Silicate Minerals Research Articles

Mitigation Measures of Swelling Characteristics in Alkali-Contaminated Red Earth using Fly Ash and GGBS Blends

Alkali contamination induces swelling in the inherently non-swelling soils, resulting in heave severely damaging the sub and superstructures. Stabilization measures must be taken in vulnerable areas to prevent such colossal losses. Considerable research has been conducted regarding the swelling behavior of soils contaminated with alkalis and the impact of subsequent stabilization techniques utilizing different industrial byproducts and pozzolanic materials. However, there is a paucity of such studies on the Red Earth (RE) of the Visakhapatnam region. Furthermore, limited attention was given to the effects of extremely low concentrations of alkalis on the swelling behavior of soils. RE in the study area of the Visakhapatnam region predominantly consists of quartz, kaolinite, and hematite. In phase 1 of the experimental analysis, RE was contaminated with a highly dilute NaOH solution (0.05 N), and the resulting swell characteristics were investigated. A free swell of 10% was observed. One-dimensional standard oedometer tests revealed an equilibrium swelling of 5.6%, indicating significant potential for substantial heave and subsequent damage. X-ray diffraction (XRD) analysis revealed the formation of natrolite and analcime zeolites with a hollow structure, which caused the swell. Peaks of silicate minerals like paragonite and ussingite were also observed, indicating the dissolution of authigenic minerals and new precipitations even at lower concentrations of NaOH. In phase 2, swell tests were conducted on a mixture of contaminated red earth (50% w/w), fly ash (25% w/w), and ground granulated blast furnace slag (GGBS, 25% w/w), and it was observed that the swelling was completely arrested. XRD analysis unveiled that even though siliceous zeolites were formed, the development of chrysotile, attapulgite, tobermorite, and dicalcium silicate effectively inhibited the swelling with their pozzolanic behavior.

Nickel isotope fractionation factors between silicate minerals and melt

Quantitative knowledge of inter-mineral and mineral–melt isotopic fractionation factors is of crucial importance to interpret variability of mass-dependent isotope ratios in terrestrial rocks and meteorites. The isotopic composition of Ni shows great promise as a tracer of planetary differentiation, but the lack of solid constraints on the sign and magnitude of equilibrium Ni isotope fractionation factors hampers its further development. We address this issue by studying Ni isotope fractionation between silicate minerals and melt using a combination of carefully selected natural samples and olivine crystallisation experiments.Mineral separates from xenoliths are used to determine the Ni isotope fractionation behaviour of pyroxenes, spinel, and garnet relative to olivine. Nickel isotope fractionation between olivine and orthopyroxene is negligible, whereas clinopyroxene shows large variability that does not reflect equilibrium. Spinel has a clear affinity for the heavier isotopes of Ni relative to olivine; garnet has the lightest Ni isotope composition at equilibrium. The key parameter that dictates the sign and magnitude of Ni isotope fractionation during partial melting and crystallisation, however, is the olivine–melt fractionation factor. We present data for a natural basalt that contains olivine phenocrysts in chemical equilibrium with the host glass, and furthermore employ olivine crystallisation experiments in a 1-atmopshere furnace. Although the experiments invariably suffer from Ni loss to the Pt wire used to suspend the experiments in the furnace, these effects were carefully considered and quantified. The experiments limit the olivine–melt Ni isotope fractionation factor to lie between zero and slightly negative, which agrees very well with the natural datum, and we derive a best estimate value for Δ60/58NiOl–melt of −0.142 ± 0.031 ‰ at 1000 K. Hence, olivine has a subtle but clearly resolvable affinity for the lighter isotopes of Ni relative to basaltic melt. The implication is that equilibrium partial melts of mantle peridotite should have a slightly heavier Ni isotope composition than their source. Available Ni isotope data for mid-ocean ridge basalts show some overlap with modelled partial melts but extend to notably lighter Ni isotope compositions, potentially reflecting source heterogeneity or diffusive fractionation during melt transport.

An inventory of UK mineral resources suitable for enhanced rock weathering

Enhanced Rock Weathering (ERW), a technology based on amending soils with crushed calcium- and magnesium-rich silicate minerals has substantial CO2 removal potential. Evaluation of the available resources of these minerals and current production capacity is crucial for early-stage deployment of this approach. A robust understanding of the potential limitations in exploiting these resources is also required to ensure the scalability of ERW. This paper provides a spatial inventory of basic silicate rock resources in the UK along with current production capacity and permitted reserves. We also integrate spatial data to assess the potential environmental and social impacts of current rock extraction. 68 active and 100 inactive quarries were identified within outcrops of basic silicate rocks which are mainly distributed in Northern Ireland and in the central belt of Scotland. 14.8 Mt yr−1 of basic silicate rock are estimated to be extracted from which up to 3.7 Mt yr−1 of basic silicate waste fines is estimated to be produced which may be available for ERW in the UK. 490 Mt of permitted reserves is associated with active and inactive queries. Spatial distribution of artificial alkaline minerals including Construction and Demolition Wastes (CDW) and legacy slags in the UK have also been included in the inventory. Transport distances are calculated between all resources and the UK's croplands where these materials may be applied for ERW. The relative appropriateness of the UK's croplands for CDR are also calculated based on their proximity to mineral resources and climate parameters controlling the rate of EW.

A feasible strategy for depressant-free flotation separation of siderite from magnesiohornblende using a highly selective collector

At present, efficient separation of siderite from Mg-Fe-Al-bearing silicate minerals, especially magnesiohornblende, by froth flotation using conventional collectors is difficult because they have similar surface properties. In this work, polyoxyethylenated laurylamine with five oxyethylene units (POE-5 laurylamine) was used as a magnesiohornblende collector for rejecting magnesiohornblende from siderite effectively during reverse flotation. Batch flotation tests illustrated that POE-5 laurylamine exhibited an outstanding collecting capacity and a high selectivity for the magnesiohornblende flotation rather than the siderite flotation. Much better floatability of magnesiohornblende than siderite was attributed to the larger amounts of POE-5 laurylamine adsorbed onto magnesiohornblende, as demonstrated by XPS results. FTIR and zeta potential measurements further revealed that the combination of hydrogen bonding and electrostatic attraction caused POE-5 laurylamine to strongly attach on the surface of magnesiohornblende compared to siderite, which favored the selective flotation of magnesiohornblende. Consequently, the efficient depressant-free flotation separation of siderite and magnesiohornblende was realized with 0.30 mM POE-5 laurylamine at pH 6.35, in which 92.88% of magnesiohornblende was effectively removed, combined with a high siderite recovery of 95.44% in the flotation concentrate. Therefore, POE-5 laurylamine can be chosen as a potential collector for efficiently recovering siderite from magnesiohornblende during reverse flotation.

Environmentally benign approach to formulate nanoclay/starch hydrogel for controlled release of zinc and its application in seed coating of Oryza Sativa plant

Improper use of conventional fertilizers has been linked to adverse effects on soil nutrient levels. To mitigate the negative impact of surface feeding fertilizers and reduce environmental pollution, a new type of seed coating material has been developed to provide nutrients in close proximity to the growing seed. In this study, a biodegradable seed coating film encapsulating micronutrients was fabricated by incorporating montmorillonite into a starch matrix using the melt processing technique. The dispersion of montmorillonite within the starch matrix was examined using X-ray diffraction (XRD), infrared spectroscopy (IR), and thermal gravimetric analysis (TGA). The results revealed polar interactions among starch, silicate layers, and the hydrogel. The XRD analysis demonstrated a shift in the diffraction peak (001) of the Zinc/montmorillonite/starch/glycerol nanocomposite film from 6.2° to 4.9°, indicating the successful intercalation of Zinc, starch, and glycerol. Furthermore, the inclusion of nanoclay improved the thermal stability of the resulting polymer composite and enhanced its ion exchange capacity, water retention, and micronutrient retention. The time-dependent release of zinc micronutrient from the montmorillonite/starch/glycerol composite film was investigated in Zn-deficient soil extract over a 20-day period. The composite film demonstrated extended release behavior of Zn2+. Subsequently, rice seeds were coated with the zinc-containing composite film using a dip-coating method, and their performance in Zn-deficient soil was evaluated. The results indicated that zinc-coated seeds exhibited improved germination percentage, vegetative growth, and yield compared to uncoated seeds.

Two-stage method recovery of metals from copper slag: Realize the resource utilization of all components

The recovery of metal from copper slag is of great significance to the resource utilization of copper slag and the sustainable development of copper smelting industry. Currently, hydrometallurgy is the traditional method used to recover mineral metals. However, as copper slag is a silicate mineral, the traditional acid-leaching process of metal results in the leaching of Si, resulting in the formation of silica gel. The silica gel can inhibit the recovery of metal while making metal difficult to separate from Si and causing filtration problems. This study proposed a two-stage method (evaporation + water washing) to selectively recover Fe and Zn from copper slag. Under the optimal conditions (evaporation: H2SO4 = 3 M; time = 60 min; temperature = 120℃; and liquid–solid ratio = 4; water washing: liquid–solid ratio = 5), the leaching efficiency of Fe, Zn, and Si reached 99.94 %, 97.40 %, and 0.15 % respectively. The separation mechanism was determined through mineral characterization (XRD, SEM, HRTEM-EDS, SAED, AFM, etc.) and the application of DLVO theory. It was found that H+ destroyed the Fe2SiO4 structure in copper slag during the evaporation stage, which promoted the release of Fe and Zn, forming soluble sulfate crystals. Simultaneously, evaporation increased the ion concentration, reducing the repulsive force between colloids, resulting in the aggregation and precipitation of silica gel into stable amorphous silica. After washing, soluble sulfate is dissolved in water. The recovered Fe can be processed to get red iron oxide (96.32 % purity), the Zn-containing solution can be recycled for electrolytic Zn, and the residue can be used to prepare geopolymer (52.47 MPa, 28 days). The two-stage method for recovering metals from copper slag is highly efficient and provides valuable insights into resource utilization of metals and Si in silicon-containing solid wastes.

Effect of natural organic residues on the adsorption capacity of layered silicate alumina clay

ABSTRACT Layered silicate clay can be modified with organic residues to enhance its adsorption properties and make it suitable for the removal of industrial hazardous substances in various industries. The modification process involves treating the clay with specific organic residues that can interact with and capture the targeted hazardous compounds effectively. Novel nano-composite adsorbing system was developed by inserting the products of powdered certain marine plant within the layers of layered silicate alumina clay (LS) through impregnation technique in order to form layered silicate alumina organic residue (LSOR). The SEM images showed clear agglomerations within the newly formed composite. Moreover, according to data obtained from Scherer equation extracted from XRD data all compounds under investigation were within the nanoscale. The newly prepared LSOR nano-composite showed a significant high adsorption capacity than the main reactants involved in the adsorbent formation process (LS and OR). The effects of various experimental factors were followed up using batch system, and kinetics and isotherms of CR dye adsorption were calculated accordingly. Adsorbent dosage, working temperature, and pH value all have a significant impact on CR removal percentage. Regarding the optimum conditions, the best temperature for CR adsorption onto LSOR is 40°C at a neutral pH medium. Adsorption isotherm study shows that the adsorption process could be followed up using Langmuir adsorption isotherm for OR while it follows Freundlich isotherm for LS adsorbent and can be followed up successfully by Temkin isotherm model in case of LSOR. Finally, field tests revealed that the LSOR nano-catalyst removed mixed dyes from industrial wastewater with a 93% performance. This outcome further solidifies the potential of LSOR nano-adsorbents as an eco-friendly solution for the treatment and reuse of industrial wastewater. It highlights the significant contribution of these new nano-adsorbents in promoting sustainable practices and addressing the challenges associated with industrial wastewater management.

Iron, copper, and rare earth minerals beneficiation in an IOCG type deposit

ABSTRACT The sample of the Sineqan mine (Arak, Iran), containing 16.5% Fe, 0.13% Cu, 475 ppm Ce, 446 ppm La, and 134 ppm Nd, was characterised and processed to investigate the possibility of separating iron, copper, and REE minerals. Microscopic studies showed that the main minerals in the sample include magnetite, hematite, goethite, specularite, pyrite, and chalcopyrite, while the gangue minerals consist of quartz, clay minerals, and carbonate minerals. The results of heavy liquid studies using Bromoform showed that by reducing the particle size from 1180 to 300 micrometre, 76.6% of iron and 72.76% of copper went into the heavy section, while 77.9% of REEs entered the light section. The magnetic separation experiments revealed that higher magnetic field intensity increased the recovery of iron, copper, and REEs with no separation between them. In summary, the results indicate that REEs are primarily present in the light section due to their association with sphene silicate mineral, and gravity separation demonstrated superior performance in terms of both recovery and selectivity. The results of this research are significant for the processing of iron oxide-type deposits that contain copper and REEs.

Study of Mechanical Properties of Silicate Minerals by Molecular Dynamics Simulation

Study of Mechanical Properties of Silicate Minerals by Molecular Dynamics Simulation

The role of magmatic-to-carbohydrothermal processes in rare earth mineralization in Hogenakkal carbonatites, India

The Paleoproterozoic Hogenakkal complex (India) consists of silicate-rich-, silicate-poor calcite carbonatite (carbonatite-I and II) and clinopyroxenite emplaced in granulite country rocks. Carbonatite-I contains abundant clinopyroxenite and K-feldspar pegmatite xenoliths. Silicate minerals are the primary governing factors in the formation of a distinctive lithology-specific REE mineralization. Carbonatite-I consists of magmatic Mg-Fe-Sr-bearing calcite (Cal-1), and REE-poor apatite (Ap-1) together with minor REE-rich apatite (Ap-2). The interaction of the carbonatite-forming magma with the clinopyroxenite and K-feldspar pegmatite xenoliths releases K, Al, and Si, forming phlogopite and pargasite-edenite. The late-magmatic carbonatite-II consists of Sr-rich calcite (Cal-2), Ap-2 and minor Ap-1. The carbohydrothermal REE-mineralization in both the carbonatites is induced by a magma-derived fluid dominated by REE, OH−, CO32−, and SO42−. The high modal abundance of silicate minerals and the continuous leaching of Si and Al from clinopyroxene, K-feldspar xenocrysts, and phlogopite by REE-enriched fluid facilitated the formation of allanite-(Ce) and actinolite in carbonatite-I. In contrast, in the silicate-poor carbonatite-II, the same fluid with low Si-saturation resulted in monazite-(Ce) + celestine-baryte±strontianite precipitation. The carbohydrothermal fluid is also responsible for the alteration of apatite to monazite-(Ce) by a dissolution-reprecipitation mechanism releasing fluorine. Consequently, localized crystallization of F-rich hydroxylbastnäsite-(Ce) is common in carbonatite-II. Complex intra-grain compositional and textural variations of monazite-(Ce) and hydroxylbastnäsite-(Ce) suggest further interaction of these minerals with evolving fluid. The waning phase of the carbohydrothermal activity is marked by an assemblage consisting of pure calcite (Cal-3) + quartz±magnetite in carbonatite-I. The Ba-Sr-REE mineralization and the overall mineral assemblages of the Hogenakkal carbonatites represent a transition from a magmatic to a carbohydrothermal stage.

Pretreatment of Carbon Steel with Hybrid Film Modified with Different Natural Inhibitors (Garlic and Cocoa)

One way to protect carbon steel from corrosion is through pretreatment and corrosion inhibitors, such as the use of silane layers that can protect against corrosion. In this study, the corrosion resistance of the tetraethyl orthosilicate/3-glycidoxypropyltrimethoxysilane hybrid film modified with garlic peel powder or cocoa shell powder on carbon steel was evaluated. By electrochemical impedance spectroscopy (EIS) it was observed that the incorporation of inhibitors promoted higher values of impedance modulus compared to the bare metal substrate or in the absence of inhibitor, and the concentration of 1.77 g/L provided the best performance for both natural inhibitors. The Fourier transform infrared spectroscopy showed that the addition of inhibitors to the hybrid film promoted better hydrolysis in the formation of the films. By the scanning electron microscopy and energy dispersive spectroscopy it was noted that there was the formation of the hybrid film on the metal surface, and the insertion of the inhibitor to the silane film enabled the formation of grains that precipitate from the deposition of the inhibitor on the substrate surface. The scanning vibrating electrode technique shows that the inhibitors improved corrosion resistance of the hybrid film, corroborating with the EIS analysis. The contact angle shows that the presence of the inhibitor in the silane film makes it less hydrophilic. The roughness profile shows that the hybrid film with cocoa has the highest roughness represented by a higher average value of average roughness (Rz).

Comprehensive influence of silane layer and interfacial thermo-mechanical effect on joining mechanism of silane pretreated Al/CFRP FSLW joint: FEA and experiment

Al/CFRP composite structure has the advantage of lightweight and high specific strength, making it a promising material for aviation, railway, and automotive applications. Silane coupling pretreatment is a chemical surface pretreatment method that can improve the mechanical properties of the Al/CFRP friction stir lap welding (FSLW) joint. To further investigate the strengthening mechanism of silane-treated Al/CFRP FSLW joint, a 6061-T6 Al/CF-PA66 FSLW experiment was carried out and the finite element analysis (FEA) was used. The thermophysical properties of semi-crystalline resin during the welding process were also considered. The joining mechanism of silane surface pretreated Al/CFRP FSLW joints was further revealed by comparing the changes in interface morphology, temperature, stress, and mechanical properties. The results indicated that the silane coupling agent forms a silane film by an Al-O-Si chemical bond at the interface. The silane film can enhance the Al/CFRP interface's tightness and reduce interfacial defects. The FSLW process affected the joint morphology and mechanical properties through interfacial temperature and stress, which were decided by welding parameters and thermophysical properties of the resin. By adjusting the thermal-mechanical effect of the Al/CFRP interface, defects can be reduced and the joining force can be improved. According to the analysis of interfacial chemical bonds and mechanical properties, the introduction of silane film enhances the hydrogen bond between Al and resin and thus enhances the mechanical properties of the interface. This study provides a new method for revealing the strengthening mechanism of silane-pretreated FSLW Al/CFRP joint.

Biocompatible organic coating fabrication via polymer/clay nanocomposites: Evaluation of mechanical improvements

AbstractThis study focuses on achieving mechanical enhancements in biocompatible organic coatings. A solvent‐based method is employed to produce biocompatible nanocomposites using polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT) as constituents to achieve this objective. Subsequently, the nanocomposites are spin‐coated onto a glass substrate, resulting in smooth and defect‐free films with a thickness of 5 μm. Through instrumented‐indentation testing, it is observed that BNT reinforcement leads to significant improvements in mechanical properties. Specifically, the addition of 0.5, 1, and 5 wt% of BNT in PVP results in enhancements of 105%, 77%, and 430% in elastic modulus, respectively, while hardness is improved by 166%, 211%, and 448%, respectively. The considerable improvements in the composite modulus cannot be adequately explained by assuming perfect adhesion between the constituents of the composite (as suggested by the Halpin–Tsai model) or by considering the contributions from the interface/network of silicate layers (as proposed by the Modified Halpin–Tsai model). Instead, the significant enhancements in hardness and modulus values are primarily attributed to a notable increase in the BNT volume fraction, ranging from 4 to 9 times, occurring under the Berkovich tip due to the aggregated silicate layers. The findings highlight the role of aggregated silicate layers in enhancing both hardness and modulus and contribute to the development of advanced biocompatible coatings with improved mechanical properties.Highlights Enhanced mechanical properties in biocompatible coatings. Biocompatible nanocomposites of polyvinylpyrrolidone (PVP) and bentonite nanoclays (BNT). Spin‐coated nanocomposite films on glass: smooth, defect‐free, 5 μm thick. BNT reinforcement boosts elastic modulus and hardness of PVP. Aggregated silicate layers under compression drive substantial mechanical improvements.

Enhancing the carbonation of γ-C2S through MgCl2 incorporation

With the growing awareness of CO2 emissions reduction in the cement industry, minerals like γ-C2S with lower calcium content and formation temperatures have shown potential as sustainable alternatives to ordinary Portland cement. Although γ-C2S possesses considerable carbonation reactivity, incorporating additives can further optimize its carbonation hardening performance. This study investigated the effect of different dosages of internally incorporated MgCl2 on the carbonation behavior of γ-C2S. Test results demonstrated that incorporating 1.87 % MgCl2 led to the maximum compressive strength and CO2 uptake. The compressive strength and CO2 uptake following 24 h of carbonation increased from 63.2 MPa and 18.23 % to 84.2 MPa and 23.95 %, respectively. XRD and TG analyses indicated that Mg2+ promoted the transformation of amorphous calcium carbonate into more stable crystalline calcite and the formation of magnesium calcite and nesquehonite. SEM imaging revealed that the generated carbonation products tightly filled the pores, enhancing the compactness and strength. However, excessive MgCl2 coating on particle surfaces hindered further carbonation. These findings reveal opportunities to further optimize the carbonation hardening properties of calcium silicate minerals and precisely tailor the morphology of calcium carbonate products for sustainable construction.

Hydrochemical Characteristics and Control Factors of Surface Water and Groundwater in Huainan Coal Mine Area

To clarify the hydrochemical characteristics and control factors of surface and underground water in Huainan mining area, 115 groups of groundwater and 30 groups of surface water samples were collected, and the hydrogeochemical characteristics of surface water and groundwater in Huainan mining area were analyzed. Additionally, the hydrochemistry evolution law was discussed by comprehensively using mathematical statistics, the Piper triangular diagram, Gibbs diagram, mineral stability field diagram, and ion ratio relationship, etc. The results showed that the groundwater and surface water in the study area were weakly alkaline, the dominant anion was HCO3-, and the dominant cations were Ca+ and Na+. The hydrochemical types of groundwater and surface water were dominated by HCO3-Ca type and HCO3-Ca·Na·Mg type, respectively. The hydrochemical composition of groundwater and surface water was mainly controlled by rock weathering, as well as by alternating adsorption of cations and evaporation concentration. Silicate and carbonate minerals were mainly dissolved in the water-rock interaction. The main ions such as Ca2+, Mg2+, and HCO3- came from the dissolution of carbonate rocks. The Cl-, SO42-, NO3-, and Ca2+ were affected by exogenous inputs caused by human activities. The chemical components of groundwater and surface water in Huainan coal mining area were affected by water-rock interactions and human activities, and groundwater was greatly affected by human activities.

Controlling the Fluorescence Behavior of Hydrophobic Pigments by Supramolecular Self-Assembling on Organic Layered Silicate Minerals.

This research focused on the supramolecular self-assembly of organic fluorescent molecules on organically modified layered silicate minerals to design and prepare layered nanocomposites with excellent fluorescence properties. Aromatic hydrocarbons are hydrophobic and poorly loaded on the hydrophilic surface of layered silicate minerals, but they are easily captured by an organically modified mineral surface. Montmorillonite (MMT) and saponite (SAP), typical 2:1 type layered silicate minerals with different octahedral cations, were modified with the cationic surfactant octadecyl trimethylammonium chloride (OTAC) and loaded with pyrene (an aromatic hydrocarbon dye) with different molar ratios to the cationic surfactant by supramolecular self-assembling to construct fluorescent nanocomposites. The effect of pyrene concentration and the octahedral cation of the 2:1 type layered silicate minerals on photoluminescence properties was investigated. The fluorescence spectra of the nanocomposites prepared under low pyrene concentrations showed two bands at around 400 and 470 nm, corresponding to the monomer and excimer emissions; the band intensity of the excimer shoots up with the increase of pyrene concentration, reflecting different contributions from monomer and dimer species and the formation of radical aggregates. The excellent heat resistance of the layered silicate structure can effectively protect pyrene molecules from external environmental influences.

Mantle Metasomatism and REE Enrichment in the Genetic Source of the Dalucao Carbonatite Complex (Sichuan, China): Insights from Elemental Geochemistry and In-Situ Sr Isotopes of Two Calcite Types

Abstract Carbonatites possess the highest rare earth element (REE) concentrations among all magmatic rocks, yet the mechanisms governing the enrichment of REEs in carbonatites remain enigmatic. Carbonatite-hosted calcites provide crucial mineralogical and geochemical insights into addressing this matter. In this study, we present a dataset comprising major and trace elemental geochemistry, as well as in-situ Sr isotopic data, for two types of calcites from the Dalucao carbonatite complex in Sichuan Province, China. Our primary objective is to shed light on the origin of fertile carbonatites. These calcites are believed to have originated at different stages of carbonatitic evolution. Type I calcites, characterized by a euhedral granular texture and a homogeneous surface, crystallized at the early stage of carbonatite magmatism. In contrast, type II calcites, closely associated with bastnäsite in a paragenesis, formed within a fluid setting of hydrothermal overprinting. Both calcite types exhibit highly radiogenic (87Sr/86Sr)i ratios, ranging from 0.7059 to 0.7060 for type I calcites and 0.7059 to 0.7068 for type II calcites. The high Sr concentrations (3646–7315 µg/g for type I calcites and 6566–13,427 µg/g for type II calcites) and uniform Pb isotopic compositions (206Pb/204Pb ratios of 18.23–18.27) in the Dalucao calcites refute the hypothesis of crustal assimilation as their genetic source. Instead, the radiogenic Sr isotopic compositions suggest that subducted marine sediments have contaminated the lithospheric mantle that generated the carbonatitic magma. Mineralogical evidence indicating the presence of abundant silicate minerals in the Dalucao carbonatites, combined with a compilation of published C-O isotopic data, suggests that these carbonatites may have resulted from low-degree partial melting (melting proportion <1%) of a metasomatized lithospheric mantle. Finally, we propose a comprehensive model for REE enrichment in the Dalucao carbonatite complex and explore the significance of tectonism in the genesis of fertile carbonatites.

Leaching tests reveal fast aluminum fluoride release from ashfall accumulated in La Palma (Canary Islands, Spain) after the 2021 Tajogaite eruption

Leaching tests conducted on fresh ashfall samples taken soon after the onset of the 2021 Tajogaite eruption occurred at the Northwest flank of the Cumbre Vieja Volcanic Ridge in La Palma (Canary Islands) have revealed relevant geochemical trends which have important environmental significance and practical implications. The ashfall deposited on most of the island during the eruptive episode (9/19/2021–12/13/2021) contains, in addition to common constituents in volcanic tephra (e.g. volcanic glass, silicates like olivine, amphibole or pyroxene, magnetite, etc.) a significant amount of very fine-grained (diameter range of 10–500 μm) crystals of highly soluble salts like AlF3, NaCl, KCl or CaSO4. These salts likely crystallized at high temperature by interaction of acid volatile phases (e.g., HF, HCl, SO2) with volcanic glass and silicate minerals during the ascending flow of the eruptive plume, though some adsorption of marine aerosols on ash surfaces during the subsequent descending flow and transport to more distal areas could have also taken place. The dissolution of these salts in the leaching tests (conducted with ultrapure distilled water during 90 min) reveals a fast release of important amounts of F−, Cl− and SO42− as major anions, and Al3+, Na+, K+, Ca2+, Mg2+ and Si4+ as major cations, in addition to minor amounts of trace metals like Mn2+, Zn2+, Ba2+ or Sr2+. The release of F− and Al3+, both potentially toxic and travelling together as aluminum fluoride species (AlF3, AlF2+, AlF4−) is particularly noteworthy and represents a potential threat for the environment (including soils, surface waters or groundwater existing beneath the ashfall layers covering the island) as well as for food safety (e.g. banana plantations) and/or human health (exposure to F- or Al-contaminated water). On the other hand, the tephra does not represent an environmental hazard as regards to other toxic elements traditionally reported for ashfall released in other volcanic eruptions, such as As, Pb, Hg or Se, which were always close to or below the limit of quantification. Besides, the Tajogaite 2021 ashfall shows a significant acid-neutralizing capacity as a result of the partial dissolution of volcanic glass in the F-rich solutions. This study presents a discussion of geochemical and mineralogical controls on element mobility during ashfall/water interaction in the environment which may be worth considering in any future restoration or land management plans for the island.

Physical Characteristics and Controlling Factors of Coal Gas Reservoir in Pingdingshan No. 10 Coal Mine

The physical properties of coal reservoirs are the main restrictions to exploration and development of Coalbed methane (CBM). The study of the physical characteristics of coal reservoirs and their controlling factors is of great significance to the safe and efficient development and utilization of CBM resources in the mining area. The Pingdingshan No. 10 coal mine was chosen for this study because of its better gas production effect at the test wells. The reservoir properties of the main coal seams of the No. 10 coal mine were tested and analyzed to comprehensively evaluate the reservoir properties, and the physical characteristics and controlling factors of the coal reservoir in Pingdingshan No. 10 coal mine were studied. The results indicate the following: (1) The gas content and methane purity of the No. 4 coal seam were significantly higher than the No. 2 seam, and therefore they have better development potential than the No. 2 seam. (2) The average adsorption time of the No. 2 coal seam was less than that of the No. 4 seam, making it easier to reach the peak production capacity of CBM wells in the short term, but was not conducive to long-term stable production of CBM. The Langmuir volume of the No. 2 coal seam samples was significantly greater than for the No. 4 coal seam; however, the No. 4 coal seam contains about three times the amount of gas in the No. 2 seam. (3) All three coal seams have high porosity, which was favorable for large amounts of CBM adsorption and storage. Micropores predominated; transitional pores were less frequent, and a few mesopores occurred; macropores were the least common. Samples from the No. 4 seam contained the highest proportion of micropores. (4) Organic pores were common in all the coal samples, with pore diameters not more than 30 µm, mainly concentrated between 50.5 and 1000 nm. Microfractures with apertures less than 70 nm were relatively frequent, mainly in the 50–65 nm range. A large number of the nanoscale microfractures were curved or jagged. (5) Fractures in the No. 2 and No. 4 coal seam samples with widths of 50 nm to 20 µm were more developed, and many were filled with kaolinite, quartz, and other minerals. (6) The samples contained mostly layered silicate minerals (kaolinite), with hard granular minerals (quartz) next, and a very small quantity of iron-type minerals, such as siderite and pyrite in dendritic form. The results of this study can provide a reference basis for the large-scale development and utilization of subsequent CBM wells.

Expression of stathmin in asbestos-like fibers-induced mesothelioma: A preliminary report.

Mesothelioma is strongly associated with exposure to asbestos fibers, however, recent studies have also linked exposure to "naturally occurring asbestos" fibers with this disease. Fluoro-edenite, a silicate mineral found in the southeast of Biancavilla (Sicily, Italy), has been identified as a potential risk factor for mesothelioma. Unfortunately, this cancer often has a poor prognosis, and current diagnostic and prognostic biomarkers are inadequate. Histological subtype, gender, and age at diagnosis are the most significant parameters for mesothelioma. Stathmin, a cytosolic protein that regulates cell growth and migration and is overexpressed in many human malignancies, has not yet been linked to mesothelioma survival or clinical-pathological variables. The aim of this study was to investigate the immunohistochemical expression of stathmin in ten mesothelioma tissue samples with available clinical and follow-up data. Paraffin-embedded tissue samples from ten mesothelioma patients were processed for immunohistochemical analyses to evaluate stathmin expression. Our findings suggest that stathmin overexpression is associated with shorter overall survival in patients with mesothelioma. Furthermore, stathmin expression was significantly correlated with the survival time of mesothelioma patients. Our results suggest that stathmin expression may serve as a potential prognostic biomarker for mesothelioma. This biomarker could be used to promptly identify patients with poor prognosis and to guide clinicians in the selection of treatment options.