Travis A. Olds

Copper(I) and Copper(II) Uranyl Heterometallic Hybrid Materials

Two copper-uranium heterometallic compounds, [(UO2)3Cu(II)O2(C6NO2)5] (1) and [(UO2)Cu(I)(C6NO2)3] (2), have been synthesized by the reaction of uranyl acetate with copper salts in the presence of isonicotinic acid. Both compounds have been characterized by single-crystal X-ray diffraction, IR, Raman, and UV-vis spectroscopy. In compound 1, interactions between copper and uranium centers occur and result in a three-dimensional pillar layered structure. Compound 1 is also the first example of a heterometallic uranyl organic framework with a trinuclear U3O18 building block. Compound 2 is the first uranyl organic framework that contains monovalent copper, which arises from the reaction of Cu(II) chloride and is assumed to be due to the oxidation of chloride at low pH.

Solution 31P NMR Study of the Acid-Catalyzed Formation of a Highly Charged {U24Pp12} Nanocluster, [(UO2)24(O2)24(P2O7)12]48–, and Its Structural Characterization in the Solid State Using Single-Crystal Neutron Diffraction

The first neutron diffraction study of a single crystal containing uranyl peroxide nanoclusters is reported for pyrophosphate-functionalized Na44K6[(UO2)24(O2)24(P2O7)12][IO3]2·140H2O (1). Relative to earlier X-ray studies, neutron diffraction provides superior information concerning the positions of H atoms and lighter counterions. Hydrogen positions have been assigned and reveal an extensive network of H-bonds; notably, most O atoms present in the anionic cluster accept H-bonds from surrounding H2O molecules, and none of the surface-bound O atoms are protonated. The D4h symmetry of the cage is consistent with the presence of six encapsulated K cations, which appear to stabilize the lower symmetry variant of this cluster. (31)P NMR measurements demonstrate retention of this symmetry in solution, while in situ (31)P NMR studies suggest an acid-catalyzed mechanism for the assembly of 1 across a wide range of pH values.

Structure and Reactivity of X-ray Amorphous Uranyl Peroxide, U2O7

Recent accidents resulting in worker injury and radioactive contamination occurred due to pressurization of uranium yellowcake drums produced in the western U.S.A. The drums contained an X-ray amorphous reactive form of uranium oxide that may have contributed to the pressurization. Heating hydrated uranyl peroxides produced during in situ mining can produce an amorphous compound, as shown by X-ray powder diffraction of material from impacted drums. Subsequently, studtite, [(UO2)(O2)(H2O)2](H2O)2, was heated in the laboratory. Its thermal decomposition produced a hygroscopic anhydrous uranyl peroxide that reacts with water to release O2 gas and form metaschoepite, a uranyl-oxide hydrate. Quantum chemical calculations indicate that the most stable U2O7 conformer consists of two bent (UO2)(2+) uranyl ions bridged by a peroxide group bidentate and parallel to each uranyl ion, and a μ2-O atom, resulting in charge neutrality. A pair distribution function from neutron total scattering supports this structural model, as do (1)H- and (17)O-nuclear magnetic resonance spectra. The reactivity of U2O7 in water and with water in air is higher than that of other uranium oxides, and this can be both hazardous and potentially advantageous in the nuclear fuel cycle.

Single-Crystal Time-of-Flight Neutron Diffraction and Magic-Angle-Spinning NMR Spectroscopy Resolve the Structure and 1H and 7Li Dynamics of the Uranyl Peroxide Nanocluster U60

Single-crystal time-of-flight neutron diffraction has provided atomic resolution of H atoms of H2O molecules and hydroxyl groups, as well as Li cations in the uranyl peroxide nanocluster U60. Solid-state magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectroscopy was used to confirm the dynamics of these constituents, revealing the transportation of Li atoms and H2O through cluster walls. H atoms of hydroxyl units that are located on the cluster surface are involved in the transfer of H2O and Li cations from inside to outside and vice versa. This exchange occurs as a concerted motion and happens rapidly even in the solid state. As a consequence of its large size and open hexagonal pores, U60 exchanges Li cations more rapidly compared to other uranyl nanoclusters.

Leószilárdite, the first Na,Mg-containing uranyl carbonate from the Markey Mine, San Juan County, Utah, USA

Abstract 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 mmlong. More commonly it occurs as pale yellow pearlescent masses to 2 mmconsisting of very small plates. Leószilárdite fluoresces green under both longwave and shortwave ultraviolet light, 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 = colourless, Y and Z = light yellow; X < Y ≈ Z. The average of six wavelength dispersive spectroscopic 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-centred octahedra that share the opposite faces of a Mg-centred octahedron at the centre (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).

Ewingite: Earth’s most complex mineral

The newly discovered mineral ewingite is the most structurally complex mineral known. Ewingite is found in the abandoned Plavno mine in the Jáchymov ore district, western Bohemia (Czech Republic), and was studied by synchrotron X-ray diffraction. The structure of ewingite contains nanometer-scale anionic uranyl carbonate cages that contain 24 uranyl polyhedra, as well as Ca and Mg cations and H2O groups located in interstitial regions inside and between the cages. The discovery of ewingite suggests that nanoscale uranyl carbonate cages could be aqueous species in some systems, and these may affect the geochemical behavior of uranium.

Collector's Note: A New Find of Manganese-rich Pumpellyite from the Manganese Mine, Copper Harbor, Keweenaw County, Michigan

Originally the mineral was described under the name ‘lotrite’ from the southern Carpathian Mountains (Murgoci 1901). Charles H. Palache, who in 1920 made the first systematic study of the secondary minerals in the altered [Michigan] copper lodes for the Calumet and Hecla Copper Mining Company, noted a green mineral which he believed to be a new mineral closely related to the zoisite-epidote family. Unaware of Murgoci’s earlier work, he submitted a manuscript to Calumet and Hecla describing the ‘new’ mineral, proposing to call it ‘kearsargeite.’ B. S. Butler didn’t like the name, and Palache changed the manuscript by crossing out ‘kearsargeite’ and penciling in ‘pumpellyite,’ in honor of Raphael Pumpelly.

Leesite, K(H2O)2[(UO2)4O2(OH)5]·3H2O, a new K-bearing schoepite-family mineral from the Jomac mine, San Juan County, Utah, U.S.A.

Abstract Leesite (IMA2016-064), K(H2O)2[(UO2)4O2(OH)5]·3H2O, is a new uranyl-oxide hydroxyl-hydrate found underground in the Jomac mine, Brown’s Rim, White Canyon mining district, San Juan County, Utah. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses provided the empirical formula K0.67Na0.004Ca0.012U4O20H15.31, based on 4 U and 20 O apfu. Sheets in the crystal structure of leesite adopt the fourmarierite anion topology, and so belong to the schoepite family of related structures that differ in the interlayer composition and arrangement, and charge of the sheet. Leesite may form as one of the principal components of “gummite” mixtures formed during the alteration of uraninite, and the unit cell of leesite resembles the previously described, but poorly understood mineral, paraschoepite. Uptake of dangerous radionuclides (90Sr, 135Cs, 137Cs, 237Np, 238Pu) into the structure of leesite and other members of the family has important implications for the safe disposal of nuclear waste.

Secondary Lead Minerals from the Copps Mine, Gogebic County, Michigan

CULLEN LAUGHLIN-YURS 513 Iron Street Norway, Michigan 49870 kc9pjm@gmail.com TRAVIS A. OLDS Materials Science of Actinides Energy Frontier Research Center 301 Stinson-Remick Hall University of Notre Dame South Bend, Indiana 46556 tolds@nd.edu DANIEL R. FOUNTAIN 167 East Buffalo Road Negaunee, Michigan 49866 dfountain906@gmail.com OWEN P. MILLS Applied Chemical and Morphological Analysis Laboratory Michigan Technological University 1400 Townsend Drive Houghton, Michigan 49931 opmills@mtu.edu Figure 1. Entrance to an adit on the Copps mine property. The white material is snow. Shawn Carlson photo (2015).

A New Occurrence of Callaghanite from Michigan's Copper Country

T mineralogy of Michigan’s world-class native copper district has been well studied, from the academic and economic viewpoints as well as collectible specimen mineralogy. In addition to native copper, the principal ore mineral, the district is home to forty-two copper species and is the type locality for three: anthonyite, calumetite, and the newly approved centennialite (Crichton and Müller 2014). However, the cessation of copper mining in the district in 1995 (closure date of the White Pine copper mine) coupled with the surprising rate at which old mine dumps are being Michigan’s Copper Country CULLEN LAUGHLIN-YURS 513 Iron Street Norway, Michigan 49870 kc9pjm@gmail.com