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Abstract

The new mineral uranoclite (IMA2020-074), (UO2)2(OH)2Cl2(H2O)4, was found in the Blue Lizard mine, San Juan County, Utah, USA, where it occurs as tightly intergrown aggregates of irregular yellow crystals in a secondary assemblage with gypsum. The streak is very pale yellow and the fluorescence is bright green-white under 405 nm ultraviolet light. Crystals are translucent with vitreous lustre. The tenacity is brittle, the Mohs hardness is about 1½, the fracture is irregular. The mineral is soluble in H2O and has a calculated density of 4.038 g·cm–3. Electron microprobe analyses provided (UO2)2(OH)2.19Cl1.81(H2O)4. The six strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 8.85(38)(002), 5.340(100)(200,110), 5.051(63)(-202), 4.421(83)(112,004,202), 3.781(38)(-212) and 3.586(57)(014,-204). Uranoclite is monoclinic, P21/n, a = 10.763(8), b = 6.156(8), c = 17.798(8) Å, β = 95.656(15)°, V = 1173.5(18) Å3 and Z = 4. The structure is the same as that of synthetic (UO2)2(OH)2Cl2(H2O) in which the structural unit is a dimer consisting of two pentagonal bipyramids that share an equatorial OH–OH edge. The dimers are linked to one another only by hydrogen bonding. This is the second known uranyl mineral containing essential Cl and the first in which Cl coordinates to U6+.

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... The mines in the Red Canyon portion of the White Canyon district in south-eastern Utah have yielded many new mineral species in recent years (e.g. Kampf et al., 2021a). Most of the new species are uranyl sulfates and most, especially from the Blue Lizard mine, contain Na as an essential charge-balancing cation. ...
Article
The new mineral scenicite (IMA2021-057), [(UO2)(H2O)2(SO4)]2·3H2O, was found in the Green Lizard, Giveaway-Simplot, Markey and Scenic mines, White Canyon district, San Juan County, Utah, USA, where it occurs as a secondary phase on granular quartz matrix in association with various combinations of deliensite, gypsum, natrozippeite, rietveldite and shumwayite. Scenicite crystals are transparent, light green-yellow, poorly formed blades or prisms, up to 0.1 mm in length. The mineral has white streak and vitreous lustre. It exhibits https://doi.org/10.1180/mgm.2022.53 Published online by Cambridge University Press 2 bright greenish-white fluorescence (405 nm laser). It is brittle with irregular, curved fracture and a Mohs hardness of ~2. It has an excellent {100} and good {001} cleavages. The calculated density is 3.497 g cm-3. Optically, the mineral is biaxial (-) with α = 1.556(2), β = 1.573(2), γ = 1.576(2) (white light); 2V = 45(3)°; extreme r < v dispersion; orientation: X = c, Y = a, Z = b; pleochroism: X and Y colourless, Z light green-yellow; X = Y < Z. The Raman spectrum exhibits bands consistent with UO 2 2+ , SO 4 2-and O-H. Electron microprobe analysis provided the empirical formula U 1.996 S 2.005 O 19 H 13.997. The five strongest X-ray powder diffraction lines are [d obs Å(I)(hkl)]: 7.69(70)(201), 5.63(100)(111), 4.92(84)(202,310), 4.80(93)(401) and 3.398(55)(020,120,511,601). Scenicite is orthorhombic, Pca2 1 , a = 21.2144(15), b = 6.8188(3) c = 11.2554(6), V = 1628.18(16) Å 3 and Z = 4. In the structure of scenicite (R 1 = 0.0365 for 1259 I > 2I), linkages of pentagonal bipyramids and tetrahedra form an infinite neutral [(UO 2)(SO 4)(H 2 O) 2 ] chain. The structure of shumwayite contains topologically identical chains.
... The Blue Lizard, Green Lizard, Giveaway-Simplot and Markey mines in the Red Canyon portion of the White Canyon district in south-eastern Utah have yielded many new mineral species in recent years (e.g. Kampf et al., 2021a). Most of the new species are uranyl sulfates and most, especially from the Blue Lizard mine, contain Na. ...
Article
The new mineral paramarkeyite (IMA2020–024), Ca2(UO2)(CO3)3·5H2O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on gypsum-coated asphaltum in association with andersonite, calcite, gypsum and natromarkeyite. Paramarkeyite crystals are transparent, pale green-yellow, striated tablets, up to 0.11 mm across. The mineral has white streak and vitreous lustre. It exhibits moderate bluish white fluorescence (405 nm laser). It is very brittle with irregular, curved fracture and a Mohs hardness of 2½. It has an excellent {100} cleavage and probably two good cleavages on {010} and {001}. The measured density is 2.91(2) g cm–3. Optically, the mineral is biaxial (–) with α = 1.550(2), β = 1.556(2), γ = 1.558(2) (white light); 2V = 60(2)°; strong r > v dispersion; orientation: Y = b; nonpleochroic. The Raman spectrum exhibits bands consistent with UO22+, CO32– and O–H. Electron microprobe analysis provided the empirical formula (Ca1.83Na0.20Sr0.03)∑2.05(UO2)(CO3)3·5H2O (+0.07 H). Paramarkeyite is monoclinic, P21/n, a = 17.9507(7), b = 18.1030(8), c = 18.3688(13) Å, β = 108.029(8)°, V = 5676.1(6) Å3 and Z = 16. The structure of paramarkeyite (R1 = 0.0647 for 6657 I > 2I) contains uranyl tricarbonate clusters that are linked by Ca–O polyhedra to form heteropolyhedral layers. The structure of paramarkeyite is very similar to those of markeyite, natromarkeyite and pseudomarkeyite.
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In this issue In this series of New Mineral Names, the theme is alteration products ranging from supergene mineralization to ambient pressure and temperature bat guano–rock interactions. The minerals highlighted here are: arrheniusite-(Ce), erssonite, krupičkaite, priscillagrewite-(Y), seaborgite, thalliomelane, thebaite, and uranoclite.
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The determination of the full crystal structure of the uranyl sulfate mineral uranopilite, (UO2 )6 (SO4)O2(OH)6·14 H2O, including the positions of the hydrogen atoms within the corresponding unit cell, has not been feasible up to date due to the poor quality of its X-ray diffraction pattern. In this paper, the complete crystal structure of uranopilite is established for the first time by means of first principles solid-state calculations based in Density Functional Theory employing a large plane wave basis set and pseudopotential functions. The computed unit-cell parameters and structural data for the non-hydrogen atoms are in excellent agreement with the available experimental data. The computed X-ray diffraction pattern is also in satisfactory agreement with the experimental pattern. The infrared spectrum of uranopilite is collected from a natural crystal specimen originating in Jáchymov (Czech Republic) and computed employing Density Functional Perturbation Theory. The theoretical and experimental vibrational spectra are highly consistent. Therefore, a full assignment of the bands in the experimental infrared spectrum is performed using a normal mode analysis of the first principles vibrational results. One overtone and six combination bands are recognized in the infrared spectrum. The elasticity tensor and phonon spectra of uranopilite are computed from the optimized crystal structure and used to analyze its mechanical stability, to obtain a rich set of elastic properties and to derive its fundamental thermodynamic properties as a function of temperature. Uranopilite is shown to have a large mechanical anisotropy and to exhibit the negative Poisson’s ratio and negative linear compressibility phenomena. The calculated specific heat and entropy at 298.15 K are 179.6 and 209.0 J·K^(-1)·mol^(-1), respectively. The computed fundamental thermodynamic functions of uranopilite are employed to obtain its thermodynamic functions of formation in terms of the elements and the thermodynamic properties of a set of chemical reactions relating uranopilite with a representative group of secondary phases of spent nuclear fuel. From the reaction thermodynamic data, the relative stability of uranopilite with respect to these secondary phases is evaluated as a function of temperature and under different hydrogen peroxide concentrations. From the results, it follows that uranopilite has a very large thermodynamic stability under the presence of hydrogen peroxide. The high stability of uranopilite under this condition justify its early crystallization in the paragenetic sequence of secondary phases occurring when uranium dioxide is exposed to sulfur-rich solutions.
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Nollmotzite (IMA2017-100), Mg[U V (U VI O 2 ) 2 F 3 O 4 ](H 2 O) 4 , is a new uranium oxide fluoride mineral found in the Clara mine, Black Forest Mountains, Germany. Electron microprobe analysis provided the empirical formula (Mg 1.06 Cu 0.02 ) Σ1.08 [U V (U VI O 2 ) 2 O 3.85 F 3.15 ][(H 2 O) 3.69 (OH) 0.31 ] Σ4.00 based on three U and 15 O + F atoms per formula unit. Nollmotzite is monoclinic, space group Cm , with a = 7.1015 (12) Å, b = 11.7489 (17) Å, c = 8.1954 (14) Å, β = 98.087 (14)°, V = 676.98 (19) Å ³ and Z = 2. The crystal structure [twinned by reticular merohedry; refined to R = 0.0369 with GoF = 1.09 for 1527 unique observed reflections, I > 3σ( I )] is based upon [U V (U VI O 2 ) 2 F 3 O 4 ] 2– sheets of β-U 3 O 8 topology and contains an interlayer with MgF 2 (H 2 O) 4 octahedra. Adjacent sheets are linked through F–Mg–F bonds, as well as via hydrogen bonds. The presence of fluorine and pentavalent uranium in the structure of nollmotzite has potentially important implications for the safe disposal of nuclear waste.
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Published two-body bond-valence parameters for cation–oxygen bonds have been evaluated via the root mean-square deviation (RMSD) from the valence-sum rule for 128 cations, using 180 194 filtered bond lengths from 31 489 coordination polyhedra. Values of the RMSD range from 0.033–2.451 v.u. (1.1–40.9% per unit of charge) with a weighted mean of 0.174 v.u. (7.34% per unit of charge). The set of best published parameters has been determined for 128 ions and used as a benchmark for the determination of new bond-valence parameters in this paper. Two common methods for the derivation of bond-valence parameters have been evaluated: (1) fixing B and solving for R o ; (2) the graphical method. On a subset of 90 ions observed in more than one coordination, fixing B at 0.37 Å leads to a mean weighted-RMSD of 0.139 v.u. (6.7% per unit of charge), while graphical derivation gives 0.161 v.u. (8.0% per unit of charge). The advantages and disadvantages of these (and other) methods of derivation have been considered, leading to the conclusion that current methods of derivation of bond-valence parameters are not satisfactory. A new method of derivation is introduced, the GRG (generalized reduced gradient) method, which leads to a mean weighted-RMSD of 0.128 v.u. (6.1% per unit of charge) over the same sample of 90 multiple-coordination ions. The evaluation of 19 two-parameter equations and 7 three-parameter equations to model the bond-valence–bond-length relation indicates that: (1) many equations can adequately describe the relation; (2) a plateau has been reached in the fit for two-parameter equations; (3) the equation of Brown & Altermatt (1985) is sufficiently good that use of any of the other equations tested is not warranted. Improved bond-valence parameters have been derived for 135 ions for the equation of Brown & Altermatt (1985) in terms of both the cation and anion bond-valence sums using the GRG method and our complete data set.
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Bluelizardite (IMA 2013-062), Na7(UO2)(SO4)4Cl(H2O)2, is a new uranyl sulfate mineral from the Blue Lizard mine, San Juan County, Utah (USA). It was found in a sandstone matrix and is associated with chalcanthite, copiapite, ferrinatrite, gypsum, kröhnkite, johannite, and several other new, unnamed Na- and Mg-containing uranyl sulfates. Bluelizardite is a supergene mineral formed by the post-mining weathering of uraninite. The mineral is monoclinic, C2/c, with a = 21.1507(6), b = 5.3469(12), c = 34.6711(9) Å, β = 104.913(3)°, V = 3788.91(17) Å3 and Z = 8. Crystals are blades up to 0.4 mm long, flattened on {001}, elongated parallel to [010] and exhibiting the forms {100}, {001} and {111}. Bluelizardite is pale yellow and has a yellowish-white streak. It has good cleavage on {001} and uneven fracture. The Mohs hardness is estimated at 2. The calculated density based on the empirical formula is 3.116 g/cm3. Bluelizardite exhibits bright yellow-green fluorescence under both long- and short-wave UV radiation. The mineral is optically biaxial (–), with α = 1.515(1), β = 1.540(1) and γ = 1.545(1) (measured with white light). The measured 2V is 48(2)° and the calculated 2V is 47.6°. The mineral does not exhibit any dispersion or pleochroism. The optical orientation is X = b, Y ≈ a, Z ≈ c*. The empirical formula of bluelizardite is Na6.94(U1.02O2)(SO4)4.00Cl0.94O0.06(H2O)2 (based on 21 anions pfu). The Raman spectrum is dominated by the symmetric stretching vibrations of the uranyl (UO22+) group and sulfate tetrahedra and by the O–H stretching and bending vibrations of the H2O molecules. The eight strongest powder X-ray diffraction lines are [dobs Å(I )(hkl) ]: 17.08(52)(002), 10.31(60)(200), 5.16(100)(mult.), 4.569(22)(402,–114), 4.238(23)(–115, 310, 008), 3.484(27)(–602,–604,–2·0·10), 3.353(28)(mult.), 3.186(36)(mult.). The crystal structure of bluelizardite (R1 = 0.016 for 4268 reflections with Iobs > 3σI) is topologically unique among known structures of uranyl minerals and inorganic compounds. It is based upon clusters of uranyl pentagonal bipyramids and sulfate tetrahedra. Two uranyl pentagonal bipyramids are linked through the two vertices of SO4 groups. The remaining three vertices of each UO7 bipyramid are occupied by SO4 groups, linked monodentately. The eight independent Na+ cations are linked through the Na–O bonds along with hydrogen bonds (involving H…O and H…Cl bonds) into a 3D framework.
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The title compound, [(UO2)2Cl2(OH)2(H2O)4], was obtained unintentionally as the product of an attempted reaction between uranium(VI) oxide dihydrate, UO3·2H2O, and hydrogen bis­(trifluoro­methyl­sulfon­yl)imide (HTf2N), in an experiment to obtain crystals of uranyl bis­(trifluoro­methyl­sulfon­yl)imide, UO2(Tf2N)2·xH2O. The structure consists of neutral dimers of uranyl (UO2 2+) units, double bridged by OH− anions. Each uranyl unit is surrounded by one Cl and four O atoms, which form an irregular penta­gon, in a plane perpendicular to the linear uranyl groups. The coordination geometry around each U atom can be considered to be distorted penta­gonal-bipyramidal. In the crystal structure the uranyl dimers are connected to each other by hydrogen-bonding inter­actions [O⋯Cl = 3.23 (1) Å].
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Over the past four decades, the number of inorganic oxide and oxy-salt phases containing stoichiometric quantities of hexavalent uranium has increased exponentially from a few dozen to well over 700, and these structures have become well-known for their remarkable compositional diversity and topological variability. Considering the entirety of these compounds (i.e., crystal structures, conditions of synthesis, and geological occurrences) offers significant insight into the behavior of uranium in the solid state and in the nascent (typically aqueous) fluids. The structure hierarchy approach adopted here aims specifically to facilitate the recognition of useful patterns in the crystal-chemical behavior of hexavalent uranium (U⁶⁺). This work represents the third attempt at a structure hierarchy of U⁶⁺compounds, with the first two being those of Burns et al. (1996) and Burns (2005), which considered 180 and 368 structures, respectively. The current work is expanded to include the structures of 727 known, well-refined synthetic compounds (610) and minerals (117) that contain stoichiometric quantities of U⁶⁺. As in the previous works, structures are systematically ordered on the basis of topological similarity, as defined predominantly by the polymerization of high-valence cations. The updated breakdown is as follows: (1) isolated polyhedra (24 compounds/0 minerals); (2) finite clusters (70 compounds/10 minerals); (3) infinite chains (94 compounds/15 minerals); (4) infinite sheets (353 compounds/79 minerals); and (5) frameworks (186 compounds/13 minerals). Within each of these major categories, structures are sub-divided on the basis of increasing connectivity of uranium (nearly always uranyl) polyhedra. In addition to elucidating common trends in U⁶⁺ crystal chemistry, this structure hierarchy will serve as a comprehensive introduction for those not yet fluent in the domain of uranium mineralogy and inorganic, synthetic uranium chemistry.
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For about 20 years, quantitative analysis of homogeneous microvolumes has been performed with the aid of correction models which transform into mass concentrations C A the ratio k A between the emerging intensities from the specimen and a standard obtained for a characteristic line of element A:
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A study of the low frequency vibrational spectra of compounds of the type L2UO2(NO3)2 (L = mono-dentate ligand), MUO2(NO3)3 (M = monovalent cation), and CS2UO2X4 (X = Cl or Br) has shown that the deformation frequency of the uranyl group occurs in the region 274–245 cm−1 but detailed assignments of the U—O (nitrate) frequencies are not given since it is shown that structurally related complexes do not necessarily give similar low frequency infrared (i.r.) and Raman spectra.
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The variation of the bond length D with the bond strength s in oxygen and halogen compounds of 3d, 4d, 5d-4f and 6d-5f elements is discussed. The functional form D(s) = D(1) (1—Alns) = D(1) —Bins is adopted and the parameters D(1) and A (or B) are given for a great many bonds.
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The crystal structures of uranyl minerals and inorganic uranyl compounds are important for understanding the genesis of U deposits, the interaction of U mine and mill tailings with the environment, transport of actinides in soils and the vadose zone, the performance of geological repositories for nuclear waste, and for the development of advanced materials with novel applications. Over the past decade, the number of inorganic uranyl compounds (including minerals) with known structures has more than doubled, and reconsideration of the structural hierarchy of uranyl compounds is warranted. Here, 368 inorganic crystal structures that contain essential U 6+ are considered (of which 89 are minerals). They are arranged on the basis of the topological details of their structural units, which are formed by the polymerization of polyhedra containing higher-valence cations. Overarching structural categories correspond to those based upon isolated polyhedra (8), fi nite clusters (43), chains (57), sheets (204), and frameworks (56) of polyhedra. Within these categories, structures are organized and compared upon the basis of either their graphical representations, or in the case of sheets involving sharing of edges of polyhedra, upon the topological arrangement of anions within the sheets.
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Raman and infrared spectra of five uranyl oxyhydroxide hydrates, becquerelite, billietite, curite, schoepite and vandendriesscheite, are reported. The observed bands are attributed to the (UO2)2+ stretching and bending vibrations, UOH bending vibrations and H2O and (OH)− stretching, bending and libration modes. The UO bond lengths in uranyls and the OH···O bond lengths are calculated from the wavenumbers assigned to the stretching vibrations. They are close to the values inferred and/or predicted from the X-ray single-crystal structure. The complex hydrogen-bonding network arrangement was proved in the structures of all the minerals studied. This hydrogen bonding contributes to the stability of these uranyl minerals. Copyright © 2006 John Wiley & Sons, Ltd. John Wiley & Sons, Ltd.
Article
A correlation of O-H stretching frequencies (from infrared spectroscopy) with O…O and R…O bond lengths (from structural data) of minerals was established. References on 65 minerals yielded 125 data pairs for the d(O…0)-v correlation; due to rare or inaccurate data on proton positions, only 47 data pairs were used for the d(H…O)-v correlation. The data cover a wide range of wavenumbers from 1000 to 3738 cm−1 and O…O distances from 2.44 to 3.5 Å. They originate from silicates, (oxy)hydroxides, carbonates, sulfates, phosphates, and arsenates with OH−, H2O, or even H3O 2 − units forming very strong to very weak H bonds. The correlation function was established in the form v(cm−1) = 3592-304 · 109 · exp(-d(O…O)/0.1321), R 2 = 0.96. Because of deviations from ideal straight H bonds, i.e. bent or bifurcated geometry, dynamic proton behavior, but also due to factor group splitting and cationic effects, data scatter considerably around the regression line. The trends of previous correlation curves and of theoretical considerations were confirmed.
Article
The changes in the structure of sabugalite have been undertaken using thermo-Raman and infrared spectroscopy based upon the results of thermogravimetric analysis. Two Raman bands are observed at 835 and 830 cm-1 assigned to the (UO2)2+ stretching vibrations resulting from the non-equivalence of the uranyl bonds (UO2)2+. These bands give calculated U-O bond lengths of 1.773 and 1.7808 Å. A low intensity band is observed at 895 cm-1 assigned to the ν3 antisymmetric stretching vibration of (UO2)2+ units. Five bands are observed in the 950 to 1050 cm-1 region in the Raman spectrum of sabugalite and are assigned to the ν3 antisymmetric stretching vibration of (PO4)3- units. Changes in the Raman spectra reflect changes in the structure of sabugalite as dehydration occurs. No (PO4)3- symmetric stretching mode is observed. This result is attributed to the non-equivalence of the PO bonds in the PO4 units. The PO4 vibrations were not affected by dehydration. Thermo-Raman spectroscopy proved to be a very powerful technique for the study of the changes in the structure of sabugalite during dehydration.
The Geology and Production History of the Uranium Deposits in the White Canyon Mining District
  • W L Chenoweth
Chenoweth W.L. (1993) The Geology and Production History of the Uranium Deposits in the White Canyon Mining District, San Juan County, Utah. Utah Geological Survey Miscellaneous Publication, 93-3.
Fermiite, Na 4 (UO 2 )(SO 4 ) 3 -3H 2 O and oppenheimerite, Na 2 (UO 2 )(SO 4 ) 2 -3H 2 O, two new uranyl sulfate minerals from the Blue Lizard mine
  • A R Kampf
  • J Plášil
  • A V Kasatkin
  • J Marty
  • J Cejka
Kampf A.R., Plášil J., Kasatkin A.V., Marty J. and Cejka J. (2015a) Fermiite, Na 4 (UO 2 )(SO 4 ) 3 -3H 2 O and oppenheimerite, Na 2 (UO 2 )(SO 4 ) 2 -3H 2 O, two new uranyl sulfate minerals from the Blue Lizard mine, San Juan County, Utah, USA. Mineralogical Magazine, 79, 1123-1142.
Uranoclite, IMA 2020-074
  • A R Kampf
  • J Plášil
  • T A Olds
  • B P Nash
  • J Marty
Kampf A.R., Plášil J., Olds T.A., Nash B.P. and Marty J. (2021) Uranoclite, IMA 2020-074. CNMNC Newsletter 59; Mineralogical Magazine, 85, 278-281, https://doi.org/10.1180/mgm.2021.5