The article provides a brief overview of the prevalence and industrial potential of vanadium in the Arctic zone of Russia in the Kola region. The occurrences and deposits of vanadium localized within the Pechenga-Imandra-Varzuga (PIV) Paleoproterozoic rift complex are considered. The most valuable and promising for the vanadium extraction are ultrabasic intrusive rocks containing complex Fe-Ti-V ores (Kolvitsky massif, Imandrovsky lopolite, etc.). Vanadium mineralization occurs sporadically throughout the entire PIV structure.

Many massive sulfide ore occurrences and deposits in the Kola region are located within the Paleoproterozoic Pechenga–Imandra–Varzuga rift belt (2.5–1.7 Ga). They are hosted by volcanosedimentary complexes of the South Pechenga (Bragino ore occurrence) and western Imandra–Varzuga structural zones (Pirrotinovoe Ushchel’e deposit, Tahtarvumchorr ore occurrence, etc.). The age of the massive sulfide ore was estimated at ca. 1.9 Ga. The ores and their host complexes underwent amphibolite-facies metamorphism, which accounts for their specific mineral composition. The types of ores in the Bragino ore occurrence are discussed, the mineral assemblages are listed, and the major ore minerals, that is, pyrrhotite, pyrite, sphalerite, marcasite, etc., are characterized.

The deposit Vasin-Mylk is located in NE Kola Peninsula and represents the pegmatites of Li-Cs-Ta specialization (LCT-type). The studied zircon grains from aplitic zone of pegmatites contain av. 0.34-0.45 apfu of Hf, while the rims of grains contain 0.52-0.54 apfu Hf and correspond to hafnon. Zones with high hafnium content are brighter in BSE and CL comparing to central parts of crystals. The crystallization temperatures of high-Hf zircon were estimated as about 550 degrees C using Ti-in-zircon thermometer. A significant change in crystallization conditions led to isomorphic substitution of Zr by Hf to form hafnon. This change is related to precipitation of aluminous minerals (spodumene, lepidolite) from alumina-oversaturated melt, combined with flux elements (B, Li and F) contributed to the strong fractionation of the Zr/Hf ratio and crystallization of high-Hf zircon at the late ("hydrothermal") stage of rare-metal pegmatite evolution. During this stage KDHf between zircon and granitic melt increases rapidly.

Namibite, Cu(BiO) 2 (VO 4 )(OH), has been found in a sample from the Alakurtti granite pegmatites for the first time in Russia. This sample has been deposited in the collection of the Museum of Geology and Mineralogy of the Geological Institute, Kola Science Centre, Russian Academy of Sciences. Bright green crusts and peels of namibite fill cavities and fractures in quartz. The mineral occurs as an aggregate of near-parallel sliced individuals. The other Bi-minerals, beyerite and bismuthite, are associated with namibite. The article provides data on morphology, chemical composition, X-ray powder pattern and Raman spectroscopy of the mineral, which are consistent with those for namibite published in literature.

In the northern Fennoscandian Shield, vanadium mineralization occurs in the Paleoproterozoic Pechenga–Imandra-Varzuga (PIV) riftogenic structure. It is localized in sulfide ores hosted by sheared basic and ultrabasic metavolcanics in the Pyrrhotite Ravine and Bragino areas and was formed at the latest stages of the Lapland–Kola orogeny 1.90–1.86 Ga ago. An additional formation of vanadium minerals was derived from contact metamorphism and metasomatism produced by the Devonian Khibiny alkaline massif in the Pyrrhotite Ravine area. Vanadium forms its own rare minerals (karelianite, coulsonite, kyzylkumite, goldmanite, mukhinite, etc.), as well as occurring as an isomorphic admixture in rutile, ilmenite, crichtonite group, micas, chlorites, and other minerals. Vanadium is inferred to have originated from two sources: (1) basic and ultrabasic volcanics initially enriched in vanadium; and (2) metasomatizing fluids that circulated along shear zones. The crystallization of vanadium and vanadium-bearing minerals was accompanied by chromium and scandium mineralization. Vanadium mineralization in Paleoproterozoic formations throughout the world is briefly considered. The simultaneous development of vanadium, chromium and scandium mineralizations is a unique feature of the Kola sulfide ores. In other regions, sulfide ores contain only two of these three mineralizations produced by one ore-forming process.

Tveitite-(Y) as pods up to 10 cm across has been found at Mt. Rovgora, the Western Keivy, Kola Peninsula, Russia, in an albite-quartz-amazonite pegmatite vein related to alkaline granite. Tveitite-(Y) grains (up to 4 cm) are parallel microintergrowths of two isostructural varieties, Ca9.5Na1.7Y5.2Ln2.0F42.6 and Ca11.4Na1.9Y4.4Ln1.4F42.0. The idealized structural formula (Z = 3) is (Y, Na)6(Ca, LREE)6(Ca, Na, HREE)6(Ca, Na)F42; the simplified formula is (Ca, REE, Na)13(Y, Na)6F42; space group R \( \bar 3 \) a = 17.020, c = 9.679 Å. [Lanthanoides are abbreviated in this paper as Ln, whereas Ln + Y as REE]. Nine fluorite samples containing from 0 to 18 mol % (REE)F3 were examined by electron microprobe, X-ray powder diffraction, and IR spectroscopy. The crystal structure of natural yttrofluorite has been determined for the first time (R aniso = 1.47 %): Fm3m, a = 5.493 Å; the structural formula is (Ca0.82Y0.12Ln0.06)F2.15. Earlier published and new data show that yttrofluorite containing (REE)F3 > 20 mol % and REE-enriched fluorite with LREE > Y (HREE) are metastable under room conditions. In nature, tveitite-(Y) is a product of solid-state transformation of metastable yttrofluorite with (REE)F3 > 20 mol %. Inferred protophases could have been exsolved into tveitite-(Y) variable in composition or tveitite-(Y) + yttrofluorite stable under normal conditions. The formation of tveitite-(Y) requires the erichment of a protophase not only in Y but also in LREE and HREE as stabilizing admixtures regularly distributed by different types of Ca-dominant structural sites. Tveitite-(Y) and yttrofluorite are geochemical indicators of a medium that is not only enriched in Y, Ln, and F, but also depleted in Na, Ca, CO2 and P.

Cymrite, BaAl2Si2O8 · nH2O, is a rare mineral formed during low-grade dynamothermal metamorphism (T = 250–300°C, P = 1–3 kbar). Cymrite has been described from many metasedimentary ores and hydrothermal rocks. In carbonatites, it has been found for the first time. Cymrite has been identified in the Kovdor and Seblyavr massifs, Kola Peninsula. In Kovdor, this mineral has been described from one of the hydrothermal veins cutting the pyroxenite-melilitite-ijolite complex at the Phlogopite deposit; cymrite is associated with thomsonite, calcite, and stivensite. In the Seblyavr pluton, cymrite occurs in thin veins of calcite carbonatite that cut pyroxenite contacting with ijolite. Cymrite from the Seblyavr pluton is associated with calcite, natrolite, pyrite, and chalcopyrite. The mineral is optically negative and uniaxial, with extinction parallel to elongation; ω ∼ 1.607(1). According to X-ray diffraction data, cymrite from Seblyavr is monoclinic, space group P1m1; unit-cell dimensions are: a = 5.33, b = 36.96, c = 7.66 Å, β = 90°, V = 1510.55 Å3. According to the results of IR spectroscopy, in the series of samples from different massifs (in the running order Kovdor-Voishor-Seblyavr), the double-layer deformation is enhanced and accompanied by a decrease in the Si-O-Si angle and weakening of hydrogen bonds of interlayer water. The empirical formulas of cymrite calculated from electron microprobe analyses are Ba0.93–0.95Ca0.01–0.02K0.00–0.05Na0.02–0.04Al1.97–2.01Si1.99–2.03O8(H2O) and Ba1.00–1.02Ca0.00–0.01Sr0.00–0.01Fe0.00–0.01Al1.94–2.00Si1.98–2.03O8(H2O) at Seblyavr and Kovdor, respectively. Cymrite from the carbonatite massifs of the Kola Peninsula was formed under hydrothermal conditions at low temperature (200–300°C), high activity of Ba and Si, and high water pressure. At Kovdor, the mineral crystallized directly from the residual solution enriched in Ba. The sequence of mineral deposition is as follows: thomsonite-cymrite-calcite-stevensite. Cymrite from the Seblyavr pluton is a product of hydrothermal alteration of primary Na-K-Ba silicates of ijolite: nepheline, feldspar, and probably celsian. Natrolite replaces cymrite indicating high alkalinity of late hydrothermal fluids.

The crystal structure of the As-containing mineral holtite II was refined by the Rietveld method. The orthorhombic unit-cell parameters are a = 4.6893(1) Å, b = 11.881(1) Å, c = 20.394(1) Å, sp. gr. Pnma, Z = 4. Holtite II has an octahedral framework structure composed of two types of nonequivalent columns of Al octahedra, which was found in the structures of dumortierite-group minerals and holtite I. The differences in the structures of holtite II and holtite I were revealed. These differences are associated with the differences in the composition and configuration of the columns of Al(1) polyhedra, which are located inside the framework and are linked to SiO 4 tetrahedra, as well as with the arrangement of pyramidal SbO 3 groups.

A new version of the structural formulas of holtite I, (Al 0.61 Ta 0.25 □)(Al 0.96 □) 2 (Al 0.96 □) 2 × (Al 0.90 □) 2 (Si 2.49 Sb 0.35 As 0.13 )O 13.46 (O 0.48 OH 0.52 )(BO 3 ), is reported. The main changes in this formula are related to the incorporation of arsenic atoms in (Sb,As)O 3 pyramides into the structure.

The key stages of development of atomic absorption spectrometry with spatial resolution are discussed. The results of studies of spatial distribution dynamics for atoms, molecules, condensed nanoparticles, temperature fields in atomisers, and the intensity of transmission radiation are generalised. The effects of spatial nonuniformities on the formation of absorption signals are considered. The advantages of atomic absorption spectrometry with spatial resolution are demonstrated using particular examples.

Simple and express coulometric method for the evaluation of the total antioxidant capacity (TAC) of human plasma based on the reaction with electrogenerated bromine is applied. TAC of plasma from patients with different ethiology of chronic renal failure was observed. The levels of antioxidant capacity for venous and arterial plasma are authentically different (15 ± 1 kCl/L versus 11.7 ± 0.7 kCl/L, p < 0.01). The application of Vitamin E and ximedon as an antioxidant treatment significantly increase TAC level of plasma. Free liposoluble antioxidants in plasma in α-tocopherol units was determined. Redox potential of plasma is measured and its correlation with lg(TAC) is obtained. Transition metal contents of Fe, Cu, Mn, Ni, and Cr in plasma of patients with chronic renal failure is significantly higher than that for a control group. Correlation analysis has shown negative linear regression between TAC value and transition metals concentration in plasma. This confirms interrelation of processes with participation of free radicals, antioxidants and transition metals as donors of electrons in chain radical processes. Moreover, it shows utility of common parameters, TAC for example, for estimation of efficiency of antioxidant defense system in living organism, in particular its antioxidant status.

The dynamics of the spatial structure of absorbing layers of silver atoms and molecules and condensed particles of sodium chloride and potassium sulfate in a transversely heated graphite atomizer during atomization of these substances from a platform and evaporation of their condensate from a tungsten probe is investigated by shadow spectral visualization. The fractional probe atomization significantly decreases the spatial inhomogeneities of absorbing layers, the level of nonselective absorption, and the suppression of atomic absorption. As a result, the photometric error decreases. The use of a probe made it possible to increase the maximum amounts of sodium chloride and potassium sulfate allowable for interference-free atomic absorption analysis in a silver sample from 100 to 4000 μg and from 20 to 750 μg, respectively. These values exceed by a factor of 5–8 the acceptable levels in the generally accepted procedure of atomization from a platform with the Pd-Mg modifier.

Thecrystalstructuresoftwomodificationsofthemineralholtite(holtiteIandII)fromtheKolaPeninsula(Russia)arepresented.Themostspecificfeatureofthecrystalstructuresofbothmodifi-cations of holtite is an octahedral framework formed by twotypesofnonequivalentcolumnsofAloctahedra.Thisframeworkwas found previously in the structures of dumortierite [1] andmagnesiodumortierite [2]. In one type of columns, pairs ofequivalent Al-octahedra share faces, whereas nonequivalentAl-octahedra in the other type of columns are linked to eachotherbyedges.InbothholtiteIandholtiteIIstructurestrian-gular BO

The technique of shadow spectral imaging was used to investigate dynamics of formation and dissipation of Ag, In, Ga, Bi, Mn, Cu and Tl atomic layers in a transversely heated graphite tube atomizer (THGA) with and without integrated platform under gas-stop and gas-flow conditions. It is shown that non-uniform heating of the tube walls and platform surface in the radial cross section is the main reason for analyte transfer from atomizer bottom to less heated sides of the tube and platform before atomization temperature is reached. This transfer in the atomizer transverse cross section can be an additional factor that reduces matrix interferences in the THGA. In all the investigated cases, the atomic absorbing layers are not spatially uniform. Absorbance gradients grow up to 0.2 mm−1 even in the case of chemically inert silver atomization. Inverse atomization of In, Bi, Ga and Tl when atoms first appear in the atomizer's upper part was detected in THGA with platform. The effect of the internal gas flow on the spatial structure of analyte atoms is less pronounced in the transversely heated atomizer as compared to the end-heated furnaces.

The dynamics of formation and dissipation of chloride, nitrate and sulfate matrix vapors in a transversely heated graphite tube atomizer (THGA) with and without integrated platform was investigated with the use of multi-channel atomic absorption spectrometry and the shadow spectral imaging technique. It is shown that non-uniform heating of the tube walls and platform in the furnace radial cross-section causes vapor transfer from atomizer bottom to less heated sides of the tube and platform. This transfer in the atomizer cross-section can be an additional reason for lower level of matrix interferences in the THGA and is a prerequisite for explosive atomization of some elements that appear as absorbance spikes. The cross-sectional structures of molecular layers and the cloud of condensed phase particles are highly inhomogeneous, resulting in absorbance gradients up to 0.2–0.5 mm−1. These structures differ significantly from those observed earlier in end-heated atomizers. Local vortices of the sheath gas, toroid-shaped and bridge-like structures of vapor layers were observed in the atomizer volume. The role of light scattering on the finally dispersed condensed phase particles in the transverse heated furnace is greater than that in the end heated atomizers because of near axis location of the cloud.

Assume that the two individuals forming a twin are related by a mirror reflection parallel to a rational plane (h k l) or by a 180°rotation with axis parallel to a rational direction [u v w].Mallard's "law" states that in both cases these elements can be complemented to a pair (h k l), [u v w] of rational elements, such that the angle between [u v w] and the normal to (h k l), called the obliquity d, satisfies d £ 6°and that the twin index S is a positive integer not larger than 6 [1,2].Discussing examples, especially of crystals with symmetries higher than orthorhombic, we shall show that this criterion is often satisfied for growth twins originating from a twinned nucleus.Growth twins formed by coalescence of two single crystals can better be described if stricter limits are imposed on d and less strict ones on S. If (h k l) is interpreted as the habit plane K 1 of a mechanical twin and [u v w] as h 2 , the observed values of the shear show that the restriction on d has to be relaxed at least for S = 1 [3].

Shadow spectral filming is used to study the spatiotemporal dynamics of the formation and dissipation of vapors of potassium sulfate and aluminum and indium nitrates in a transversely heated graphite furnace atomizer. The integrated platform, the Pd–Mg modifier, the internal flow of the sheath gas, the magnetic field of the nonselective background corrector, and the diffusion of oxygen from the ambient air are responsible for specific nonuniformities in the spatial structure of the vapor cloud. The nonuniformities result to a large extent from the transverse nonisothermal conditions of the graphite furnace. The explosive splashes of aluminum vapors interfering with the analysis are generated at the cold side walls of the graphite furnace, where the vapors are condensed in the process, rather than on the particles of the dry residue of the sample. The beating of the magnetic-field induction inside the graphite furnace atomizer caused by the overlapping of the fields of the heating current (50 Hz) and the background corrector (54 Hz) results in low-frequency (4–5 Hz) oscillations of the spatial position of the vapor cloud. The matrix modifier can stimulate these oscillations.