Individual Minerals Research Articles

MODELING AND EXPERIMENTS TO ESTIMATE RADON EMANATION FACTOR IN SOIL-GRAIN SIZE AND MOISTURE EFFECT.

The influence of soil grain size on its radon emanation mechanism was investigated by developing a Monte-Carlo model. The proposed model supplements the previous formulations by accounting for the effect elicited by specific surface area of the sample. The specific surface area of a sample is governed by its grain size and it strongly influences the emanation rate which is a surface phenomenon. The emanation study was further extended to include the moisture effect. Experiments were carried out with two soil samples; Soil-2 and Soil-4 collected from different terrains, to analyze the role played by moisture in the emanation mechanism. The above model was augmented with provisions to include the moisture input. The model could reproduce the experimental results. There is an abrupt increase in the emanation factor when the moisture content changes from 0 to 2%. Thereafter, the increase is gradual and finally becomes steady when the moisture level reaches 10%. Soil-2 and Soil-4 showed sizeable difference in their radon emanation factor values. This could be explained based on the parent226Ra distribution pattern which stems from the mineralogical composition of the samples. Quartz was predominantly found in Soil-2, whereas Soil-4 shows peaks corresponding to minerals namely ilmenite, Rutile and Zircon confirming relatively higher concentration of heavy minerals than Soil-2. The emanation factor values of the individual minerals reported in the literature were used to decide upon the 226Ra distribution depth and with this input the model to ascertain the experimental observations.

Space weathering simulation of micrometeorite bombardment on silicates and their mixture for space application

AbstractMissions to planetary bodies require innovative techniques for the in situ investigation of their surfaces, especially when landings are planned. Therefore, Raman spectroscopy as an excellent laboratory tool for rapid mineralogical analysis of both terrestrial and extraterrestrial rocks has been successfully proposed for the investigation of planetary surfaces. Examples are the Raman laser spectrometer (RLS) of the joint ESA and Roscosmos mission ExoMars 2022 as well as Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) and SuperCam onboard NASA's Mars2020 Perseverance Rover; another is the Raman spectrometer for Martian Moons eXploration (MMX) (RAX), which is being developed for the in situ exploration of the Mars' moon Phobos. When preparing such space missions, it is essential to be prepared for all possible outcomes, such as samples exhibiting space weathering (SW). In this work, we study the influence of micrometeorite bombardment on bodies without atmosphere as one trigger of SW. This type of SW effect is simulated with an excimer laser irradiating the investigated samples with an energy density of ~2.5 J/cm2 for each pulse. As possible components on Phobos, we investigated the silicates olivine (Fo91) and pyroxene (En87) and their mixtures with Raman spectroscopy before and after laser irradiation. Surprisingly, the characteristic Raman bands of the individual minerals in the spectra are not influenced by this kind of SW. On the other hand, the fluorescence‐dominated background signal induced by laser irradiation is reduced, possibly due to the formation of nanophase Fe, which then facilitates a better interpretation of the individual mineral peaks.

A Hylogger-Itrax core-scanner comparison for multi-scale high-resolution petrophysical characterisation workflow

Recent advances in core scanning technologies allow for fast and non-destructive chemical and mineral profiling of rock samples for mineral services and oil and gas exploration. The aim of these automatic core scan methods is to obtain valuable information for profiling drill core cuttings with minimum sample preparation at relatively high speed. In the last decade, a core logging system using an automated infrared-based hyperspectral line-profiling system, Hylogger, has progressed to become an effective standard for the Australian mineral exploration industry. Its results are used to rapidly obtain mineralogical information allowing the characterisation of different geological formations in near real-time. The interpretation of Hylogger data can be challenging for certain complex mineral mixtures. Here we solve this issue by augmenting the Hylogger interpretation with elemental analysis using the Itrax core scanner equipped with an X-ray fluorescence (XRF) spectrometer. The Itrax core scanner produces high-resolution elemental data of major, minor and trace elements in one dimension. We analyse and compare the Hylogger and Itrax data, with each dataset independently cross-checked using X-ray diffraction (XRD) and thin-section petrology and propose a workflow harvesting the mutual strengths of each method. The recommended workflow consists of rapid screening using Hylogger and XRF analysis, providing new insights into the mineralogy based on comparative multiscale element-mineral analysis. The workflow is tested on four different types of volcanic rock samples, where infrared spectra of individual minerals overlap. We tested tuffaceous ash, basaltic, dolerite, and basaltic-andesitic rocks. Our study shows that embedding Itrax core scanner data into the workflow provides a solution to the challenges of interpreting Hylogger data in complex mineral samples. The proposed workflow provides a total system for multiscale, high-resolution petrophysical analyses and rock property modelling.

Genetic analysis on infrared-predicted milk minerals for Danish dairy cattle

A group of milk components that has shown potential to be predicted with milk spectra is milk minerals. Milk minerals are important for human health and cow health. Having an inexpensive and fast way to measure milk mineral concentrations would open doors for research, herd management, and selective breeding. The first aim of this study was to predict milk minerals with infrared milk spectra. Additionally, milk minerals were predicted with infrared-predicted fat, protein, and lactose content. The second aim was to perform a genetic analysis on infrared-predicted milk minerals, to identify QTL, and estimate variance components. For training and validating a multibreed prediction model for individual milk minerals, 264 Danish Jersey cows and 254 Danish Holstein cows were used. Partial least square regression prediction models were built for Ca, Cu, Fe, K, Mg, Mn, Na, P, Se, and Zn based on 80% of the cows, selected randomly. Prediction models were externally validated with 8 herds based on the remaining 20% of the cows. The prediction models were applied on a population of approximately 1,400 Danish Holstein cows with 5,600 infrared spectral records and 1,700 Danish Jersey cows with 7,200 infrared spectral records. Cows from this population had 50k imputed genotypes. Prediction accuracy was good for P and Ca, with external R2 ≥ 0.80 and a relative prediction error of 5.4% for P and 6.3% for Ca. Prediction was moderately good for Na with an external R2 of 0.63, and a relative error of 18.8%. Prediction accuracies of milk minerals based on infrared-predicted fat, protein, and lactose content were considerably lower than those based on the infrared milk spectra. This shows that the milk infrared spectrum contains valuable information on milk minerals, which is currently not used. Heritability for infrared-predicted Ca, Na, and P varied from low (0.13) to moderate (0.36). Several QTL for infrared-predicted milk minerals were observed that have been associated with gold standard milk minerals previously. In conclusion, this study has shown infrared milk spectra were good at predicting Ca, Na, and P in milk. Infrared-predicted Ca, Na, and P had low to moderate heritability estimates.

Establishing a pIRIR procedure for De determination of composite mineral grains from volcanic terranes: A case study of sediments from Liang Bua, Indonesia

Volcanic sediments are generally difficult to date using luminescence dating methods, but many important archaeological and palaeoanthropological sites are located in volcanic regions. Here we present an improved dating procedure for grains with composite mineralogies deposited at Liang Bua, the type locality of Homo floresiensis in Indonesia, using the post-infrared infrared stimulated luminescence (pIRIR) signal. Individual mineral grains that emit detectable pIRIR signals are composed of a range of feldspar varieties, quartz, clay minerals, heavy minerals and volcanic glass, rendering the isolation of individual potassium-rich feldspar grains infeasible. We investigate the luminescence behaviour of these composite mineral grains in detail, including their thermal stability, anomalous fading and dose-response characteristics. A standardised growth curve is developed to enable more time-efficient measurements, together with a ‘micro-aliquot’ approach in which each hole on a disc contains approximately 8–10 grains. Less than 1% of grains yield detectable pIRIR signals when measured individually, so the use of micro-aliquots provides, in effect, a means of estimating the equivalent dose (D e ) at single-grain resolution. Our results show that the pIRIR signal measured at 275 °C is suitable for estimating D e values of these composite grains, without the need for residual dose or fading corrections. • Improved pIRIR procedure to date Liang Bua, type locality of Homo floresiensis. • Analysed composite mineral grains in this volcanic region at single-grain resolution. • Established SGC parameters for the time-efficient measurement of equivalent dose. • Number of accepted data points increased six-fold using new preparation methods.

Beneficiation of Talc-Magnesite Ore with Cu-Co Mineralization

Magnesite ore with a low chalcopyrite – cobaltite mineralization was subjected to a series of separations designed to evaluate thepossible concentration of the two accessory minerals. Although the Cu-Co grade in the ore (> 0.01% Co, > 0.1% Cu) is significantlylower than the typical economic grades, content of the main valuable mineral for which the ore is mined and processed incombination with a listing of cobalt as a critical raw material, coupled with their higher price might compensate for the additionalbeneficiation stages. The ore was first crushed and subsequently classified to -100 μm and +100 -400 μm size fractions. The finefraction was upgraded by froth flotation processing in laboratory froth flotation cell. The coarser fraction was processed in severalseparation stages including gravity separation on shaking table, magnetic separation and corona electrostatic separation. The sameprocedure was also repeated with a higher-grade sample as a verification of the procedures. Preliminary results suggest that theaccessory minerals can be separated from the talc-magnesite ore and individual mineral concentrates with about 19% Co and 28%Cu were prepared. However, further work must be done to achieve desirable recoveries for the processing to be economically viable.

Intrinsic Mechanical Properties of Individual Biogenic Mineral Units in Biomineralized Skeletons.

A bioinspired study on replicating the superior damage tolerance of bioceramic composites requires a detailed understanding of the intrinsic properties of biogenic mineral units. Here, we investigate and compare the intrinsic properties of biogenic calcite (Atrina rigida) and aragonite (Sinanodonta woodiana) by conducting microbending experiments on the separated prismatic building blocks. Analyzed bending results indicate that the biogenic calcite has a higher modulus (36.24 ± 14.4 GPa for A. rigida vs. 29.9 ± 10.5 GPa for S. woodiana) and strength (446.5 ± 141.5 MPa for A. rigida vs. 338.6 ± 63.2 MPa for S. woodiana) than the biogenic aragonite, while the nanoindentation results indicate the opposite trend. Further systematic fractographic analysis suggests that the biogenic calcite fractures like amorphous glass, while the biogenic aragonite resembles polycrystalline ceramics. These contradictory behaviors of biogenic calcite and aragonite under tension-dominated (microbending) and indentation loading conditions are attributed to their different intrinsic structures, i.e., intracrystalline organic inclusions in single-crystal calcite vs. interlocked nanograins in polycrystalline aragonite.

Looking through a crystal ball: Understanding the future of Vietnam's minerals and mining industry

This paper examines what might happen to the mining industry in Vietnam over the next decade. Using production figures up until 2019, results indicate that the total production of eight key minerals will sharply increase across the nation. However, production of some individual minerals, such as bauxite, iron, phosphate, and coal are forecast to increase in the immediate future. By contrast, gold is predicted to decrease while production rates for lead, zinc and tin are projected to remain unchanged. Despite these shifts, it is expected that the mining industry will remain a key sector of the economy regarding revenue contribution over the next decade. Due to pressures such as debt liabilities, increased public spending and high mineral demand from China, the Vietnamese government will continue to support the mining industry. However, Vietnam's "resource curse" and its volatility have created adverse impacts, which we argue, has resulted in a dependency on mineral extraction that requires a focus on national economic diversity. Additionally, in Vietnam's current milieu, law reform, dominant limitation of State-owned Enterprises (SOEs) and reducing corruption in the mining sector, are acknowledged as critical for developing a mining industry that is competitive and attracts increased FDI into the future.

How Deep Learning Networks could be Designed to Locate Mineral Deposits

Whether using a shallow neural network with one hidden layer, or a deep network with many hidden layers, the training data must represent subgroups of the deposit type being explored to be useful. Published examples of neural networks have mostly been limited to one individual mineral deposit for training. Variation of geologic features among deposits within a type are so large that a single deposit cannot provide proper information to train a neural net to generalize and guide exploration for other deposits. Models trained with only one deposit tend to be academic successes but are not of practical value in exploration for other deposits. This is why it takes much experience examining many deposits to properly train an economic geologist—a neural network is not any different. Two examples of shallow neural networks are used to demonstrate the power of neural networks to possibly locate undiscovered deposits and to provide some suggestions of how to deal with missing data. The training data needs to include information spatially related to known deposits and hopefully information from many different deposits of the type. Lessons learned from these and other examples point to a proposed sampling plan for data that could lead to a generalized neural network for exploration. In this plan, 10 or more well-explored gold-rich porphyry copper deposits from around the world with 100 or more sample sites near and some distance from each deposit would probably capture important variability among such deposits and provide proper data to train and test a shallow neural network to predict locations of undiscovered deposits.

The possibility of application of computer simulation to predict the direction of the reaction during injection of reservoir waters

Currently, practically the entire volume of water extracted in the process of hydrocarbon exploitation is utilized by injection into deposits. Changes in the physico-chemical parameters (pH, red-ox potential, temperature, etc.) of the water during extraction and the contact of the injected water with the native water and deposit rock may result in the precipitation of sediment particles and suspensions. It causes clogging of the near-wellbore zone and limits the amount of water that can be injected with the injection well. Due to the high complexity of the system: the injected water–reservoir rock, and a wide range of interactions between individual components, the analytical data does not always allow for the correct interpretation of the course of the processes and determination of their impact on the permeability of the near-well zone. Using the results of physico-chemical analyses of the composition of separator water samples with different properties – two samples with low mineralization S1K (575 mg/dm3) and S4K (551 mg/dm3), a sample with high S2K (306 428 mg/dm3) and medium mineralization S3K (79 858 mg/dm3) – calculations were performed using the PHREEQC program for the three databases: phreeqc.dat, wateq4f.dat and pitzer.dat. It was found that in the case of low mineralization waters, the results obtained in each of the databases are similar for the minerals present in all the databases. However, in the case of solutions with high mineralization, there are significant differences in the obtained results. The calculated solubility indices allowed to determine the direction of the precipitation/dissolution reaction of individual minerals in the deposit and to indicate the risks, mainly with the formation of iron compounds deposits, for the operation of the injection well. Laboratory tests of water mixing were also carried out. The formation of iron oxide deposits that could damage the near-well zone was observed, which confirmed the results obtained during computer simulations.

Geometallurgical characterisation of a Channel Iron Deposit (CID) Ore

ABSTRACT Channel iron deposits (CID), comprising pisolitic or goethitic ores, remain a prominent iron ore resource in Western Australia. Previous research work on CID pointed out their complexity in genesis, geology, geomorphology, and petrology, which provides some basic information for downstream processing. Sintering investigations have mainly focused on the overall sintering performance and the quality of sinter products rather than the behaviour of the ore components during sintering. However, individual mineral phases in the ores have their own characteristics during reaction with fluxing materials in the sintering process. In this study, the complex mineral phases in a CID goethitic ore are compared with traditional hematite ore. They are classified into several categories based on the mineral composition, including the basic mineral phases: goethite matrix, hydro-hematite, and quartz, and combined minerals: quartz-dispersed hydro-hematite, quartz-dispersed goethite, goethite with dispersed quartz and clay (gibbsite/kaolinite), and ferruginised wood. The changes of the goethitic ore when heated to different temperatures were also investigated. More cracks appeared in the ore with increasing temperature due to dehydration of the goethite matrix. The temperature induced goethite-to-hematite transformation occurred between 260°C and 300°C, as shown in TGA-DSC curves and confirmed by XRD analysis. The colour of the goethitic ore changed from brown to vermillion after 300°C due to the phase transformation, and to ochreous at 1150°C and further to black above 1250°C due to the decomposition of hematite to magnetite.

The Fe/S ratio of pyrrhotite group sulfides in chondrites: An indicator of oxidation and implications for return samples from asteroids Ryugu and Bennu

Determining compositional trends among individual minerals is key to understanding the thermodynamic conditions under which they formed and altered, and is also essential to maximizing the scientific value of small extraterrestrial samples, including returned samples and meteorites. Here we report the chemical compositions of Fe-sulfides, focusing on the pyrrhotite-group sulfides, which are ubiquitous in chondrites and are sensitive indicators of formation and alteration conditions in the protoplanetary disk and in small Solar System bodies. Our data show that while there are trends with the at.% Fe/S ratio of pyrrhotite with thermal and aqueous alteration in some meteorite groups, there is a universal trend between the Fe/S ratio and degree of oxidation. Relatively reducing conditions led to the formation of troilite during: (1) chondrule formation in the protoplanetary disk (i.e., pristine chondrites) and (2) parent body thermal alteration (i.e., LL4 to LL6, CR1, CM, and CY chondrites). Oxidizing and sulfidizing conditions led to the formation of Fe-depleted pyrrhotite with low Fe/S ratios during: (1) aqueous alteration (i.e., CM and CI chondrites), and (2) thermal alteration (i.e., CK and R chondrites). The presence of troilite in highly aqueously altered carbonaceous chondrites (e.g., CY, CR1, and some CM chondrites) indicates they were heated after aqueous alteration. The presence of troilite, Fe-depleted pyrrhotite, or pyrite in a chondrite can provide an estimate of the oxygen and sulfur fugacities at which it was formed or altered. The data reported here can be used to estimate the oxygen fugacity of formation and potentially the aqueous and/or thermal histories of sulfides in extraterrestrial samples, including those returned by the Hayabusa2 mission and due to be returned by the OSIRIS-REx mission in the near future.

Integrated Laser-Induced Breakdown Spectroscopy (LIBS) and Multivariate Wavelet Tessellation: A New, Rapid Approach for Lithogeochemical Analysis and Interpretation

This paper demonstrates a novel approach that uses wavelet tessellation in rapid analysis of raw geochemical data produced by laser-induced breakdown spectroscopy (LIBS) to produce pseudologs that are representative of stratigraphy. Single-line LIBS spectral data for seven major rock-forming elements (Al, Ca, Fe, Mg, Si, Na and K) were collected from a synthetic 22-sample rock-block comprising two distinct lithological groups based on mineralogy, chemistry and texture: plutonic rocks and marble. Seven sublithologies are identified within the rock-block from traditional laboratory whole-rock geochemical analysis: marble, Mg-marble, granite, quartz monzonite, foidolite, granodiorite and gabbroic diorite. Two-domain clustering (k = 2) on raw spectral LIBS data combined with wavelet tessellation was applied to generate a simplified lithological stratigraphy of marble and plutonic rocks and generate a pseudolog identical to the rock-block stratigraphy. A pseudolog generated from seven-domain clustering (k = 7) and wavelet tessellation successfully discriminated most sublithologies within the rock-block slabs, especially marble slabs. Small-scale units were identified within the more mineralogically and geochemically complex plutonic slabs. The spatial resolution of the LIBS analysis, with a measurement spacing of ~0.35 mm, allowed for assessment of individual mineral compositions and rock textures, and small-scale units within the plutonic rocks can be correlated to specific coarse-grained minerals or mineralogical associations. The application of the wavelet tessellation method to raw LIBS geochemical data offers the possibility of rapid and objective lithogeochemical analysis and interpretations which can predate further analysis (quantitative) and supplement geological logging.

Lithologic Controls on Silicate Weathering Regimes of Temperate Planets

Abstract Weathering of silicate rocks at a planetary surface can draw down CO2 from the atmosphere for eventual burial and long-term storage in the planetary interior. This process is thought to provide essential negative feedback to the carbonate-silicate cycle (carbon cycle) to maintain clement climates on Earth and potentially similar temperate exoplanets. We implement thermodynamics to determine weathering rates as a function of surface lithology (rock type). These rates provide upper limits that allow the maximum rate of weathering in regulating climate to be estimated. This modeling shows that the weathering of mineral assemblages in a given rock, rather than individual minerals, is crucial to determine weathering rates at planetary surfaces. By implementing a fluid-transport-controlled approach, we further mimic chemical kinetics and thermodynamics to determine weathering rates for three types of rocks inspired by the lithologies of Earth's continental and oceanic crust, and its upper mantle. We find that thermodynamic weathering rates of a continental crust-like lithology are about one to two orders of magnitude lower than those of a lithology characteristic of the oceanic crust. We show that when the CO2 partial pressure decreases or surface temperature increases, thermodynamics rather than kinetics exerts a strong control on weathering. The kinetically and thermodynamically limited regimes of weathering depend on lithology, whereas the supply-limited weathering is independent of lithology. Our results imply that the temperature sensitivity of thermodynamically limited silicate weathering may instigate a positive feedback to the carbon cycle, in which the weathering rate decreases as the surface temperature increases.

Tracing seawater- and terrestrial-sourced REE signatures in detritally contaminated, diagenetically altered carbonate rocks

As two typical non-skeletal carbonates, ooids and calcified microbial structures have a potential for use in paleo-seawater rare earth element (REE) and yttrium (REY) reconstruction, but strong diagenetic alteration and detrital contamination may cover/overprint their primary carbonate REY signatures and significantly undermine their reliability and usability in recovering original aqueous information from carbonate rocks. In this study, we analyzed a series of Cambrian (Stage 3) oolites and microbialites with minor terrigenous admixtures in the Hannan-Micangshan area, South China using various fractions (bulk rock, acid soluble and insoluble, individual siliciclastic and heavy minerals), and solution- and laser ablation (LA)-based analytical techniques. The acetic acid digested samples exhibit enriched middle REEs (MREEs) and light REEs (LREEs) when normalized to shales, which may indicate the effects of carbonate and detrital diagenetic alteration. The LA-based analysis of the ooid cortices and calcified microbes revealed varying REE patterns from flat to heavy REE (HREE)-enriched features despite their average REY compositions being similar to those of the acetic acid digested samples. In contrast, the early isopachous cements exhibit seawater-like REY patterns with the least diagenetic and contamination characteristics, which potentially indicate seawater-sourced porewater fluids approaching the composition of the overlying surface ocean in the shore settings. In addition, we identified HREE-enriched detrital fractions (mostly distributed in the clay-sized particles) in all three study sections, which are likely sourced from the neighboring mafic igneous rocks in the Hannan-Micangshan area. This HREE-enriched signature would significantly mislead our judgement of the coexisting carbonate REY characteristics (e.g., Ce anomalies and Y/Ho ratios) if the contamination fraction could not be rigorously excluded. Although large quantities of contaminated (to varying degrees) LA-based data cannot be used for paleoceanographic reconstruction, their unique values have been demonstrated to indicate their terrigenous mineralogical sources based on multiple groups of contamination fingerprint elements, which conforms well to the elemental compositions of individual siliciclastic and heavy minerals. For detritally contaminated, diagenetically altered shallow-water carbonate rocks, in general, the LA technique can be applied not only to paleoceanographic reconstruction based on the most pure and least altered components (i.e., early marine cements) but also to provenance analysis based on fine-grained particles admixed in the ooid cortices and calcified microbes.

Trace element geochemistry of coarse-grained angrites from Northwest Africa: Implications for their petrogenesis on the angrite parent body.

The angrites are a class of achondrites that encompass a wide range of igneous textures from quenched, volcanic, and subvolcanic stones to slowly cooled, plutonic rocks. The compositions of the various geochemical reservoirs generating this variety of rocks have not been investigated fully because historically the numbers and masses of angrites available for study have been quite small. However, the rapid increase in meteorites from Northwest Africa (NWA) has enabled a renewed opportunity for such an investigation. In particular, three samples, NWA 2999, 4590, and 4801, have provided a new window into our understanding of the origin and petrogenesis of the coarse-grained (plutonic) angrites. We report here the trace element abundances in individual mineral grains of pyroxene, plagioclase, olivine/kirschsteinite, and phosphate and in the whole-rock samples. We utilize these data to constrain the petrogenetic history of each of these samples on the angrite parent body (e.g., parental melt compositions and oxygen fugacity conditions) and assess genetic relationships to previously investigated angrites. The trace element abundances in each of the three coarse-grained angrites studied here indicate a unique history for each. The observed trace element abundances and patterns in NWA 2999 show similarities with previously studied fine-grained, volcanic angrites and potentially indicate a common geochemical source reservoir, even though NWA 2999 is temporally distinct from the volcanic angrites. In contrast, NWA 4590 has trace element characteristics analogous to other coarse-grained angrites (e.g., Lewis Cliff [LEW] 86010), suggesting that these samples originated from geochemically similar source reservoirs. The third angrite, NWA 4801, exhibits geochemical characteristics most similar to the plutonic, coarse-grained angrites, but also appears to have some affinities in its trace element characteristics to the volcanic, fine-grained angrites. This suggests that NWA 4801 may represent a petrogenetic link between two distinct geochemical reservoirs on the angrite parent body. In aggregate, the trace element distributions in these three plutonic angrites suggest that while they may have originated up to several million years after the fine-grained angrites, they sampled a range of source reservoirs on the angrite parent body. Some of these source reservoirs were likely similar to those of the fine-grained angrites, but others had distinct geochemical characteristics.

Distinct Mineralogy and Age of Individual Lava Flows in Atla Regio, Venus Derived From Magellan Radar Emissivity.

NASA's Magellan mission revealed that many Venus highlands exhibit low radar emissivity values at higher altitudes. This phenomenon is ascribed to the presence of minerals having high dielectric constants, produced or stabilized by temperature-dependent chemical weathering between the rocks and the atmosphere. Some large volcanoes on Venus have multiple reductions of radar emissivity at varying altitudes. The authors present morphological maps of major lava flow units at Maat, Ozza, and Sapas montes and compare them to radar emissivity. Sapas has a single reduction in emissivity values at 6,054.6 km, while Maat and Ozza have several reductions at altitudes of 6,052.5-6,056.7 km. Emissivity values are highly spatially correlated to individual lava flows indicating that minerals in the rocks control the emissivity signature. The emissivity patterns at these volcanoes require at least four individual ferroelectric mineral compositions in the rocks that are highly conductive at Curie temperatures of 693-731 K. These temperatures are compatible with chlorapatite and some perovskite oxides. Modeling the minimum volumes of ferroelectrics (10-100s ppm) shows the volume and type of ferroelectric may vary over the lifetime of a single volcano. The modeled volumes of ferroelectrics in Ozza and Sapas are greater than in Maat, consistent with the production of ferroelectrics via weathering over a longer period of time, and supporting the idea that Maat has younger volcanic activity. The stratigraphic relationship of Maat's youngest flows with impact craters may indicate the timeframe of the production of specific ferroelectrics via chemical weathering is over 9-60 Ma.

Mineralogical and Chemical Specificity of Dusts Originating from Iron and Non-Ferrous Metallurgy in the Light of Their Magnetic Susceptibility

This study aims at detailed characteristics and comparison between dusts from various iron and non-ferrous metal production processes in order to identify individual mineral phases, chemical composition, and their influence on the values of magnetic susceptibility. Various analytical methods used include inductively coupled plasma optical emission spectroscopy, X-ray diffraction, scanning electron microscopy, and Mössbauer spectroscopy integrated with magnetic susceptibility measurements and thermomagnetic analysis. Metallurgical wastes that have arisen at different production stages of iron and non-ferrous steel are subjected to investigation. The analyzed dust samples from the iron and non-ferrous metallurgy differ in terms of magnetic susceptibility as well as their mineral and chemical composition. The research confirmed the presence of many very different mineral phases. In particular, interesting phases have been observed in non-ferrous dust, for example challacolloite, which was found for the first time in the dusts of non-ferrous metallurgy. Other characteristic minerals found in non-ferrous metallurgy dusts are zincite, anglesite, and lanarkite, while dusts of iron metallurgy contain mostly metallic iron and iron-bearing minerals (magnetite, hematite, franklinite, jacobsite, and wüstite), but also significant amounts of zincite and calcite.

Revealing the doping mechanism of barium in sulfoaluminate cement clinker phases

The doping mechanism of Ba in sulfoaluminate cement (SAC) clinker was systematically studied. Results from density functional theoretical simulations, backscattered electron diffraction and X-ray diffraction show that Ba ions prefer to incorporate into the mineral C4A3S¯ by substituting Ca atoms while little enter into the other two minerals, C2S and C4AF. Such doping preference was also certified by the results of individual mineral of C4A3S¯ and C4AF, respectively. Further analyses from partial density of states, electron density difference and local distortions indicate that the Ba-doping preference in C4A3S¯ is attributed to the efficiency of newly formed bonds, which is enhanced by electronic structure matching and small local distortions. The understandings are essential in guiding the production of Ba-bearing SAC clinker by utilizing industrial barium slags, thus should be very important in sustainable production of SAC clinkers, environmental governance and industrial collaborative disposal of waste.

Impact of Micronutrients on Hypertension: Evidence from Clinical Trials with a Special Focus on Meta-Analysis.

Hypertension (HT) is one of the pivotal risk factors for various detrimental diseases like cardiovascular diseases (CVDs), cerebrovascular disease, and renal dysfunction. Currently, many researchers are paying immense attention to various diet formula (dietary approach) with a special focus on micro and macronutrients along with modified lifestyle and standard anti-hypertensive drugs. Micronutrients (minerals/vitamins) play a central role in the regulation of blood pressure (BP) as they aid the function of macronutrients and also improve the anti-hypertensive functions of some anti-hypertensive agents. Even though several studies have demonstrated the beneficial effects of micronutrients on controlling BP, still some ambiguity exists among the nutritionists/doctors, which combination or individual mineral (dietary approach) contributes to better BP regulation. Therefore, this critical review article was attempted to delineate the underlying role of micronutrients (minerals and vitamins) for the management and prevention or delaying of HT and their related complications with strong affirmation from clinical trials as well as its mechanism of controlling BP. Moreover, the major source and recommended daily allowance (RDA) of various micronutrients are included in this review for guiding common readers (especially HT subjects) and dieticians to choose/recommend a better micronutrient and their combinations (other nutrients and standard anti-hypertensive drugs) for lowering the risk of HT and its related co-morbid conditions like CVDs.