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Seaborgite (IMA2019-087), LiNa6K2(UO2)(SO4)5(SO3OH)(H2O), is a new mineral species from the Blue Lizard mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found on gypsum in association with copiapite, ferrinatrite, ivsite, metavoltine, and römerite. Seaborgite occurs in sprays of light-yellow, long flattened prisms or blades, up to about 0.2 mm in length. Crystals are elongated on [100], flattened on {010}, and exhibit the forms {100}, {010}, {001}, and {10-1}. The mineral is transparent with vitreous luster and very pale-yellow streak. It exhibits bright lime-green fluorescence under a 405 nm laser. The Mohs hardness is ~2½. The mineral has brittle tenacity, curved or conchoidal fracture, and one good cleavage on {100}. The measured density is 2.97(2) g·cm-3. The mineral is immediately soluble in RT H2O. The mineral is optically biaxial (–), α = 1.505(2), β = 1.522(2), γ = 1.536(2) (white light); 2Vmeas = 85(1)°; moderate r < v dispersion; orientation X ^ a ≈ 10°; pleochroic X colourless, Y and Z light green-yellow; X < Y ≈ Z. Seaborgite EPMA and LA-ICP-MS analyses undermeasured Li, K, and Na. The empirical formula using Li, Na, and K based on the structure refinement is Li1.00Na5.81K2.19(UO2)(SO4)5(SO3OH)(H2O). Seaborgite is triclinic, P–1, a = 5.4511(4), b = 14.4870(12), c = 15.8735(15) Å, α = 76.295(5), β = 81.439(6), γ = 85.511(6)°, V = 1203.07(18) Å3, and Z = 2. The structure (R1 = 0.0377 for 1935 I > 2I) contains [(UO2)2(SO4)8]4– uranyl-sulfate clusters that are linked into a band by bridging LiO4 tetrahedra. The bands are linked through peripheral SO4 tetrahedra forming a thick heteropolyhedral layer. Channels within the layers contain a K site, while an additional K site, six Na sites, and an SO3OH group occupy the space between the heteropolyhedral layers.

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Weathering of ore minerals proceeds through initial transient products to many crystalline secondary minerals. However, the initial products are usually poorly characterized or overlooked because of their extremely small particle size, poor crystallinity, and chemical variability. Here, we document the strength of the precession-assisted three-dimensional (3D) electron diffraction in the characterization of such nanocrystalline phases in a case study on uraninite-sulfide weathering in Jaćhymov (Czech Republic). The glassy, yellow-to-green near-amorphous coatings on the ore fragments contain at least two phases. 3D electron diffraction identified K 0.268 [(U 6+ O 2) 2 O(OH) 2.25 ](H 2 O) 0.676 as the dominant phase, yet unknown from nature, with fourmarierite topology of its uranyl sheets. The minor phase was characterized as K-rich fourmarierite, but its crystallinity was too low for complete structure refinement. Glassy and brownish coatings occur on samples that are not rich in uraninite. They are mainly composed of schwertmannite, i.e., iron oxides with structural sulfate and, in the case of our material, with a substantial amount of adsorbed uranium. This material contains up to 17 wt % of UO 3,total and 0.5−1.4 wt % of CuO according to the WDS study. Surprisingly, X-ray photoelectron spectroscopy showed that the adsorbed uranium is a mixture of U(IV) and U(VI), the reduced species formed most probably during Fe(II) oxidation to Fe(III) and coeval precipitation of schwertmannite. Hence, here, uraninite weathering produces initial nanocrystalline phases with fourmarierite-sheet topology. In the abundance of iron, schwertmannite forms instead and adsorbs much uranium, both tetra-and hexavalent. This study demonstrates the power of 3D electron diffraction techniques, such as precession electron diffraction tomography, to study the alteration nanosized phases. Such nanocrystalline phases and minerals should be expected in each weathering system and may impart significant control over the fate of metals and metalloids in such systems.
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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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The Gladstone–Dale relationship allows one to derive a compatibility index of the physical and chemical data used to characterize a mineral. Minerals of the following groups are reviewed: carbonates, sulfates, phosphates, vanadates, vanadium oxysalts, chromates, molybdates, tungstates, germanates, iodates, nitrates, oxalates, antimonites, antimonates, sulfites, halides, and borates. The mineral species in the Fair, Poor and Incomplete categories in these groups require further study.
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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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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.
The published version is subject to change. Cite as Authors (Year) Title
This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press. DOI: https://doi.org/10.2138/am-2020-7540. http://www.minsocam.org/ Always consult and cite the final, published document. See http:/www.minsocam.org or GeoscienceWorld Krivovichev, S.V. (2018): Ladders of information: what contributes to the structural complexity 320 of inorganic crystals. Zeitschrift für Kristallographie, 233, 155-161.
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SO 4 ) 3 (SO 3 OH)(H 2 O), a new uranyl sulfate mineral from the Blue 332 Lizard mine
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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
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