Mineral Components Research Articles

A simple and efficient method for palynological sample preparation

AbstractThe extraction of organic microfossils is a process that requires techniques based on the elimination of the mineral components of the rock (mainly silicates and carbonates) and the subsequent concentration of the microfossils. These techniques are very diverse and have in common the dissolution of the rock (maceration) with hydrofluoric acid and concentrated hydrochloric acid to extract the organic matter, which is potentially made up of dispersed organic matter and organic walled microfossils. In this process, there are at least two fundamental objectives. First, that the process respects the fidelity of the organic microfossil record (diversity and preservation). Second, effective elimination of dispersed organic matter, obtaining the maximum concentration of microfossils and microscopic slides with a homogeneous dispersion that allows optimal observing conditions. The method described in this paper is based on a filtration process of the organic matter resulting from the maceration process, employing polyester filters and a vacuum inversion system. In the standard vacuum process, the dispersed organic matter clogs the pores of the filter. The vacuum inversion injects filtered water that unclogs the pores of the filter vessel. The alternation between normal and reverse vacuum results in the progressive elimination of the dispersed organic matter and the concentration of the organic microfossils in a rapid and non-aggressive process.

Study on physical and chemical structure modification law and mechanism of coal based on organic acidification

Deep coal seams in China have the characteristics of low permeability, low porosity, and poor gas permeability, which makes the extraction of coalbed methane very difficult. To study the modification effect of acidic solutions on coal pore structure and mineral components, this study used three different concentrations (5%, 10%, and 15%) of organic acids (HCOOH and CH3COOH) to treat coal. Through industrial/elemental analysis, low-temperature nitrogen adsorption experiments, and x-ray fluorescence spectroscopy detection experiments, the pore size distribution, mineral elements, and oxides of the acidified coal were analyzed. The strength of the acid solution's modification effect on coal was analyzed, as well as the relationship between different mineral elements and changes in pore structure. The results show that the two acids have a pore expanding effect on coal, with an increase in average pore size; the pore size distribution is between 2 and 50 nm, belonging to mesopores; acetic acid has a stronger overall dissolution efficiency on inorganic minerals, while formic acid has a better effect on the removal of Ca and P elements, but none of them can effectively remove silicoaluminates; the content of Ca element in coal is positively correlated with the specific surface area provided by mesopores; and iron dolomite is not sensitive to the reaction with acetic acid, resulting in an opposite trend in Fe content and mesoporous specific surface area. Organic acid solution changes the pore and fracture distribution structure of coal through chemical dissolution by dissolving the mineral components inside the coal, thereby affecting its internal structural characteristics.

Solar Wind Ion Sputtering from Airless Planetary Bodies: New Insights into the Surface Binding Energies for Elements in Plagioclase Feldspars

Our understanding of the ion-sputtering contribution to the formation of exospheres on airless bodies has been hindered by the lack of accurate surface binding energies (SBEs) of the elements in the various mineral and amorphous compounds expected to be on the surfaces of these bodies. The SBE for a given element controls the predicted sputtering yield and energy distribution of the ejecta. Here, we use molecular dynamics computations to provide SBE data for the range of elements sputtered from plagioclase feldspar crystalline end members, albite and anorthite, which are expected to be important mineral components on the surfaces of the Moon and Mercury. Results show that the SBE is dependent on the crystal orientation and the element’s coordination, meaning multiple SBEs are possible for a given element. Variation in the SBEs among the different surface positions has a significant effect on the predicted yield and energy distribution of the ejecta. We then consider sputtering by H, He, and a solar wind mixture of 96% H and 4% He. For each of these cases, we derive best-fit elemental SBE values to predict the ejecta energy distribution from each of the (001), (010), and (011) cleavage planes. We demonstrate that the He contribution to the sputtering yield cannot be accounted for by multiplying the 100% H results by some factor. Lastly, we average our results over all three possible lattice orientations and provide best-fit elemental SBE values that can be easily incorporated into sputtering yield models.

Rock Physics Modeling Studies on the Elastic and Anisotropic Properties of Organic-Rich Shale

Shale gas reservoirs have a large amount of resources, a wide range of burial, and great development potential. In order to evaluate the elastic properties of the shale, elastic wave velocity and anisotropy measurements of Longmaxi shale samples were carried out in the laboratory. Combined with the results of back scattering scanning electron microscopy (SEM) and digital mineral composition tests, the relationship between the anisotropy and the mineral components of the shale samples is discussed. It is found that the clay and kerogen combination distributed with an inorganic mineral background is the main cause of anisotropy. Then, the elastic properties of the organic-rich shale are analyzed with the anisotropic differential equivalent medium model (DEM). The clay and kerogen combination is established with kerogen as the background medium and clay mineral as the additive phase. The bond transformation is used to rotate the combination so that its directional arrangement is consistent with the real sedimentary situation of the stratum. Then, the clay and kerogen combination is added to the inorganic mineral matrix, with the organic and inorganic pores added to characterize the anisotropy of the shale to the greatest extent. It is found that the error between the wave velocity results calculated from the model and measured in the laboratory is less than 10%, which means the model is reliable. Finally, the effects of the microcracks and aspect ratio, kerogen content, and maturity on the elastic and anisotropic properties of shale rocks are simulated and analyzed with this model. The degree of anisotropy increases with the decrease in the pore aspect ratio and the increase in the microcracks content. The greater the kerogen content and maturity, the greater the anisotropy of rock. This study is of great significance for predicting the “sweet spot” of shale gas and optimizing hydraulic fracturing layers.

Osteoplastic biomaterials from organic and mineral components of the bone matrix: a literature review

Introduction. The bones of the human and animal have a unique ability to remodel. The ability to constantly renew bone tissue determines the healing of fractures and the adaptation of bones to mechanical loads. However, the process of bone self-healing is effective only for defects of non-critical size. In segmental and critical defects, endogenous stimulation of bone tissue regeneration is required. In this regard, there remains a need to design osteoplastic biomaterials with improved pro-regenerative action. Every year, new data appear that expand our understanding of the methods and mechanisms for stimulating bone tissue restoration using artificial osteoplastic materials. Aim. Characteristics of modern methods of constructing biomimetic materials from organic and mineral components of bone matrix. Materials and methods. The literature review was conducted using the PubMed and ScienceDirect databases. Query dates — may–july 2024, query depth — 1965–2024. Main content of the review. Effective use of bone polymers for the creation of biomimetic osteoplastic materials is possible only with an understanding of the principles of molecular-cellular interaction of biopolymers with bone cells and tissues. By now, it has been established that the ability of collagen to influence the functional activity of cells involved in the reparative regeneration of bone tissue is due to the presence of special patterns in its structure - binding sites with cellular receptors, which are formed by a specific sequence of amino acids in the collagen polypeptide chain. In the case of inorganic bone material, the functionally significant elements are the chemical composition and crystal structure of calcium phosphate salts. A current trend in the design of osteoplastic materials is to impart biomimetic properties to them. At the molecular level, this approach is implemented using as intrafibrillar and extrafibrillar mineralization of collagen fibrils. At the tissue and organ level, biomimicry is achieved through the use of three-dimensional bioprinting technologies. Conclusion. Thus, thanks to advances in biology, physics, chemistry and engineering sciences, it was possible to develop new technologies for designing osteoplastic materials that imitate the structure and function of native bone tissue. The use of biomaterials created using biomimetics principles increases the efficiency of bone tissue damage restoration.

Nutritional and Phytochemical Profile of Commonly Consumed Spices in Nigeria

Background: Spices which are widely used in Nigeria have aroma, enhance taste of food and Possess medicinal values. Objectives: This study aimed to determine the nutritionaland phytochemical profile of commonly consumed spices in Nigeria. Materials and Methods: Raw materials and other ingredients used for this study were purchased from Oja-Oba in Owo Local Government, Ondo State. The spices were analysed for proximate and mineral components using standard method as described by AOAC (2012). Sodium and potassium were determined using flame photometer and calcium, selenium, copper, zinc, magnesium, and iron were determined using atomic absorption spectrophotometer. Phytochemical analyses were carried out using standard procedures. Results: The proximate composition showed that protein was significantly (p≤0.05) high at 14.41% in Uziza seed and low at 11.60% in tumeric. Ginger contained high moisture content at 10.63%, while Uziza seed had the least value of 8.58%. High ash content was recorded in gingerat 5.27% and lowest at 3.70% in Uziza. Tumeric had the highest value of 65.57% for carbohydrate, while Uziza had the least value of 60.06%. Mineral composition showed high value of calcium in Uziza seed (402.03mg/100g). Nutmeg showed a high value of magnesium (13.3mg/100g) and turmeric indicated the highest value of potassium (405.43mg/100g), sodium (135.17mg/100g) for Uziza seed. The highest content of iron was recorded at 3.34mg/100g. Turmeric had a high value of zinc at 3.77 mg/100g and copper at 97 mg/100g, respectively. The spices contained an appreciable amount of phytochemicals. However, turmeric was significantly higher in alkaloids, flavonoids and polyphenols. Conclusion:This study showed that spices have greater use in medicine and as a food supplement.

High-precision digital rock construction and electrical property upscaling in tight sandstone

The lithology and rock physical properties of tight sandstone reservoirs become increasingly complex, resulting in a more challenging reservoir evaluation process. Conventional rock physics experiments are too restrictive to adequately investigate formation properties. The emerging digital rock physics (DRP) technology in recent years effectively overcomes these constraints. Nevertheless, the current DRP faces two major challenges: the integration of multiple-resolution images and the upscaling of rock physics properties (electricity). In this paper, we propose an innovative method for assigning electrical characteristics to voxel units, enabling the integration of multi-resolution images, as well as a novel approach for establishing a new saturation model to achieve electrical property upscaling. Initially, core samples are selected and drilled based on logging data and lithology analysis, followed by multi-resolution scanning experiments, including X-ray CT, QEMSCAN, and MAPS. After that, mineral components are segmented, and multi-component digital rocks are constructed. Considering mineral voxel as the analytical units, pore characteristics within each mineral, which are extracted from MAPS, are used to generate 3-D pores by QSGS method. These generated 3-D pores are then merged with their respective mineral voxel. Subsequently, the electrical properties of the merged models are simulated and assigned to multi-component digital rock. This process enables the integration of multi-resolution images, leading to the construction of high-precision digital rocks. Additionally, high-precision digital rock-based electrical modeling is conducted, and a new saturation model is then established by combining digital rock physics, experiment rock physics, and theoretical rock physics. Finally, the new saturation model is applied to calculate saturation, accomplishing electrical property upscaling. Application results show the new saturation model improves the accuracy of saturation evaluation, demonstrating the feasibility of the upscaling method for electrical properties.

Air-drying causes an alteration in density fractionation of soil materials from organic horizons containing volcanic ash

Density fractionation is commonly used to isolate organic matter in soils based on organo-mineral associations. Not only mineral horizons but also organic horizons contain mineral components. Soil samples for density fractionation are sometimes air-dried or freeze-dried, which can introduce unexpected biases in the results. In this study, we compared the density fraction distributions in wet, air-dried, and freeze-dried organic horizon samples rich in reactive Al and Fe minerals. On Mt. Chokai, a volcano in northern Japan, samples were collected from organic horizons from three representative vegetation types: K1 (dwarf pine and dwarf bamboo at the summit), K2 (dwarf bamboo on the back slope), and K3 (snow meadow with predominantly Poaceae at the foot slope). Wet, air-dried, and freeze-dried samples were subjected to sequential density fractionation using cutoff values of 1.6 and 1.8 g cm–3. We then determined the mass, organic carbon, and total nitrogen distributions in the isolated fractions. Air-drying altered the mass, organic carbon, and total nitrogen distribution of each density fraction. Although we observed differences in the mass distributions of the freeze-dried and wet samples in the snow meadow samples (K3), the mass distributions in the K1 and K2 samples did not change significantly between the freeze-dried and wet samples. Therefore, freeze-drying is recommended as a pretreatment to minimize the effects of drying on density fractionation, particularly for soil samples with no drying history, high organic matter content, and/or high levels of reactive Al and Fe minerals.

From Structure to Strength: Analyzing the Impact of Sulfuric Acid on Pig Bone Demineralization Through FTIR, LIBS, and AAS.

The present research aimed to investigate the demineralizing effects of sulfuric acid on pig bone. Alterations in collagen and phosphate contents and changes in the elemental composition of the bone during the 14-day-long immersion in sulfuric acid solutions of different concentrations were estimated using ATR-FTIR, LIBS, and AAS. FTIR spectra at amide I (1800-1600 cm-1) and phosphate ν1/ν3 (PO43-) (1300-900 cm-1) domains were scrutinized using the deconvolution method for monitoring changes in the protein secondary structure and mineral content. The results implicated sulfuric acid as a powerful demineralization agent and effective in targeting mineral components, such as hydroxyapatite, while leaving the collagen matrix relatively preserved with a complex secondary structure. Collagen maturity marker values gave valuable insights into the structural integrity of the bone. LIBS and AAS indicated changes in bone hardness; phosphorous-to-carbon ratio; and calcium, phosphorous, and magnesium content in the solutions left after the immersion period. The changes in the ratio of ionic-to-atomic calcium lines in the LIBS spectra indicated hardening of the bone, with increasing acid concentration and prolonged action, due to the deposition of calcium sulfate on the surface. The calcium concentration in the solutions decreased with increased acid concentration, while the change in phosphorus and magnesium concentrations was reversed.

Removal of Pb2+ in aqueous solution by diatom-derived biochar: Role of inherent Ca/Mg minerals

Mineral components can significantly enhance the adsorption capacity of contaminants on biochar, yet research on the changes in mineral crystal structure within biochar and their effects on adsorption performance remains limited. In this study, biochar was prepared from diatom, an abundant and eco-friendly biomass, at various pyrolysis temperatures. Adsorption experiments were conducted to evaluate the removal of Pb²⁺ using diatom-derived biochar under different conditions. The results indicated that the primary mechanism of Pb²⁺ removal involved ion exchange between the inherent Ca/Mg minerals and Pb²⁺, followed by the formation of PbCO₃ and Pb₂(CO₃)₂(OH)₂ on biochar surface. Inherent Ca/Mg minerals contributed 93.1 % to Pb2+ adsorption capacity. Additionally, adsorption capacity of Pb²⁺ were found enhanced with increased pyrolysis temperature, which was due to the change of inherent Ca-minerals crystal structure in diatom-derived biochar. Furthermore, diatom-derived biochar demonstrated excellent adsorption capacity for Pb²⁺ up to 1027.0 mg·g⁻¹. The adsorption kinetics fitted well with pseudo-second-order model, and the adsorption isotherm was well-described by the Langmuir model. An increase in pH favored the adsorption process. These findings suggest that diatom-derived biochar could serve as a promising adsorbent for heavy metals in water.

Characteristics of rock strength failure and identification of hazardous areas in the roof of deep mining stope

The roof of deep mining stopes is notoriously unstable and challenging to manage due to high in-situ stress and deteriorating rock conditions. To address this issue, a comprehensive approach was employed, incorporating indoor physical experiments, numerical simulations, and field tests to investigate the stope roof rock composition characteristics and strength failure modes in the Laoyingshan deep coal mine. The study revealed the distribution characteristics of the high in-situ stress field in this mining area and delineated different levels of hazards in the roof. The results indicate that, under identical lithological conditions, the mineral composition of deep rock formations is complex. Changes in some mineral components and properties were observed, leading to increased expansiveness and water absorption in clay minerals such as sodium montmorillonite and kaolinite within the basic roof layer. In simulated tests of surrounding rock strength in deep mining stopes, as stress levels approached 2 MPa, the damage factor increased, showing a trend of localized concentration. Internal damage began to exhibit noticeable spatial evolutionary expansion patterns and gradual nucleation. When stress exceeded 8 MPa, rocks transitioned from macroscopic fracture surfaces to microscopic fragmentation zones, with a sudden decrease in stiffness degradation values, internal instantaneous collapse, and phenomena akin to “rock burst” under high stress disturbance. In-situ stress testing determined that the stress field in the deep mining zone of Laoyingshan is in a thrust fault stress state, with horizontal stress predominance. The maximum stress direction is predominantly southwest-northeast, with stress magnitude reaching 25.49 MPa. By arranging post-mining and pre-mining borehole observation stations and utilizing image grayscale fracture recognition technology in MATLAB, the roof was classified into four danger levels: “extremely broken,” “broken,” “significant fractures,” and “minor fractures.” Main control measures for coupling grouting in deep-shallow zonation rigidity were proposed based on these classifications.

Adsorption and biodegradation of butyl xanthate in mine water by Pseudomonas sp. immobilized on yak dung biochar

The butyl xanthate (BX) in mining wastewater poses significant environmental challenges due to its toxicity and persistence. This study aimed to evaluate the effectiveness of Pseudomonas sp. immobilized on yak dung biochar (Ps.@YDBC600) for BX degradation, emphasizing the synergistic effects of biochar adsorption and microbial degradation. BX removal efficiency of free Pseudomonas sp. cells was assessed under various environmental conditions, with optimal degradation observed at 30 °C and an initial pH of 5.0. Yak dung biochar prepared at 600 °C (YDBC600) was selected due to its high surface area, porosity, and favorable adsorption properties, enhancing the immobilization and activity of Pseudomonas sp. The absorption of BX by biochar followed a two-compartment first-order kinetic model and primarily involved hydrogen bonding, hydrophobic interactions, and pore filling. The primary crystalline mineral component of YDBC600 and Ps.@YDBC600 before and after the adsorption and degradation of BX was SiO₂. The Ps.@YDBC600 was shown to significantly enhance BX removal efficiency compared to free Pseudomonas sp. cells or biochar alone. Molecular studies indicated that biochar facilitated BX degradation by providing a stable environment for Pseudomonas sp. and optimizing metabolic resource allocation. The primary by-products, including CS₂, HS–, ROCOS–, ROCSSH and (ROCSS)₂ were effectively minimized (each by-product was reduced more than 80%), reducing secondary pollution. These findings demonstrated the potential of Pseudomonas sp. immobilized on biochar as an effective approach for treating BX-contaminated mining wastewater, offering a sustainable approach to environmental remediation and management.

Advancements in Nanohydroxyapatite: Synthesis, Biomedical Applications, and Composite Developments

Abstract Nanohydroxyapatite (nHA) is distinguished by its exceptional biocompatibility, bioactivity, and biodegradability, qualities attributed to its similarity to the mineral component of human bone. This review discusses the synthesis techniques of nHA, highlighting how these methods shape its physicochemical attributes and, in turn, its utility in biomedical applications. The versatility of nHA is further enhanced by doping with biologically significant ions like magnesium or zinc, which can improve its bioactivity and confer therapeutic properties. Notably, nHA-based composites, incorporating metal, polymeric, and bioceramic scaffolds, exhibit enhanced osteoconductivity and osteoinductivity. In orthopedic field, nHA and its composites serve effectively as bone graft substitutes, showing exceptional osteointegration and vascularization capabilities. In dentistry, these materials contribute to enamel remineralization, mitigate tooth sensitivity, and are employed in surface modification of dental implants. For cancer therapy, nHA composites offer a promising strategy to inhibit tumor growth while sparing healthy tissues. Furthermore, nHA-based composites are emerging as sophisticated platforms with high surface ratio for the delivery of drugs and bioactive substances, gradually releasing therapeutic agents for progressive treatment benefits. Overall, this review delineates the synthesis, modifications, and applications of nHA in various biomedical fields, shed light on the future advancements in biomaterials research.

New Spheromorphic Problematics Gaparella from the Lower Cambrian of Western Mongolia

From the lower part of the Tommotian Stage of the Lower Cambrian of Western Mongolia, ridge Hevte-Tsakhir-Nuruu described a new problematical sphaeromorhical microfossils Gaparella elenae sp. nov.; a new combination of generic and specific names Gaparella kuanchuanpuensis (Qian, 1977). has been proposed. Despite its very peculiar morphology, the genus Gaparella Missarzhevsky in Missarzhevsky et Mambetov, 1981 is more often mentioned in the list of synonyms of the genus Archaeooides Qian, 1977. The taphonomic variability of Mongolian Gaparella is shown and the morphology is reconstructed: these were hollow spheres, with a perforated double thin wall; between the holes, which were located chaotically on small elevations, a system of canals was developed; the wall may have been organic with an admixture of mineral components. Based on their lifestyle, these fossils were probably planktonic filter feeders. Their level of organization appears to have been consistent with Porifera; most likely these were juvenile forms.

Unveiling the nutritional treasure trove: A comparative analysis of two Azolla species for potential food applications

The study investigates the nutritional potential of Azolla pinnata and Azolla caroliniana for its food applications. Nutritional evaluation revealed it as a valuable source of major and minor nutrients. Both species exhibited an abundance of vitamins as well as essential macro and micro mineral components. The essential amino acid profile ranged from 41.96% to 42.91%, and non-essential amino acids comprising of 57.1–58.02%. Fatty acid analysis indicated a significant amount of polyunsaturated fatty acids (26.96% - 28.06%) and Monounsaturated fatty acids were present in the range of 8.34–8.81%. The ω3:ω6 ratio favored a healthy balance in both species indicating a ratio of 4:1. Protein quality indices showed encouraging values with regard to Protein Efficiency Ratio (PER), Essential Amino Acid Index (EAAI), Nutritional Index (NI), Biological Value (BV), and Chemical Score (CS) for both species. Findings suggested Azolla species as promising candidate for its food applications. A balanced and varied diet is essential for human health, and to meet this, Azolla can be explored as a complementary source of nutrient along with other major dietary sources.

Automated identification of soil functional components based on NanoSIMS data

NanoSIMS technique allows to investigate the micro-spatial organization in complex structures in multiple scientific fields such as material science, cosmochemistry, and biogeochemistry. In soil biogeochemistry applications, NanoSIMS-based approaches aim to disentangle the interactions of organic matter (OM) and mineral phases in the heterogeneous soil microstructure. Investigating the spatial arrangement of distinct organic and mineral functional components is necessary to understand how these components interact and contribute to biogeochemical processes in soil systems. Identifying soil functional components within NanoSIMS measurements necessitates advanced and efficient data processing tools capable of accessibility and automation. We have developed a pre-processing tool to streamline NanoSIMS data preparation and handling. The tool is provided as an open-source software toolbox (NanoT). In addition, a two-step unsupervised segmentation method was developed to identify soil functional components based on NanoSIMS analyses. To illustrate the segmentation method, here we describe its application to two exemplary NanoSIMS measurements. This allows to distinguish mineral- and OM-dominated regions, as well as different mineral phases. To improve the detection of iron oxides and aluminosilicates, the 56Fe16O− channel was separately processed. The presented NanoSIMS-based processing workflow helps to disentangle functional components within a biogeochemically-diverse microstructure in soils and further warrants applications to a wide range of complex environmental samples.

High-Temperature Hydrothermal Fluid Evolution, Archean Alkalic Intrusion-Related Mineralization, Karari-Whirling Dervish Gold Deposit, Western Australia

Abstract Genetic models that propose a magmatic-hydrothermal source for the gold ore fluid in Archean gold deposits hosted by, or spatially associated with, felsic to intermediate magmas are contentious. The Archean Karari-Whirling Dervish gold deposit (>1 Moz at approximately 3 g/t Au), Kurnalpi terrane, Yilgarn craton, Western Australia, provides an opportunity to test such models because it is hosted by quartz-poor, volcaniclastic metasedimentary rocks that were intruded by Neoarchean oxidized syenitic magma. A carapace of hydrothermal alteration in felsic to intermediate volcaniclastic rocks that overlie the eastern intrusive complex evolved from pervasive potassic (biotite) alteration through structurally controlled tabular zones of sodic (albitic) alteration to localized potassic (K-feldspar) alteration within the albitized rocks; the last of these was directly associated with gold. Low-grade gold was deposited with hydrothermal K-feldspar in a pervasive fracture network as nanoparticles or crystallographic substitution in disseminated pyrite, probably as a result of redox reactions between an oxidized, potassic ore fluid and reduced, sodic host rocks. Subsequent fracturing of the volcaniclastic host rocks, under increasing fluid pressure, produced biotite-rutile-pyrite stringers and quartz-pyrite veins with K-feldspar-dolomite-pyrite alteration selvages. Pyrite associated with both of these events contains numerous inclusions of native gold and constitutes the high-grade component of mineralization (>3 g/t Au). Geothermometric data (biotite-apatite, Ti-in-biotite, Zr-in-rutile) indicate that these hydrothermal events took place at temperatures between 500° and 650°C; other mineral compositional (biotite, rutile) and S isotope data (δ34S is –11 to 0 per mil) show that the hydrothermal fluids responsible for potassic (biotite) and potassic (K-feldspar) alteration were moderately to strongly oxidized. The ∆33S signature of pyrite indicates a mantle source, and allows only minor or no crustal involvement, for the ore fluid. The fluid responsible for high-temperature, oxidized hydrothermal alteration and gold mineralization is identified as the magmatic-hydrothermal phase that exsolved from spatially associated syenitic magmas. On the basis of this interpretation, Karari-Whirling Dervish is classified as an alkalic intrusion-related gold deposit.

Micromechanical properties and fractal homogenization of coal based on nanoindentation

Distinct from hard rock, coal is relatively soft and fragmented. It is not only challenging to prepare test coal samples that meet the requirements of standard mechanical experiments but also impossible to recycle them for repeated testing. There is an urgent need to explore new mechanical testing methods to enhance the study of the mechanical properties of coal. In this study, the micromechanical parameters of the coal matrix solid phase were acquired through targeted nanoindentation technology. The elemental composition, surface morphology, and pore structure characteristics of each indentation point were determined by energy dispersive spectrometer, optical microscope observation, and high-pressure mercury injection experiments. The fractal homogenization equation is deduced based on fractal geometry and the Mori–Tanaka method. The validity of the fractal homogenization approach is verified by integrating the micromechanical parameters and pore structure characteristics of coal, and the impact of the microstructural parameters on the macroscopic mechanical properties of coal is discussed. The results show that the proportion of clay minerals in the solid phase of the coal is the greatest (81.18%), with the main mineral components being kaolinite and illite. The elastic modulus is 1.974 ± 1.036 GPa, the hardness is 0.131 ± 0.108 GPa, and the ratio of upper and lower pore scales conforms to the fractal calibration rate. The macroscopic equivalent elastic modulus rises along with the increase in the fractal dimension. When the fractal dimension is constant, the macroscopic equivalent elastic modulus decreases with the increase in λmin/λmax and increases with the increase in solid phase elastic modulus.

The Chemerpil gravimagnetic anomaly as a modern reflection of the unique Precambrian volcanic-plutonic magnetite-gold mineralisation structure of the Ukrainian Shield (Middle Bug area)

The article is devoted to the peculiarities of genesis and mineralogical potential of Chemerpol iron-magnetite structure, its difference from other similar objects of Central Bug area. As an independent geological-geophysical object it was established according to the data of gravimetric and magnetometric survey of medium scale as a complex localised maximum of subisometric shape with diameter of 1.7 km and area of 2.8 km2. In regional structural and tectonic terms, this maximum is confined to the Sinitsiv block of the Golovanovsk suture zone. As of today, the Chemerpol structure has been sufficiently investigated by mapping drilling and various geophysical methods at the level of the crystalline basement surface. Based on the obtained data, the main petrophysical complexes involved in its structure have been determined. The industrial and mineralogical potential of the Chemerpolska structure is estimated at 100 million tons of magnetite quartzites and carbonate formations, as well as 2 tons of exogenous gold in the weathering crust. No estimates have been made of the underlying gold deposits. Copper mineralisation, represented by the natural copper, chalcopyrite and chalcosine, has been identified in the weathering crust and crystalline basement. By structural and tectonic features, petrophysical and mineralogical diversity, the Chemerpolska structure can be attributed to local pipe volcanic-magmatic objects. Its closest well-studied geological analogues may be such Precambrian "stratified" iron-oxide-gold-copper deposits as Solobot and others of the Carajas ore district in Brazil. For geological verification of new conclusions about the peculiarities of the Chemerpol structure and its actual ore potential, it is necessary to continue its study based, first of all, on the data of targeted structural exploration drilling and deep seismic and electrical exploration methods. The economic efficiency of extraction of the main mineral components of the Chemerpolska structure - gold and magnetite iron - can be increased due to the accompanying use of non-metallic calcifiers for the manufacture of sintering flux, soil deoxidation, raw materials for road pavement.

Effect of inorganic salt composition on strength, microstructure and leaching toxicity of coal-based solid waste backfill materials

This study explores the potential of coal-fired slag, desulfurized gypsum and modified magnesium slag as cementing agents for coal-based solid waste backfill materials. Inorganic salts like CaCl2, Na2SO4 and Na2SiO3 were used as excitants to investigate their combined impact on the mechanical properties, microstructure and leaching risk of hazardous elements from the coal-based solid waste backfill materials. The findings show that the addition of inorganic salt boosts the alkalinity within the liquid-phase reaction system. This disrupted the hydration-blocking membrane, accelerating the dissolution and reaction rate of the silica-alumina mineral components within the cementitious material. Concurrently, the inorganic salt ions consumed the early alkaline hydration products, destroying the hydration reaction equilibrium and facilitating the formation of hydration products like AFt, C-S-H gel, C-A-S-H gel, and Friedel's salt. This increase in the solid-phase volume content and microscopic densities in the reaction system improved the early mechanical properties of the coal-based solid waste backfill materials. Additionally, after a 28-day curing period, the leaching concentration of deleterious elements in the coal-based solid waste backfill material containing inorganic salt components was below the permissible concentration limit of the Class III groundwater quality standard. This eco-friendly backfill material is promising for mine backfilling, a potential substitute for traditional cement-based backfill material.