or all of the calcite are replaced by iron oxides and gypsum. In oxidized vanadiferous uranium ores the uranium is fixed in the relatively insoluble minerals carnotite and tyuyamunite, and the excess vanadium commonly combines with one or more of the following: calcium, sodium, potassium, magnesium, aluminum, iron, copper, manganese, or barium, or rarely it forms the hydrated pentoxide. The relatively stable vanadium silicates are little