Search

Siliceous sandstone (including quartzites), petrified wood, and agates located in Alabama and Mississippi were utilized as a toolstone resource during every recognized cultural period in the Lower Mississippi Valley region of the Southeastern United States. Regrettably, these materials have not been the focus of many provenance‐related investigations. Recent analyses of quartzite and sandstone from other regions in North America and from the Pyrenees were successful in discriminating sources using petrographic techniques. The current study examines the application of visible/near‐infrared reflectance and Fourier transform infrared reflectance (FTIR) spectroscopy on sourcing siliceous materials besides chert, particularly sandstones, orthoquartzites (quartz sandstone), petrified woods, and agates. This source characterization investigation focuses on a case study involving materials gathered from eight distinct collection sites, encompassing nine different siliceous resources collected in Alabama and Mississippi. These materials were sourced from two distinct geological formations: the Hattiesburg and Tallahatta. Results demonstrate the ability of non‐destructive reflectance spectroscopy and introduces a new outlier modeling method that detects, clusters, and separately models outliers with their own set of basis vectors. Principal component analyses, least absolute shrinkage and selection operator regression, linear discriminant function analysis (LDA), and random forest classification are used in this paper to better identify outlier elements as well as discriminate for stone materials accurately (between 67% and 100%). Although this is the first reflectance spectroscopy investigation used to characterize these materials for provenance applications, the preliminary results compare favorably with other provenance techniques whose aim is to quantify between‐formation (inter) and within‐formation (intra) outcrop variation. The quantified and differentiated sources, based on the hyperspectral signatures of the material, will provide a better understanding of prehistoric reliance on these lithic resources and produces a proxy to determine mobility, social interaction, and other past behavior. [ABSTRACT FROM AUTHOR]

Zircon is the premier geochronometer used to date igneous and metamorphic processes, constrain sediment provenance, and monitor key events in Earth history such as the growth of continents and the evolution of the biosphere. Zircon U-Pb systematics can be perturbed by the loss or gain of uranium and/or lead, which can result in disagreement between the apparent radiometric ages of the two U-Pb decay systems – a phenomenon that is commonly termed 'discordance'. Discordance in zircon can be difficult to reliably interpret and therefore discordant data are traditionally culled from U-Pb isotopic datasets, particularly detrital zircon datasets. Here we provide a data reduction scheme that extracts reliable age information from discordant zircon U-Pb data found in detrital zircon suites, tracing such processes as fluid flow or contact metamorphism. We provide the template for data reduction and interpretation, a suite of sensitivity tests using synthetic data, and ground-truth this method by analyzing zircons from the well-studied Alta Stock metamorphic aureole. Our results show accurate quantification of a ~23 Ma in situ zircon alteration event that affected 1.0–2.0 Ga detrital zircons in the Tintic quartzite. The 'discordance dating' method outlined here may be widely applicable to a variety of detrital zircon suites where pervasive fluid alteration or metamorphic recrystallization has occurred, even in the absence of concordant U-Pb data. [ABSTRACT FROM AUTHOR]

The timing and mechanism of the crustal extension that caused blocks of continental crust to rift and drift northwards from the northern Gondwana margin during the Early Palaeozoic are currently debated. Here, we present new field, geochemical and U-Pb zircon data from peri-Gondwanan Central Sakarya terrane in NW Turkey to shed light on the timing and petrogenesis of extensional magmatism and subsequent passive margin development of the northern Gondwana margin. Our 1/25.000 scale mapping of a selected area (250 km2) has revealed a south-vergent thrust stack comprising three slices. The Middle Slice of the thrust stack consists of a gneiss-amphibolite complex that has a basement-cover type stratigraphy (before regional metamorphism). The basement unit consists of meta-granitoids, intruded by meta-syenite and banded amphibolites, with geochemical characteristics reflecting I&S-type, A-type and within plate alkaline/transitional-type magmatism, respectively. The cover meta-clastic sediments have amphibolite lenses with MORB and back-arc basin-type geochemistry. Meta-granitoid bodies yielded zircon U-Pb ages of 507 ± 16 Ma, 503 ± 12 Ma, and 488 ± 2.6 Ma (Late Cambrian-Early Ordovician), whereas the meta-syenites gave ages of 473.9 ± 5.7 Ma and 471.4 ± 2.5 Ma (late Early Ordovician); also, age of the banded amphibolite was dated as 473.3 ± 4 Ma. The youngest detrital zircon population in the pebbly quartzite sample within cover meta-sediments (458 ± 3 Ma) constrains the maximum depositional age to around early Late Ordovician. The late Early Ordovician bimodal magmatism, a key focus of our study, is interpreted to have formed in response to the Rheic Ocean rifting along the northern margin of Gondwana. The Late Cambrian granitic magmatism, a precursor to bimodal magmatism, can be explained by lithospheric thinning and upwelling of the asthenosphere to form anatectic silicic melts. The unconformity between the basement and cover units may represent the initiation of a new phase of extension at the N Gondwana margin that culminated in the northward drifting of the Central Sakarya and the opening of Palaeotethys, associated with back-arc basic magmatism in Late Ordovician-Silurian. [ABSTRACT FROM AUTHOR]

We present significant findings of the Kausani Granite Gneiss within the Inner Lesser Himalayan Sedimentary Zone (iLHSZ) just north of the North Almora Thrust (NAT). The Kausani Granite Gneiss body lies within the quartzite of the Someshwar Formation and has a tectonized contact and a discordant relationship on the north side. Detailed seismic profiling across the body also confirms a similar result. Cathodoluminescence images of zircon from the Kausani body show no inheritance of older cores. The U–Pb ages from the zircon populations separated from the Kausani body give a crystallization age of 1866 ± 3 Ma. Along with the Upalda granite gneiss and Toneta granite gneiss near the Alakhnanda Thrust in the Garhwal Himalaya and the Dungeshwari granite gneiss near the Dailekh Thrust in Nepal, the Kausani Granite Gneiss north of NAT Kumaun Himalaya forms a major terrain boundary. These gneissic bodies mark the southernmost extent of felsic magmatism at NAT, rather than the Main Central Thrust. An about 1.8 billion years‐old magmatic event in the LHSZ suggests that it is a currently active continental margin inside the 'Greater India' region, now situated in the Himalayan domain. However, the Pb‐loss modelling of the U–Pb zircon data reveals thermal events during the Himalayan Orogeny (~45 Ma). [ABSTRACT FROM AUTHOR]

The later Acheulian assemblages (ca. 534–< 390 ka) from Amanzi Springs in South Africa show a preferential selection for large flake blanks when undertaking large cutting tool manufacture. However, due to the small number of giant cores from the site, we have limited insight into the technical preparation of quartzite raw material packages for large flake production. Here, we present an actualistic experimental study to better understand these procedures at the site and to gain perspective on how knappers may have reduced quartzite boulders of differing internal qualities. Our results highlight the influence of raw material constraints and how the overall morphology of quartzite boulders in turn impacts giant core reduction sequences and large flake blank morphologies. Finally, the experimental study exemplifies the need for high levels of knapping expertise to deal with tough, heterogeneous quartzite varieties. [ABSTRACT FROM AUTHOR]

Abstract Studying crystal anisotropy is of great importance for understanding the thermal–mechanical coupling behavior of crystalline rocks in deep underground engineering. In this study, a microscopic parameter calibration method incorporating the size effect is proposed. Subsequently, a thermal–mechanical coupling model accounting for the quartz crystal anisotropy is established to investigate the thermal–mechanical coupling behavior of monomineral quartzite. The results show that thermal-induced microcracks are exclusively distributed along crystal boundaries, and initiate preferentially from crystal boundaries with a larger average linear thermal expansion coefficient, eventually leading to the formation of a crack network. With the increase in temperature, the peak strength of monomineral quartzite increases slightly at first and then decreases rapidly, and the transition threshold temperature is 200 °C. Both elastic modulus and Poisson’s ratio show a monotonic pattern, with abrupt changes occurring at 200 and 300 °C, respectively. The monomineral quartzite exhibits a significant compaction stage under uniaxial compression, and the ductile strengthening critical temperature for monomineral quartzite are between 400 and 500 °C. The quartz crystal anisotropy leads to an anisotropic distribution of inclination angles for tensile microcracks under high temperatures while having no obvious effect on the shear microcracks. In addition, the average size of fragments generated under uniaxial compression is influenced by thermal cracking, demonstrating an initial decrease followed by an increase, and the distribution of fragment sizes is solely correlated with the temperature, which is more concentrated with the increase in temperature.

Abstract The microstructure of realistic fluid–rock systems evolves to minimize the overall interfacial energy, enabling local variations in fluid geometry beyond ideal models. Consequently, the permeability–porosity relationship and fluid distribution in these systems may deviate from theoretical expectations. Here, we aimed to better understand the permeability development and fluid retention in deep-seated rocks at low fluid fractions by using a combined approach of high-resolution synchrotron radiation X-ray computed microtomography imaging of synthesized rocks and numerical permeability computation. We first synthesized quartzite using a piston-cylinder apparatus at different fluid fractions and wetting properties (wetting and non-wetting systems with dihedral angles of 52° and 61°–71°, respectively) under conditions of efficient grain growth. Although all fluids should be connected along grain edges and tubules in the homogeneous isotropic wetting fluid–rock system enabling segregation by gravitational compaction in natural settings, the fluid connectivity rapidly decreased to ~ 0 when the total fluid fraction decreased to 0.030–0.037, as the non-ideality of quartzite, including the interfacial energy anisotropy (i.e., grain faceting), became critical. In non-wetting systems, where the minimum energy fluid fraction based solely on the dihedral angle is ~ 0.015–0.035, the isolated (disconnected) fractions was 0.048–0.062. A streamline computation in the non-wetting system revealed that with decreasing total porosity, flow focusing into fewer channels maintained permeability, allowing the effective segregation of the connected fluids. These results provide insight into how non-wetting fluids segregate from rocks and exemplify the fraction of retained fluids in non-wetting systems. Thus, the findings suggest a potential way for wetting system fluids to be transported into the deep Earth's interior, and the amount of fluids dragged down to the Earth’s interior could be higher than what was previously estimated.

Recent excavations at Millukmungee 1, a limestone rock shelter along the upper bank of the Buchan River in GunaiKurnai Country (southeastern Australia), uncovered archaeological evidence of Mid- to Late Holocene occupation spanning c. 5000 years. Here we report on the stone artefacts and faunal remains, especially in light of a paucity of published details on artefact types and technologies for this part of southeast Australia. Results indicate that this part of the site was occupied only rarely from 5590–5050 cal BP (the uncertainty range for the oldest artefact from the excavation) to 2340–2030 cal BP. During this period, most of the artefacts were made from silcrete, quartz, chert, and quartzite. Small backed artefacts are present during this phase, all dating between 4570–1940 cal BP. A single, much larger backed artefact (elouera) dates to later, ≤290 cal BP. After 1960 cal BP, activities focussed on the production of flakes from locally available quartz and, to a lesser extent, hornfels; large pebbles obtained from the nearby Buchan River channel were flaked during this period. Occupation ceased with the onset of settler colonialism in the mid-1800s CE. [ABSTRACT FROM AUTHOR]

The microstructure of realistic fluid–rock systems evolves to minimize the overall interfacial energy, enabling local variations in fluid geometry beyond ideal models. Consequently, the permeability–porosity relationship and fluid distribution in these systems may deviate from theoretical expectations. Here, we aimed to better understand the permeability development and fluid retention in deep-seated rocks at low fluid fractions by using a combined approach of high-resolution synchrotron radiation X-ray computed microtomography imaging of synthesized rocks and numerical permeability computation. We first synthesized quartzite using a piston-cylinder apparatus at different fluid fractions and wetting properties (wetting and non-wetting systems with dihedral angles of 52° and 61°–71°, respectively) under conditions of efficient grain growth. Although all fluids should be connected along grain edges and tubules in the homogeneous isotropic wetting fluid–rock system enabling segregation by gravitational compaction in natural settings, the fluid connectivity rapidly decreased to ~ 0 when the total fluid fraction decreased to 0.030–0.037, as the non-ideality of quartzite, including the interfacial energy anisotropy (i.e., grain faceting), became critical. In non-wetting systems, where the minimum energy fluid fraction based solely on the dihedral angle is ~ 0.015–0.035, the isolated (disconnected) fractions was 0.048–0.062. A streamline computation in the non-wetting system revealed that with decreasing total porosity, flow focusing into fewer channels maintained permeability, allowing the effective segregation of the connected fluids. These results provide insight into how non-wetting fluids segregate from rocks and exemplify the fraction of retained fluids in non-wetting systems. Thus, the findings suggest a potential way for wetting system fluids to be transported into the deep Earth's interior, and the amount of fluids dragged down to the Earth's interior could be higher than what was previously estimated. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

T his study aimed to produce autoclaved aerated concrete (AAC) by using glass and ceramic waste in 10%, 20%, 30%, 40%, and 50% proportions as a substitute material for quartzite, and samples were produced under low pressure and heat (2.3 bar and 135 °C). The microstructural properties were investigated by employing scanning electron microscopy (SEM) analysis. Unit weight, porosity, water absorption, ultrasonic wave velocity, compressive strength, and thermal conductivity parameters were experimentally investigated and compared to a control sample produced without waste. Test results showed that waste addition leads to decreasing porosity, water absorption, and increasing unit weight. Additionally, uniaxial compressive strength, thermal conductivity, and ultrasonic wave velocity values were increased by adding waste. The test results showed that glass and ceramic waste can be used as a quartzite sand replacement in the production of AAC and the optimum replacement proportions for the waste materials was 10%. [ABSTRACT FROM AUTHOR]

Studying the dynamics of groundwater in mining areas is important from the perspective of impact on ecosystems. This study determines water stress for subarctic mining areas using modern methods—remote sensing, machine learning, GIS. The study is carried out using the example of the Kostomuksha mining cluster, located in the northwestern part of the Republic of Karelia, Russia. Water stress was studied based on changes in NDMI in different vegetation land cover classes. To bring different values of remote sensing data to a single scale, the method of normalization by pseudo-invariant features (PIF) was applied. Landscape, climatic, topographic, and anthropogenic factors that control changes in humidity were studied, for a total of 15 variables. The importance of predictors was assessed using the recursive feature elimination method. The most important predictors are vegetation LCC, valley depth, distance to road, elevation, and KdistQ. The topographical features of the area have a large influence on the natural dynamics of NDMI. The greatest negative changes occur on steep slopes, as well as hills and ridges. The accumulation of water in the valleys forms the positive dynamics of NDMI. The interaction of the influence of mining with natural patterns of changes in vegetation humidity has been studied. The greatest negative changes are manifested for all vegetation classes within the newly formed groundwater depression cones. In areas of previously formed depression cones, the adaptation of vegetation to water stress is noted. Deciduous vegetation in wetlands has been determined to be most sensitive to anthropogenic stress. [ABSTRACT FROM AUTHOR]

The possibility of using the enrichment tailings of KMA ferruginous quartzites is considered. The chemical composition of waste from Lebedinsky MPP was investigated. It was established that the main components of the waste are quartz, magnetite, as well as dolomite, calcium, and magnesium carbonates. It is shown that the chemical composition and particle size distribution of waste are characterized by stability, which allows it to be used as a corrective additive to ceramic mixtures in the production of wall ceramics. [ABSTRACT FROM AUTHOR]

Conventional convolutional neural networks (CNN) are deficient in the rock type recognition due to large convolutional kernels and numerous network parameters necessitated for recognition of complex images. The advanced convolutional neural network, Visual Geometry Group-16 (VGG16) model, which is based on multiple small convolutional kernels and fully connected layers, attains higher classification accuracy, yet is limited by low computational efficiency. In this paper, we propose a novel approach that integrates the advanced VGG16 with the Principal Component Analysis (PCA), a dimensionality reduction technique. This integration, referred to as the PCA-VGG16 model, aims to enhance the computational efficiency of automatic rock type identification. A dataset comprising 3000 images of six rock types: limestone, shale, dolomite, quartzite, marble, and granite, is assembled for training and testing of the PCA-VGG16 model. The feasibility of the PCA-VGG16 model for classification prediction is demonstrated through evaluation metrics including accuracy, loss value, and F1-score. A comparative analysis with the CNN and VGG16 models reveals that the proposed PCA-VGG16 model exhibits superior classification accuracy and reduced training durations, making a very promising advancement in the field. Furthermore, an in-depth analysis is conducted to understand the impact of dataset size and key hyperparameters (such as epochs and batch size) on the classification accuracy of the PCA-VGG16 model. The findings indicate that a minimum dataset of 1500 sample images is necessary to achieve a classification accuracy above 90%. For optimal model performance, a division of training, validation, and test sets approximately at 6:2:2, along with two epochs and a batch size of 128, is recommended in this study. [ABSTRACT FROM AUTHOR]

River sand is an essential component used as a fine aggregate in mortar and concrete. Due to unrestrained exploitation, river sand resources are gradually being exhausted. This requires alternative solutions. This study deals with the properties of cement mortar containing different levels of manufactured sand (MS) based on quartzite, used to replace river sand. The river sand was replaced at 20%, 40%, 60% and 80% with MS (by weight or volume). The mechanical properties, transfer properties, and microstructure were examined and compared to a control group to study the impact of the replacement level. The results indicate that the compressive strength can be improved by increasing such a level. The strength was improved by 35.1% and 45.5% over that of the control mortar at replacement levels of 60% and 80%, respectively. Although there was a weak link between porosity and gas permeability in the mortars with manufactured sand, the gas permeability decreased with growing the replacement level. The microstructure of the MS mortar was denser, and the cement paste had fewer microcracks with increasing the replacement level. [ABSTRACT FROM AUTHOR]

Quartzite aggregates have poor adhesion with asphalt binder due to the higher silica content present in the mineral composition. Apart from conventional asphalt mixture testing methods, the surface free energy (SFE)-based adhesion evaluation method is most widely used in recent times to predict compatibility between aggregate and asphalt binder and moisture susceptibility in asphalt mixtures. This study tried to improve quartzite aggregates' adhesion properties by modifying the aggregates' surface with a nano-organosilicon (NOS), and two silane coupling agents (SCA) were used in modifying the aggregates' surface. Results showed that surface modifications by chemical treatments reduced the aggregate's SFE by increasing the aggregate nonpolar components to make a better bond with asphalt binder, which is also a non-polar material. From tensile strength ratio (TSR) results, it is found that the asphalt mixtures prepared with surface-modified aggregates showed better resistance to moisture damage with a 12%–15% increase in TSR. SFE indices like adhesion energy and energy ratio (ER) also showed significant improvement in adhesion between aggregates and asphalt binder, even in the presence of moisture. The ER values were above acceptable limits after surface treatments and showed a 100% increase compared with control mixes. SCA-1 and SCA-2 treatments effectively improved moisture damage in hot-mix asphalt with quartzite aggregates. One-way ANOVA was used to predict the effect of treatment methods and aggregate types on conventional TSR values and advanced SFE indices. The statistical results proved significant improvements in TSR and ER after the treatment of aggregates, but aggregate types do not make significant changes. [ABSTRACT FROM AUTHOR]

Sediment grains are progressively rounded during their transport down a river. For more than a century, Earth scientists have used the roundness of pebbles within modern sediment, and of clasts within conglomerates, as a key metric to constrain the sediment's transport history and source area(s). However, the current practices of assessment of pebble roundness are mainly qualitative and based on time-consuming manual measurement methods. This qualitative judgement provides the transport history only in a broad sense, such as classifying distance as "near" or "far". In this study, we propose a new model that quantifies the relationship between roundness and the transport distance. We demonstrate that this model can be applied to the clasts of multiple lithologies including modern sediment, as well as conglomerates, deposited by ancient river systems. We present field data from two Himalayan catchments in Nepal. We use the normalized isoperimetric ratio (IRn), which relates a pebble's area (A) to its perimeter (P), to quantify roundness. The maximum analytical value for IRn is 1, and IRn is expected to increase with transport distance. We propose a non-linear roundness model based on our field data, whereby the difference between a grain's IRn and the maximum value of 1 decays exponentially with transport distance, mirroring Sternberg's model of mass loss or size reduction by abrasion. This roundness model predicts an asymptotic behaviour for IRn , and the distance over which IRn approaches the asymptote is controlled by a rounding coefficient. Our field data suggest that the roundness coefficient for granite pebbles is 9 times that of quartzite pebbles. Using this model, we reconstruct the transport history of a Pliocene paleo-river deposit preserved at the base of the Kathmandu intermontane basin. These results, along with other sedimentary evidence, imply that the paleo-river was much longer than the length of the Kathmandu Basin and that it must have lost its headwaters through drainage capture. We further explore the extreme rounding of clasts from Miocene conglomerate of the Siwalik zone and find evidence of sediment recycling. [ABSTRACT FROM AUTHOR]

The Tyennan Domain of western Tasmania is a structurally emplaced, complexly deformed lithotectonic sheet (allochthon). It comprises stacked, isoclinally folded slabs of allochthonous high-grade schist including garnet schist and quartzite, amphibolite and rare eclogite (uppermost unit), overlying low-grade pelite, overlying low-grade quartzite and platy quartzite (middle unit), overlying parautochthonous low-grade dolomitic pelite, quartzite and dolostone (lowermost unit). It is a product of Cambrian continental margin subduction, rebound and exhumation coupled with ophiolite obduction. Tyennan rocks were transported to maximum depths of ∼60–80 km sufficient to generate high-P metamorphism. Their deformation involved progressive shear, large shear strains and large shear displacements with a bulk west-over-east sense of shear related to the direction of subduction and buoyant exhumation. The Tyennan Domain shows a unique crustal architecture, including: (1) metamorphic sheets with 100 km lengths, 50 km widths and 5–10 km structural thicknesses, (2) a leading edge fold nappe with ∼200 km axial surface trace length, (3) megasheath folds with 20–25 km dimensions, and (4) asymmetric folds within regional scale shear lozenges as macro-augen. It provides an unparalleled window beneath the now, largely eroded, obducted ophiolite sheet and provides structural insight into the mechanics of continental margin subduction–obduction. Deformation has been partitioned through the composite exhumed 'slab' with domains of isoclinal macrofolds transitioning into regional scale sheath folds bounded by zones of higher strain. The higher strain zones are characterised by transposition foliation, rootless mesoscopic isoclinal folds, small-scale sheath folds, overprinting crenulation cleavages and platy mylonitic to schistose zones in quartzite. The uppermost, high-grade part of the Tyennan allochthon is clearly a composite, ∼1 km thick 'sheet' made up of a 'welded' amalgam of largely pelitic fragments that had been subducted to different depths, assembled and deformed during buoyant ascent to the current structural level. The Tyennan Domain represents the subducted part of a microcontinent during a Cambrian arc–microcontinent collision outboard of the eastern Pacific margin of Gondwana. The Tyennan Domain consists of stacked, recumbent and isoclinally folded slabs of allochthonous high-grade schist and low-grade pelite-quartzite, overlying parautochthonous low-grade dolomitic marl, quartzite and dolostone. Isoclinal, asymmetric, macrofold 'wave trains', megasheath folds and a 'leading edge' fold nappe with ∼200 km length scale dominates the structure of the Tyennan Domain. [ABSTRACT FROM AUTHOR]

We investigated the mineral assemblage, mineral and bulk-rock chemistry, and zircon U–Pb age of a manganiferous quartzite layer in the Lanterman Range, northern Victoria Land, Antarctica. The mineral assemblage consists primarily of phengite and quartz, along with spessartine-rich garnet, Mn 3+ and rare earth element–yttrium (REY)-zoned epidote-group minerals, and titanohematite. Mineral inclusions such as tephroite, rutile and pyrophanite are hosted in porphyroblasts of the latter three minerals and suggest prograde blueschist-facies to low- T eclogite-facies metamorphism (M 1). Epidote-group minerals commonly exhibit multiple growth zones of piemontite and/or epidote (M 1), REY-rich piemontite (M 2), REY-rich epidote (M 3), and epidote (M 4) from core to rim. Pseudobinary f O 2 – X diagrams at constant P – T support the stability of an epidote-group mineral-bearing assemblage under highly oxidized conditions during prograde M 2 to peak M 3 metamorphism. In marked contrast, tephroite-bearing assemblages (M 1) are limited to relatively reduced environments and Mn-rich, silica-deficient bulk-rock compositions. Mn nodules have such characteristics, and the contribution of this hydrogenous component is inferred from bulk-rock chemical features such as a strong positive Ce anomaly. The major-element composition of the manganiferous quartzite suggests a protolith primarily consisting of a mixture of chert and pelagic clay. The presence of rare detrital zircons supports terrigenous input from a craton and constrains the maximum time of deposition to be ca. 546 Ma. The lack of arc-derived detrital zircons in the quartzite and the predominance of siliciclastic metasedimentary rocks among the surrounding rocks suggest that the deep-sea protolith was most likely deposited in an arc/back-arc setting at a continental margin. High- P metamorphism associated with terrane accretion during the Ross orogeny took place in the middle Cambrian (ca. 506 Ma), broadly coeval with the metamorphic peak recorded in the associated high- P rocks such as mafic eclogites. Finally, it is noteworthy that the high- P manganiferous quartzite was amenable to exhumation because the paleo-position of the protolith was likely distal from the leading edge of the downgoing slab. [ABSTRACT FROM AUTHOR]

Geological mapping of over 50 km2 area has been carried out in and around Obulapuram area, SE of Sandur Schist Belt. The Sandur Schist Belt (SSB), a part of Eastern Dharwar Craton (EDC) is a NW–SE trending lens-shaped late Archaean volcano-sedimentary belt. The litho-types exposed include peninsular gneiss of PGC, fuchsite quartzite, meta-basalt with intercalation of amphibolite, phyllite, metagabbro and quartzite, banded magnetite quartzite (BMQ), banded hematite quartzite (BHQ) belonging to the Donimalai Formation of Sandur Group. Granites, dolerite dykes, gabbro dykes and quartz veins are younger intrusives. Basement Peninsular Gneiss and intrusive granite are exposed towards the southern and eastern side of the study area. The area has undergone two phases of deformation, of which the earlier D1 deformation is quite pronounced producing the NW–SE trending S0∥S1 regional structures of the area. D1 deformation is responsible for the development of tight isoclinal and macroscopic (F1) folds. D2 deformation resulted in the development of open to close mesoscopic (F2) folds and broad warps with axial traces along ENE-WSW direction and crenulation cleavage (S2). The area is predominantly characterised by regional green schist facies of metamorphism, which increases to amphibolite facies near the contact of the schist belt with gneisses and intrusive granites. [ABSTRACT FROM AUTHOR]

Malang quartzite contains a highly silica content. The silica changes the structural composition of Zeolite Y. Currently, a heterogeneous catalyst is developed to optimize transesterification of Off Grade CPO (Crude Palm Oil). The aims of this study are: (1) synthesize K2O/Zeolite Y using silica from Malang quartzite, (2) synthesize methyl esters from Off Grade CPO using K2O/Zeolite Y catalyst, and (3) to evaluate quartzite based-silica contribution in Zeolite Y for the reaction activity via GC-MS analysis. The experimental stages were: the oil preparation, esterification of the prepared oil, preparation of K2O/zeolite Y catalyst, and the transesterification. This study applied variations of [KOH] in Zeolite Y (10, 20, and 30 % w/w) and the concentration of the transesterification catalyst (2, 3, and 4 % w/w). The K2O/Zeolite Y catalyst was successfully synthesized by impregnation method. Methyl esters of Off Grade CPO resulted the highest yield of 95.05 % with 4 wt% of 30-K2O/Zeolite Y (30 % KOH impregnation). The synthesized methyl esters have a density of 0.877 g/mL, a viscosity of 4.6 cSt, a refractive index of 1.445 and an acid number of 0.384 mg/g according to the standard (SNI 7182:2015). The main components of the methyl ester based on GC-MS results were methyl octanoate, methyl decanoate, methyl dodecanoate, methyl 9-octadecanoate, methyl octadecanoate and methyl tetracosanoate. Using quartzite-based silica, a co-activity of the reaction has occurred.

Among the crystalline rocks of the Middle Bug region, which are mapped as the Dniester-Bug series in the valley of the Yatran river in the area of the village Rogove, quartzites were discovered, which, unlike the quartzites of the Bug series, are mainly composed of quartz with a small number of feldspars. At the same time, hypersthene plays a prominent role in their composition. To find out the time of crystallization of monazite and the primary nature of quartzite, a sample of hypersthenic quartzite (sample 24/16), which is common on the left bank of the Yatran River (Rogove village), was taken. Under binoculars and a polarizing microscope, the internal structure of zircon crystals was studied in artificial preparations, and the spatial relationship with rock-forming minerals was studied in transparent sections under a polarizing microscope. Age was determined based on the results of U-Pb isotopic dating of multigrain monazite samples. Chemical preparation of multigrain samples of monazite for isotopic dating was performed according to the standard method [5]. A mixed 235U+206Pb tracer was used to determine the content of uranium and lead in monazites. According to the results of U-Pb isotopic dating, the time of crystallization of monazites from hypersten-containing quartzite of the Yatran river basin occupies an intermediate position (2044,7±9,2 million years) between the age of monazites from quartzites common in Kosharo-Olexandrivska structures (2062,4±4,4 million years) and Shamrayivka structures (1857,5±1,1 million years).

This study has carried out three-dimensional nonlinear elastoplastic analyses to understand the behaviour of tunnels constructed in rock having reinforced concrete lining when subjected to impact loading. The Lagrangian analysis tool has been used to create geometry and mesh the different parts of the present rock tunnel model through Abaqus/Explicit software. 3D lagrangian elements have been used to model the rock and concrete lining. The hoop and longitudinal bars of the reinforcement cage have been modelled using a beam element. The impact resistance behaviour of rock tunnel constructed in three different stages of weathered Quartzite has been simulated to understand the stability characteristics of the tunnel. The three-dimensional missile has been considered a rigid material to incorporate the maximum penetration in the rock when it hits the tunnel surface from 100 m. The four different missile weights i.e. 50 kg, 100 kg, 150 kg and 200 kg have been considered to contemplate the extent of deformation and damage In the tunnel. Moreover, the effect of overburden depth variation has been incorporated in terms of H/D ratio, which is defined as the ratio of overburden depth to diameter of the tunnel. The Ducker-Prager constitutive model with strain-rate dependence and dynamic increase factor is considered to simulate the behaviour of Quartzite rock. Johnson-Cook material model is used for steel bars of reinforcement cage and Ducker-Prager model with strain-rate and dynamic increase factor has been considered for reinforced concrete lining of the tunnel. The analyses results were studied for deformation, particle velocity, particle acceleration and damage in rockmass surrounding the tunnel and its reinforced concrete lining. It has been observed that reinforced concrete lining experiences a significant amount of compression and tension damage at the crown of the tunnel and this damage remains concentrated in the middle one-third section of tunnel length irrespective of change in weight of missile and H/D ratio. It has been concluded that a slightly weathered Quartzite rock tunnel has 18% more impact resistance than a medium weathered rock tunnel and 41% from a highly weathered rock tunnel. Moreover, the particle velocity is found to be inversely proportional to the strength of the surrounding rockmass. Further, particle acceleration generated due to impact loading changes proportionally with the rise in the degree of weathering in rocks. Also, it has been concluded that rock tunnels having a H/D ratio of 2.0 has 4-times higher impact resistance in terms of tension damage than the rock tunnels having a H/D ratio of 0.5. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the electric pulse disintegration of a natural mineral. The object of the study is the natural mineral quartzite of the Aktas deposit of the Republic of Kazakhstan. For the destruction and grinding of quartzite, a working cell of an electric pulse unit was developed. Electric pulse crushing is a modern technique for grinding a variety of materials, which provides the desired degree of grinding with a certain granulometric composition of the product and has a high ability of selective crushing. With the help of this technology, quartzite grinding was carried out with an increase in the capacity of capacitor banks from 0.25 mF to 1 mF, the pulse discharge voltage changed from 20 kV to 30 kV, the number of pulse discharges from 500 to 1,000, the inner diameter of the working cell from 60 mm to 80 mm. The results of the disintegration of a natural mineral by the electric pulse method allowed us to determine the degree of grinding of the finished product. The obtained results can be used in the study and optimization of the extraction of natural minerals, which is important for ensuring the sustainable use of natural resources and balanced economic development. Crushed quartzite is used in various industries, including the production of optical fibers, electronics and photovoltaic devices. A material with a particle diameter of 0.1 to 0.4 millimeters is used to create glass, ceramic and porcelain products, as well as insulation materials. Due to its homogeneous composition containing up to 98 % silicon oxide (SiO2) and excellent absorbent properties, quartz sand is also used as a filter material for water purification. [ABSTRACT FROM AUTHOR]

Abstract—The results of study and comparison of geochemical characteristics of quartzite sandstones of the Upper Riphean Khobeyu and Lower Paleozoic Obeiz formations of the Circumpolar Urals are presented. It has been established that the composition of quartzite sandstone of both formations was formed mainly from recycled material of ancient metaterrigenous rocks, with the participation of destruction products of igneous rocks of felsic (Obeiz Formation) and basic (Khobeyu Formation) composition and weathering crust material. The accumulation of the Lower Paleozoic psammites was accompanied by a gradual change of clastic sources, with increasing contribution of granitoid clastics. [ABSTRACT FROM AUTHOR]

The dominant road traffic particle sources are wear particles from the road and tire interface, and from vehicle brake pads. The aim of this work was to investigate the effect of road and brake wear particles on pulmonary function and biomarkers in isolated perfused rat lungs. Particles were sampled from the studded tire wear of three road pavements containing different rock materials in a road simulator; and from the wear of two brake pad materials using a pin-on-disk machine. Isolated rat lungs inhaled the coarse and fine fractions of the sampled particles resulting in an estimated total particle lung dose of 50 μg. The tidal volume (TV) was measured during the particle exposure and the following 50 min. Perfusate and BALF were analyzed for the cytokines TNF, CXCL1 and CCL3. The TV of lungs exposed to rock materials was significantly reduced after 25 min of exposure compared to the controls, for quartzite already after 4 min. The particles of the heavy-duty brake pads had no effect on the TV. Brake particles resulted in a significant elevation of CXCL1 in the perfusate. Brake particles showed significant elevations of all three measured cytokines, and quartzite showed a significant elevation of TNF in BALF. The study shows that the toxic effect on lungs exposed to airborne particles can be investigated using measurements of tidal volume. Furthermore, the study shows that the choice of rock material in road pavements has the potential to affect the toxicity of road wear PM10. [ABSTRACT FROM AUTHOR]

Quartzite aggregates are widely available siliceous aggregates that are weak in adhesion with asphalt binder. This study focused on improving the moisture susceptibility of hot mix asphalt (HMA) using chemical treatments to quartzite aggregates. Hydrated lime (HL), nano-organosilane additive (NOS), and two silane coupling agents (SCA) were used to treat aggregates. Moisture susceptibility was investigated using different tests such as retained stability, indirect tensile strength (ITS), and fracture energy. Scanning electron microscope (SEM) analysis was conducted to identify surface modifications and the treatment mechanisms, it was observed that HL treatment forms the rough surface over the aggregate by precipitating CaCO3, on the other hand, SCA treatments make perfect hydrophobic nano-layer over the surface of the aggregates. After the boil test, Coating retention was quantified with image processing, and coating retention was increased to greater than 95 percent compared to control mixes (i.e. 40–45 percent). The tensile strength ratio (TSR) of HMA with treated aggregates was increased by 20–25 percent to control mixes. HL and SCA-1 showed better TSR and fracture energy ratio (FER). Based upon the study results, it was concluded that chemical treatment methods can able to reduce the moisture induce damage of HMA with quartzite aggregates. [ABSTRACT FROM AUTHOR]

The 3D modelling of basic bodies of the Koperberg Suite (1060 to 1030 Ma) and their wall rocks from Narrap Mine illustrates the distribution, geometries and, by implication, processes that determined the ascent and emplacement of the mantle-derived mafic magmas into the partially-molten, mid-crustal granite-gneiss sequence of the Okiep Copper District in Namaqualand. The lens-like, discontinuous geometry of basic bodies suggests the transfer of the mafic magmas as self-contained, buoyancy-driven hydrofractures. The presence of both shallowly-dipping, foliation-parallel sills and subvertical lenses in zones of steep foliation development, so-called steep structures, indicates an emplacement of the mafic magmas under low deviatoric stresses and irrespective of the regional stress field. Instead, the emplacement of the mafic magmas parallel to pre-existing anisotropies (tectonic fabrics or lithological contacts) highlights those differences in tensile strength and fracture toughness parallel to or across anisotropies determined the propagation of the magmas. This also accounts for the common occurrence of basic bodies in steep structures in which the vertical gneissosity promoted the buoyancy-driven ascent of the mafic magmas. On a regional scale, the mechanical stratification of the subhorizontal, sheet-like granite gneisses and interlayered metasediments exerted important controls on the ascent of Koperberg Suite magmas. The preferential emplacement of basic bodies in schist and gneiss units suggests that the lower rigidity of the ductile wall rocks facilitated magma emplacement through a combination of viscous wall-rock deformation and fracture blunting that led to the arrest of the magma-filled hydrofractures. Multiple intrusive relationships of successively emplaced magma batches suggest that later magmas reutilised earlier established magma pathways, particularly in steep structures. High-rigidity lithologies, such as the massive Springbok Quartzite, in contrast, only allowed for smaller fracture apertures and limited dilation, resulting in the pinching of basic bodies and rather stringer-like geometries. It is conceivable that the higher fracture toughness of the quartzite may also have prevented propagation of the mafic magmas through the Springbok Quartzite and, instead, led to the ponding of basic bodies below the metasediments. The geometry and structural and lithological controls of basic bodies at Narrap Mine are similar to Koperberg Suite intrusions documented from many of the other mine workings in the Okiep Copper District. This suggests similar underlying emplacement controls of the cupriferous rocks, which can be extrapolated on a regional scale and that may guide exploration. [ABSTRACT FROM AUTHOR]

Sediment grains are progressively rounded during their transport down a river. For more than a century, Earth scientists have used the roundness of pebbles within modern sediment, and of clasts within conglomerates, as a key metric to constrain the sediment's transport history and source area(s). However, the current practices of assessment of pebble roundness are mainly qualitative and based on time consuming manual measurement methods. This qualitative judgement provides the transport history only in a broad sense, such as classifying distance as 'near' or 'far'. In this study, we propose a new model that quantifies the relationship between roundness and the transport distance. We demonstrate that this model can be applied to the clasts of multiple lithologies including modern sediment as well as conglomerates deposited by ancient river systems. We present field data from two Himalayan catchments in Nepal. We use the Normalized Isoperimetric Ratio (IRn) which relates a pebble's area (A) to its perimeter (P), to quantify roundness. The maximum analytical value for IRn is 1, and IRn is expected to increase with transport distance. We propose a non-linear roundness model based on our field data, whereby the difference between a grain's IRn and the maximum value of 1 decays exponentially with transport distance, mirroring Sternberg's model of mass loss or size reduction by abrasion. This roundness model predicts an asymptotic behaviour for IRn , and the distance over which IRn approaches the asymptote is controlled by a rounding coefficient. Our field data suggest that the roundness coefficient for granite pebbles is eight times that of quartzite pebbles. Using this model, we reconstruct the transport history of a Pliocene paleo-river deposit preserved at the base of the Kathmandu intermontane Basin. These results, along with other sedimentary evidence, imply that the paleo-river was much longer than the length of the Kathmandu Basin, and that it must have lost its headwaters through drainage capture. We further explore the extreme rounding of clasts from Miocene conglomerate of the Siwaliks Zone and find evidence of sediment recycling. [ABSTRACT FROM AUTHOR]

Some circular fossils showing radial structures concentrated in a small area have been recorded from the Criadero Quartzite, 1 km north from El Centenillo village (Iberian Central Zone, SE Spain). The fossils resembling cnidarians have been studied in detail, both at the field and in the laboratory. The specimens have been preserved in thick-grained quartz sandstones. They were analysed in thin sections and rock samples using optical microscopy, micro-reflectance spectroscopy, Fourier transform infrared–attenuated total reflectance spectroscopy, scanning electron microscopy with energy-dispersive X-ray spectroscopy and epifluorescence microscopy. The radial structure is composed of ridges and grooves, which correspond to clear and dark ochre bands filled with middle-sized, angular-elongated quartz grains without tractive structures. Mineralogical analyses reveal that composition is based on quartz and illite in both areas. The morphological and compositional features of the fossils have been compared with a set of ichnofossils of multiple taxonomic origins and ages without conclusive results. The preservation is probably produced by the existence of microbial mats on the sand floor and the impression of moulds by authigenic cementation by an unidentified organism. To elucidate the nature of the producer, potentially soft-bodied cnidarian, including fossil medusae and sea anemone, further investigations are needed. [ABSTRACT FROM AUTHOR]

Understanding the composition, formation and evolution of the oldest continental crust is crucial for comprehending the mechanism and timing of crustal growth and differentiation on early Earth. However, the preservation of the ancient continental crust is limited due to extensive reworking by later tectonothermal events. In the Lulong area of eastern Hebei, abundant ca. 3.8–3.4 Ga detrital zircons of the fuchsite quartzite have been previously identified. Nonetheless, the provenance and Hf isotopic compositions of the fuchsite quartzite remain unclear. In this study, we present new detrital zircon ages and Hf isotopic for the fuchsite quartzite in the Lulong area to establish the timing of deposition, the provenance and the regional stratigraphic relationship. Zircon U-Pb dating indicates that the fuchsite quartzite was deposited between 3.3–3.1 Ga and most grains were sourced from the 3.8 Ga TTG gneisses and Paleoarchean magmas. Field investigations and regional correlations reveal that the fuchsite quartzite from the Lulong area is equivalent to that of the Caozhuang area. Zircon Hf isotopic data from eastern Hebei Province (Lulong and Caozhuang areas) and Anshan and Xinyang areas indicate that the oldest crustal growth event of North China Craton occurred in the Hadean. [ABSTRACT FROM AUTHOR]

The lithostratigraphy of Early Paleozoic metasediments from southern Fiordland is described, with three groups and 14 formations formally defined. In southwest Fiordland, the Fanny Bay Group is a quartz-rich succession of metamorphosed sandstone, mudstone, and quartzite; the Cameron Group is a lithologically variable succession of metavolcanic, psammitic, pelitic and calc-silicate rocks; the Edgecumbe Group is a volcaniclastic succession of metaconglomerate, metasandstone, and metabasalt. South-central Fiordland schists and gneisses are subdivided into either amphibolitic, pelitic, or psammitic lithological associations. Based on fossils, detrital zircon ages, intrusive relationships, and correlation with rocks in northwest Nelson, Fanny Bay Group is most likely latest Cambrian to Late Ordovician whereas Cameron and Edgecumbe groups, together with the south-central Fiordland metamorphic rocks, are likely to be middle to late Cambrian. Fanny Bay lithostratigraphy most closely matches that of the Buller Terrane of northwest Nelson, whereas the Edgecumbe Group most closely matches the northwest Nelson Cambrian lithostratigraphy of the Takaka Terrane. Cameron Group and south-central Fiordland metasediments are similar to each other but their relationship to northwest Nelson rocks is unclear. The Old Quarry Fault separates the Fanny Bay Group from the Edgecumbe and Cameron groups, and is probably a southern continuation of northwest Nelson's Anatoki Fault. [ABSTRACT FROM AUTHOR]

The correction notice in the Scientific Reports journal addresses errors in the original article titled "Technology and provenience of the oldest pottery in the northern Pannonian Basin indicates its affiliation to hunter-gatherers." The correction specifically focuses on inaccuracies in the Abstract and Discussion sections related to the tempering practices of pottery in different regions. The corrected version of the article is now available online, authored by Jan Petřík, Karel Slavíček, Katarína Adameková, Victory A. J. Jaques, Martin Košťál, Peter Tóth, Libor Petr, Dalibor Všianský, Tomas Zikmund, Jozef Kaiser, Jozef Bátora, and Penny Bickle. [Extracted from the article]

In this study, we report a high concentration of cobalt (Co) in the rocks of Ajabgarh Group of Delhi Supergroup from Nasibpur and the surrounding areas of Southwest Haryana, India, which forms a part of the North Delhi Fold Belt (NDFB). Metasedimentary and magmatic phases of the rocks contained high cobalt content ranging from 166 to 3657 ppm. The maximum concentration of cobalt (2371-3657 ppm) was observed in quartzite samples from the Nasibpur area. Cobalt enrichment in these rocks can be attributed to magmatic-hydrothermal and metamorphic fluids in relation to geological features such as shear and foliation zones, which provide a high fluid/rock ratio. Overall, the applications of cobalt are numerous and crucial. The present study warrants further extensive exploration efforts in order to assess the abundance of this valuable metal, as the global cobalt market is increasing in response to a low-carbon economy. [ABSTRACT FROM AUTHOR]

The inadequate management of waste from the mining industry can lead to several environmental problems. For instance, the extraction of quartzite, an ornamental stone, generates quartzite waste (or residues or tailings) (QTZ), which is commonly deposited in the environment, causing landscape degradation, contamination by dust, and silting of rivers. To mitigate this scenario and stimulate the circular economy, this literature review focuses on the use of quartzite tailings in construction materials. A systematic search was carried out in the Scopus, Web of Science, and Google Scholar databases, including articles in English and Portuguese published between 2007 and 2022. The results showed that the use of QTZ as aggregate in cement-based composites is viable, as this waste has physical, chemical, mineralogical, and microstructural characteristics similar to conventional natural aggregate. Quartzite waste has been successfully adopted in precast concrete, cladding, and laying mortars, soil–cement bricks, and interlocking pavements. Many works brought the physical and mechanical characterization of the proposed construction materials, with gaps being observed mainly in terms of durability and performance. In conclusion, the use of QTZ in construction materials is a promising alternative, especially in cement-based composites. An important advantage is that this material requires little or no prior processing. However, the reuse of quartzite tailings is still limited, showing that more academic studies, private initiatives, and public policies are required. [ABSTRACT FROM AUTHOR]

Slope failures along the road sections cause huge problems every year in Sikkim. A slope instability analyses was performed along the road sections in parts of West Sikkim. The study was supported by geotechnical analyses like rock mass rating (RMR) and slope mass rating (SMR). In order to identify different failure types stereographic plotting based kinematic analyses was performed. Out of 33 study sites for the geotechnical analyses, 24 sites were identified as wedge failure and the remaining 9 sites were identified as the planar failure. Highly metamorphosed rocks like quartzite, phyllite and gneiss were the common rocks found in the area, comprising the discontinuities like joints were found up to 4 sets in certain locations. Other tectonic discontinuities include main central thrust (MCT), Tista lineament and other inferred thrust. Several such structural discontinuities and the weak lithology have made the area extremely vulnerable. The RMRbasic values varies from 26–60 in the study area which falls in the good to average category rocks. Adjustment factors were added to the RMRbasic to calculate the SMR values, which ranges between 26–74 and falls in good to bad rock mass description. Based on the different values for the SMR ratings, supportive measures were recommended for the different study locations. These are spot or systematic bolting, spot shotcrete, systematic anchors, systematic shotcrete, toe wall, dental concrete, systematic reinforced shotcrete, re-excavation, deep drainage, etc. and bioengineering treatment. [ABSTRACT FROM AUTHOR]

The Mesnard Quartzite of Paleoproterozoic age is believed to represent among the first preserved cratonal continental rocks in the Lake Superior region, was deposited above Archean basement in the Marquette structural trough and is estimated to contain more than 99% sandstone (now quartzite) beds. The Mesnard Quartzite is interpreted to have been deposited largely by tidal currents. Evidence of tidal current deposition includes lack of wave-influenced structures such as hummocky cross-beds, and presence of strongly unidirectional paleocurrents from cross-beds, mud-drapes on cross-bed foresets, evidence of current reversal including herringbone cross-bedding and sigmoidal cross-bedding. Sandstone bedding types include homogeneous or structureless beds, parallel-laminated beds, cross-beds, and symmetric ripple marks. Unidirectional paleocurrents from cross-beds are largely subparallel to the axis of the Marquette structural trough, leading to the interpretation that the trough was subsiding during deposition. Cross-bed set thickness and symmetric ripple marks both support the interpretation of shallow water marine deposition, likely only a few meters. Although the Mesnard Quartzite is on the order of 110 m thick, there is no evidence of internal sequence boundaries or flooding surfaces, and low accommodation during deposition is inferred. The climate during deposition is interpreted to be humid, and tropical to subtropical based on the quartz arenite composition. Deposition likely occurred in a failed rift basin or in an intracratonic extensional basin. [ABSTRACT FROM AUTHOR]

Purpose. The research purpose is to study the forms of gold occurrence in the Takyr graben alluvial-proluvial deposits in order to develop a low-waste resource-saving processing technology. Methods. At the first stage, in the course of field studies, the geological structure of the site is specified, samples are taken for mineralogical-technological analysis, which includes the following procedures: studying granulometric and mineral composition of detrital material; fractional gravitational beneficiation of the source material; fractional beneficiation of material pre-processed in the autogenous mill (AG mill); studying free (native) and bound gold in beneficiation products, their quantitative assessment. The samples are processed under the three-stage scheme using an autogenous mill for sample preparation. Findings. For the first time, the geological structure of the site has been specified with the identification of the deposits in the Turangi and Tuzkabak suites within its boundaries, as well as granulometric and petrographic composition of gold-bearing deposits, and the specifics of gold bearing. The detrital material, represented by quartz with a sharply subordinate amount of quartzite, quartz diorites and jasperoids, is practically identical in all fractions. Originality. For the first time, various types of gold mineralization have been identified in placer sands: clastogenic, newlyformed hypergene, newly-formed hydrothermal and residual. Fractional beneficiation makes it possible to estimate the gold content in each fraction and gravitational beneficiation products, as well as the ratio of free and bound native gold in different fractions. The largest amount of free native gold has been revealed in fractions of -0.25 + 0.1 mm (60%) and -0.074 + 0.044 mm (~40%). Gold is high-grade (96.5%) with an admixture of silver and iron. Together with gold, ilmenite, zircon, scheelite, native bismuth, as well as barite, galena, sphalerite, and dolomite have been identified. Practical implications. The research results make it possible to reassess the prospects of similar objects, to adjust the scheme and methodology for processing stream-sediment samples, to solve the issues of productive sand processing technology, as well as to improve the efficiency of geological exploration and eliminate the "underestimation" of gold deposits. The results obtained can be recommended for implementation by both domestic and foreign organizations specializing in the exploration and mining of gold deposits. [ABSTRACT FROM AUTHOR]

The production of synthetic iron castings in Russia comprises 50% of all alloys produced; therefore, increasing their smelting efficiency is an urgent task in the industry. This process depends primarily on the efficiency of industrial frequency induction crucible furnaces using acid lining. In the present study, the properties of quartzite, which forms the basis of such a lining, were investigated. An analysis of the proposed variants for changing the composition of the acid lining for use at temperatures of 1550–1600 °C was conducted. Following the preliminary temperature treatment of raw quartzite, which was then subjected to a sintering regime, we determined the conditions under which it was possible to obtain a phase state, allowing for the operation of the lining at temperatures above 1450 °C. We determined the use of an electrocorundum of two fractions as an additive to the traditional composition of the acid lining. The industrial testing of a new liner composition for the smelting of synthetic cast iron in an induction crucible melting furnace with a single steel scrap-metal filling was assessed, which required the use of an increased amount of carburizing agent. The positive results obtained can be explained by the study of the spent lining, which withstood 345 smelting methods of genophasic rent analysis. The results of the test are based on the results obtained in a study conducted on the finished coating of the product. [ABSTRACT FROM AUTHOR]

The major raw material documented in the archeological sites of Olduvai Gorge (Tanzania) is a geological material with crystalline appearance, white or colorless, foliated or seemingly massive only at the outcrop scale, with a very high quartz-rich composition, and apparently of metamorphic origin, named by us in this paper: Crystalline Quartz-rich Raw Material (CQRM). Since the early days of research in Olduvai Gorge, a long-lasting terminological imprecision has allowed defining this material in a confused way as quartz or quartzite. Stubbornness in terminological imprecision reflects the complexity and specificity of CQRM related to a protracted and complex geological history composed by quartz-bearing metamorphic rocks of varied types and origins from recycling and/or tectonic reworking of much older Precambrian orogens and cratons. Currently the term quartzite is preferred by most researchers, despite being materials that have an appearance macro- and microscopic similar to quartz and show a response to fracture mechanics, and cutting-edge functional response is closer to quartz. In our view, it is crucial to undertake a comprehensive analysis of the CQRM from the structural, metamorphic, and petrological perspectives. Bearing this in mind, the main objective of the present study is to build a robust and conclusive petrological background that will enable an accurate identification and classification of this quartz-rich mineral resource. This geological material should be identified as “quartz.” The most diagnostic features supporting this interpretation can be summarized as some of the microstructural relics identified concur undoubtedly with a hydrothermal origin of the quartz and the recognition of special deformational structures at macro and micro scale point to tectono-metamorphic overprint of the hydrothermal quartz under granulite-facies conditions during the Panafrican orogenesis about 640 Ma ago. [ABSTRACT FROM AUTHOR]

In this paper, we outline a study conducted on altered rocks in Central Kazakhstan, in particular, focusing on secondary quartzites. The study reveals a connection between copper-porphyry deposits in Central Kazakhstan and secondary quartzites. Recent research has unveiled gold mineralization in various secondary quartzite massifs, which has spurred further investigations in the region. Over the past three decades, extensive studies have been conducted that have demonstrated similarities among the gold deposits in this area and epithermal gold-silver deposits in volcanic-plutonic arcs around the world. By identifying patterns in the distribution of gold mineralization and developing regional exploration criteria, researchers have comprehensively assessed 48 secondary quartzite massifs and have prioritized promising areas for further exploration. Valuable findings have emerged from detailed examinations of the Akgirek and Birlestik massifs, which have involved drilling exploration wells up to a depth of 250 m. These investigations have shed light on the depth distribution of metasomatites and their association with gold mineralization. Consequently, these findings strengthen our belief in the significant potential for gold mineralization in the secondary quartzites of the Jungar-Balkhash folded system. [ABSTRACT FROM AUTHOR]