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, a_o = 8.80 ± 0.02A, b_o - 3.95 ± 0.01A, c_o - 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 Division of Raw Materials of the U. S. Atomic Energy Commission.