Method Validation for Determination of Thallium by Inductively Coupled Plasma Mass Spectrometry and Monitoring of Various Foods in South Korea

Thallium (Tl) is a rare element and one of the most harmful metals. This study validated an analytical method for determining Tl in foods by inductively coupled plasma mass spectrometry (ICP-MS) based on food matrices and calories. For six representative foods, the method’s correlation coefficient (R2) was above 0.999, and the method limit of detection (MLOD) was 0.0070–0.0498 μg kg−1, with accuracy ranging from 82.06% to 119.81% and precision within 10%. We investigated 304 various foods in the South Korean market, including agricultural, fishery, livestock, and processed foods. Tl above the MLOD level was detected in 148 samples and was less than 10 μg kg−1 in 98% of the samples. Comparing the Tl concentrations among food groups revealed that fisheries and animal products had higher Tl contents than cereals and vegetables. Tl exposure via food intake did not exceed the health guidance level.

Methodology and algorithm to correct the thermal neutron porosity for the effect of rare elements and rock minerals with high neutron absorption probability

The thermal neutron porosity is routinely acquired in almost every well. When combined with the density, gamma ray and resistivity logs, the basic petrophysical parameters of a reservoir are evaluated. The design of the thermal neutron tool is simple, but its interpretation is complex and affected by the formation constituents. The most challenging situation occurs when the formation contains elements with high absorption probability of the thermal neutrons. The existence of such elements changes the neutron transport parameters and results in a false increase in the measured porosity. The problem is reported by many users throughout the years. In 1993, higher thermal neutron porosity is reported due to the existence of an iron-rich mineral, Siderite, in the Nazzazat and Baharia formations in Egypt. Siderite and all iron-rich minerals have high thermal neutrons absorption probability. Recently, in 2018, high thermal neutron porosity in Unayzah field in Saudi Arabia is also reported due to the existence of few parts per million of gadolinium. Gadolinium is a rare element that has high probability of thermal neutron absorption. Currently, none of the existing commercial petrophysics software(s) have modules to correct the thermal neutron porosity for such effects. This represents a challenge to the petrophysicists to properly calculate the actual reservoir porosity. In this paper, the effects of the rare elements and other minerals with high thermal neutron absorption probability on the thermal neutron porosity are discussed, and a correction methodology is developed and tested. The methodology is based on integrating the tool design and the physics of the neutron transport to perform the correction. The details of the correction steps and the correction algorithm are included, tested and applied in two fields.

Extraction of the Rare Element Vanadium from Vanadium-Containing Materials by Chlorination Method: A Critical Review

Vanadium as a rare element has a wide range of applications in iron and steel production, vanadium flow batteries, catalysts, etc. In 2018, the world’s total vanadium output calculated in the form of metal vanadium was 91,844 t. The raw materials for the production of vanadium products mainly include vanadium-titanium magnetite, vanadium slag, stone coal, petroleum coke, fly ash, and spent catalysts, etc. Chlorinated metallurgy has a wide range of applications in the treatment of ore, slag, solid wastes, etc. Chlorinating agent plays an important role in chlorination metallurgy, which is divided into solid (NaCl, KCl, CaCl2, AlCl3, FeCl2, FeCl3, MgCl2, NH4Cl, NaClO, and NaClO3) and gas (Cl2, HCl, and CCl4). The chlorination of vanadium oxides (V2O3 and V2O5) by different chlorinating agents was investigated from the thermodynamics. Meanwhile, this paper summarizes the research progress of chlorination in the treatment of vanadium-containing materials. This paper has important reference significance for further adopting the chlorination method to treat vanadium-containing raw materials.

U-Pb dating and composition of columbite from Vishteritsa: Implication for timing of granite magmatism and rare-element granitic pegmatites in the Western Rhodopes, Bulgaria

The economic significance of pegmatites as a source of strategic rare metals for high-tech products and green energy motivated the present study on Ta–Nb oxides from Vishteritsa rare-element beryl–columbite LCT pegmatites of the Rila–West Rhodopes Batholith in the Western Rhodopes, Bulgaria. Here, we present the first U/Pb age data from columbite with application of the LA–ICP–MS U–Pb technique and a new X36 columbite standard reference material. The obtained Concordia age of 47.57 ± 0.32 Ma with a small spread of the individual 206Pb/238U ages between 45 and 51.3 Ma argues for Early Eocene magmatism and pegmatite formation. The host granite of the rare-element pegmatites is dated 51.94 ± 0.61 Ma with LA–ICP–MS U–Pb technique on zircon and suggests a fertile Early Eocene magmatic period in the Western Rhodopes. EPMA data for the composition of the columbite is used to refine the formula of the mineral (Mn0.554Fe0.427U0.006)0.987(Nb1.826Ta0.085Ti0.116)2.03O6 and define it as columbite-(Mn). Application of the in-situ LA–ICP–MS data technique establishes a series of typical trace elements (Ti, U, Zr, Hf, Y, W, and Zn) that are usually found in content above 500 ppm. The studied columbite is enriched in heavy rare earth elements (HREE sum: 306–697 ppm) and depleted in light REE and Eu. These geochemical characteristics are collectively interpreted as evidence for crystallization from highly fractionated fluid-rich magma. High UO2 content reaching 0.89 wt. % is characteristic for the Vishteritsa columbite. The decrease of U proximal to cracks and in outer crystal zones documents U-mobility during overprinting hydrothermal processes.

Liraite, ideally NaCa2Mn2[Fe3+Fe2+]Mn2(PO4)6(H2O)2, a new phosphate mineral of the wicksite group from the Ceferino Namuncurá pegmatite, Córdoba, Argentina

ABSTRACT Liraite, ideally NaCa2Mn2[Fe3+Fe2+]Mn2(PO4)6(H2O)2, is a new mineral found in the Ceferino Namuncurá pegmatite, Pocho Department, Córdoba province, Argentina. It occurs in ellipsoidal nodules up to 20 cm in diameter in the intermediate zone of a Muscovite-Rare Element class pegmatite. Secondary phosphates, such as varulite, robertsite, fluorapatite, phosphosiderite, and Sr-rich metaswitzerite, together with minor quartz in veinlets, are associated minerals. Liraite is interpreted to have formed by reaction of phosphate minerals with Na-bearing hydrothermal fluids. It is dark brown with greenish hues (nearly black) in massive aggregates and dark olive green in translucent slices with a dark brownish green streak and a vitreous luster. It is brittle with an irregular fracture, one very good cleavage, and a good cleavage orthogonal to the very good cleavage. The Mohs hardness is 5, and the measured and calculated densities are 3.52(1) and 3.529(1) g/cm3, respectively. In transmitted light it is pleochroic X = Y = olive, Z = yellowish brown with X = Y > Z and optical orientation X = 2V(calc.) = 69.2°. The refractive indicies measured with monochromatic light (λ = 589 nm) are α = 1.732 (3), β = 1.739 (3), γ = 1.754 (3). Liraite is orthorhombic (Pcab) and has unit-cell parameters a = 12.608(6) Å, b = 12.918(6) Å, c = 11.737(4) Å, V = 1911.6(14) Å3, Z = 4. The six strongest reflections in the X-ray powder diffraction pattern are as follows: [d in Å, (I), (hkl)] 2.7452, 100, (421); 2.8563, 65, (014); 2.9266, 49, (004); 2.7061, 30, (412); 2.0966, 29, (334); 2.7693, 26, (402). The crystal structure was refined to an R index of 1.94% based on 2910 observed (>4σF) reflections measured with MoKα X-radiation. Chemical analysis by electron microprobe of the structure crystal (holotype specimen) gave Na2O 1.58, FeO 5.29, Fe2O3 11.45, CaO 10.52, MgO 0.77, MnO 24.00, P2O5 41.55, SrO 0.72, ZnO 0.19, H2O (calc.) 3.50, total 99.57 wt.% where water was calculated from the crystal-structure analysis and the Fe3+/Fe2+ ratio was determined by charge balance. The empirical formula calculated on the basis of 26 oxygen atoms is (Na0.53□0.47)Σ1.00(Ca1.93Sr0.07)Σ2.00(Fe3+1.48Fe2+0.76Mn3.48Mg0.20Zn0.02)Σ5.94P6.02O24(H2O)2, ideally NaCa2M(1)Mn2M(2)[Fe3+Fe+2]M(3)Mn2(PO4)6(H2O)2. The Gladstone-Dale relation gives a compatibility index of 1 – (KP/KC) = 0.010 (superior). This new member of the wicksite group is Mn-rich, and, like bederite, has Mn dominant at the M(1) and M(3) sites. However, the Na site in liraite is Na-dominant with M(2)[Fe3+Fe2+], whereas bederite is □-dominant with M(2)Fe3+2. Liraite has a very low MgO content, and even with all available Mg assigned to the M(2) site, Fe2+ > Mg at M(2). Consequently, liraite is the first wicksite-group mineral with endmember M(2) composition [Fe3+Fe2+].

AGE AND COMPOSITION OF THE EARLY PALEOZOIC MAGMATIC ASSOCIATIONS AND RELATED RARE-ELEMENT PEGMATITES IN THE SOUTH-EASTERN PART OF THE SANGILEN BLOCK, TUVA-MONGOLIAN MASSIF

The article presents new data on ages (U-Pb zircon dating, SIMS SHRIMP-II) and chemical compositions of rocks from gabbro-granitic and granite-leucogranitic magmatic associations. These rocks preceded the formation of Li-enriched spodumene pegmatites of the Tserigiyngol-Burchin ore cluster (Russian: ЦБРУ), one of the main clusters in the South Sangilen pegmatite belt (SSB) located in the Tuva-Mongolian massif being a part of the Central Asian Fold Belt. We investigated the rocks from the Upper Tserigiyngol, Uchuglyk and Temenchulu plutons, and pegmatites from two neighbouring fields. We distinguish three impulses of granitic magmatism (517±7, 508±7, and 488±6 Ma), which are attributed to different stages of the Early Paleozoic collision orogeny (520-480 Ma). The period when the Li-enriched pegmatites were formed (494±7 Ma) is close to the magmatism impulse at 488±6 Ma. Differences are discovered in compositional and isotopic (Sm-Nd) features of granites dominating at the following stages of collisional orogeny: (1) early collision (517±7 Ma) – I-type granites, eNd(T)=0–1.5, TNd (DM-2st)=1.2–1.1 b.y., and (2) late collision (488±6 Ma) – A-2-type granites, eNd(T)=–3.0…–1.6, TNd (DM-2st)=1.5–1.4 b.y., which are due to different sources. Our study shows that facies transitions are absent between the late-collision granites (488±6 Ma) and the spodumene pegmatites from the Tserigiyngol-Burchin ore cluster (494±7 Ma), although these rocks are close in age. In terms of geochemical features, the spodumene pegmatites from the cluster are strongly different from both the late-collision granites and spodumene pegmatites from other SSB fields, including the large Tastyg lithium deposit. We have analysed the role of interactions between the crustal and mantle materials in the formation of granitoid sources in the Tserigiyngol-Burchin ore cluster, and described their evolution in time and the influence on the pegmatite rare-element specialization.

Tellurium: A Rare Element with Influence on Prokaryotic and Eukaryotic Biological Systems

Metalloid tellurium is characterized as a chemical element belonging to the chalcogen group without known biological function. However, its compounds, especially the oxyanions, exert numerous negative effects on both prokaryotic and eukaryotic organisms. Recent evidence suggests that increasing environmental pollution with tellurium has a causal link to autoimmune, neurodegenerative and oncological diseases. In this review, we provide an overview about the current knowledge on the mechanisms of tellurium compounds’ toxicity in bacteria and humans and we summarise the various ways organisms cope and detoxify these compounds. Over the last decades, several gene clusters conferring resistance to tellurium compounds have been identified in a variety of bacterial species and strains. These genetic determinants exhibit great genetic and functional diversity. Besides the existence of specific resistance mechanisms, tellurium and its toxic compounds interact with molecular systems, mediating general detoxification and mitigation of oxidative stress. We also discuss the similarity of tellurium and selenium biochemistry and the impact of their compounds on humans.

Rare element minerals’ assemblage in El Quemado pegmatites (Argentina): insights for pegmatite melt evolution from gahnite, columbite-group minerals and tourmaline chemistry and implications for minerogenesis

The pegmatite district of El Quemado (NW Pampean Ranges, NW Argentina) hosts several Ordovician pegmatite bodies of the LCT (Li, Cs, Ta) type. We present paragenetic assemblages for a set of samples from two of the El Quemado pegmatite groups, Santa Elena and Tres Tetas, and mineral chemistry analyses for gahnite, columbite-group minerals, tourmaline, micas, albite, microcline, and discuss the relation between their major element composition and the degree of evolution of pegmatite melts. The chemical composition of rare element minerals allows recognizing an evolutive trend reaching highly differentiated compositions, with complex paragenetic assemblages including Li-, Zr-, U-, Zn-, P-, Mn- and Ta-bearing minerals. The temperature of crystallization during the magmatic phase was below 400 °C. Non-pervasive hydrothermal alteration, testified by a moderate presence of phyllosilicates, affected the pegmatite bodies. Chlorite geothermometry indicates that the circulation of post-magmatic hydrothermal fluids occurred at a temperature ranging between 200 °C and 250 °C. The mineralogical features recognized in the El Quemado pegmatite rocks have implications for the metallogenesis of the region, suggesting that the pegmatites potentially contributed to the genesis of Ta-Nb oxide placer mineralizations.