Mineral Growth Research Articles

Polycyclic aromatic hydrocarbon (PAH) remediation during vermicomposting and composting: Mechanistic insights through PAH-budgeting.

Knowledge on the mechanism of earthworm-induced removal of polycyclic aromatic hydrocarbons (PAH) in vermicomposting systems and interaction with nutrient mineralization and microbial growth is scarce in literature. Moreover, the PAH accumulation capacity of Eudrilus eugeniae has not been studied. This research, therefore, investigates the apportionment dynamics of 13 PAH compounds in aerobic composting and vermicomposting (Eisenia fetida and E. eugeniae) systems using novel budget equations. The PAH removal efficiency of vermicomposting was significantly higher (2-threefold) than composting with concurrent microbial augmentation (p < 0.01). However, the 4-6 ring compounds reduced more significantly (30-50%) than the 3-ring PAHs (p < 0.01), and E. eugeniae was an equally competitive PAH-accumulator compared to E. fetida. The budget equations revealed that although the bioaccumulation capabilities of earthworms were retarded due to PAH exposure, earthworms facilitated PAH-immobilization in decomposed feedstock. A marked increase in bacterial, fungal, and actinomycetes proliferation in PAH-spiked vermibeds with parallel removal of the PAHs indicated that earthworm-induced microbial enrichment plays a vital role in PAH detoxification during vermicomposting. Correlation analyses strongly implied that earthworm-driven mineralization-humification balancing and microbial enrichment could be the critical mechanism of PAH remediation under vermicomposting.

CO2 Mineralization by MgO Nanocubes in Nanometric Water Films.

Water films formed by the adhesion and condensation of air moisture on minerals can trigger the formation of secondary minerals of great importance to nature and technology. Magnesium carbonate growth on Mg-bearing minerals is not only of great interest for CO2 capture under enhanced weathering scenarios but is also a prime system for advancing key ideas on mineral formation under nanoconfinement. To help advance ideas on water film-mediated CO2 capture, we tracked the growth of amorphous magnesium carbonate (AMC) on MgO nanocubes exposed to moist CO2 gas. AMC was identified by its characteristic vibrational spectral signature and by its lack of long-range structure by X-ray diffraction. We find that AMC (MgCO3·2.3-2.5H2O) grew in sub-monolayer (ML) to 4 ML thick water films, with formation rates and yields scaling with humidity. AMC growth was however slowed down as AMC nanocoatings blocked water films access to the reactive MgO core. Films could however be partially dissolved by exposure to thicker water films, driving AMC growth for several more hours until nanocoatings blocked the reactions again. These findings shed new light on a potentially important bottleneck for the efficient mineralization of CO2 using MgO-bearing products. Notably, this study shows how variations in the air humidity affect CO2 capture by controlling water film coverages on reactive minerals. This process is also of great interest in the study of mineral growth in nanometrically thick water films.

Surface analysis of (Ti,Mg)N coated bone fixation devices following the rabbit femur surgery.

Magnesium (Mg) enhances the bone regeneration, mineralization and attachment at the tissue/biomaterial interface. In this study, the effect of Mg on mineralization/osseointegration was determined using (Ti,Mg)N thin film coated Ti6Al4V based plates and screws in vivo. TiN and (Ti,Mg)N coated Ti6Al4V plates and screws were prepared using arc-PVD technique and used to fix rabbit femur fractures for 6 weeks. Then, mineralization/osseointegration was assessed by surface analysis including cell attachment, mineralization, and hydroxyapatite deposition on concave and convex sides of the plates along with the attachment between the screw and the bone. According to Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analyses; cell attachment and mineralization were higher on the concave sides of the plates from both groups in comparison to the convex sides. However, mineralization was significantly higher on Mg-containing ones. The mean gray value indicating mineralized area after von Kossa staining was found as 0.48 ±0.01 and 0.41 ±0.04 on Mg containing and free ones respectively. Similarly, Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) analyses showed that hydroxyapatite growth was abundant on the Mg-containing and concave sides of the plates. Enhanced mineralization and strong attachment to bone were also detected in EDS and SEM analyses of Mg-containing screws. These findings indicated that (Ti,Mg)N coatings can be used to increase attachment at the implant tissue interface due to accelerated mineralization, cell attachment, and hydroxyapatite growth.

Anomalous patterns of clay minerals in fault zones

The anomalous enrichment of clay minerals in fault zones is considered a key factor affecting the seismic behavior of faults, fault permeability, and mineralization. This process also weakens the rock strength and triggers deformation, instability, and geological disasters. Nevertheless, the geological factors affecting the growth and anomalous enrichment patterns of clay minerals in fault zones are not systematically understood. In this study, the anomalous enrichment patterns of clay minerals within 220 natural faults are investigated (detailed information can be found in Appendix A). The main geological factors and processes affecting the anomalous enrichment of clay minerals in fault zones are revealed. The main formation modes and occurrence forms of the clay minerals in fault zones are investigated. The anomalous patterns of clay minerals in fault zones are classified into four categories and eight types, i.e., the felsic anomaly category (illite type and kaolinite type), mafic anomaly category (chlorite type), ultramafic anomaly category (smectite type, serpentine + talc type, vermiculite type, and palygorskite + sepiolite type), and argillaceous anomaly category (mixed-layer type). The 220 case studies include different types of faults and fault rocks. Thus, the results are promising for a wide range of engineering geological applications, e.g., analysis of fault activity and permeability changes and studying the genetic mechanisms of geological disasters near faults.

Managing Mineral Growth in Early Modern Mining

Managing Mineral Growth in Early Modern Mining

Вплив доз мінерального удобрення та стимуляторів росту на продуктивність гібридів соняшнику

Вплив доз мінерального удобрення та стимуляторів росту на продуктивність гібридів соняшнику

Experimental and theoretical investigations of stable Sr isotope fractionation during its incorporation in aragonite

Strontium partitioning and isotope fractionation between aragonite and fluid have been determined experimentally at low values of the fluid saturation state (Ω) with respect to this mineral (1.1 ≤ Ωaragonite ≤ 2.2), and the measured isotope fractionation has been compared with the results of first-principles simulations. For the latter, Density Functional Theory (DFT) was used for estimation of the equilibrium Sr isotope fractionation between aragonite and Sr2+(aq). The obtained results suggest that, for values of Ωaragonite close to unity, the apparent distribution coefficient of Sr in aragonite (DSr,aragonite=XSrCO3XCaCO3(CaSr)fluid) exhibits values higher than one that rapidly decrease at increasing aragonite growth rate. Under equilibrium conditions (i.e. Ωaragonite=1) a DSr,aragoinite value of 2.7 can be extrapolated. Additionally, for aragonite growth rates rp ≤ 10−8.0±0.2 (mol/m2/s) the Sr isotope fractionation between aragonite and the fluid (i.e. Δ88/86Sraragonite-fluid) shows a constant value of −0.1±0.05‰, whereas it decreases to −0.40‰ when the growth rate increases to 10−7.7(mol/m2/s). The surface reaction kinetic model (SRKM) developed by DePaolo (2011) has been used to describe the dependence of DSr,aragonite and Δ88/86Sraragonite-fluid on mineral growth rate. In this model the best fit for DSr,aragonite and Δ88/86Sraragonite-fluid were 4 and −0.01‰, respectively, whereas the kinetic isotope fractionation factor for Δ88/86Sraragonite-fluid was −0.6‰. The results of first-principles calculations yield an equilibrium Sr isotope fractionation factor of −0.04‰ which is in excellent agreement with the experimental value of the present study. These results are the first experimental measurements of Sr isotope fractionation during inorganic aragonite precipitation as a function of growth rate and the first DFT calculations of Sr equilibrium fractionation in the aragonite-fluid system. The results of this study provide new insight into the mechanisms controlling stable Sr isotope composition in aragonite, which has implications for using Sr isotopes for paleo-reconstructions of natural archives, particularly those of abiogenic origin.

In-situ redox conditions in hydrothermal diamond-anvil cell experiments using various metal gaskets

Hydrothermal diamond-anvil cells (HDACs) have been widely used in various research fields since they were introduced in 1993. Unlike temperature (T) and pressure (P), the redox states of the samples in HDAC experiments were poorly controlled or measured; they were usually estimated by observing the reduction/disappearance of redox-sensitive mineral(s) (e.g., Mo metal) and corresponding formation and growth of such mineral(s) (e.g., MoO2) without in-situ redox measurement. In this study, we demonstrated the generation of H2 during experiments using various metal gaskets, including inert (Re) and chemically more reactive metals (Ni, Co, Mo, and W), in the pure H2O system under various P-T conditions. A technique for quantitative Raman spectroscopic analysis of H2 in HDAC is designed. Based on this technique, the oxygen fugacity (fO2) values of Mo-MoO2 buffer at the experimental P-T conditions were then calculated from these measured H2 pressures. We demonstrated that steady-state redox control can be maintained at a fixed T between 400 and 500 °C in HDAC experiments using a Mo gasket for durations of up to two hours and for those using a Re gasket with an additional Mo rod in the sample between 400 and 800 °C for durations of up to 90 min, regardless of the considerable changes in sample pressure. This demonstration was established by the balance between the rates of H2 generation and H2 loss from the sample chamber. The loss of H2 enhanced the consumption of H2O and therefore reduced the sample pressures during the experiments.We believe that hydrogen contents in every HDAC experiment, which attempt to control the redox state, need in situ measurement, then estimate the real redox state and compare it to thermodynamic equilibrium prediction. To enhance in situ redox control and measurements, modifications of HDAC are required for improving the quantitative Raman spectroscopic analysis technique in both sensitivity and accuracy.

Understanding Hierarchical Structure Construction Strategies and Biomimetic Design Principles: A Review

Organisms use gene and cell engineering to tailor the mineralization process and synthesize structure composites with special functions and favorable properties. This spurs scientists to design functional materials based on learning from nature. Herein, a systematic review of the biomimetic synthesis and hierarchical structure design of calcium carbonate–based minerals is presented. First, biomimetic synthesis strategies, including additive‐induced, template‐oriented, and gel‐mediated routes to direct the construction of the hierarchical structure, are reviewed. The molecular‐recognition technique and directional assembly pathway are then summarized to precisely describe the interactions between inorganic minerals and organic matter, and direct the mineral growth. Next, the underlying mineralization mechanisms governing the evolution of the complex morphology and structure are discussed. Nonclassical pathways that control mineral growth, including the theories of the amorphous phase, oriented attachment, mesocrystal formation, and liquid precursor, are concluded. Finally, herein, the applications of calcium carbonate–based minerals are discussed. Unique hierarchical structure endows minerals with special functions, including optical performance, biomedical applications, and environmental and ecological restoration. Overall, in this report, the biomimetic synthesis of calcium carbonate–based minerals is reviewed, covering the fundamental principles, construction of the hierarchical structure, underlying mechanisms of mineral growth, and functional designs.

Zeolitization of a devitrified high-silica rhyolitic tuff producing dachiardite: A comparison of hydrothermal experiments with the corresponding reaction progress modeling

We have investigated the hydrothermal alteration of polished wafers of tuff reacted with dilute groundwater at 90 °C, 150 °C and 250 °C for time periods ranging from 2 months to nearly 1 year. The polished rock wafer provided a convenient surface upon which to grow secondary minerals. Reaction product minerals were identified and analyzed at the end of each experiment and, along with the evolving fluid chemistry, were compared to computational results from corresponding reaction progress models.At 250 °C after a few months the run products in the experiment were dominantly the mordenite group zeolite minerals: dachiardite (a Ca-rich variety) and mordenite, itself. At 150 °C after a few months of reaction only minor amounts of clay were produced, but after 1 year of reaction at this temperature both mordenite group zeolites were again present. At this lower temperature the total amount of run products was much smaller. At 90 °C no run products could be seen at all, even after 1 year of reaction. The reaction progress modeling results for reaction products were in good relative agreement with the experimental results.The higher the temperature, and the greater the extent of reaction, the better the fluid phase modeling results agreed with the actual experimental results. At 250 °C the agreement was good for nearly all elements. At 150 °C agreement for pH, SiO2, Na and K were good, but less good for Al, Mg and Ca, especially after short reaction times. At 90 °C agreement for pH, SiO2 and Na was reasonable, but not as good for the other elements, and all modeling results for short reaction times did not match experimental results as well as the longer time results.This study demonstrates that reaction progress modeling provides a powerful tool for predicting hydrothermal rock-water interactions, with results expected to improve, as more and better quality thermodynamic and kinetic data become available and as process-oriented simulators incorporate better and more comprehensive sub-models for mineral dissolution and growth.

Lettuce in Monoculture or in Intercropping with Tomato Changes the Antioxidant Enzyme Activities, Nutrients and Growth of Lettuce

Intercropping systems are a widely used agricultural practice by smallholder farmers to enhance food security and to use natural resources more efficiently. The objective of this study was to evaluate two lettuce cvs under an intercropping system. Enzymatic growth, yield and economic benefit were evaluated. The experiment was carried out from August to February in Jaboticabal (Brazil) using tomato plants as a main crop and Lucy Brown and Vanda cvs of lettuce as secondary crops. The catalase, superoxide dismutase and peroxidase activity of lettuce plants was analyzed. Mineral nutrient content, growth, yield parameters and commercial economic benefit were measured. Significant differences in stress and activity enzymatic indicators were found versus cultivars of lettuce. The loss of abiotic factors such as radiation or its effect on enzymatic stress indicators was greater than its effect on yield. Yield loss in the intercropping systems was different for each cultivar system, with cv Lucy Brown showing greater yield loss than cv Vanda. Economic benefit was only found for the Vanda lettuce cv. Although the benefits of intercropping have been demonstrated as very appropriate cultural management, the choice of cultivars involved might be the determining factor for the agronomic success of the system.

Nacre-Mimetic Nanocomposite Aerogels with Exceptional Mechanical Performance for Thermal Superinsulation at Extreme Conditions.

Thermal protection under extreme conditions requires materials with excellent thermal insulation properties and exceptional mechanical properties to withstand a variety of complex external stresses. Mesoporous silica aerogels are the most widely used insulation materials due to their ultralow thermal conductivity. However, they still suffer from mechanical fragility and structural instability in practical applications. Herein, we report a nacre-mimetic nanocomposite aerogel synthesized via in-situ growth of inorganic minerals in a lamellar cellulose nanofibrous network. The multiscale structural adaptation of the inorganic-organic components endows nanocomposite aerogels with rapid configuration recovery during ambient pressure drying. The resulted aerogels show ultralow thermal conductivities (17.4mW m-1 K-1 at 1.0 atm). Our aerogels also integrate challenging mechanical properties, including high compressive stiffness to resist deformation under the pressure of an adult, superelasticity to prevent static and dynamic stress cracking even under the crushing of a vehicle (1.6 t), and high bending flexibility to adapt to any surface. Moreover, they exhibit excellent structural stability under fatigue stress/strain cycles over a wide temperature range (-196 to 200°C).The combination of high thermal insulation performance and excellent mechanical properties offers a potential material system for robust thermal superinsulation under extreme conditions, especially for aerospace applications. This article is protected by copyright. All rights reserved.

Effect of organic mineral fertilizers and growth regulator on winter durum wheat crops under irrigation conditions in the Terek-Sulak subprovince of the republic of Dagestan

The current study has been carried out to determine the effect of mineral and organic mineral fertilizers, as well as a growth regulator on the productivity of promising winter durum wheat varieties, under irrigation conditions of meadow-chestnut heavy loamy soil in the Terek-Sulak subprovince of the Republic of Dagestan. In 2019–2021 there were laid on two trials on the experimental plot. In the first case, there were studied four variants of the effect of fertilizers on the productivity of promising varieties ‘Krupinka’ (control), ‘Krucha’, ‘Odari’ under irrigation conditions. There was used ammophos (background), 65 kg/ha a.i. under plowing; ammophos (background), 65 kg/ha a.i. for plowing + Polydon bio universal, 0.5 l/ha in the tillering phase + Polydon bio universal, 0.5 l/ha in the earing phase; ammophos (background), 65 kg/ha a.i. under arable land + ammonium nitrate 150 kg/ha in spring tillering + Polydon bio universal 0.5 l/ha in the tillering phase + Polydon bio universal 0.5 l/ha in the earing phase; ammophos (background), 65kg/ha a.i. for plowing + ammonium nitrate 150 kg/ha in spring tillering. In the second, three winter durum wheat varieties were treated before sowing with 0.5 l/t of Sprintalga and foliar top dressing was carried out in the spring tillering phase, in comparison with the control when seeds were treated with 10 l/t of the working liquid disinfectant Maxim KS. The conducted study has shown that the largest productivity of the studied winter durum wheat varieties was achieved in the third variant of the trial, where grain productivity of 8.36 t/ha was achieved for the variety ‘Odari’, the variety ‘Krucha’ was in second place with 7.91 t/ha of productivity, which was on 0.27 t/ha more than for the control variety ‘Krupinka’ and on 0.45 t/ha less than in the variety ‘Odari’. The use of a growth regulator has shown its significant effect on the grain productivity improvement. Seed treatment of winter durum wheat varieties and crops in the tillering phase with Sprintalgi had a positive effect on the growth, development, and improvement of grain yield. On average, over the years of research, the largest grain yield of 7.88 t / ha was obtained for the variety ‘Odari’, in the variant of seed and crop treatment with a growth regulator Sprintalgi. The productivity difference in the variant with seed treatment with Sprintalgi and with the working liquid treater Maxim KS was 0.67 t/ha for the variety ‘Odari’, 0.71 t/ha for ‘Krucha’ and 0.79 t/ha for ‘Krupinka’.

Direct use of original granular steel slag to prepare multi-phased clinker: Sintering mechanism and properties

Multi-phased sintering technology is an innovative process that directly utilize granular steel slag to calcinate cement clinker. In this study, we synthesized a type of multi-phased clinker with high fractions of original crude granular steel slag and investigated its sintering mechanism and properties. It is found that the diffusion of the molten liquid phase of granular steel slag to the surrounding area influenced the crystallization and growth of the clinker mineral, consequently, a gradient distribution high-ferrite multi-phased clinker was formed. Steel slag changed the clinker mineralogical composition and resulted in the ferrite phase reaching 18.07–28.09%. Laboratory tests showed that the multi-phased clinker with high content of steel slag was technically viable and still obtained exceptional properties. The grindability and soundness of multi-phased clinker were comparable to the ordinary Portland clinker, and the burnability was considerably higher than conventional raw meal. All of which suggested that this process was robust and provided more comprehensive theoretical basis for the industrial application.

Maximizing medical cannabis growth and quality: An evaluation of the effects of ecological water regeneration in greenhouse cultivation

The use of medical cannabis for therapeutic treatment of various medical conditions has gained popularity due to its pain-relieving, anti-inflammatory, and sleep-improving properties. In greenhouse and closed buildings cultivation, optimizing water and nutrient management is essential for achieving maximum yield and quality. Water quality used for irrigation is critical for cannabis plant growth and yield, as it affects mineral uptake. This study assesses the impact of an ecological water regenerator system, based on physical and electromagnetic principles, on the growth and quality of medical cannabis cultivated in a greenhouse. These techniques restore water quality to its optimal state, promoting optimal hydration and nutrition of medical cannabis plants. The results show that using the ecological water regenerator system significantly enhances mineral uptake and growth stimulation, improving water and nutrient management and enabling the supply of an optimal amount of water and nutrients to the plants. Consequently, this approach promotes vigorous and productive growth, indicating that incorporating an ecological water regenerator is an effective approach for optimizing and enhancing medicinal cannabis cultivation. Compared to bulk water, using regenerated water significantly improves cannabis plant growth, flower biomass, and THC levels while reducing water and fertilizer usage. This innovative system can achieve new standards of quality and performance in the sustainable cultivation of medical cannabis.

Leaf Mineral Contents and Growth Characteristics of Strawberry Grown in Aquaponic System with Different Growing Media in a Plant Factory

This study was aimed to determine the effects of grow media on the mineral contents of the leaves and growth characteristics of strawberry grown under aquaponics system in a plant factory. For aquaculture, 12 fish (Cyprinus carpio) (total weight, 2.0 kg) were raised in an aquaponics tank (W 0.7 m × L 1.5 m × H 0.45 m, 472.5 L) filled with 367.5 L of water at a density of 5.44 kg·m-3 and total 34 of strawberry seedlings were transplanted in the pots filed with 200 g of orchid stone, hydroball or polyurethane sponge in the growing bed (W 0.7 m × L 1.5 m × H 0.22 m) laid out with holly acrylic sheet (140×60 mm, Ø80) on the top of the system. The pH and EC of the aquaponic solution was ranged from 7.6 to 4.9 and 0.24－0.91 dS·m-1, respectively. The concentration of NO3-N was about 28% lower than that of the hydroponic standard solution, and K, Fe and B were 10, 27 and 3.8 times lower, respectively; however, the mineral contents of strawberry leaves were in the appropriate ranges with lower contents in the leaves grown with sponge media. The organic content (OM), nitrogen (N), phosphorus (P), and potassium (K) of the sludge were 61.5, 5.72, 8.92, and 0.24%, respectively. The leaf area, leaf number, and dry and fresh weights of shoot at 81 DAT were significantly higher in the hydroball, and the average number of fruits per plant was significantly higher in both the orchid stone and hydroball. There was no significant difference in the fresh and dry weights of fruits. Integrated all the results suggest that the orchid stone and hydroball media are more effective to utilize nutrients in solid particles of aquaponic solution, compared to the polyurethane sponge.

Assessing an aqueous flow cell designed for in situ crystal growth under X-ray nanotomography and effects of radiolysis products.

Nucleation and growth of minerals has broad implications in the geological, environmental and materials sciences. Recent developments in fast X-ray nanotomography have enabled imaging of crystal growth in solutions in situ with a resolution of tens of nanometres, far surpassing optical microscopy. Here, a low-cost, custom-designed aqueous flow cell dedicated to the study of heterogeneous nucleation and growth of minerals in aqueous environments is shown. To gauge the effects of radiation damage from the imaging process on growth reactions, radiation-induced morphological changes of barite crystals (hundreds of nanometres to ∼1 µm) that were pre-deposited on the wall of the flow cell were investigated. Under flowing solution, minor to major crystal dissolution was observed when the tomography scan frequency was increased from every 30 min to every 5 min (with a 1 min scan duration). The production of reactive radicals from X-ray induced water radiolysis and decrease of pH close to the surface of barite are likely responsible for the observed dissolution. The flow cell shown here can possibly be adopted to study a wide range of other chemical reactions in solutions beyond crystal nucleation and growth where the combination of fast flow and fast scan can be used to mitigate the radiation effects.

Cardiovascular Calcification Heterogeneity in Chronic Kidney Disease.

Patients with chronic kidney disease (CKD) exhibit tremendously elevated risk for cardiovascular disease, particularly ischemic heart disease, due to premature vascular and cardiac aging and accelerated ectopic calcification. The presence of cardiovascular calcification associates with increased risk in patients with CKD. Disturbed mineral homeostasis and diverse comorbidities in these patients drive increased systemic cardiovascular calcification in different manifestations with diverse clinical consequences, like plaque instability, vessel stiffening, and aortic stenosis. This review outlines the heterogeneity in calcification patterning, including mineral type and location and potential implications on clinical outcomes. The advent of therapeutics currently in clinical trials may reduce CKD-associated morbidity. Development of therapeutics for cardiovascular calcification begins with the premise that less mineral is better. While restoring diseased tissues to a noncalcified homeostasis remains the ultimate goal, in some cases, calcific mineral may play a protective role, such as in atherosclerotic plaques. Therefore, developing treatments for ectopic calcification may require a nuanced approach that considers individual patient risk factors. Here, we discuss the most common cardiac and vascular calcification pathologies observed in CKD, how mineral in these tissues affects function, and the potential outcomes and considerations for therapeutic strategies that seek to disrupt the nucleation and growth of mineral. Finally, we discuss future patient-specific considerations for treating cardiac and vascular calcification in patients with CKD-a population in need of anticalcification therapies.

Geochemical internal variations of Salem Dolerite dykes from Southern Granulite Terrane: Implications of petrogenetic processes in the dyke conduits

&#x0D; &#x0D; &#x0D; Salem dolerites were collected across the dyke from various parts of the studied area for identifying the differentiation process of magma in the conduits from the compositional profile. The thick dolerites show NNW-SSE, NE-SW, and NW-SE trends. The studied dyke shows systematic composition increasing and decreasing in the chilled margin and centre of the dyke as the texture and concentration of plagioclase and pyroxene increase. Chilled margins show microcrystalline to intersertal, and the centre of the dyke show sub ophitic textures. The compatible oxide MgO, element Ni and the Mg number (100Mg/(Mg+FeT)) increased and the incompatible oxides TiO2, P2O5, and elements Zr decreased from the chilled margin to the centre of the dyke in the compositional profile show reverse fractionation trends (opposite to fractional crystallization) in the studied dykes except for Seeliyampatti dyke. The Seeliyampatti dolerites show opposite compositional variations indicating a normal fractionation trend from the other dykes of the study area. The reverse fractional trends in dykes resulting in the progressive increase of cumulate minerals growth against the dyke wall called the «cumulate process», however, the normal fractional trend in Seeliyampatti resulting in the progressive increase of more evolved magma successively removes the early chilled margin and fills the thick dyke with less compatible and more incompatible components toward the centre of the dyke. Although the normal trend in thick dyke considered the exceptional liquid process of magma differentiation that was formed more like fractional crystallization. Factor analysis also supports the differentiation process of magma. The first factor accounts total variance of 57.68% showing the positively loaded incompatible element and negatively loaded compatible elements.&#x0D; &#x0D; &#x0D;

Fe(III) Biomineralization in the Surface Microlayer of Acid Mine Waters Catalyzed by Neustonic Fe(II)-Oxidizing Microorganisms

The formation of thin mineral films or encrustations floating on the water surface of low-flow or stagnant zones of acid mine drainage (AMD)-affected streams is probably among the most exotic features that can be found in mining areas. However, most fundamental questions about their origin (biotic vs. abiotic), structure, mineralogy, physical stability and metal-retention capacity remain unanswered. This study aims to reveal the factors promoting their formation and to clarify their composition in detail. With this purpose, the major mineral phases were studied with XRD in surface film samples found in different mine sites of the Iberian Pyrite Belt mining district (SW Spain), and the major oxide and trace metal concentrations were measured with XRF and/or ICP-MS. Fe(III) minerals dominated these formations, with mineralogy controlled by the pH (jarosite at pH~2.0, schwertmannite at pH 2.5–3.5, ferrihydrite at pH &gt; 6.0). Other minerals have also been identified in minor proportions, such as brushite or khademite. These mineral formations show an astounding capacity to concentrate, by orders of magnitude (×102 to ×105), many different trace metals present in the underlying aqueous solutions, either as anionic complexes (e.g., U, Th, As, Cr, V, Sb, P) or as divalent metal cations (e.g., Cu, Zn, Cd, Pb). These floating mineral films are usually formed in Fe(II)-rich acidic waters, so their formation necessarily implies the oxidation of Fe(II) to Fe(III) phases. The potential involvement of Fe(II)-oxidizing microorganisms was investigated through 16S rRNA gene amplicon sequencing of water underneath the Fe(III)-rich floating mineral films. The sequenced reads were dominated by Ferrovum (51.7 ± 0.3%), Acidithiobacillus (18.5 ± 0.9%) and Leptospirillum (3.3 ± 0.1%), three well-known Fe(II)-oxidizing genera. These microorganisms are major contributors to the formation of the ferric mineral films, although other genera most likely also play a role in aspects such as Fe(III) sequestration, nucleation or mineral growth. The floating mineral films found in stagnant acidic mine waters represent hotspots of biosphere/hydrosphere/atmosphere interactions of great value for the study of iron biogeochemistry in redox boundaries.