Crystallochemical Formula Research Articles

CRYSTALLOCHEMICAL FEATURES OF Ti- AND Sb-RICH NEZILOVITE

A variety of the mineral nezilovite, containing antimony and an elevated amount of titanium, has been studied using microprobe and X-ray diffraction analysis. The diffraction experiment was performed on a crystal presenting an aggregate of nezilovite and högbomite with close unit-cell parameters. The parameters of the hexagonal cell of the nezilovite studied are a = 5.8855(2) Å, c = 23.092(1) Å, V = 692.73 (4) Å3,sp. gr. P63/mmc. The structural model is refined using a limited number of unique reflections 231F 4σ(F) to R = 0.08. The crystallochemical formula is (Z = 2) PbZn2(Ti0.9Al0.1)(Al0.6Sb )Mn Fe O18.5(O,OH)0.5. The distribution of cations of this composition over structure sites is established. A basis of the mineral structure is a set of spinel layers, consisting of edge-sharing Fe3+ octahedra. They alternate with two heteropolyhedral layers: Zn tetrahedra combine (Al,Sb) octahedra in one layer, and five-vertex Ti polyhedra combine dimers of Mn3+ octahedra in the other layer.

Genetic features of tourmaline from the magnesian skarns of Kuhilal deposit, Southwestern Pamir

Background. Although the Kuhilal deposit of Mg skarns has been thoroughly studied, tourmaline in their composition has never been considered [5, 6, 16]. Uvite, a tourmaline variety, was mentioned in the list of rare minerals only with its crystallochemical formula [17]. L.N. Shabynin, a great connoisseur of skarns, noted the rarity of tourmaline in Mg skarns of various deposits. Tourmaline of this type is characterized by a strong variation in ferruginosity and a significant content of Ca. At the same time, Ca:Na varies from 2:3 to 20:1 [15]. According to N.N. Pertsev, another major specialist in skarns, tourmaline is a rare mineral of Mg skarn deposits [11]. The boron-iron ore deposit of Tayozhnoe, Aldan shield, is an exception. This deposit belongs to skarns, where a widespread development of tourmaline was noted [12]. Tourmaline (dravite) of this deposit was found only in silicate metamorphic rocks containing marbles and Mg skarns.Aim. To determine the paragenesis, crystal morphology, chemical composition, and genetic characteristics of tourmaline from Kuhilal Mg skarns.Materials and methods. Large aggregates (more than 10 cm across) and crystals of apple-green tourmaline from the Mg skarns of the Kuhilal deposit were investigated. Samples of Mg skarns containing tourmaline were collected and documented by the authors during fieldwork research at the Kuhilal deposit in 2017. The samples were examined by mineralogical and petrographic methods, X-ray diffraction analysis using a DRONE-3M (analyst A.V. Fedorov, Sergo Ordzhonikidze Russian State University for Geological Prospecting), microprobe analysis using a Cameca SX 100 in 15 kV 30 nA shooting mode (analyst V.I. Taskaev, IGEM RAS), and X-ray fluorescence analysis using an AXIOS advanced spectrometer with an X-ray tube equipped with a 3 kW Rh anode and Philips PW-2400 with a sensitivity of 10-4% (analyst A.I. Yakushev, IGEM RAS). The majority of studies were conducted at the Department of Mineralogy and Gemology of the Sergo Ordzhonikidze Russian State University for Geological Prospecting.Results. Tourmaline from the Mg skarns of the Kuhilal deposit has been studied for the first time. This mineral is rare for skarn rocks. Two tourmaline mineral associations were identified: with spinel and forsterite, and with chlorite and serpentine. In terms of chemical composition, tourmaline isattributed to fluorine-containing uvite with a close to zero ferruginosity. Uvite is characterized by a lenticular shape with a rarely observed, underdeveloped prism. Its mineralogical properties, chemical composition, and formation conditions were analyzed. Tourmaline can be used to make inexpensive jewelry inserts.Conclusion. Tourmaline crystallization occurred under the conditions of granulite facies of regional metamorphism. For boron formation, an apo-sedimentary, evaporite source is assumed.

SOME IMPORTANT CHARACTERISTICS OF POLYMETALLIC LEAD-ZINC ORE IN HAJVALIA MINE, KOSOVO

In this paper are presented general geological data for the polymetallic Hajvalia deposit. In particular, we have presented the scientific results regarding the chemical and mineralogical composition of sulfur mineralizations from the Hajvalia deposit. The distribution of the main metals used during the mining activity in this deposit has been studied with special emphasis. From the microscopic description of the mineral samples in the Hajvalia deposit, the following mineral compositions result: sphalerite, galena, pyrite, chalcopyrite, marcasite, arsenopyrite, pyrrhotite, tenanntite, as well as non-metallic minerals. The geochemical associations indicate the strong connection of Pb with Zn and Ag, and less with Cd and Cu. There is another association of Sb with Cd in antagonism with Cu, and an association of Bi with Cu in antagonism with As. Electron probe analysis shows that galena is quite pure with sporadic high content of Ag (up to 100 ppm). The Fe content in the sphalerite is quite homogeneous and varies from 9 to 11.5%, or 0.18 Fe atoms in the crystallochemical formula. As is known, the Fe content in sphalerite depends on the temperature of the mineral formation and, in some cases, can be used as a geothermometer. The main characteristic of galenites is their "purity", with a very high content of Pb. Ag stands out among the other elements, as does the presence of Hg, more Sb than Bi. The characteristic is the presence of Te and Se in isomorphism with S, always with a predominance of Te. In contrast to galena, the contents of Ag as well as Se and Te are lower while it is found more often in Bi than Sb.

Fossil Bioapatites with Extremely High Concentrations of Rare Earth Elements and Yttrium from Deep-Sea Pelagic Sediments

Detailed geochemical and mineralogical insights into some of the richest rare earth elements and yttrium (REY)-containing bioapatites from ocean-floor sediments have been provided by combining laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), electron probe microanalysis (EPMA), Rietveld X-ray diffraction analysis, and Ce L3-edge high energy-resolution X-ray absorption near edge structure (HR-XANES) spectroscopy. Bioapatites at 1.94 and 4.70 m below the seafloor (mbsf) of the Clarion-Clipperton Zone (CCZ) of the Pacific Ocean have 26,600 (RSD = 15.7%, n = 20) and 30,300 (RSD = 14.6%, n = 10) mg/kg (mg/kg) total REY, respectively, and bioapatites at 2.28 and 6.95 mbsf of the Peru Basin have 15,500 (RSD = 15.6%, n = 20) and 15,700 (RSD = 17.8%, n = 29) mg/kg total REY, respectively. All bioapatite specimens have a variety of isomorphic substitutions in all atomic positions of the crystallographic structure. The average crystallochemical formula of bioapatites at 6.95 mbsf of the Peru Basin is [(PO4)2.71(SiO4)0.04(CO3,SO4)0.25][Ca4.57Na0.29Y0.04][F0.87Cl0.21]. All other substituents are below 0.04 atoms per formula unit. HR-XANES provides the first direct evidence for trivalent Ce in sediment apatites. The strong negative geochemical anomaly of Ce in fossil bioapatites is well explained by the occurrence of four valent Ce-MnO2 and CeO2 within the sediment and in seafloor ferromanganese nodules.

Crystal structure of (K1.5Na0.5)Ca3Si3O10.

Single crystals of (K1.52Na0.48)Ca3Si3O10 [idealized (K1.5Na0.5)Ca3Si3O10, di(pot-assium, sodium) tricalcium tris-ilicate], were obtained from the crystallization of a glass with a molar oxide ratio of K2O:Na2O:CaO:SiO2 = 1.5:0.5:6:6 that was annealed at 1273 K. The crystal structure can be characterized as a mixed-anion oxidosilicate with isolated [SiO4] tetra-hedra as well as [Si4O12] vierer single rings. The insular and cyclic silicate anions occur in the ratio 2:1, resulting in the idealized crystallochemical formula K3NaCa6[SiO4]2[Si4O12]. Charge compensation is provided by K+, Na+ (occupying the same sites) and Ca2+ cations. The two unique Ca2+ cations are coordinated by six O atoms, forming distorted octa-hedra. By sharing common corners, edges and faces, these [CaO6] polyhedra build up octa-hedral layer-like motifs parallel to (010). (K/Na)+ ions reside in voids between the the silicate anions and the calcium centered octa-hedra and are coordinated by eight to nine oxygen ligands. (K1.5Na0.5)Ca3Si3O10 is isotypic with K2Ca3Si3O10 indicating the existence of a solid-solution series K2-x Na x Ca3Si3O10.

Crystal Structures of Rb- and Ag-Substituted Forms of Natural Zeolite Amicite

The crystal structures of ion-exchange products of the zeolite-group mineral amicite from Khibiny Alkaline Massif with silver and rubidium salts have been studied. The investigated samples are monoclinic (sp. gr. P21 and I2/a); their crystallochemical formulas (Z = 1) are Ag8(Al8Si8O32) ⋅ 10.6H2O and K0.4Na0.7Rb6.9(Al8Si8O32) ⋅ 4.5H2O; the unit cell parameters are a = 9.272(2) and 10.043(2) A, b = 9.997(2) and 9.748(2) A, c = 10.380(3) and 10.265(2) A, β = 90.821(8)° and 90.09(3)°, V = 962.0(4) and 1005.0(3) A3, respectively. In the Ag-amicite structure, 22 partially occupied sites of the extra-framework components (Ag and H2O) are localized. In the Rb-amicite structure, most of rubidium atoms are located in two sites with the occupancies of 0.414(6) and 0.389(5). The cross-sectional areas of the zeolite channels are 3.5 × 4.5 and 2.3 × 6.3 A2 for Ag-amicite and 3.0 × 4.3 and 3.0 × 3.9 A2 for Rb-amicite.

Synthesis and Structure of New Glutarate-Containing U(VI), Np(V), and Pu(VI) Compounds

The structures of three new glutarate-containing compounds have been characterized. These compounds are (CN3H6)2[(UO2)2(C5H6O4)3] · 4H2O (I), (CN3H6)4[(NpO2)2(C5H6O4)3] · 12H2O (II), and [PuO2(C5H6O4)(H2O)] (III), where C5H6O$$_{4}^{{2 - }}$$ are glutarate anions and CN3H$$_{6}^{ + }$$ are guanidium cations. It was established that the structures of crystals I and II contain [(AnO2)2(C5H6O4)3]z– layers (An = U(VI) or Np(V) and z = 2 or 4, respectively), which can be described by the A2Q$$_{3}^{{02}}$$ crystallochemical formula, where A is UO$$_{2}^{{2 + }}$$ or NpO$$_{2}^{ + }$$ and Q02 are glutarate ions. The structure of crystal III contains two interpenetrating [PuO2(C5H6O4)(H2O)] frameworks and can be described by the AQ21M1 crystallochemical formula, where A = PuO$$_{2}^{{2 + }}$$, Q21 = C5H6O$$_{4}^{{2 - }}$$, and М1 = H2O. The influence of topological isomerism on the structures of the glutarate-containing complexes belonging to the A2Q023 and AQ21M1 crystallochemical groups was discussed.

Synthesis and Structure of Uranyl Succinate Complexes with Cyanoguanidine and Diethylacetamide

[UO2(suc)(C2N4H4)2] · 2H2O (I) and [UO2(Deaa)4(H2О)][(UO2)2(C4H4O4)3] · 2Deaa (II) crystals (suc2– is succinate ion, C2N4H4 is cyanoguanidine, and Deaa is N,N-diethylacetamide С6Н13NO) have been synthesized, and their IR spectroscopy and X-ray diffraction analysis have been performed. It is established that the I structure is formed by chains belonging to the crystallochemical group AQ02M$$_{2}^{1}$$ (A = UO$$_{2}^{{2 + }}$$, Q02 = suc2–, M1 = C2N4H4) of uranyl complexes. The II structure contains two types of complex groups: one-core cations [UO2(Deaa)4(H2О)]2+ and layered anions [(UO2)2(suc)3]2–, with the corresponding crystallochemical formulas AM$$_{5}^{1}$$ and A2Q$$_{3}^{{02}}$$ (A = UO$$_{2}^{{2 + }}$$, M1 = Deaa and Н2О, Q02 = suc2–). The nonvalent interactions in structure II and its carbamide-containing analog are analyzed by the method of molecular Voronoi–Dirichlet polyhedra.

The effect of organic cations on the structure of uranyl glutarate complexes

Two novel uranyl glutarate coordination polymers were characterized by single crystal X-ray diffraction and IR spectroscopy. The structure of the first compound with [N(CH3)3(CH2C6H5)]2[(UO2)2(C5H6O4)3]·H2O (1) composition (where C5H6O42− = C3H6(COO−)2 = glt2− are glutarate anions) contains [(UO2)2(glt)3]2− chains with A2Q023 crystallochemical formula (CCF) (A = UO22+, Q02 = C5H6O42−). The second structure with [N(C2H5)4]2[(UO2)3(C5H6O4)4(H2O)2]·2H2O (2) composition contains another type of chains with [(UO2)3(glt)4(H2O)2]2− composition and A3Q024M12 (A = UO22+, Q02 = glt2−, M1 = H2O) CCF. 1D uranyl glutarate complexes in 1 and 2 differ in UO22+:glt2− ratio leading to the different topology. While [(UO2)2(glt)3]2− chains in 1 have a simple “ladder” topology common for uranyl dicarboxylates structures, in 2 [(UO2)3(glt)4(H2O)2]2− units have additional spacing due to the presence of extra uranium atom with different coordination. The topological difference is described in terms of coordination sequences. The analysis of non-covalent interactions in 1 and 2 was done in topos-Intermol program package and the small contribution of π-staking was revealed in 1.

A Novel Sodium and Chromium Borophosphate Na{Cr[BP2O7(OH)3]}: Synthesis, Crystal Structure, Hydrogen Bonding, and Comparative Crystal Chemistry

A novel sodium and chromium borophosphate, obtained by hydrothermal synthesis in the Na2O–P2O5–B2O3–Cr2O3–Н2О system, has been investigated using X-ray diffraction and IR spectroscopy. The monoclinic cell parameters are found to be a = 10.4220(3) A, b = 8.2468(2) A, c = 9.2053(3) A, β = 116.568(4)°, and V = 707.63(4) A3; sp. gr. С2/с. The structure is interpreted and refined to the final reliability factor R1 = 2.23% in the anisotropic approximation of atomic displacements using 1311 reflections, I > 2σ(I). The novel compound is relative to the family of alkaline borophosphates with the general formula A{M[BP2O7(OH)3]} (A is an alkaline or alkaline-earth element; M is a transition метал) and is described by the crystallochemical formula (Z = 4) Na{Cr[BP2O7(OH)3]}, where the compositions of borophosphate anion and microporous framework are in square brackets and braces, respectively. The presence of alternative systems of strong symmetric hydrogen bonds is established; the localization of all hydrogen atomic sites has made it possible to analyze them in detail. An additional electron density peak is found, which can be interpreted as a statistically distributed proton H+. The IR spectrum is characteristic of compounds with strong hydrogen bonding; it confirms the statistical proton distribution over subsites around the inversion center. It is suggested that representatives of this family may possess proton conductivity.

The Equilibrium of Clay Minerals with Aqueous Solutions in Soils

Abstract—The paper presents a study into the total chemical and mineralogical compositions of fine colloids (fraction <0.08 μm) in the upper horizons of soils of contrasting compositions and properties. Based on the analytical data, the crystallochemical formulas of clay minerals with a 2:1 structure have been calculated, and the chemical potentials of independent components and the activity coefficients of the main end-members have been determined. Using the Selector software, the equilibrium phase-multicomponent composition of soils has been obtained, and the similarity and difference in the crystal chemistry of 2:1 clay minerals produced by two different methods are shown. The calculated Gibbs energy values of these minerals are close to the calorimetric data for smectites. It is demonstrated that the contents of typical elements in 2:1 clay minerals reflect the genetic properties of soils. In soils of alkaline series (Solonetz), such minerals are relatively enriched in sodium and magnesium; in soils of acidic series (Podzoluvisols and Cambisols), in hydrogen and iron; and in soils of the neutral series (Chernozems, Arenosols, and Umbric Gleysols), in calcium.

Hydroxyl Ammonium and Diethyl Ammonium Glutaratouranylates: Synthesis and Structure

The structures of two new coordination polymers, namely, hydroxyl ammonium glutaratouranylate NH3OH[UO2(C5H6O4)(C5H7O4)] · H2O (I) and diethyl ammonium glutaratouranylate NH2(C2H5)2[UO2(C5H6O4) (C5H7O4)] · 2H2O (II), have been characterized by single-crystal X-ray diffraction. It has been established that the structures of complexes I and II contain [UO2(C5H6O4)(C5H7O4)]–infinite chains with the crystallochemical formula AQ02B01 ( $$\rm{A = UO_2^{2+}}, Q^{02} = C_5H_6O_4^{2-}, B^{01} = C_5H_7O_4^{-}$$ ). Despite the identical compositions, uranyl glutarate chains in the studied structures appreciably differ from each other by their geometry and linking. The specific features of nonbonded interactions in the structures of complexes I and II have been characterized by the Voronoi–Dirichlet method of molecular polyhedra.

Garavellite and associated sulphosalts from the Strieborná vein in the Rožňava ore field (Western Carpathians)

Abstract The article presents the first description of a complete and continuous series from berthierite to garavellite sulphosalts in the Western Carpathians. Berthierite is a common main or accessory phase of Sb mineralizations in the Western Carpathians, and occurs at many localities and ore deposits as well. On the other side, garavellite or Bi-rich berthierite is a relatively rare accessory phase. The highest Bi content in garavellite reaches up to 38.04 wt. % which represents 0.90 apfu, and its crystallochemical formula can be written as Fe0.97Sb1.07Bi0.90S3.98. Raman band shifts were observed in the isomorphic berthierite–garavellite series. Garavellite occurs in the younger stages of sulphidic mineralization, and associates with tetrahedrite, berthierite, Bi-chalcostibite, Sb-bismuthinite, Bi-stibnite, ullmanite and cinnabarite. It creates irregular grains and veinlets in pre-existing tetrahedrite, or forms myrmekite intergrowths with chalcopyrite in tetrahedrite. Bi content in chalcostibite is up to 0.20 apfu. Besides the tetrahedrite, pre-existing sulphosalts are the members of the tintinaite–kobellite series, Bi-jamesonite and bournonite. The Sb/(Sb+Bi) ratio of minerals of the tintinaite–kobellite series varies from 0.37 to 0.80. The maximum content of Bi in jamesonite is up to 1.22 apfu. A vertical zonation at the ore vein body (mining levels 6 / 180 a.s.l., 8 / 80 a.s.l., 10 / 20 b.s.l.) is represented by the Sb decrease along with the Bi increase with increasing depth. Bi content continuously decreases during the older ore mineralization stage and Sb increases at the younger mineralization stage. Both of the stages have been enriched by Sb as well.

Ghassoul – Moroccan clay with excellent adsorption properties

Ghassoul, Mg-rich clay consisting mainly of stevensite and containing also additional minerals (sepiolite, quartz, dolomite, gypsum, celestine) is mined in Morocco where the only known deposit in the world is located in Moulouya Valley in Fès-Meknès region. Ghassoul, formed by diagenetic transformation of dolomite in Tertiary fresh-water or brackish-water lacustrine environment, was used for centuries as a natural soap and shampoo. In 1884, the very first scientific report about this material was published by A. A. Damour who provided information about chemical composition of ghassoul. Over the next one hundred years, this material became a subject of geologists' interest until 1998 when the first study focused on practical applications of ghassoul was reported. Between 1998 and 2016, twenty-eight studies were published, twenty-four of which were focused on practical use. According to the studies, the ghassoul can be successfully used as an adsorbent of heavy metals and organic compounds, as a precursor of cordierite ceramics, and, recently, also as a component of functional composites for catalysis or photocatalysis. However, the greatest interest is still in adsorption.This review article is divided into three main sections. The first one provides information about chemical composition, crystallochemical formula, cation exchange capacity, specific surface area, and density of ghassoul. The second and the third section contain data obtained by various authors from experiments on adsorption of heavy metals (As, Cd, Cr, Cu, Hg, Mn, Pb, and Zn) or organic compounds (basic yellow 87, methyl violet, methylene blue, orange G, rhodamine B, metalaxyl, and tricyclazole), respectively. Dose of ghassoul, initial concentration of adsorbate, adsorption capacity, contact time, temperature, and pH are listed in two tables (the first one for heavy metals, the second one for organic compounds). Some of the articles contain tables comparing the adsorption capacity of ghassoul with adsorption capacities of other materials reported elsewhere. Comments on the comparisons are also provided in this article and it is shown that only few materials can compete with adorption capacity of ghassoul.

Crystallochemical Features of the Simplest and Mixed-Layered Bismuth Oxides

The family of bismuth ferroelectrics with a layered structure has generated considerable interest for researchers from both theoretical and practical perspectives for over half a century. The theoretical interest is due to the original structure of the compounds which have a high temperature of blurred ferroelectric transition, and the practical interest is due to the possibility of obtaining multifunctional materials. The crystallochemical analysis of the least studied species of the family, namely, the simplest compositions of the Bi2O3–second oxide type and complex intergrowth structures, compounds with the so-called mixed-layered structure of the grids, is presented. Crystallochemical formulas are proposed to describe the compositions of the above-mentioned types of structures, which should promote more purposeful synthesis of new compounds of the family.

Potassium and magnesium succinatouranilates – Synthesis and crystal structure

Single crystal X-ray diffraction has been applied to determine the structures of two new uranyl coordination polymers: K2[(UO2)2(C4H4O4)3] (1) and [Mg(H2O)6] [(UO2)2(C4H4O4)3]·2H2O (2), where C4H4O42- is succinate anion. Crystals of 1 and 2 contain polymeric complex anions [(UO2)2(C4H4O4)3]2- with the same A2Q023 crystallochemical formula (A=UO22+, Q02=C4O4H42-), and have layered (1) or chain (2) structure. It has been found, that conformation of succinate ions is one of the factors, which affects the structure of [(UO2)2(C4H4O4)3]2- anions. IR spectra of these new compounds are in good agreement with crystallographic data. Topological analysis of the uranium dicarboxylates with A2Q023 crystallochemical formula has shown the presence of five isomers which differ from each other in coordination sequences and / or dimensionality.

Pyroxenoids of pyroxmangite–pyroxferroite series from xenoliths of Bellerberg paleovolcano (Eifel, Germany): Chemical variations and specific features of cation distribution

The pyroxferroite and pyroxmangite from xenoliths of aluminous gneisses in the alkaline basalts of Bellerberg paleovulcano (Eifel, Germany) have been studied by electron-probe and X-ray diffraction methods and IR spectroscopy. The parameters of the triclinic unit cells are found to be a = 6.662(1) A, b = 7.525(1) A, c = 15.895(2) A, α = 91.548(3)°, β = 96.258(3)°, and γ = 94.498(3)° for pyroxferroite and a = 6.661(3) A, b = 7.513(3) A, c = 15.877(7) A, α = 91.870(7)°, β = 96.369(7)°, and γ = 94.724(7)° for pyroxmangite; sp. gr. \(P\overline 1 \). The crystallochemical formulas (Z = 2) are, respectively, M(1–2)(Mn0.5Ca0.4Na0.1)2 M(3–6)(Fe, Mn)4 M7[Mg0.6(Fe, Mn)0.4][Si7O21] and M(1–3)(Mn, Fe)3 M(4–6)[(Fe, Mn)0.7Mg0.3]3 M7[Mg0.5(Fe, Mn)0.5][Si7O21]. For these and previously studied representatives of the pyroxmangite structural type, an analysis of the cation distribution over sites indicates wide isomorphism of Mn2+, Fe2+, and Mg in all cation M(1–7) sites and the preferred incorporation of Сa and Na into large seven-vertex M1O7 and M2O7 polyhedra and Mg into the smallest five-vertex M7O5 polyhedron.

Mineralogy and genetic characteristics of the Rudnik Pb-Zn/Cu,Ag,Bi,W polymetallic deposit (Central Serbia) - New occurrence of Pb(Ag)Bi sulfosalts

The mineral aschamalmite, of heyrovskyite-like composition, but different in structure, from the Rudnik Pb–Zn/Cu,Ag,Bi,W polymetallic deposit in the central part of Serbia has been investigated. This polymetallic deposit includes over 90 hydrothermal and skarn-replacement orebody types, primarily hosted by Cretaceous sediments and occassionally by Oligocene dykes and sills of dacitic composition, and contact-metamorphic-metasomatic rocks. These rocks are host to an assemblage of pyrrhotite, colloform pyrite, chalcopyrite, galena, arsenopyrite, native bismuth and scheelite as well as minor pyrite, sphalerite, bismuthinite, argentopentlandite, and native silver. The chemical composition of the ore is very complex, where weight contents of valuable metals range as follows (%): Zn 0.49–4.49; Pb 0.90–5.66; Cu 0.08–2.18; WO 3 0.05–1.18; Ag 0.005–0.030; Bi 0.005–0.081; and Cd 0.002–0.016. In reflected light, aschamalmite is optically anisotropic, with moderately high bireflectance ranging from slightly greenish to slightly gray. Electron-microprobe analysis gave an average crystallochemical formulae of (Pb 5.82 Ag 0.20 ) Σ6.02 Bi 2.03 (S 8.93 Te 0.02 Se 0.01 ) Σ8.96 . The strongest diffraction maximums of the X-ray powder pattern [ d (in A)(I)] are 3.419(100), 3.382(92), and 3.334(66). Monoclinic unit cell parameters are a =13.727(7); b =4.122(3); c =31.32(2) A; β =90.72(5) o ; and V =1771.8(1) A 3 . Mineral assemblages and genesis of the Rudnik polymetallic deposit are discussed in detail and the sulfobismuthite mineralization has been compared with similar well-known global deposits.

The unified method for computing thermodynamic properties of natural zeolites based on their crystallochemical formulas

The standard thermodynamic potentials of natural zeolites in universal stoichiometric representation are computed. The enthalpies are estimated using linear deconvolution into chemical elements for calibration minerals. The entropies are computed using the additive scheme for oxide components; the Gibbs free energies are computed based on the calculated standard thermodynamic functions and entropies of thermochemically simple compounds.

Crystal structures of new uranyl glutarate coordination polymers (NH4)2[(UO2)2(glt)3]·nH2O (n = 3 or 6) and R[UO2(glt)(Hglt)]·H2O (R = Na, K, Rb or Cs)

Six novel uranyl compounds with glutarate anions, (NH4)2[(UO2)2(glt)3]·6H2O (1), (NH4)2[(UO2)2(glt)3]·3H2O (2) and R[UO2(glt)(Hglt)]·H2O, where R=Na (3), K (4), Rb (5) or Cs (6), were synthesized and characterized by single crystal X-ray diffraction. The uranyl cations in 1 and 2 form complexes with an A2Q023 crystallochemical formula, whereas the uranyl complexes in 3–6 correspond to an AQ02B01 crystallochemical formula (A=UO22+, Q02=glt2−, B01=Hglt−). The structures of 1 and 2 are 2D coordination polymers. In 3–6, the main structural units are [UO2(glt)(Hglt)]− chains united by hydrogen bonds into sheets (3 and 4) or interpenetrating frameworks (5 and 6). The crystal structures of more than 30 uranyl compounds with anions of glutaric, thiodiglycolic, iminodiacetic and oxidiacetic acids were used to analyze the coordination abilities of dicarboxylate anions with uranium.