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Polezhaevaite-(Ce) NaSrCe[F.sub.6] is a new member of the gagarinite mineral group [hexagonal, [P6.sub.3]/m, a = 6.207(7) [Angstrom], c = 3.801(9) [Angstrom], V = 126.8(2) [[Angstrom].sup.3], Z = 1 ]. It is found in a natrolitized microcline-aegirinesodalite lens within apatite-rich urtite at Mt. Koashva (Khibiny massif, Kola Peninsula, Russia) in association with aegirine, albite, arfvedsonite, astrophyllite, burbankite, catapleiite, chlorbartonite, djerfisherite, elpasolite, fluorapatite, fluorite, galena, hydroxylapatite, ilmenite, lamprophyllite, lorenzenite, leucophanite, microcline, natrolite, nepheline, orickite, pectolite, pyrochlore, sodalite, sphalerite, strontiofluorite, tainiolite, titanite, vinogradovite, and villiaumite. Polezhaevaite-(Ce) occurs as parallel and sheaf-like aggregates of extremely thin fibers (up to 1 mm long and 4.2 g/[cm.sup.-3]. The mean chemical composition determined by electron microprobe is (wt%): Na 5.27, Ca 3.08, Sr 29.72, Ba 0.48, La 11.76, Ce 14.12, Pr 0.49, Nd 3.09, F 31.95, total 99.96. Empirical formula calculated on the basis of F = 6 apfu is: [([Na.sub.0.82][Ca.sub.0.18]).sub.[summation]=100][([Sr.sub.1.21] [Ce.sub.0.36][La.sub.0.30][Ca.sub.0.09] [Nd.sub.0.08][Ba.sub.0.01]).sub.[summation]=2.06][F.sub.6] (charge imbalance is +0.05). Its simplified formula is NaSrCe[F.sub.6]. The strongest X-ray powder-diffraction lines [d in [Angstrom], (I), (hkl)] are: 5.416(40)(100), 3.120(100)(101, 110), 2.198(70) (201), 1.796(90)(121, 211, 300, 102), 1.554(30)(220), 1.173(70)(321, 231, 140, 410, 132, 312, 113). The mineral is named in honor of Lyudmila Ivanovna Polezhaeva (b. 1935), a Russian expert in electron microprobe analysis of minerals for her contribution to the mineralogy of alkaline rocks. Keywords: Polezhaevaite-(Ce), new mineral, gagarinite group, peralkaline hydrothermal formation, Khibiny massif, Kola Peninsula, Russia DOI: 10.2138/am.2010.3361

Experimental distribution coefficients of rare earth elements (REEs) between Fe oxyhydroxides (FeOOH) and Mn dioxide ([delta]-Mnp[O.sub.2]) and solutions [[K.sub.D](REE)] exhibit anomalous variations: preferential uptake of light REEs by Mn dioxide, a step-like trend in [K.sub.D](REE) in the Er-Tm-Yb-Lu region, and fractionation of [K.sub.D](Y) from [K.sub.D]([H.sub.O]). Extended X-ray absorption fine structure (EXAFS) spectroscopy was applied to determine coordination states of Er, Tm, Yb, Lu, and Y adsorbed onto FeOOH and [delta]-Mn[O.sub.2] to assess structural changes around the REE site. The structures obtained, combined with previously determined structures of light REEs-sorbed Fe and Mn samples, corresponded to variations found in [K.sub.D](REE). The structural parameters in the first coordination sphere suggest that La, Pr, and Nd adsorbed onto [delta]-Mn[O.sub.2] have a distorted tenfold-coordination sphere and differ greatly from La-, Pr-, Nd-, and Sm-sorbed FeOOH, which have a mixture of eightfold- and ninefold-coordination spheres. In contrast, heavy REEs including Y adsorbed onto Fe and Mn samples' local structures have an eightfold-coordination sphere. The preferential uptakes of light REEs by [delta]-Mn[O.sub.2] are explained by the structural change. The irregular variations of heavy REEs and Y fractionation from Ho in [K.sub.D](REE) do not, however, correspond to any change found in the coordination sphere. During characterization of the first coordination sphere, the W-type tetrad effect appears in the series variation of interatomic distances of [REE.sup.3+.sub.aq] and REE-sorbed FeOOH and [delta]-Mn[O.sub.2]. The occurrence of a tetrad effect indicates that the interatomic distances relate not only to the electrostatic field but also to a quantum field. Keywords: X-ray absorption spectra, rare earth elements, iron oxyhydroxide, manganese dioxide, structural change, tetrad effect, Y fractionation from Ho

Research has been conducted on lanthanide complexes. The isolation of the series of these complexes has been carried out in investigating their crystal structures, and the results of solution studies demonstrate that the molecules dissociate in solution forming monomeric species.

Research has been conducted on the three-dimensional channel-like lanthanide complexes. The synthesis and characterization of these complexes which have been constructed via the use of various compounds including 1,2,4,5-benzenetetracarboxylic acid have been carried out and the details are reported.

Research has been conducted on the triple-helical lanthanide complexes with 2,6-dipicolinic acid. The analyses of the paramagnetic NMR shifts in these complexes carried out via the use of the crystal-field techniques demonstrate the existence of two different helical structures.

Magmatic fluorapatites of five African carbonatite complexes were analyzed for rare-earth (REE) and trace elements by electron microprobe and high-resolution synchrotron micro-XRF to explore the fluorapatite composition during different stages of carbonatite magma evolution. Early crystallized fluorapatites have La concentrations mostly below 1,500 ppm and low [SIGMA]REE. They display convex-upward shaped REE patterns with [(La/Nd).sub.cn] [less than or equal to] 1 and low [(La/Yb).sub.cn] ratios < 100. In contrast, fluorapatites from fractionated carbonatites have straight REE patterns with [(La/Nd).sub.cn] > 1 and [(La/Nd).sub.cn] generally above 100, and have La up to 1 wt% at a high [SIGMA]REE. Model calculations with the fractionating mineral assemblage fluorapatite + calcite [+ or -] clinopyroxqne suggest REE distribution coefficients for fluorapatite/carbonatite melt with a positive slope throughout from La to Lu, in order to meet the relationships observed in the natural fluorapatites. The calculations oppose closed system conditions of magma fractionation along the liquid lines of descent, but suggest periods of instantaneous fluorapatite crystallization. Fluorapatite trace element characteristics are therefore thought to be indicative for carbonatite evolution, and can reflect the relative degree of magma fractionation. We suggest that the [(Eu/Eu*).sub.cn] and Y evolution in the fluorapatites is a manifestation of an aqueous fluid immiscibly coexisting with the carbonatite magma from early evolution on, which is able to continuously extract divalent Eu and Y from the carbonatite magma.

Plagioclase separates from the Layered Series (LS), Upper Border Series (UBS), and Marginal Border Series (MBS) of the Skaergaard intrusion were analyzed to examine major and trace element variations. In general, plagioclase from the LS, UBS, and MBS show similar trends in major elements vs. crystallization: Si[O.sub.2], [Na.sub.2]O, and [K.sub.2]O progressively increase, and CaO and MgO progressively decrease with fractionation. No abrupt changes in the trends of major components of Skaergaard plagioclase during the differentiation of the intrusion are observed. Trace elements in plagioclase reflect changes in the Skaergaard magma and changes in plagioclase distribution coefficients with differentiation. Sr, Ga, and probably Ba are included elements in Skaergaard plagioclase, but were excluded from the other cumulus phases, and as a result systematically increased in the magma and plagioclase during differentiation.. Be, Cs, Hr, Rb, Ta, U, and Zr, and the transition metals Co, Cr, Cu, Ni, Sc, V, and Zn were excluded elements in Skaergaard plagioclase, and remained low in plagioclase during differentiation. Changes in the abundances of these elements in plagioclase during differentiation reflect changes in their abundance in the magma. With the exception of the lower zone, which is enriched in the light rare earth elements, rare earth elements in LS plagioclase, in general, increase with differentiation of the Skaergaard intrusion, but decrease dramatically at the UZa/UZb boundary where abundant apatite first appears. Rare earth elements in UBS plagioclase followed a similar trend to LS plagioclase, except during the initial and final stages of differentiation. UBS plagioclase is much more enriched in rare earth elements during the final 20% of crystallization, except for Eu, which is similar in plagioclase from the two series. The observed trends suggest that the floor and roof sequences became isolated from each other and that the floor sequence may have been more reducing and the roof sequence more oxidizing during the final 20% of crystallization. As the Skaergaard magma ceased convection, or convected as isolated cells, during the final stages of differentiation, volatile elements may have accumulated in the UBS magma, resulting in an increase in f[O.sub.2], and a decrease in Eu/Sm in UBS plagioclase. The observed trends of rare earth elements in plagioclase from the LS and UBS fit well with theoretical calculations that assume closed-system crystallization, and would be difficult to reconcile with any model requiring significant discharge of magma from the chamber during the final 20% of crystallization. The enrichment of light rare earth elements in plagioclase, suggests that the lower part of the intrusion re-equilibrated with a late, light rare earth element-rich fluid or melt. The recharge model proposed by earlier workers to explain anomalous Sr and Nd isotopes appears unlikely in light of the two to fourfold enrichment of light rare earth elements in these samples.

Zircons from anatectic melts of the country rocks of three Proterozoic mafic-ultramafic intrusions from the Sveconorwegian Province in SW Sweden were microanalyzed for U-Th-Pb and rare earth elements. Melting and interaction of the wall rocks with the intrusions gave rise to new magmas that crystallized zircon as new grains and overgrowths on xenocrysts. The ages of the intrusions can be determined by dating this newly crystallized zircon. The method is applied to three intrusions that present different degrees of complexity, related to age differences between intrusion and country rocks, and the effects of post-intrusive metamorphism. By careful study of cathodoluminescent images and selection of ion probe spots in zircon grains, we show that this approach is a powerful tool for obtaining accurate and precise ages. In the contact melts around the 916 [+ or -] 11 Ma Hakefjorden Complex, Pb-loss occurred in some U-rich parts of xenocrystic zircon due to the heat from the intrusion. In back-veins of the 1624 [+ or -] 6 Ma Olstorp intrusion we succeeded in geo-chemically distinguishing new magmatic from xenocrystic zircon despite small age differences. At Boras the mafic intrusion mixed with country rock granite to form a tonalite in which new zircon grew at 1674 [+ or -] 8 Ma. Reworking of zircon occurred during 930 + 33/-34 Ma upper amphibolite facies Sveconorwegian metamorphism. Pb-loss was the result of re-equilibration with metamorphic fluids. REE-profiles show consistent differences between xenocrystic, magmatic, and metamorphic zircon in all cases. They typically differ in Lu/[La.sub.N], Ce/Ce *, and Eu/Eu *, and igneous zircon with marked positive Ce/Ce * and negative Eu/Eu * lost its anomalies during metamorphism.

Scientists have discovered a relation between the magnetic properties of elements and compounds and superconductivity. Rare earth metals, such as lutetium, holmium, and erbium, are being used in superconduction experiments due to the similarity in chemical properties of their ions.

Terbium ions are immobilized on silica gel through ethylenediaminetetraacetic acid (EDTA) or diethylenetriaminepentaacetic acid (DTPA) ligands. The resulting materials are utilized as solid-phase detection systems in liquid chromatography. Terbium(III) luminescence is observed when organic compounds that can transfer energy to Tb(III) by an intramolecular process are present. Peak tailing caused by slow dissociation of transferring compounds from the Tb(III) is significantly reduced if potassium acetate is added to the mobile phase. The solid phases slowly turn a bluish-green color unless triethylenetetraamine is added to the mobile phase. The color change is believed to be caused by bonding of trace amounts of transition metal ions to the solid phase. Detection of carboxylic acid-containing compounds such as indole-2-carboxylic acid, indole-3-acetic acid, 5-methoxyindole-2-carboxylic acid, kynurenic acid, and quinolinic acid is more sensitive with the Tb-DTPA phase than the Tb-EDTA phase, whereas detection of salicylic acid is more sensitive with Tb-EDTA than with Tb-DTPA. The use of time-resolved detection methods significantly enhances the sensitivity. Linearity, reproducibility, limits of detection, and chromatographic separations are examined for several compounds.

Electron microprobe and secondary ion mass spectrometer (SIMS) detect the major-element and REE compositions of 14 diamondiferous eclogites from the Udachnaya kimberlite in Yakutia, Siberia. Differences in the nature of the source material and the processes are found between the Siberian and the South African eclogites. LREE depletions are shown by many reconstructed REE compositions. Some depletions need material of eclogitie or pyroxenitic affinities to undergo partial melting, which leads to the depletion of LREE, and the HREE are left at the original levels. Other depletions conform to the origin of normal or Type I ocean floor basalt. In South Africa, many eclogites are consistent with a protolith of 'anomalous' or Type II ocean floor basalt.

Bastnasite-(Ce) is the most abundant rare earth fluorcarbonate ore mineral, found mainly in Mountain Pass, CA, and Bayan Obo, China. Three-dimensional x-ray diffraction indicates the presence of the pure phase in the bastnasite group and revealed interesting points on the crystal and atomic structure of bastnasite-(Ce). The results also show that the syntaxial intergrowths of the different members of the bastnasite group are due to the (CeF) and (CO3) layers which provide growth surface in the fluorcarbonates, in turn causing changes in the solid phase in equilibrium with the ore fluid.

Research has been conducted on unsymmetrical selenides. The synthesis of these compounds and the reaction pathway which involves generation of the lanthanum phenylselenolate intermediate have been developed and are described.

Research has been conducted on molecular adamantanoids. The diastereoselective self-assembly of these adamantanoids has been achieved via the treatments of lanthanide nitrate/perchlorate and C (sub)2 -symmetric 2,2'-hydroxy-1,1'-binaphthalene-6,6'-dicarboxylic acid, and the results demonstrate that adamantanoids possess perfect T symmetry.

Research has been conducted on polyoxometalates. The preparation of these compounds in aqueous solution, and their characterization via elemental analyses are described.

Research has been conducted on heptadentate ligand tris[6-((2-N,N-diethylcarbamoyl)pyridyl)methyl]amine. The authors describe the synthesis of this ligand which has pyridinecarboxamide arms connected to central nitrogen.

Research has been conducted on tris(2-pyridylmethyl)amine ligands. The authors described the stereocontrolled synthesis of these compounds as potential ligands of lanthanide cations.

Research has been conducted on lanthanide(III) complexes with the di-deprotonated form of the bibracchial lariat ether. The structural and photophysical study of these complexes has been carried out, and the authors report that X-ray crystal structures of these complexes demonstrate a nine-coordinated and deeply buried metal ion in the dianionic receptor cavity.

Research has been conducted on heteroleptic porphyrinate double-deckers. The authors describe the synthesis and spectroscopic characterization of these complexes.

Research has been conducted on acryloyloxazolidinone and cyclopentadiene. The authors have demonstrated that the Diels-Alder reaction between these compounds is catalyzed by lanthanide(III) triflate complexes and by i-Pr- and (R,R)-Ph-pybox, and that the enantioselectivity of the reaction is affected by the molecular sieves.

Research has been conducted on monoporphyrinate trivalent lanthanide complexes with monoanionic ligands. The authors describe the synthesis, characterization and single-crystal X-ray diffraction structures of these complexes.

Research has been conducted on coordination polymers. The authors report the synthesis of these polymers carried out via the hydrothermal reactions of lanthanide chlorides with benzenedicarboxylic acid isomers, and describe the characterization of the polymers via X-ray diffraction.

Research has been conducted on heptacoordinated lanthanide(III) complexes. The authors describe the synthesis and (super)1 H NMR spectroscopic studies of these complexes.

Research has been conducted on lanthanide(III) ions. The authors have investigated the factors affecting the aggregation of these ions in order to produce polynuclear complexes, and they report that these factors have been studied via utilization of 1-aziridineethanol as a source of acyclic and macrocyclic chelates.

Research has been conducted on lanthanide nitrates. Results demonstrate that the reaction of these compounds with bis(diphenylphosphino)methane dioxide produces complexes with distinct classes of structure.

Research has been conducted on (super)t butyl-ester groups. Results demonstrate that the hydrolysis of these groups leads to the nondentate podand which exists as a interconverting conformers' mixture in solution.

Research has been conducted on transitio-metal-containing Zintl compound Eu (sub)10 Mn (sub)6 Sb (sub)13. The authors describe the preparation of this compound via high-temperature tin-flux synthesis, and report that its structure has been investigated via the use of single-crystal X-ray diffraction.

Research has been conducted on spherical Lindquist type polyoxometalate compound. The authors describe the use of this compound as a noncoordinating anionic template for construction of three-dimensional lanthanide-aromatic monocarboxylate dimer supramolecular networks.

Research has been conducted on 2,6-di(o-anisol)phenyl-based bis(alkoxide) and bis(amide) compounds of ytterbium, yttrium, and samarium. The authors describe the synthesis and molecular structures of these compounds, and report the results of NMR analysis carried out for the diamagnetic yttrium compounds.

Research has been conducted on RE(sub)2 Cl (sub)3, where RE= La, Ce, and Li (sub)2 CN (sub)2. The authors report that the solid state metathesis reactions between the compounds haveproduced rare earth chloride carbodiimide nitrides.

Research has been conducted on lanthanide ions. The authors describe the synthesis of polymerizable and saturated metal-chelating lipids via the use of chelidamic acid.

Research has been conducted on anionic bis(phthalocyaninato)lanthanides. The authors have investigated the f-electronic ground state structures of these complexes, and report the results.

Research has been conducted on 2,6-bis(5,6-dialkyl-1,2,4-triazin-3-yl)pyridines. The authors describe the abilities of these molecules to separate actinides(III) from lanthanides(III) in nitric acid solution.

Research has been conducted on one-dimensional lanthanide-transition heterometallic chains. The authors report that these chains have been synthesized via self-assembly between well-designed orthogonal metalloligands and lanthanide(III) ions.

Research has been conducted on lanthanide aqua ions. The authors demonstrate that hydrogen-bonding network is formed between these ions, water and small host molecule cyclotriveratrylene.

Research has been conducted on mixed rare earth/alkali metal halide complexes. The authors describe the structure, vibrational properties and bonding of these complexes which have been investigated theoretically.

Research has been conducted on light lanthanide extraction complexes. The authors describe the characterization of these complexes carried out with X-ray absorption fine structure spectroscopy, MS and IR.

Research has been conducted on RE(IO (sub)3) (sub)3, where RE is Nd, Sm, Eu, reactions with I (sub)2 O (sub)5 and MoO (sub)3. Results demonstrate that these reactions provide access to RE(MoO (sub)2)(IO (sub)3) (sub)4 (OH), and that pure phases are determined from powder X-ray diffraction data.

Research has been conducted on ferrocenecarboxylato-bridged lanthanide dimers. The authors describe the synthesis of these compounds and their characterization by single-crystal X-ray crystallography.

Research has been conducted on molecular-based magnetic materials. The authors report that the cyclic cylindrical tetranuclear structure of these materials is a convenient molecular design used for the production of a large magnetic moment and large magnetic anisotropy.

Standardized buffered polyoxoanion solutions and competitive titrations was used in studying the stoichiometry of the lanthanide(III) complexes of the (alpha1-P2W17O61)(super 10-). The stoichiometry of the Lu3+ analogue was examined by 31P NMR spectroscopy. Luminescence excitation spectroscopy was used in determining the stoichiometry of the Eu3+ complex. Results indicated that the C1 symmetry of the lanthanide complexes was preserved in solution. Lanthanides with smaller ionic radii formed stable complexes while lanthanum analogues were not stable in solutions of high lithium content.