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Paramarkeyite, a new calcium-uranyl-carbonate mineral from the Markey mine, San Juan County, Utah, USA
Abstract
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 > 2I) 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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Uranyl carbonates are one of the largest groups of secondary uranium(VI)-bearing natural
phases being represented by 40 minerals approved by the International Mineralogical Association, overtaken only by uranyl phosphates and uranyl sulfates. Uranyl carbonate phases form during the direct alteration of primary U ores on contact with groundwaters enriched by CO2, thus playing an important role in the release of U to the environment. The presence of uranyl carbonate phases has also been detected on the surface of “lavas” that were formed during the Chernobyl accident. It is of interest that with all the importance and prevalence of these phases, about a quarter of approved minerals still have undetermined crystal structures, and the number of synthetic phases for which the structures were determined is significantly inferior to structurally characterized natural uranyl carbonates. In this work, we review the crystal chemistry of natural and synthetic uranyl carbonate phases. The majority of synthetic analogs of minerals were obtained from aqueous solutions at room temperature, which directly points to the absence of specific environmental conditions (increased P or T) for the formation of natural uranyl carbonates. Uranyl carbonates do not have excellent topological diversity and are mainly composed of finite clusters with rigid structures. Thus the structural architecture of uranyl carbonates is largely governed by the interstitial cations and the hydration state of the compounds. The information content is usually higher for minerals than for synthetic compounds of similar or close chemical composition, which likely points to the higher stability and preferred architectures of natural compounds.
The new mineral feynmanite (IMA2017-035), Na(UO2)(SO4)(OH)·3.5H2O, was found in both the Blue Lizard and Markey mines, San Juan County, Utah, USA, where it occurs as a secondary phase on pyrite-rich asphaltum in association with chinleite-(Y), gypsum, goethite, natrojarosite, natrozippeite, plášilite, shumwayite (Blue Lizard) and wetherillite (Markey). The mineral is pale greenish yellow with white streak and fluoresces bright greenish white under a 405 nm laser. Crystals are transparent with vitreous luster. It is brittle, with Mohs hardness of ~2, irregular fracture and one perfect cleavage on {010}. The calculated density is 3.324 g cm-3. Crystals are thin needles or blades, flattened on {010} and elongate on [100], exhibiting the forms {010}, {001}, {101} and {10-1}, up to about 0.1 mm in length. Feynmanite is optically biaxial (–), α = 1.534(2), β = 1.561(2), γ = 1.571(2) (white light); 2Vmeas. = 62(2)°; no dispersion; optical orientation: X = b, Y ≈ a, Z ≈ c; and pleochroism: X colourless, Y very pale green yellow, Z pale green yellow (X < Y < Z). Electron microprobe
analyses (WDS mode) provided (Na0.84Fe0.01)(U1.01O2)(S1.01O4)(OH)·3.5H2O. The five strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 8.37(100)(010), 6.37(33)(-101,101), 5.07(27)(-111,111), 4.053(46)(004,021) and 3.578(34)(120). Feynmanite is
monoclinic, P2/n, a = 6.927(3), b = 8.355(4), c = 16.210(7) Å, β = 90.543(4)°, V = 938.1(7) Å3 and Z = 4. The structure of feynmanite (R1 = 0.0371 for 1879 Io > 2I) contains edge-sharing pairs of pentagonal bipyramids that are linked by sharing corners with SO4 groups, yielding a [(UO2)2(SO4)2(OH)2]2– sheet based on the phosphuranylite anion topology. The sheet is topologically identical to those in deliensite, johannite and plášilite. The dehydration of feynmanite to plášilite results in interlayer collapse involving geometric reconfiguration of
the sheets and the ordering of Na.
The new mineral markeyite (IMA2016-090), Ca9(UO2)4(CO3)13·28H2O, was found in the Markey mine, San Juan County, Utah, USA, where it occurs as a secondary phase on asphaltum in association with calcite, gypsum and natrozippeite. The mineral is pale yellowish-green with white streak and fluoresces bright bluish white under a 405 nm laser. Crystals are transparent and have vitreous to pearly lustre. It is brittle, with Mohs hardness 1 1/2 to 2, irregular fracture and three cleavages: perfect on {001}; good on {100} and {010}. The measured density is 2.68 g cm⁻³. Crystals are blades, flattened on {001} and elongate on [010], exhibiting the forms {100}, {010}, {001}, {110}, {101}, {011} and {111}. Markeyite is optically biaxial (-) with α = 1.538(2), β = 1.542(2) and γ = 1.545(2) (white light); the measured 2V is 81(2)°; the dispersion is r < v (weak); the optical orientation is X = c, Y = b, Z = a; and pleochroism is X = light greenish yellow, Y and Z = light yellow (X > Y ≈ Z). Electron microprobe analyses (energy-dispersive spectroscopy mode) yielded CaO 18.60, UO3 42.90, CO2 21.30 (calc.) and H2O 18.78 (calc.), total 101.58 wt.% and the empirical formula Ca8.91(U1.01O2)4(CO3)13·28H2O. The six strongest powder X-ray diffraction lines are [dobs A(I)(hkl)]: 10.12(69)(001), 6.41(91)(220,121), 5.43(100)(221), 5.07(33)(301,002,131), 4.104(37)(401,141) and 3.984(34)(222). Markeyite is orthorhombic, Pmmn, a = 17.9688(13), b = 18.4705(6), c = 10.1136(4) A, V = 3356.6(3) A³ and Z = 2. The structure of markeyite (R1 = 0.0435 for 3427 Fo > 4σF) contains uranyl tricarbonate clusters (UTC) that are linked by Ca-O polyhedra forming thick corrugated heteropolyhedral layers. Included within the layers is an additional disordered CO3 group linking the Ca-O polyhedra. The layers are linked to one another and to interlayer H2O groups only via hydrogen bonds. The structure bears some similarities to that of liebigite.
Leószilárdite (IMA2015-128), Na6Mg(UO2)2(CO3)6·6H2O, was found in the Markey Mine, Red Canyon, White Canyon District, San Juan County, Utah, USA, in areas with abundant andersonite, natrozippeite, gypsum, anhydrite, and probable hydromagnesite along with other secondary uranium minerals bayleyite, čejkaite, and johannite. The new mineral occurs as aggregates of pale yellow bladed crystals flattened on {001} and elongated along [010], individually reaching up to 0.2 mm in length. More commonly it occurs as pale yellow pearlescent masses to 2 mm consisting of very small plates. Leószilárdite fluoresces green under both LW and SW UV, and is translucent with a white streak, hardness of 2 (Mohs), and brittle tenacity with uneven fracture. The new mineral is readily soluble in room temperature H2O. Crystals have perfect cleavage along {001}, and exhibit the forms {110}, {001}, {100}, {101}, and {-101}. Optically, leószilárdite is biaxial (-), α = 1.504(1), β = 1.597(1), γ = 1.628(1) (white light); 2V (meas.) = 57(1)°, 2V (calc.) = 57.1°; dispersion r > v, slight. Pleochroism: X = colorless, Y and Z = light yellow; X < Y ≈ Z. The average of six wavelength dispersive spectroscopic (WDS) analyses provided Na2O 14.54, MgO 3.05, UO3 47.95, CO2 22.13, H2O 9.51, total 97.18 wt%. The empirical formula is Na5.60Mg0.90U2O28C6H12.60, based on 28 O apfu. Leószilárdite is monoclinic, C2/m, a = 11.6093(21), b = 6.7843(13), c = 15.1058(28) Å, β = 91.378(3)°, V = 1189.4(4) Å3 and Z = 2. The crystal structure (R1 = 0.0387 for 1394 reflections with Iobs > 4σI), consists of uranyl tricarbonate anion clusters [(UO2)(CO3)3]4- held together in part by irregular chains of NaO5(H2O) polyhedra sub parallel to [010]. Individual uranyl tricarbonate clusters are also linked together by three-octahedron units consisting of two Na-centered octahedra that share the opposite faces of a Mg-centered octahedron at the center (Na-Mg-Na), and have the composition Na2MgO12(H2O)4. The name of the new mineral honours the Hungarian-American physicist, inventor, and biologist Dr. Leó Szilárd (1898-1964).
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.
The improvements in the crystal structure refinement program SHELXL have been closely coupled with the development and increasing importance of the CIF (Crystallographic Information Framework) format for validating and archiving crystal structures. An important simplification is that now only one file in CIF format (for convenience, referred to simply as `a CIF') containing embedded reflection data and SHELXL instructions is needed for a complete structure archive; the program SHREDCIF can be used to extract the .hkl and .ins files required for further refinement with SHELXL. Recent developments in SHELXL facilitate refinement against neutron diffraction data, the treatment of H atoms, the determination of absolute structure, the input of partial structure factors and the refinement of twinned and disordered structures. SHELXL is available free to academics for the Windows, Linux and Mac OS X operating systems, and is particularly suitable for multiple-core processors.
The new computer program
SHELXT
employs a novel dual-space algorithm to solve the phase problem for single-crystal reflection data expanded to the space group
P
1. Missing data are taken into account and the resolution extended if necessary. All space groups in the specified Laue group are tested to find which are consistent with the
P
1 phases. After applying the resulting origin shifts and space-group symmetry, the solutions are subject to further dual-space recycling followed by a peak search and summation of the electron density around each peak. Elements are assigned to give the best fit to the integrated peak densities and if necessary additional elements are considered. An isotropic refinement is followed for non-centrosymmetric space groups by the calculation of a Flack parameter and, if appropriate, inversion of the structure. The structure is assembled to maximize its connectivity and centred optimally in the unit cell.
SHELXT
has already solved many thousand structures with a high success rate, and is optimized for multiprocessor computers. It is, however, unsuitable for severely disordered and twinned structures because it is based on the assumption that the structure consists of atoms.
Structural complexity of minerals is characterized using information contents of their crystal structures calculated according to the modified Shannon formula. The crystal structure is considered as a message consisting of atoms classified into equivalence classes according to their distribution over crystallographic orbits (Wyckoff sites). The proposed complexity measures combine both size- and symmetry-sensitive aspects of crystal structures. Information-based complexity parameters have been calculated for 3949 structure reports on minerals extracted from the Inorganic Crystal Structure Database. According to the total structural information content, IG, total, mineral structures can be classified into very simple (0–20 bits), simple (20–100 bits), intermediate (100–500 bits), complex (500–1000 bits), and very complex (> 1000 bits). The average information content for mineral structures is calculated as 228(6) bits per structure and 3.23(2) bits per atom. Twenty most complex mineral structures are (IG, total in bits): paulingite (6766.998), fantappieite (5948.330), sacrofanite (5317.353), mendeleevite-(Ce) (3398.878), bouazzerite (3035.201), megacyclite (2950.928), vandendriesscheite (2835.307), giuseppetite (2723.097), stilpnomelane (2483.819), stavelotite-(La) (2411.498), rogermitchellite (2320.653), parsettensite (2309.820), apjohnite (2305.361), antigorite (m = 17 polysome) (2250.397), tounkite (2187.799), tschoertnerite (2132.228), farneseite (2094.012), kircherite (2052.539), bannisterite (2031.017), and mutinaite (2025.067). The following complexity-generating mechanisms have been recognized: modularity, misfit relationships between structure elements, and presence of nanoscale units (clusters or tubules). Structural complexity should be distiguished from topological complexity. Structural complexity increases with decreasing temperature and increasing pressure, though at ultra-high pressures, the situation may be different. Quantitative complexity measures can be used to investigate evolution of information in the course of global and local geological processes involving formation and transformation of crystalline phases. The information-based complexity measures can also be used to estimate the 'ease of crystallization' from the viewpoint of simplexity principle proposed by J.R. Goldsmith (1953) for understanding of formation of simple and complex mineral phases under both natural and laboratory conditions. According to the proposed quantitative approach, the crystal structure can be viewed as a reservoir of information encoded in its complexity. Complex structures store more information than simple ones. As erasure of information is always associated with dissipation of energy, information stored in crystal structures of minerals must have an important influence upon natural processes. As every process can be viewed as a communication channel, the mineralogical history of our planet on any scale is a story of accumulation, storage, transmission and processing of structural information.
The discovery of the diffraction of X-rays on crystals opened up a new era in our understanding of nature, leading to a multitude of striking discoveries about the structures and functions of matter on the atomic and molecular scales. Over the last hundred years, about 150 000 of inorganic crystal structures have been elucidated and visualized. The advent of new technologies, such as area detectors and synchrotron radiation, led to the solution of structures of unprecedented complexity. However, the very notion of structural complexity of crystals still lacks an unambiguous quantitative definition. In this Minireview we use information theory to characterize complexity of inorganic structures in terms of their information content.
The aim of this paper is to present a practical and accurate program of correction based on a new mathematical description of φ(ϱz), which allows a global correction combining atomic number and absorption correction [ZA]. Characteristic and continuum fluorescence corrections are also included to complete the program. Elements of atomic number in the range 4 <Z < 92 and X-ray emission linesKα,Kβ,Lα,Lβ,Mα andMβ are taken into account by the program which is especially designed for difficult cases (light elements, low overvoltages, low accelerating voltages).
This correction program written in Fortran is designed to work off line under DOS or WINDOWS graphic operating systems on PC compatible microcomputers. The WINDOWS user interface environment makes the software easy to use. The computation and plot of φ(ϱz) depth distribution function as well as the printing of physical parameters enable the user to easily optimize the experimental conditions.
This procedure has been tested on various databases (Pouchou and Pichoir, Love et al. and Bastin et al.) for medium to heavy elements. For the light elements (O, C andB) Bastin's database has been used. The results presented furthermore reveal the good accuracy of the method and allow a comparison with other correction procedures.
The topological complexity of a crystal structure can be quantitatively evaluated using complexity measures of its quotient graph, which is defined as a projection of a periodic network of atoms and bonds onto a finite graph. The Shannon information-based measures of complexity such as topological information content, I(G), and information content of the vertex-degree distribution of a quotient graph, I(vd), are shown to be efficient for comparison of the topological complexity of polymorphs and chemically related structures. The I(G) measure is sensitive to the symmetry of the structure, whereas the I(vd) measure better describes the complexity of the bonding network.
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+.
The new minerals natromarkeyite, Na 2 Ca 8 (UO 2) 4 (CO 3) 13 (H 2 O) 24 ⋅3H 2 O (IMA2018-152) and pseudomarkeyite, Ca 8 (UO 2) 4 (CO 3) 12 (H 2 O) 18 ⋅3H 2 O (IMA2018-114) were found in the Markey mine, San Juan County, Utah, USA, where they occur as secondary phases on asphaltum. Natromarkeyite properties are: untwinned blades and tablets to 0.2 mm, pale yellow green colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness 1½ to 2; irregular fracture; three cleavages ({001} perfect, {100} and {010} good); density = 2.70(2) g cm-3 ; biaxial (-) with α = 1.528(2), β = 1.532(2) and γ = 1.533(2); and pleochroism is X = pale green yellow, Y ≈ Z = light green yellow. Pseudomarkeyite properties are: twinned tapering blades and tablets to 1 mm; pale green yellow colour; transparent; white streak; bright bluish white fluorescence (405 nm laser); vitreous to pearly lustre; brittle; Mohs hardness ≈ 1; stepped fracture; three cleavages ({10 1} very easy, {010} good, {100} fair); density = 2.88(2) g cm-3 ; biaxial (-) with α = 1.549(2), β = 1.553(2) and γ = 1.557(2); and it is nonpleochroic. The Raman spectra of markeyite, natromar-keyite and pseudomarkeyite are very similar and exhibit bands consistent with UO 2 2+ , CO 3 2-and O-H. Electron microprobe analyses provided the empirical formula Na 2.01 Ca 7.97 Mg 0.03 Cu 2+ 0.05 (UO 2) 4 (CO 3) 13 (H 2 O) 24 ⋅3H 2 O (-0.11 H) for natromarkeyite and Ca 7.95 (UO 2) 4 (CO 3) 12 (H 2 O) 18 ⋅3H 2 O (+0.10 H) for pseudomarkeyite. Natromarkeyite is orthorhombic, Pmmn, a = 17.8820(13), b = 18.3030(4), c = 10.2249(3) Å, V = 3336.6(3) Å 3 and Z = 2. Pseudomarkeyite is monoclinic, P2 1 /m, a = 17.531(3), b = 18.555(3), c = 9.130(3) Å, β = 103.95(3)°, V = 2882.3(13) Å 3 and Z = 2. The structures of natromarkeyite (R 1 = 0.0202 for 2898 I > 2σI) and pseudomarkeyite (R 1 = 0.0787 for 2106 I > 2σI) contain uranyl tricarbonate clusters that are linked by (Ca/Na)-O polyhedra forming thick corrugated heteropolyhedral layers. Natromarkeyite is isostructural with markeyite; pseudomarkeyite has a very similar structure.
Uroxite (IMA2018-100), [(UO2)2(C2O4)(OH)2(H2O)2]·H2O, and metauroxite (2019-030), (UO2)2(C2O4)(OH)2(H2O)2, are the first two uranyl-oxalate minerals. Uroxite was found in the Markey mine, Red Canyon, Utah, USA and in the Burro mine, Slick Rock district, Colorado, USA. Metauroxite was found only in the Burro mine. Both minerals are post-mining, secondary phases found in efflorescent crusts on mine walls. Uroxite occurs as light yellow, striated blades exhibiting moderate neon-green fluorescence, ca 2 Mohs hardness, good {101} and {010} cleavages, density(calc) = 4.187 g/cm3; optics: biaxial (–), α = 1.602(2), β = 1.660(2), γ = 1.680(2) (white light), 2Vmeas. = 59(1)°, moderate r > v dispersion, orientation Y = b, Z ^ a = 35° in obtuse β, nonpleochroic. Metauroxite occurs as light yellow crude blades and tablets exhibiting weak green-gray fluorescence, ca 2 Mohs hardness, good {001}cleavage, densitycalc = 4.403 g/cm3; approximate optics: α′ = 1.615(5), γ′ = 1.685(5). Electron probe microanalysis provided UO3 79.60, C2O3 10.02, H2O 10.03, total 99.65 wt.% for uroxite and UO3 82.66, C2O3 10.40, H2O 7.81, total 100.87 wt.% for metauroxite; C2O3 and H2O based on the structures. Uroxite is monoclinic, P21/c, a = 5.5698(2), b = 15.2877(6), c = 13.3724(9) Å, β = 94.015(7)°, V = 1135.86(10) Å3 and Z = 4. Metauroxite is triclinic, P–1, a = 5.5635(3), b = 6.1152(4), c = 7.8283(4) Å, α = 85.572(5), β = 89.340(4), γ = 82.468°, V = 263.25(3) Å3 and Z = 1. In the structure of uroxite (R1 = 0.0333 for 2081 I > 2I reflections), UO7 pentagonal bipyramids share corners forming [U4O24] tetramers, which are linked by C2O4 groups to form corrugated sheets. In the structure of metauroxite (R1 = 0.0648 for 1602 I > 2I reflections) UO7 pentagonal bipyramids share edges forming [U2O12] dimers, which are linked by C2O4 groups to form zig-zag chains.
Meyrowitzite, Ca(UO 2)(CO 3) 2 ·5H 2 O, is a new mineral species from the Markey mine, Red Canyon, San Juan County, Utah, U.S.A. It is a secondary phase found on calcite-veined asphaltum in association with gypsum, markeyite, and rozenite. Meyrowitzite occurs as blades up to about 0.2 mm in length, elongate on [010], flattened on {100}, and exhibiting the forms {100}, {001}, {101}, {110}, and {011}. The mineral is yellow and transparent with vitreous luster and very pale yellow streak. Fluorescence under a 405 nm laser is from weak greenish yellow to moderate greenish blue. The Mohs hardness is ca. 2, tenacity is brittle, fracture is irregular, and there is one perfect cleavage, {101}. The measured density is 2.70(2) g/cm 3. The mineral is optically biaxial (+) with α = 1.520(2), β = 1.528(2), and γ = 1.561(2) (white light). The 2V(meas) = 53.0(6)°; weak dispersion, r > v; optical orientation: Z = b, Y ^ a ≈ 19° in obtuse β; pleochroism pale yellow, X ≈ Y < Z. Electron microprobe analyses provided the empirical formula Ca 0.94 (U 1.00 O 2)(CO 3) 2 ·5(H 2.02 O) on the basis of U = 1 and O = 13 apfu, as indicated by the crystal structure determination. Meyrowitzite is monoclinic, P2 1 /n, a = 12.376(3), b = 16.0867(14), c = 20.1340(17) Å, β = 107.679(13)°, V = 3819.3(12) Å 3 , and Z = 12. The structure (R 1 = 0.055 for 3559 I o > 2σI) contains both UO 7 pentagonal bipyramids and UO 8 hexagonal bipyramids, the latter participating in uranyl tricarbonate clusters (UTC). The two kinds of bipyramids and the carbonate groups link to form a novel corrugated heteropolyhedral sheet. This is the first structural characterization of a uranyl-carbonate mineral with a U:C ratio of 1:2. Meyrowitzite is apparently dimorphous with zellerite.
Magnesioleydetite and straßmannite, two new uranyl sulfates minerals with sheet structures from Red Canyon, Utah - Anthony R. Kampf, Jakub Plášil, Anatoly V. Kasatkin, Barbara P. Nash, Joe Marty
Complexity is one of the important characteristics of crystal structures, which can be measured as the amount of Shannon information per atom or per unit cell. Since complexity may arise due to combination of different factors, herein we suggest a method of ladder diagrams for the analysis of contributions to structural complexity from different crystal-chemical phenomena (topological complexity, superstructures, modularity, hydration state, etc.). The group of minerals and inorganic compounds based upon the batagayite-type [M(TO
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.
The new minerals klaprothite (IMA2015-087), Na6(UO2)(SO4)4(H2O)4, péligotite (IMA2015-088), Na6(UO2)(SO4)4(H2O)4, and ottohahnite (IMA2015-098), Na6(UO2)2(SO4)5(H2O)7·1.5H2O, were found in the Blue Lizard mine, San Juan County, Utah, USA, where they occur together as secondary phases. All three minerals occur as yellowish green to greenish-yellow crystals, are brittle with irregular fracture, have Mohs hardness of about 2½ and exhibit bright bluish-green fluorescence, and all are easily soluble in RT H2O. Only klaprothite exhibits cleavage; perfect on {100} and {001}. Quantitative EDS analyses yielded the empirical formulas Na6.01(U 26 1.03O2)(S0.993O4)4(H2O)4, Na5.82(U1.02O2)(S1.003O4)4(H2O)4 and Na5.88(U0.99O2)2(S1.008O4)5(H2O)8.5 for klaprothite, péligotite and ottohahnite, respectively. Their Raman spectra exhibit similar features. Klaprothite is monoclinic, P21/c, a = 9.8271(4), b = 9.7452(3), c = 20.8725(15) Å, β =98.743(7)°, V = 1975.66(17) Å3 and Z = 4. Péligotite is triclinic, P-1, a = 9.81511(18), b =9.9575(2), c = 10.6289(8) Å, α = 88.680(6)°, β = 73.990(5)°, γ = 89.205(6)°, V = 998.22(8) Å3 and Z = 2. Ottohahnite is triclinic, P-1, a = 9.97562(19), b = 11.6741(2), c = 14.2903(10) Å, α = 113.518(8)°, β = 104.282(7)°, γ = 91.400(6)°, V = 1464.59(14) Å3 and Z = 2. The structures of klaprothite (R1 = 2.22%) and péligotite (R1 = 2.28%) both contain [(UO2)(SO4)4]6– clusters in which one SO4 group has a bidentate linkage with the UO7 polyhedron; Na–O polyhedra link clusters into thick heteropolyhedral layers and link layers into frameworks; the structures differ in the configuration of Na-O polyhedra that link the layers. The structure of ottohahnite (R1 = 2.65%) contains [(UO2)4(SO4)10]12– clusters in which each UO7 polyhedron has a bidentate linkage with one SO4 group; Na–O polyhedra link clusters into a thin heteropolyhedral slice and also link the slices into a framework. The minerals are named for Martin Heinrich Klaproth (1743–1817), Eugène-Melchior Péligot (1811–1890) and Otto Hahn (1879–1968).
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.
X-ray diffraction studies have revealed that K4UO2(CO3)3 is isostructural with (NH4)4UO2(CO3)3; the crystal is monoclinic with a = 10.247(3), b = 9.202(2), c = 12.226(3) Å, β = 95.11(2)°, Z = 4, and space group C2/c. Three carbonate anions are arranged in bidentate fashion in the equatorial plane of UO22+; one of these occupies a C2 site and the other two occupy C1 sites. All carbonates are significantly distorted from D3h symmetry. The binding of carbonates to uranyl is strong and thus the lattice can be considered to be composed of [UO2(CO3)3]4− anions and K+ cations. The Raman and infrared spectra exhibit fewer lines than predicted for such a crystal. Tentative assignments are suggested for the more prominent bands of the constituent polyatomic species.
Diffuse reflectance (20,000–30,000 cm−1) and luminescence (18,000–21,000 cm−1) spectra of polycrystalline Na4[UO2(CO3)3] have been measured in the temperature range of 4.2–300 K; the i.r. (50–2000 cm−1) and Raman (50–2000 cm−1) spectra have been recorded at room temperature. The vibrational spectra exhibit all frequencies expected for a UO2L3 complex of D3h symmetry with bidentate ligands L. The symmetric and asymmetric stretching vibrations of the uranyl ion occur at wave numbers as low as 808 and 843 cm−1, respectively, indicating strong uranium ← carbonate bonding. The diffuse reflectance spectra consist of four overlapping electronic transitions, the lowest one with origin at 20,680 cm−1 is also seen in emission. The absorption bands are assigned to the spin and parity forbidden components of the πu→δu and πu→φu one-electron excitations. From the splitting of the excited configurations π3uδ1u and π3uφ1u the spin-orbit coupling constant is calculated to be ζ5ƒ = 1750 cm−1. Possible relationships between measurable spectroscopic properties of the uranyl ion and the strength of bonding in the equatorial plane are discussed.
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.
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 crystal structure of liebigite, previously only incompletely known from a short note, has been determined from X-ray 4-circle diffractometer data and refined toR=0.030 for 3005 observed reflections. Liebigite from Joachimsthal, Bhmen, was used. It was found to crystallize in the polar orthorhombic space groupBba2–C
2v
17
witha=16.699(3),b=17.557(3),c=13.697(3) ,V=4016 3 and a cell content of 8 Ca2UO2(CO3)311H2O. The structure contains UO2(CO3)3 units which are linked by two kinds of CaO4(H2O)4 polyhedra and one kind of CaO3(H2O)4 polyhedron to form puckered Ca2UO2(CO3)38H2O layers parallel to (010). These layers are interconnected only by hydrogen bonds, both directly as well as via three additional interlayer H2O molecules, two of which show positional disorder.Die Kristallstruktur des Minerals Liebigit, die bis jetzt nur unzureichend bekannt war, wurde mit Rntgen-Vierkreisdiffraktometer-Daten bestimmt und fr 3005 beobachtete Reflexe aufR=0,030 verfeinert. Der untersuchte, von Joachimsthal, Bhmen, stammende Liebigit kristallisiert in der polaren rhombischen RaumgruppeBba2–C
2v
17
mita=16,699(3),b=17,557(3),c=13,697(3) ,V=4016 3 und einem Zellinhalt von 8 Ca2UO2(CO3)311H2O. Die Struktur enthlt UO2(CO3)3-Gruppen, die durch zwei Arten von CaO4(H2O)4-Polyedern und eine Art von CaO3(H2O)4-Polyedern zu buckeligen Ca2UO2(CO3)38H2O-Schichten parallel (010) verknpft sind. Diese Schichten sind nur durch Wasserstoffbrcken verbunden, und zwar sowohl direkt als auch mittels dreier zustzlicher freier Wassermolekle, von denen zwei eine Lagenfehlordnung aufweisen.
Leószilárdite, the first Na, Mg-containing uranyl carbonate from the Markey mine
- T Olds
- L R Sadergaski
- J Plášil
- A R Kampf
- P Burns
- I M Steele
- J Marty
- S M Carlson
- O P Mills
Olds T., Sadergaski L.R., Plášil J., Kampf A.R., Burns P., Steele I.M., Marty J.,
Carlson S.M. and Mills O.P. (2017) Leószilárdite, the first Na,
Mg-containing uranyl carbonate from the Markey mine, San Juan
County, Utah, USA. Mineralogical Magazine, 81, 743-754.
Vibrational spectroscopy of the uranyl minerals -infrared and Raman spectra of the uranyl minerals. II. Uranyl carbonates. Bulletin mineralogicko-petrologického oddělení Národního muzea (Praha)
- J Čejka
Čejka J. (2005) Vibrational spectroscopy of the uranyl minerals -infrared and
Raman spectra of the uranyl minerals. II. Uranyl carbonates. Bulletin
mineralogicko-petrologického oddělení Národního muzea (Praha), 13, 62-72 [and references therein, in Czech].
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.
CO 3 ) 2 ⋅5H 2 O, a new mineral with a novel uranylcarbonate sheet
- Ca Meyrowitzite
Meyrowitzite, Ca(UO 2 )(CO 3 ) 2 ⋅5H 2 O, a new mineral with a novel uranylcarbonate sheet. American Mineralogist, 103, 603-610.
Paramarkeyite, IMA 2021-024. CNMNC Newsletter 62
- Kampf
The Gladstone-Dale relationship – Part 1: derivation of new constants
- Mandarino
The geology and production history of the uranium deposits in the White Canyon Mining District, San Juan County, Utah
- Chenoweth
Vibrational spectroscopy of the uranyl minerals – infrared and Raman spectra of the uranyl minerals. II. Uranyl carbonates
- Čejka