Journal of

GEOsciences

  (Formerly Journal of the Czech Geological Society)

Original paper

Travis A. Olds, Anthony R. Kampf, Samuel L. Perry, Xiaofeng Guo, Joe Marty, Timothy P. Rose, Peter C. Burns

Navrotskyite, K₂Na₁₀(UO₂)₃(SO₄)₉·2H₂O, a new sodium and potassium uranyl-sulfate mineral from the Blue Lizard mine, Red Canyon, White Canyon District, San Juan County, Utah

Journal of Geosciences, volume 68 (2023), issue 3, 249 - 259

DOI: http://doi.org/10.3190/jgeosci.378

Navrotskyite (IMA 2019-026), K₂Na₁₀(UO₂)₃(SO₄)₉·2H₂O, is a new potassium-sodium-uranyl-sulfate mineral from the Blue Lizard mine, San Juan County, Utah, USA. The new mineral occurs on sandstone and asphaltite matrix in close association with belakovskiite, blödite, bobcookite, changoite, fermiite, ferrinatrite, ilsemannite, ivsite, meisserite, pseudomeisserite-(NH₄), seaborgite and tamarugite. Navrotskyite is orthorhombic, space group Pbcm (#57), with unit cell parameters a = 5.4456(13), b = 21.328(5), c = 33.439(8) Å, V = 3883.8(2) ų and Z = 4. Crystals are acicular tapered needles up to about 1 mm in length, typically occurring as radial sprays and tightly intergrown aggregates resembling fibre-optic bundles. Crystals are elongated on [100] and exhibit only the {012} prism form, resulting in diamond-shaped cross-sections. The terminations are generally not well-formed, but broken crystals are truncated by good {100} cleavage. No twinning was observed. Navrotskyite is pale greenish yellow in color, has a white or very pale-yellow streak and fluoresces neon yellow green under both long- and short-wave UV. It is transparent with vitreous to silky luster. The mineral exhibits a splintery, uneven fracture and has a Mohs hardness of about 2. The calculated density based on the empirical formula is 3.46 g/cm³. The mineral is optically biaxial (-), with α = 1.520(2), β = 1.557(2) and γ = 1.565(2) (white light). The measured 2V is 48.2(5)° and the calculated 2V is 48.9°. Dispersion is imperceptible and no pleochroism was observed. The optical orientation is X = a, Y = c, Z = b. The empirical formula is K_2.06Na_9.98U_3.02S_8.98O₄₄H_3.97 based on 44 O apfu. The eight strongest powder X-ray diffraction lines are [d_obs Å(I)(hkl)]: 5.28(100)(110), 3.050(44)(049, 119), 10.70(43)(020), 3.845(36)(046,134,116), 3.225(30)(153), 3.533(29)(060,061,136), 2.822(29)(139) and 5.59(27)(006). The crystal structure of navrotskyite (R₁ = 0.0289 for 4032 reflections with I > 2σI) contains infinite [(UO₂)(SO₄)₃]^4- chains that extend along [100] and that link to neighbouring chains via a complex network of K-O and Na-O bonds. Related topologies based on the same UL₃-type chain are also observed in the minerals fermiite, meisserite and pseudomeisserite-(NH₄), all of which occur in the same general assemblage as navrotskyite.