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Minerals, Volume 10, Issue 2 (February 2020) – 118 articles

Cover Story (view full-size image): In this study, we focused on the dynamics of the organic matter in coastal lagoons. We investigated a marine-fed lagoonal network in Cayo Coco, on the north coast of Cuba. Microbial mats and biofilms were identified as the potential sources of organic material in addition to the surrounding mangrove, soils, and suspended particulate matter (SPM). The origin and evolution of the sedimentary organic matter preserved within the lagoonal sediments were analyzed using geochemical parameters such as elemental (TOC, TN, and [C/N]atomic ratio) and isotopic (δ13Corg and δ15NTN) signals on four sedimentary cores retrieved from different locations in the lagoon, which were compared with the geochemical signatures of the potential sources. View this paper
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17 pages, 2458 KiB  
Article
Evaluation of Bio-Based Extraction Methods by Spectroscopic Methods
by Mathilde Monachon, Magdalena Albelda-Berenguer, Tiziana Lombardo, Emilie Cornet, Friederike Moll-Dau, Janet Schramm, Katharina Schmidt-Ott and Edith Joseph
Minerals 2020, 10(2), 203; https://doi.org/10.3390/min10020203 - 24 Feb 2020
Cited by 8 | Viewed by 2873
Abstract
New technologies are in development regarding the preservation of waterlogged archaeological wood items contaminated with Fe/S species. To this purpose, a bio-based treatment to extract these harmful species before further damages occur is presented. Thiobacillus denitrificans and desferoxamine were employed based on their [...] Read more.
New technologies are in development regarding the preservation of waterlogged archaeological wood items contaminated with Fe/S species. To this purpose, a bio-based treatment to extract these harmful species before further damages occur is presented. Thiobacillus denitrificans and desferoxamine were employed based on their specific properties to solubilize iron sulfides and uptake iron. The biological treatment was compared with oxidizing and complexing agents (sodium persulfate and ethylene diamine tetraacetate) traditionally used in conservation-restoration. Mock-ups of fresh balsa as well as fresh and archeological oak and pinewood were prepared to simulate degraded waterlogged wood by immersion in corrosive Fe/S solutions. The efficiency of both biological and chemical extraction methods was evaluated through ATR-FTIR and Raman spectroscopies and validated by statistical approach. Results showed that treatments did not affect the wood composition, meaning that no wood degradation was induced. However, the chemical method tended to bleach the samples and after treatment, reduced sulfur species were still identified by Raman analyses. Finally, statistical approaches allowed validating ATR-FTIR results. Full article
(This article belongs to the Special Issue Modern Raman Spectroscopy of Minerals)
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16 pages, 3249 KiB  
Article
Evaluation of a Spatial Heterodyne Spectrometer for Raman Spectroscopy of Minerals
by Alina Zettner, Ardian B. Gojani, Thomas Schmid and Igor B. Gornushkin
Minerals 2020, 10(2), 202; https://doi.org/10.3390/min10020202 - 24 Feb 2020
Cited by 10 | Viewed by 4660
Abstract
Spatial heterodyne spectroscopy (SHS) is a novel spectral analysis technique that is being applied for Raman spectroscopy of minerals. This paper presents the theoretical basis of SHS and its application for Raman measurements of calcite, quartz and forsterite in marble, copper ore and [...] Read more.
Spatial heterodyne spectroscopy (SHS) is a novel spectral analysis technique that is being applied for Raman spectroscopy of minerals. This paper presents the theoretical basis of SHS and its application for Raman measurements of calcite, quartz and forsterite in marble, copper ore and nickel ore, respectively. The SHS measurements are done using a broadband (518–686 nm) and resolving power R 3000 instrument. The spectra obtained using SHS are compared to those obtained by benchtop and modular dispersive spectrometers. It is found that SHRS performance in terms of resolution is comparable to that of the benchtop spectrometer and better than the modular dispersive spectrometer, while the sensitivity of SHRS is worse than that of a benchtop spectrometer, but better than that of a modular dispersive spectrometer. When considered that SHS components are small and can be packaged into a handheld device, there is interest in developing an SHS-based instrument for mobile Raman spectroscopy. This paper evaluates the possibility of such an application. Full article
(This article belongs to the Special Issue Modern Raman Spectroscopy of Minerals)
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17 pages, 3564 KiB  
Article
Volcanic and Saline Lithium Inputs to the Salar de Atacama
by Linda Godfrey and Fernanda Álvarez-Amado
Minerals 2020, 10(2), 201; https://doi.org/10.3390/min10020201 - 24 Feb 2020
Cited by 30 | Viewed by 7283
Abstract
The Li-rich brine contained within the halite body of the Salar de Atacama is uncommon for two reasons: First, it has an exceptionally high Li concentration, even compared to other closed basins in the Li triangle of South America; and second, it is [...] Read more.
The Li-rich brine contained within the halite body of the Salar de Atacama is uncommon for two reasons: First, it has an exceptionally high Li concentration, even compared to other closed basins in the Li triangle of South America; and second, it is widespread within the halite nucleus and not restricted to a localized area. This study focusses on the southern half of the salar where Li production occurs and draws comparisons with its northern neighboring basin through which the Loa river flows. Concentration and isotope data for water inflowing to this part of the salar were obtained from surface inflow as well as wells located within the alluvial fans on its eastern margin. Lithium varies between 0.2 and 20 mg/L before reaching the salar where small amounts of the brine and or salts that precipitated from it can increase its concentration up to 400 mg/L or higher. The δ7Li of the inflow water varies between +4.9‰ and +11.2‰ and increases to +12.6‰ within the salar margin, consistent with salar brine based on reported measurements. Boron isotopes indicate that it is unlikely that solutes are derived from sedimentary evaporites or mineral cements, unlike the situation in the adjacent Loa basin. Water that flows through an aquifer laterally confined by a basement block and a line of volcanoes has a notably higher δ7Li than other inflow water, around +9‰, and increasing to +10.5‰. δ7Li values are overall higher than were measured in the adjacent Loa basin, indicating that here the water–rock reactions for Li are more evolved due to longer residence times. Lithium concentrations increased with sodium and chloride, but sedimentary evaporites are shown to be unimportant from δ11B. This is accounted for two ways: evaporated saline inflow leaks from higher elevation basins and inflows are partly derived from or modified by active volcanic systems. Active and dormant volcanoes plus the massive Altiplano–Puna magmatic body are important as heat sources, which enhance water–rock reactions. The large topographic difference between the mean elevation of Altiplano on which these volcanoes sit and the salar surface allows hydrothermal fluids, which would otherwise stay deep below the surface under the modern arc, to uplift at the salar. Full article
(This article belongs to the Special Issue Evolution of Li-rich Brines)
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24 pages, 7915 KiB  
Article
Genesis of Volcanic Rocks in the Zijinshan Ore District, SE China: Implications for Porphyry-Epithermal Mineralization
by Zheng-Zheng Feng, Zhong-Jie Bai, Hong Zhong, Wei-Guang Zhu and Shi-Ji Zheng
Minerals 2020, 10(2), 200; https://doi.org/10.3390/min10020200 - 24 Feb 2020
Cited by 2 | Viewed by 2996
Abstract
Volcanic rocks, as the extrusive counterparts of the mineralized intrusions, can provide important information on the magma source, petrogenesis, and metallogenic conditions of the coeval porphyry-epithermal system. Shanghang Basin volcanic rocks are spatially and temporally related to a series of adjacent porphyry-epithermal Cu–Au [...] Read more.
Volcanic rocks, as the extrusive counterparts of the mineralized intrusions, can provide important information on the magma source, petrogenesis, and metallogenic conditions of the coeval porphyry-epithermal system. Shanghang Basin volcanic rocks are spatially and temporally related to a series of adjacent porphyry-epithermal Cu–Au deposits, and they can be used as a window to study the related deposits. Two laser-ablation–inductively coupled plasma–mass spectrometry zircon U–Pb analyses of the volcanic rocks yield weighted mean ages of ~105 Ma, identical to the age of the coeval porphyry-epithermal mineralization. Rocks have SiO2 contents of 55.4 to 74.8 wt % and belong to the high-K to shoshonitic series, characterized by strong differentiation of light rare-earth elements (REEs) relative to heavy REEs (mean LaN/YbN = 16.88); enrichment in light REEs, Rb, Th, and U; and depletion in Nb, Ta, Zr, Hf, and Ti. The volcanic rocks display (87Sr/86Sr)i values of 0.709341 to 0.711610, εNd(t) values of −6.9 to −3.3 εHf(t) values of −3.95 to −0.30, and δ18O values of 6.07‰–6.79‰, suggesting that the parental magmas were derived from a mantle source enriched by subduction-related progress. SiO2 content shows a strong negative correlation with the contents of some major and trace elements, indicating that fractional crystallization played an important role in the generation of these rocks. A binary mixing model of Hf–O isotopes gives an estimated degree of crustal contamination of 30%. In addition, magnetite crystallized early, and the samples showed high zircon EuN/EuN* values (0.48–0.68), indicating that the parental magma had a high oxygen fugacity. The inferred suppression of plagioclase crystallization and increasing hornblende crystallization during magma evolution suggest that the magma was water rich. The high-water content and high oxygen fugacity of the magma promoted the dissolving of sulfides containing Cu and Au in the source area and contributed to the migration of ore-forming elements. Full article
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16 pages, 6061 KiB  
Article
Effect of Sodium Chloride Concentration on Saturated Permeability of Remolded Loess
by Panpan Xu, Qiying Zhang, Hui Qian and Wengang Qu
Minerals 2020, 10(2), 199; https://doi.org/10.3390/min10020199 - 22 Feb 2020
Cited by 33 | Viewed by 5154
Abstract
Loess contains many sodium and chloride ions that can easily be leached when seepage occurs, thus affecting the mechanical properties of loess. This study investigated a series of sodium chloride solution concentrations to explore their influence on the permeability of remolded loess, as [...] Read more.
Loess contains many sodium and chloride ions that can easily be leached when seepage occurs, thus affecting the mechanical properties of loess. This study investigated a series of sodium chloride solution concentrations to explore their influence on the permeability of remolded loess, as well as the underlying mechanism of such. The results indicated that the saturated hydraulic conductivity of remolded loess increases with time in response to different sodium chloride concentrations, and the sample was more permeable with increasing concentration. Moreover, the salt effect promoted the dissolution of calcite and dolomite, and the cation exchange stimulated the leaching of other cations, thus leading to further structural loosening. Furthermore, the aggregation of clay particles increased, thus forming a larger pore space among aggregates and providing effective channels for permeation. These findings provide a theoretical basis for an improved understanding of channel degradation in the loess area of Northwest China. Full article
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15 pages, 7571 KiB  
Article
Agates from Western Atlas (Morocco)—Constraints from Mineralogical and Microtextural Characteristics
by Jaroslav Pršek, Magdalena Dumańska-Słowik, Tomasz Powolny, Lucyna Natkaniec-Nowak, Tomasz Toboła, Damian Zych and Dominika Skrepnicka
Minerals 2020, 10(2), 198; https://doi.org/10.3390/min10020198 - 22 Feb 2020
Cited by 11 | Viewed by 4455
Abstract
Agate samples collected from the vicinity of Asni and Agouim (Western Atlas, Morocco) were investigated using microscopic observations supported by Raman micro-spectroscopy. The agates are marked by the presence of various microtextures typical of epithermal vein deposits, including jigsaw-puzzle, feathery, and lattice-bladed. The [...] Read more.
Agate samples collected from the vicinity of Asni and Agouim (Western Atlas, Morocco) were investigated using microscopic observations supported by Raman micro-spectroscopy. The agates are marked by the presence of various microtextures typical of epithermal vein deposits, including jigsaw-puzzle, feathery, and lattice-bladed. The first two indicate that the formation of agates was likely marked by recrystallization of metastable silica phases (i.e., opaline silica or massive chalcedony). The presence of lattice-bladed (after barite and calcite) quartz may be, in turn, ascribed to the boiling-related conditions that could have triggered the formation of abundant copper and iron sulfides found within silica matrix. Additionally, the local occurrence of growth lines (so-called Bambauer quartz) and intergrowth of length-slow and length-fast chalcedony are linked to the variations of physico-chemical conditions during rock formation (alkaline-acidic). According to Raman spectroscopy, silica matrix of the agates is made of α-quartz with a local admixture of moganite (from 0.0 up to 78 wt.%), but also contains numerous solid inclusions of hematite, celadonite, as well as poorly-organized carbonaceous material and rutile. These phases were likely emplaced during low-temperature hydrothermal activity of SiO2-bearing fluids that originated from post-magmatic hydrothermal activity developed within host rocks and/or meteoric waters. Full article
(This article belongs to the Special Issue Agates: Types, Mineralogy, Deposits, Host Rocks, Ages and Genesis)
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30 pages, 2789 KiB  
Review
Mineral Processing and Metallurgical Treatment of Lead Vanadate Ores
by Ivan Silin, Klaus M. Hahn, Devrim Gürsel, Dario Kremer, Lars Gronen, Srećko Stopić, Bernd Friedrich and Hermann Wotruba
Minerals 2020, 10(2), 197; https://doi.org/10.3390/min10020197 - 22 Feb 2020
Cited by 18 | Viewed by 11829
Abstract
Vanadium has been strongly moving into focus in the last decade. Due to its chemical properties, vanadium is vital for applications in the upcoming renewable energy revolution as well as usage in special alloys. The uprising demand forces the industry to consider the [...] Read more.
Vanadium has been strongly moving into focus in the last decade. Due to its chemical properties, vanadium is vital for applications in the upcoming renewable energy revolution as well as usage in special alloys. The uprising demand forces the industry to consider the exploration of less attractive sources besides vanadiferous titanomagnetite deposits, such as lead vanadate deposits. Mineral processing and metallurgical treatment of lead vanadate deposits stopped in the 1980s, although the deposits contain a noteworthy amount of the desired resource vanadium. There has been a wide variety of research activities in the first half of the last century, including density sorting and flotation to recover concentrates as well as pyro- and hydrometallurgical treatment to produce vanadium oxide. There have been ecological issues and technical restrictions in the past that made these deposits uninteresting. Meanwhile, regarding the development of mineral processing and metallurgy, there are methods and strategies to reconsider lead vanadates as a highly-potential vanadium resource. This review does not merely provide an overview of lead vanadate sources and the challenges in previous mechanical and metallurgical processing activities, but shows opportunities to ensure vanadium production out of primary sources in the future. Full article
(This article belongs to the Special Issue Battery Minerals)
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14 pages, 4029 KiB  
Article
Investigation of Unmanned Aerial Vehicles-Based Photogrammetry for Large Mine Subsidence Monitoring
by Danijela Ignjatović Stupar, Janez Rošer and Milivoj Vulić
Minerals 2020, 10(2), 196; https://doi.org/10.3390/min10020196 - 21 Feb 2020
Cited by 31 | Viewed by 3479
Abstract
With the exploitation of underground sources, nature receives a huge negative impact on the local environment introducing surface subsidence. A mining region needs to be observed in sequences before, during, and after coal extraction from the coal mine. Different measuring methods exist to [...] Read more.
With the exploitation of underground sources, nature receives a huge negative impact on the local environment introducing surface subsidence. A mining region needs to be observed in sequences before, during, and after coal extraction from the coal mine. Different measuring methods exist to monitor subsidence, and all of them apply various instrumentation. A choice of methodology depends on access to a field of observation and requested accuracy. Obviously, the most accurate results provide geometric leveling, but, many times, the terrain does not allow surveyors to walk over the dangerous outfields. Looking for the most adequate and feasible method, this research did a comparison between observation of the same points, applying statistical analysis of differences between the reference points heights, and tested methods. Monitoring procedure comprised utilization of total stations (TS), global navigation satellite system (GNSS), and unmanned aerial vehicles (UAV). In this paper, the Velenje coal mine was taken as a case study, and observation data were collected during 2017. Full article
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18 pages, 11518 KiB  
Article
U–Pb Dating of Zircon and Zirconolite Inclusions in Marble-Hosted Gem-Quality Ruby and Spinel from Mogok, Myanmar
by Myint Myat Phyo, Hao A.O. Wang, Marcel Guillong, Alfons Berger, Leander Franz, Walter A. Balmer and Michael S. Krzemnicki
Minerals 2020, 10(2), 195; https://doi.org/10.3390/min10020195 - 21 Feb 2020
Cited by 16 | Viewed by 6904
Abstract
The Mogok area in Myanmar (Burma) is known since historic times as a source for some of the finest rubies and spinels in the world. In this study, we focus on in-situ U–Pb geochronological analyses of zircon and zirconolite, either present as inclusions [...] Read more.
The Mogok area in Myanmar (Burma) is known since historic times as a source for some of the finest rubies and spinels in the world. In this study, we focus on in-situ U–Pb geochronological analyses of zircon and zirconolite, either present as inclusions in gem-quality ruby and spinel or as accessory minerals in ruby- and spinel-bearing marble and adjacent granulite facies gneisses. The age determination was carried out using both laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) and sector-field mass spectrometry (LA-ICP-SF-MS). In addition, we present multi-element data (REE) of zircon and zirconolite collected with LA-ICP-TOF-MS to further characterize these inclusions. Most of the studied zircon grains display growth zoning (core/rim) regardless if as inclusion in gemstones, or as accessory mineral in host rock samples. U–Pb dating was conducted on both core and rim of zircon grains and revealed most ages ranging from ~200 Ma in the core to ~17 Ma in the rim. The youngest U–Pb ages determined from the rim of zircon inclusions in gem-quality ruby and spinel are 22.26 ± 0.36 Ma and 22.88 ± 0.72 Ma, respectively. This agreement in U–Pb ages is interpreted to indicate a simultaneous formation of ruby and spinel in the Mogok area. In ruby- and spinel-bearing marble from Bawlongyi, the youngest zircon age was determined as 17.11 ± 0.22 Ma. Furthermore, U–Pb age measured on the rim of zircon grains in a biotite-garnet gneiss reveals a Late Oligocene age (26.13 ± 1.24 Ma), however older ages up to Precambrian age were also recorded in the cores of zircon as accessory minerals from this gneiss. These old ages point to a detrital origin of the analysed zircon cores. Although non-matrix matched standard was applied, zirconolite U–Pb age results are narrower in distribution from ~35 Ma to ~17 Ma, falling within the range of zircon ages. Based on results which are well in accordance with previous geochronological data from the Mogok Metamorphic Belt (MMB), we deduce that gem-quality ruby and spinel from Mogok probably formed during a granulite-facies regional metamorphic event in Oligocene to Early Miocene, related to post collision tectonics of the Eurasian and Indian plates. Our data not only provide key information to understand the formation of gem-quality ruby and spinel in the so-called Mogok Stone Tract, but also provide assisting evidence when determining the country of origin of gemstones in gemmological laboratories. Full article
(This article belongs to the Special Issue Mineralogy and Geochemistry of Ruby)
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19 pages, 9045 KiB  
Article
Upper Paleozoic Transitional Shale Gas Enrichment Factors: A Case Study of Typical Areas in China
by Feiteng Wang and Shaobin Guo
Minerals 2020, 10(2), 194; https://doi.org/10.3390/min10020194 - 20 Feb 2020
Cited by 5 | Viewed by 2405
Abstract
Based on the shale gas research experience in North America, large-scale geological evaluations have been conducted in China to determine the enrichment characteristics of deep marine shale gas, leading to the discovery of the Fuling, Changning and Weiyuan shale gas fields. However, research [...] Read more.
Based on the shale gas research experience in North America, large-scale geological evaluations have been conducted in China to determine the enrichment characteristics of deep marine shale gas, leading to the discovery of the Fuling, Changning and Weiyuan shale gas fields. However, research on Upper Paleozoic transitional shale gas remains limited, restricting the subsequent exploration and development. Therefore, taking the Lower Permian Shanxi and Pennsylvanian Taiyuan Formations in the northeastern Ordos Basin and the Upper Permian Longtan Formation in southwestern Guizhou as examples, gas logging, gas desorption, thermal simulation, maximum vitrinite reflectance (Rmax), and X-ray diffraction (XRD) were used to study the influence of lithological associations, sedimentary facies, gas generation thresholds, and pore evolution on transitional shale gas, and then Upper Paleozoic transitional shale gas enrichment factors of the northeastern Ordos Basin and southwestern Guizhou were analysed. The results show that carbonaceous mudstone adjacent to coal seams presents a high gas content level, and is primarily developed in swamps in the delta plain environment, and swamps and lagoons in the barrier coastal environment. The gas generation threshold maturity (Rmax) of transitional shale is 1.6% and the corresponding threshold depths of the northeastern Ordos Basin and southwestern Guizhou are estimated to be 2265 m and 1050 m. Transitional shale pore evolution is jointly controlled by hydrocarbon generation, clay minerals transformation, and compaction, and may have the tendency to decrease when Rmax < 1.6% or Rmax > 3.0%, but increase when Rmax ranges between 1.6% and 3.0%, while the main influential factors of pore evolution differ in each period. Continuous distribution of transitional shale gas enrichment areas can be formed along the slope adjacent to coal seams with a moderate maturity range (1.6%–3.0%) in the northeastern Ordos Basin, and transitional shale gas can be enriched in the areas adjacent to coal seams with a moderate maturity range (1.6%–3.0%), abundant fractures, and favorable sealing faults in southwestern Guizhou. Full article
(This article belongs to the Section Mineral Deposits)
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29 pages, 38822 KiB  
Article
Authigenesis at the Urals Massive Sulfide Deposits: Insight from Pyrite Nodules Hosted in Ore Diagenites
by Nataliya P. Safina, Irina Yu. Melekestseva, Nuriya R. Ayupova, Valeriy V. Maslennikov, Svetlana P. Maslennikova, Dmitry A. Artemyev and Ivan A. Blinov
Minerals 2020, 10(2), 193; https://doi.org/10.3390/min10020193 - 20 Feb 2020
Cited by 8 | Viewed by 3113
Abstract
The pyrite nodules from ore diagenites of the Urals massive sulfide deposits associated with various background sedimentary rocks are studied using optical and electron microscopy and LA-ICP-MS analysis. The nodules are found in sulfide–black shale, sulfide–carbonate–hyaloclastite, and sulfide–serpentinite diagenites of the Saf’yanovskoe, Talgan, [...] Read more.
The pyrite nodules from ore diagenites of the Urals massive sulfide deposits associated with various background sedimentary rocks are studied using optical and electron microscopy and LA-ICP-MS analysis. The nodules are found in sulfide–black shale, sulfide–carbonate–hyaloclastite, and sulfide–serpentinite diagenites of the Saf’yanovskoe, Talgan, and Dergamysh deposits, respectively. The nodules consist of the core made up of early diagenetic fine-crystalline (grained) pyrite and the rim (±intermediate zone) composed of late diagenetic coarse-crystalline pyrite. The nodules are replaced by authigenic sphalerite, chalcopyrite, galena, and fahlores (Saf’yanovskoe), sphalerite, chalcopyrite and galena (Talgan), and pyrrhotite and chalcopyrite (Dergamysh). They exhibit specific accessory mineral assemblages with dominant galena and fahlores, various tellurides and Co–Ni sulfoarsenides in sulfide-black shale, sulfide–hyaloclastite–carbonate, and sulfide-serpentinite diagenites, respectively. The core of nodules is enriched in trace elements in contrast to the rim. The nodules from sulfide–black shale diagenites are enriched in most trace elements due to their effective sorption by associated organic-rich sediments. The nodules from sulfide–carbonate–hyaloclastite diagenites are rich in elements sourced from seawater, hyaloclastites and copper–zinc ore clasts. The nodules from sulfide–serpentinite diagenites are rich in Co and Ni, which are typical trace elements of ultramafic rocks and primary ores from the deposit. Full article
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9 pages, 1389 KiB  
Article
Critical Synergistic Concentration of Binary Surfactant Mixtures
by Jan Zawala, Agata Wiertel-Pochopien and Przemyslaw B. Kowalczuk
Minerals 2020, 10(2), 192; https://doi.org/10.3390/min10020192 - 20 Feb 2020
Cited by 17 | Viewed by 3930
Abstract
This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl [...] Read more.
This paper presents a simple method for determination of synergism in binary surfactant mixtures. A homologous series of cationic alkyltrimethylammonium bromides (CnTAB, with n = 8, 12, 16, 18) mixed with three non-ionic surfactants (n-octanol, methyl isobutyl carbinol, tri(propylene glycol) butyl ether) was chosen as a model system. In addition to the cationic-non-ionic system, the mixture of anionic-non-ionic surfactants (sodium dodecyl sulphate and tri(propylene glycol) butyl ether) was investigated. The foam behavior of one-component solutions and binary mixtures was characterized as a function of surfactant concentration, number of carbons (n) in alkyl chain of CnTAB as well as type of surfactant. It was shown that synergism in foamability could be produced by the ionic-non-ionic systems, and the concentration below the synergism occurs, called the critical synergistic concentration (CSC), that can be easily predicted based on the surface tension data on individual components. Full article
(This article belongs to the Special Issue Surfactants at Interfaces and Thin Liquid Films)
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19 pages, 4661 KiB  
Article
A Mineralisation Age for the Sediment-Hosted Blackbush Uranium Prospect, North-Eastern Eyre Peninsula, South Australia
by Urs Domnick, Nigel J. Cook, Cristiana L. Ciobanu, Benjamin P. Wade, Liam Courtney-Davies and Russel Bluck
Minerals 2020, 10(2), 191; https://doi.org/10.3390/min10020191 - 20 Feb 2020
Cited by 2 | Viewed by 2582
Abstract
The Blackbush uranium prospect (~12,580 tonnes U at 85 ppm cut-off) is located on the Eyre Peninsula of South Australia. Blackbush was discovered in 2007 and is currently the single example of sediment-hosted uranium mineralisation investigated in any detail in the Gawler Craton. [...] Read more.
The Blackbush uranium prospect (~12,580 tonnes U at 85 ppm cut-off) is located on the Eyre Peninsula of South Australia. Blackbush was discovered in 2007 and is currently the single example of sediment-hosted uranium mineralisation investigated in any detail in the Gawler Craton. Uranium is hosted within Eocene sandstones of the Kanaka Beds and, subordinately, within a massive saprolite derived from the subjacent Hiltaba-aged (~1585 Ma) granites, affiliated with the Samphire Pluton. Uranium is mainly present as coffinite in different lithologies, mineralisation styles and mineral associations. In the sandstone and saprolite, coffinite occurs intergrown with framboidal Fe-sulphides and lignite, as well as coatings around, and filling fractures within, grains of quartz. Microprobe U–Pb dating of coffinite hosted in sedimentary units yielded a narrow age range, with a weighted average of 16.98 ± 0.16 Ma (343 individual analyses), strongly indicating a single coffinite-forming event at that time. Coffinite in subjacent saprolite generated a broader age range from 28 Ma to 20 Ma. Vein-hosted coffinite yielded similar ages (from 12 to 25 Ma), albeit with a greater range. Uraninite in the vein is distinctly older (42 to 38 Ma). The 17 ± 0.16 Ma age for sandstone-hosted mineralisation roughly coincides with tectonic movement as indicated by the presence of horst and graben structures in the Eocene sedimentary rocks hosting uranium mineralisation but not in stratigraphically younger sedimentary rocks. The new ages for hydrothermal minerals support a conceptual genetic model in which uranium was initially sourced from granite bedrock, then pre-concentrated into veins within that granite, and is subsequently dissolved and reprecipitated as coffinite in younger sediments as a result of low-temperature hydrothermal activity associated with tectonic events during the Tertiary. The ages obtained here for uranium minerals within the different lithologies in the Blackbush prospect support a conceptual genetic model in which tectonic movement along the reactivated Roopena Fault, which triggered the flow of U-rich fluids into the cover sequence. The timing of mineralisation provides information that can help optimise exploration programs for analogous uranium resources within shallow buried sediments across the region. The model presented here can be predicted to apply to sediment-hosted U-mineralisation in cratons elsewhere. Full article
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24 pages, 12700 KiB  
Article
Third Worldwide Occurrence of Juangodoyite, Na2Cu(CO3)2, and Other Secondary Na, Cu, Mg, and Ca Minerals in the Fore-Sudetic Monocline (Lower Silesia, SW Poland)
by Łukasz Kruszewski, Mateusz Świerk, Rafał Siuda, Eligiusz Szełęg and Beata Marciniak-Maliszewska
Minerals 2020, 10(2), 190; https://doi.org/10.3390/min10020190 - 20 Feb 2020
Cited by 2 | Viewed by 3737
Abstract
Na-Cu carbonates are relatively rare secondary minerals in weathering zones of ore deposits. Hereby we describe mineral composition and crystal chemistry of the most important secondary (Na)Cu minerals and their Na- and Mg-bearing associates forming rich paragenesis in Rudna IX mine. A non-bulky [...] Read more.
Na-Cu carbonates are relatively rare secondary minerals in weathering zones of ore deposits. Hereby we describe mineral composition and crystal chemistry of the most important secondary (Na)Cu minerals and their Na- and Mg-bearing associates forming rich paragenesis in Rudna IX mine. A non-bulky Ca-rich dripstone-like paragenesis from Lubin Główny mine is also characterized, using Powder X-Ray Diffraction, Rietveld, and Electron Microprobe methods. Light blue juangodoyite (3rd occurrence worldwide) and darker chalconatronite are the most important members of the Rudna IX paragenesis, being associated with malachite, aragonite (intergrown with hydromagnesite and northupite), and probably cornwallite. Most of the minerals are chemically close to their ideal composition, with minor Mg substitution in malachite. Cu chlorides are mainly represented by clinoatacamite and probably herbertsmithite. Additional, minor phases include trace Cu minerals langite, wroewolfeite, and a lavendulan-group mineral, and monohydrocalcite. Separate halite-rich encrustations are shown to be filled with eriochalcite, ktenasite, and kröhnkite. The most likely to be confirmed coexisting species include paratacamite, wooldridgeite/nesquehonite, johillerite, melanothallite, and kipushite. The Lubin paragenesis mainly comprises aragonite, gypsum, rapidcreekite, and monohydrocalcite, with trace vaterite. Blue colouration is mainly provided by a yet unspecified Ni-, Co-, Mg-, and Mn-bearing Cu-Zn-Ca arsenate mineral close to parnauite. Full article
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17 pages, 5696 KiB  
Article
The Formation of Barite and Celestite through the Replacement of Gypsum
by Pablo Forjanes, José Manuel Astilleros and Lurdes Fernández-Díaz
Minerals 2020, 10(2), 189; https://doi.org/10.3390/min10020189 - 19 Feb 2020
Cited by 26 | Viewed by 8623
Abstract
Barite (BaSO4) and celestite (SrSO4) are the end-members of a nearly ideal solid solution. Most of the exploitable deposits of celestite occur associated with evaporitic sediments which consist of gypsum (CaSO4·2H2O) or anhydrite (CaSO4 [...] Read more.
Barite (BaSO4) and celestite (SrSO4) are the end-members of a nearly ideal solid solution. Most of the exploitable deposits of celestite occur associated with evaporitic sediments which consist of gypsum (CaSO4·2H2O) or anhydrite (CaSO4). Barite, despite having a broader geological distribution is rarely present in these deposits. In this work, we present an experimental study of the interaction between gypsum crystals and aqueous solutions that bear Sr or Ba. This interaction leads to the development of dissolution-crystallization reactions that result in the pseudomorphic replacement of the gypsum crystals by aggregates of celestite or barite, respectively. The monitoring of both replacement reactions shows that they take place at very different rates. Millimeter-sized gypsum crystals in contact with a 0.5 M SrCl2 solution are completely replaced by celestite aggregates in less than 1 day. In contrast, only a thin barite rim replaces gypsum after seven days of interaction of the latter with a 0.5 M BaCl2 solution. We interpret that this marked difference in the kinetics of the two replacement reactions relates the different orientational relationship that exists between the crystals of the two replacing phases and the gypsum substrate. This influence is further modulated by the specific crystal habit of each secondary phase. Thus, the formation of a thin oriented layer of platy barite crystals effectively armors the gypsum surface and prevents its interaction with the Ba-bearing solution, thereby strongly hindering the progress of the replacement reaction. In contrast, the random orientation of celestite crystals with respect to gypsum guarantees that a significant volume of porosity contained in the celestite layer is interconnected, facilitating the continuous communication between the gypsum surface and the fluid phase and guaranteeing the progress of the gypsum-by-celestite replacement. Full article
(This article belongs to the Special Issue Barite)
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14 pages, 3949 KiB  
Article
Power Generation: Feedstock for High-Value Sulfate Minerals
by Lucian C. Staicu, Tomasz Bajda, Lukasz Drewniak and Laurent Charlet
Minerals 2020, 10(2), 188; https://doi.org/10.3390/min10020188 - 19 Feb 2020
Cited by 5 | Viewed by 3703
Abstract
Coal-fired power facilities generate a polymetallic effluent (Flue Gas Desulfurization—FGD) rich in sulfate. FGD effluents may be considered an important secondary resource. This paper investigates the recovery of sulfate as barite (BaSO4), a mineral with high commercial value and a critical [...] Read more.
Coal-fired power facilities generate a polymetallic effluent (Flue Gas Desulfurization—FGD) rich in sulfate. FGD effluents may be considered an important secondary resource. This paper investigates the recovery of sulfate as barite (BaSO4), a mineral with high commercial value and a critical raw material. Using equimolar BaCl2, >99% desulfurization of an FGD effluent produced by a coal-fired power plant operating in central Poland was achieved, yielding up to 16.5 kg high purity barite m−3. The recovered barite was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric (TGA), scanning electron microscopy analysis (SEM), surface properties (PZC), density, and chemical stability (TCLP), and was compared with a commercial reference material. Barite recovery also led to the reduction in concentration of Al (86%), Cu (52%), K (69%), Mo (62%), Se (40%), Sr (91%), and U (75%) initially present in the FGD effluent. TCLP results indicate the entrapment and the stabilization of ~70% Se and ~90% Al in the barite structure. Based on this dataset, an in-depth characterization of the recovered barite is presented, and the removal mechanism of the elements is discussed. The study also provides a preliminary cost benefit analysis of the process. To our best knowledge, this is the first work showing barite recovery and metal removal from FGD effluents using a one-step process. Full article
(This article belongs to the Special Issue Barite)
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19 pages, 4018 KiB  
Article
Pickeringite from the Stone Town Nature Reserve in Ciężkowice (the Outer Carpathians, Poland)
by Mariola Marszałek, Adam Gaweł and Adam Włodek
Minerals 2020, 10(2), 187; https://doi.org/10.3390/min10020187 - 19 Feb 2020
Cited by 5 | Viewed by 2571
Abstract
Pickeringite, ideally MgAl2(SO4)4·22H2O, is a member of the halotrichite group minerals XAl2(SO4)4·22H2O that form extensive solid solutions along the joints of the X = Fe-Mg-Mn-Zn. The few [...] Read more.
Pickeringite, ideally MgAl2(SO4)4·22H2O, is a member of the halotrichite group minerals XAl2(SO4)4·22H2O that form extensive solid solutions along the joints of the X = Fe-Mg-Mn-Zn. The few comprehensive reports on natural halotrichites indicate their genesis to be mainly the low-pH oxidation of pyrite or other sulfides in the Al-rich environments of weathering rock-forming aluminosilicates. Pickeringite discussed here occurs within the efflorescences on sandstones from the Stone Town Nature Reserve in Ciężkowice (the Polish Outer Carpathians), being most probably the first find on such rocks in Poland. This paper presents mineralogical and geochemical characteristics of the pickeringite (based on SEM-EDS, XRPD, EPMA and RS methods) and suggests its possible origin. It belongs to the pickeringite–apjohnite (Mg-Mn joints) series and has the calculated formula Mg0.75Mn0.21Zn0.02Cu0.01Al2.02(S0.99 to 1.00O4)4·22H2O (based on 16O and 22H2O). The unit cell parameters refined for the monoclinic system space group P21/c are: a = 6.1981(28) Å, b= 24.2963(117) Å, c = 21.2517(184) Å and β = 100.304(65)°. The Raman spectra (SO4) bands are the intensive 994 cm−1 and a low-intensive 975 cm−11), low-intensive 1081, 1123 and 1145 cm−13), 524, 467 and 425cm−12), 615 cm−14), while those at 344 and 310 cm−1 are attributed to νg H2O and at 223 cm−1 to the lattice modes. Crystallization of pickeringite within the particular tor resulted from a certain set of conditions: climatic (e.g., season, temperature, humidity), physicochemical (e.g., pH, concentration), mineral (the presence of pyrite), and site-related (location and efflorescence protection). The sulfate ions could have been derived from oxidation of pyrite in the Ciężkowice sandstones and possibly are related to local mineral waters. Full article
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19 pages, 4462 KiB  
Article
Metallogenic Setting and Evolution of the Pados-Tundra Cr-Bearing Ultramafic Complex, Kola Peninsula: Evidence from Sm–Nd and U–Pb Isotopes
by Pavel A. Serov, Tamara B. Bayanova, Ekaterina N. Steshenko, Evgeniy L. Kunakkuzin and Elena S. Borisenko
Minerals 2020, 10(2), 186; https://doi.org/10.3390/min10020186 - 19 Feb 2020
Cited by 10 | Viewed by 3152
Abstract
The article presents new Sm–Nd and U–Pb geochronological data on rocks of the poorly studied Pados-Tundra Cr-bearing complex. It is part of the Notozero mafic–ultramafic complex (western Kola Peninsula) and occurs at the border of the Paleoproterozoic Lapland Granulite Belt and the Archean [...] Read more.
The article presents new Sm–Nd and U–Pb geochronological data on rocks of the poorly studied Pados-Tundra Cr-bearing complex. It is part of the Notozero mafic–ultramafic complex (western Kola Peninsula) and occurs at the border of the Paleoproterozoic Lapland Granulite Belt and the Archean Belomorian composite terrain. The Pados-Tundra complex hosts two major zones, the Dunite and Orthopyroxenite Blocks. Dunites are associated with four levels of chromite mineralization. Isotope Sm–Nd studies of dunites, harzburgites, and orthopyroxenites from the central part of the complex have been carried out. The isochron Sm–Nd age on 11 whole-rock samples from a rhythmically layered series of the complex is 2485 ± 38 Ma; the mineral Sm–Nd isochron for harzburgites shows the age of 2475 ± 38 Ma. It corresponds with the time of large-scale rifting that originated in the Fennoscandian Shield. When the rhythmically layered series of the intrusion and its chromite mineralization were formed, hornblendite dykes intruded. The U–Pb and Sm–Nd research has estimated their age at ca. 2080 Ma, which is likely to correspond with the occurrence of the Lapland–Kola Ocean. According to isotope Sm–Nd dating on metamorphic minerals (rutile, amphibole), the age of postmetamorphic cooling of rocks in the complex to 650–600 °C is 1872 ± 76 Ma. The U–Pb age on rutile from a hornblendite dyke (1804 ± 10 Ma) indicates further cooling to 450–400 °C. The conducted research has determined the early Proterozoic age of rocks in the rhythmically layered series in the Pados-Tundra complex. It is close to the age of the Paleoproterozoic ore magmatic system in the Fennoscandian Shield that developed 2.53–2.40 Ga ago. Later episodes of alterations in rocks are directly related to main metamorphic episodes in the region at the turn of 1.9 Ga. Results of the current study expand the geography of the vast Paleoproterozoic East Scandinavian Large Igneous Province and can be applied for further studies of similar mafic–ultramafic complexes. Full article
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11 pages, 2483 KiB  
Article
Chemical Weathering of Granite in Ice and Its Implication for Weathering in Polar Regions
by Hyun Young Chung, Jaewoo Jung, Du Hyeong Lee, Sunghan Kim, Min Kyung Lee, Jae Il Lee, Kyu-Cheul Yoo, Yong Il Lee and Kitae Kim
Minerals 2020, 10(2), 185; https://doi.org/10.3390/min10020185 - 19 Feb 2020
Cited by 6 | Viewed by 4390
Abstract
Recently, it has been reported that some chemical reactions are enhanced in below-freezing conditions. Despite the high denudation typical of polar regions, chemical weathering that occurs under ice has not been investigated. In this study, we investigated the dissolution of granite in ice. [...] Read more.
Recently, it has been reported that some chemical reactions are enhanced in below-freezing conditions. Despite the high denudation typical of polar regions, chemical weathering that occurs under ice has not been investigated. In this study, we investigated the dissolution of granite in ice. The mixture of granite and deionized water (DW) or solution adjusted to pH 2 or 3 was split into two groups: the test group was frozen at −20 °C, while the control was maintained at room temperature. After 29 days of batch experiments, the filtrate was analyzed to measure the concentrations of cations and silica. The filtered powder was analyzed to investigate the mineral compositions and crystallinities of the granite before and after the experiments. Despite the low temperature, a significant quantity of cations (Na+, K+, Mg2+, Ca2+) were dissolved out, even from the ice samples. During X-ray diffraction (XRD) analysis, the decreased crystallinities of granite in ice samples were identified regardless of the pH condition. To verify the observed freeze concentration effect, the concentration of granite in the ice grain boundaries was observed using optical microscopy with a cold chamber. The low concentration of silica in the ice samples could explain the silica anomaly in polar regions. This study also provides a new perspective for the dissolution mechanism in polar regions. Full article
(This article belongs to the Special Issue Clays and Micro-Organisms: From Nature to Industry)
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24 pages, 5385 KiB  
Article
Low Temperature Serpentinite Replacement by Carbonates during Seawater Influx in the Newfoundland Margin
by Suzanne Picazo, Benjamin Malvoisin, Lukas Baumgartner and Anne-Sophie Bouvier
Minerals 2020, 10(2), 184; https://doi.org/10.3390/min10020184 - 18 Feb 2020
Cited by 16 | Viewed by 4886
Abstract
Serpentinite replacement by carbonates in the seafloor is one of the main carbonation processes in nature providing insights into the mechanisms of CO2 sequestration; however, the onset of this process and the conditions for the reaction to occur are not yet fully [...] Read more.
Serpentinite replacement by carbonates in the seafloor is one of the main carbonation processes in nature providing insights into the mechanisms of CO2 sequestration; however, the onset of this process and the conditions for the reaction to occur are not yet fully understood. Preserved serpentine rim with pseudomorphs of carbonate after serpentine and lobate-shaped carbonate grains are key structural features for replacement of serpentinite by carbonates. Cathodoluminescence microscopy reveals that Ca-rich carbonate precipitation in serpentinite is associated with a sequential assimilation of Mn. Homogeneous δ18O values at the µm-scale within grains and host sample indicate low formation temperature (<20 °C) from carbonation initiation, with a high fluid to rock ratio. δ13C (1–3 ± 1‰) sit within the measured values for hydrothermal systems (−3–3‰), with no systematic correlation with the Mn content. δ13C values reflect the inorganic carbon dominance and the seawater source of CO2 for carbonate. Thermodynamic modeling of fluid/rock interaction during seawater transport in serpentine predicts Ca-rich carbonate production, at the expense of serpentine, only at temperatures below 50 °C during seawater influx. Mg-rich carbonates can also be produced when using a model of fluid discharge, but at significantly higher temperatures (150 °C). This has major implications for the setting of carbonation in present-day and in fossil margins. Full article
(This article belongs to the Special Issue Geological and Mineralogical Sequestration of CO2)
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17 pages, 3148 KiB  
Article
Quantifying the Distribution Characteristics of Geochemical Elements and Identifying Their Associations in Southwestern Fujian Province, China
by Jian Wang and Renguang Zuo
Minerals 2020, 10(2), 183; https://doi.org/10.3390/min10020183 - 18 Feb 2020
Cited by 10 | Viewed by 3326
Abstract
The distribution of geochemical elements in the surficial media is the end product of geochemical dispersion under complex geological conditions. This study explored the frequency and spatial distribution characteristics of geochemical elements and their associations. It quantifies the frequency distribution via mean, variance, [...] Read more.
The distribution of geochemical elements in the surficial media is the end product of geochemical dispersion under complex geological conditions. This study explored the frequency and spatial distribution characteristics of geochemical elements and their associations. It quantifies the frequency distribution via mean, variance, skewness and kurtosis, followed by measuring the spatial distribution characteristics (i.e., spatial autocorrelation, heterogeneity and self-similarity) via semivariogram, q-statistic and multifractal spectrum, and further identify the elemental associations based on these distribution parameters using hierarchical clustering. A criterion was defined to identify the importance of parameters in the clustering procedure. A case study processing a geochemical dataset of stream sediment samples collected in southwestern Fujian province of China was carried out to illustrate and validate the procedure. The results indicate that studies of the frequency and spatial distribution characteristics of geochemical elements can enhance the knowledge of geochemical dispersions. The associations identified based on the frequency and spatial distribution parameters are different from those obtained by conventional cluster analysis. Spatial distribution characteristics cannot be neglected when investigating the distribution patterns of geochemical elements and their associations. The findings can enhance the knowledge of the geochemical dispersion in the study area and might benefit the following-up mineral exploration. Full article
(This article belongs to the Section Mineral Deposits)
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26 pages, 4516 KiB  
Article
Mineralogical Constraints on the Potassic and Sodic-Calcic Hydrothermal Alteration and Vein-Type Mineralization of the Maronia Porphyry Cu-Mo ± Re ± Au Deposit in NE Greece
by Vasilios Melfos, Panagiotis Voudouris, Margarita Melfou, Matías G. Sánchez, Lambrini Papadopoulou, Anestis Filippidis, Paul G. Spry, Anna Schaarschmidt, Reiner Klemd, Karsten M. Haase, Alexandre Tarantola and Constantinos Mavrogonatos
Minerals 2020, 10(2), 182; https://doi.org/10.3390/min10020182 - 18 Feb 2020
Cited by 10 | Viewed by 8766
Abstract
The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the [...] Read more.
The Maronia Cu-Mo ± Re ± Au deposit is spatially related to a microgranite porphyry that intruded an Oligocene monzonite along the Mesozoic Circum-Rhodope belt in Thrace, NE Greece. The magmatic rocks and associated metallic mineralization show plastic and cataclastic features at the south-eastern margin of the deposit that implies emplacement at the ductile-brittle transition, adjacent to a shear zone at the footwall of the Maronia detachment fault. The conversion from ductile to brittle deformation caused a rapid upward magmatic fluid flow and increased the volume of water that interacted with the host rocks through high permeable zones, which produced extensive zones of potassic and sodic-calcic alteration. Potassic alteration is characterized by secondary biotite + K-feldspar (orthoclase) + magnetite + rutile + quartz ± apatite and commonly contains sulfides (pyrite, chalcopyrite, pyrrhotite). Sodic-calcic alteration consists of actinolite + sodic-calcic plagioclase (albite/oligoclase/andesine) + titanite + magnetite + chlorite + quartz ± calcite ± epidote-allanite. The high-oxidation state of the magmas and the hydrothermal fluid circulation were responsible for the metal and sulfur enrichments of the aqueous fluid phase, an increase in O2 gas content, the breakdown of the magmatic silicates and the production of the extensive potassic and sodic-calcic alterations. Brittle deformation also promoted the rapid upward fluid flow and caused interactions with the surrounding host rocks along the high temperature M-, EB-, A- and B-type veins. Full article
(This article belongs to the Section Mineral Deposits)
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20 pages, 21331 KiB  
Review
E. S. Fedorov Promoting the Russian-German Scientific Interrelationship
by Peter Paufler and Stanislav K. Filatov
Minerals 2020, 10(2), 181; https://doi.org/10.3390/min10020181 - 18 Feb 2020
Cited by 4 | Viewed by 4149
Abstract
At the dawn of crystal structure analysis, the close personal contact between researchers in Russia and Germany, well documented in the “Zeitschrift für Krystallographie und Mineralogie”, contributed significantly to the evolution of our present knowledge of the crystalline state. The impact of the [...] Read more.
At the dawn of crystal structure analysis, the close personal contact between researchers in Russia and Germany, well documented in the “Zeitschrift für Krystallographie und Mineralogie”, contributed significantly to the evolution of our present knowledge of the crystalline state. The impact of the Russian crystallographer E. S. Fedorov upon German scientists such as A. Schoenflies and P. Groth and the effect of these contacts for Fedorov are highlighted hundred years after the death of the latter. A creative exchange of ideas paved the way for the analysis of crystal structures with the aid of X-ray diffraction. Full article
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17 pages, 6369 KiB  
Article
Application of Dynamic Analysis Methods into Assessment of Geometric Properties of Chalcedonite Aggregates Obtained by Means of Gravitational Upgrading Operations
by Tomasz Gawenda, Damian Krawczykowski, Aldona Krawczykowska, Agnieszka Saramak and Alona Nad
Minerals 2020, 10(2), 180; https://doi.org/10.3390/min10020180 - 18 Feb 2020
Cited by 13 | Viewed by 3551
Abstract
The aim of the paper is an assessment of geometrical properties of regular and irregular particles of chalcedonite enrichment products carried out in a laboratory ring jig. The investigative program included experiments of aggregate enrichment, along with visual analyses made for the obtained [...] Read more.
The aim of the paper is an assessment of geometrical properties of regular and irregular particles of chalcedonite enrichment products carried out in a laboratory ring jig. The investigative program included experiments of aggregate enrichment, along with visual analyses made for the obtained products, separately for regular and irregular particles. Several shape coefficients were calculated, and the most effective ones in terms of assessment of particle regularity were selected from among them. Particle size distributions for feed and enrichment products were also determined using the idea of minimum Feret’s diameter, and the intensity of dust emission by individual products was measured as well. The results obtained by the visual system were discussed in the context of their application in the assessment of enrichment operations carried out in a water jig. Full article
(This article belongs to the Special Issue Selected Papers from the Mineral Engineering Conference—MEC 2019)
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10 pages, 2172 KiB  
Article
Experimental Study on Preparation of Ferropericlase by Oxalate Coprecipitation
by Yanjun Xiao, Tong Sun and Yong-Hong Zhao
Minerals 2020, 10(2), 179; https://doi.org/10.3390/min10020179 - 17 Feb 2020
Cited by 5 | Viewed by 3049
Abstract
It is always a goal of scientists to develop new techniques to identify the composition of mantle materials and understand geodynamic processes accurately. Ferropericlase (Mg,Fe)O is a prominent mineral in the lower mantel. It is a common practice in the research community to [...] Read more.
It is always a goal of scientists to develop new techniques to identify the composition of mantle materials and understand geodynamic processes accurately. Ferropericlase (Mg,Fe)O is a prominent mineral in the lower mantel. It is a common practice in the research community to prepare ferropericlase using a solid-phase synthesis method or high-pressure experiment synthesis method. This conventional method contains a number of ambiguities a great deal of time is needed. In this paper, we have addressed the drawbacks of the conventional technique using a liquid-phase synthesis method to prepare ferropericlase. During the experiment, oxalic acid was added to a mixed solution of ferrous sulfate and magnesium chloride and mixed according to the molar ratio. The formed magnesium iron oxalate precipitate was sintered and reduced into the final sample. Furthermore, the final sample was analyzed using XRD and SEM. Compared to the solid-phase method, this coprecipitation method could produce ferropericlase with a shorter sintering time, lower sintering temperature, and a reduction in the amount of gas consumed. XRD and SEM results show that the liquid-phase method produced samples with better composition homogeneity. Full article
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13 pages, 2183 KiB  
Article
Characteristics of Precipitation of Rare Earth Elements with Various Precipitants
by Kenneth N. Han
Minerals 2020, 10(2), 178; https://doi.org/10.3390/min10020178 - 17 Feb 2020
Cited by 70 | Viewed by 11273
Abstract
The effective and selective leaching of rare earth elements (REEs) from various sources is frequently possible in practice by adopting a carefully coordinated strategy incorporating a selective precipitation of these elements from undesired ones in solution. In this study, the behavior of chemical [...] Read more.
The effective and selective leaching of rare earth elements (REEs) from various sources is frequently possible in practice by adopting a carefully coordinated strategy incorporating a selective precipitation of these elements from undesired ones in solution. In this study, the behavior of chemical precipitation of REEs with commonly used precipitants such as sulfate, carbonate, fluoride, phosphate, and oxalate was examined using thermodynamic principles and calculations. It was found that the pH of the system has a profound effect on determining particular chemical species of precipitants, which are subsequently responsible for the precipitation of REEs. The role of various anions such as Cl, NO3, and SO42− derived from the acid used in the leaching process on the precipitation behavior of REEs was examined. These anions form complexes with REEs and display a very positive effect on the precipitation behavior. The nitrate environment exhibits most conducive to precipitation followed by sulfate and then chloride. Full article
(This article belongs to the Special Issue Leaching of Rare Earth Elements from Various Sources)
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18 pages, 6367 KiB  
Article
Diagenetic Origin of Bipyramidal Quartz and Hydrothermal Aragonites within the Upper Triassic Saline Succession of the Iberian Basin: Implications for Interpreting the Burial–Thermal Evolution of the Basin
by María J. Herrero, Rafaela Marfil, Jose I. Escavy, Ihsan Al-Aasm and Michael Scherer
Minerals 2020, 10(2), 177; https://doi.org/10.3390/min10020177 - 15 Feb 2020
Cited by 2 | Viewed by 3369
Abstract
Within the Upper Triassic successions in the Iberian Basin (Spain), the occurrence of both idiomorphic bipyramidal quartz crystals as well as pseudohexagonal aragonite crystals are related to mudstone and evaporite bearing sequences. Bipyramidal-euhedral quartz crystals occur commonly at widespread locations and similar idiomorphic [...] Read more.
Within the Upper Triassic successions in the Iberian Basin (Spain), the occurrence of both idiomorphic bipyramidal quartz crystals as well as pseudohexagonal aragonite crystals are related to mudstone and evaporite bearing sequences. Bipyramidal-euhedral quartz crystals occur commonly at widespread locations and similar idiomorphic crystals have been described in other formations and ages from Europe, America, Pakistan, and Africa. Similarly, pseudohexagonal aragonite crystals are located at three main sites in the Iberian Range and are common constituents of deposits of this age in France, Italy, and Morocco. This study presents a detailed description of the geochemical and mineralogical characteristics of the bipyramidal quartz crystals to decipher their time of formation in relation to the diagenetic evolution of the sedimentary succession in which they formed. Petrographic and scanning electron microscopy (SEM) analyses permit the separation of an inner part of quartz crystals with abundant anhydrite and organic-rich inclusions. This inner part resulted from near-surface recrystallization (silicification) of an anhydrite nodule, at temperatures that were <40 °C. Raman spectra reveal the existence of moganite and polyhalite, which reinforces the evaporitic character of the original depositional environment. The external zone of the quartz contains no anhydrite or organic inclusions and no signs of evaporites in the Raman spectra, being interpreted as quartz overgrowths formed during burial, at temperatures between 80 to 90 °C. Meanwhile, the aragonite that appears in the same Keuper deposits was precipitated during the Callovian, resulting from the mixing of hydrothermal fluids with infiltrated waters of marine origin, at temperatures ranging between 160 and 260 °C based on fluids inclusion analyses. Although both pseudohexagonal aragonite crystals and bipyramidal quartz appear within the same succession, they formed at different phases of the diagenetic and tectonic evolution of the basin: bipyramidal quartz crystals formed in eo-to mesodiagenetic environments during a rifting period at Upper Triassic times, while aragonite formed 40 Ma later as a result of hydrothermal fluids circulating through normal faults. Full article
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16 pages, 3022 KiB  
Article
Different Insights into Silicate Rectorite Modification and Its Role in Removal of Heavy Metal Ions from Wastewater
by Ya Gao, Hao Jiang, Xianyuan Li, Sultan Ahmed Khoso, Guoyuan Xiang and Wenping Han
Minerals 2020, 10(2), 176; https://doi.org/10.3390/min10020176 - 15 Feb 2020
Cited by 6 | Viewed by 2379
Abstract
In the field of water management, the separation of metal contaminants from wastewater is very important and challenging. This study systematically investigated the effect and underlying mechanism of silicate rectorite (REC) on the removal of heavy metal ions (Cr(VI) and Pb(II)) from wastewater. [...] Read more.
In the field of water management, the separation of metal contaminants from wastewater is very important and challenging. This study systematically investigated the effect and underlying mechanism of silicate rectorite (REC) on the removal of heavy metal ions (Cr(VI) and Pb(II)) from wastewater. The adsorption and removal capacity of REC was further improved by its novel modification with ferric chloride hexahydrate. Compared to natural REC, the modified rectorite (Fe-REC) showed comparatively superior adsorption efficiency for both Cr(VI) and Pb(II) due to the chemisorption of Fe3+ on the REC surface as its oxidation state (Fe–O, Fe–OH, Fe–OOH). Adsorption on Cr(VI) attributed to the reaction between iron hydroxy complexes (FeOH2+, Fe(OH)2+ and Fe(OH)3(aq)) and Cr(VI) species (HCrO4 and CrO42−) in the aqueous solution. This reaction was perfectly consistent with the binding energy shifts in O 1s and Fe 2p species, as reflected by XPS analysis. While, the existence of –Al–OH and –Si–OH in silicate REC slurry reacted with PbOH+ colloids produced from lead ions hydrolysis to promote Pb(II) adsorption. Zeta potential after modification and removal occurred to shift positively or negatively to testify the adsorption of Fe3+ and heavy metal ions. Freundlich and Langmuir isotherms conformed adsorption process for Cr(VI) and Pb(II), respectively. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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12 pages, 1353 KiB  
Article
Determination of Metal Concentration in Road-Side Trees from an Industrial Area Using Laser Ablation Inductively Coupled Plasma Mass Spectrometry
by Jee Young Kim, Jaeseon Park, Jongwoo Choi and Jinwook Kim
Minerals 2020, 10(2), 175; https://doi.org/10.3390/min10020175 - 14 Feb 2020
Cited by 9 | Viewed by 2515
Abstract
Historical pollution can be elucidated with variations of elements’ concentration in tree rings by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). However, the capacity of chemical elements’ absorption significantly depends on the tree species and element types. Metal concentrations in the [...] Read more.
Historical pollution can be elucidated with variations of elements’ concentration in tree rings by using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). However, the capacity of chemical elements’ absorption significantly depends on the tree species and element types. Metal concentrations in the rings for five species (Platanus occidentalis, Salix koreensis, Chamaecyparis obtusa, Pinus densiflora, Ginkgo biloba) were investigated in light of metal pollution history in ambient air of D industrial site located in Daejeon, Korea. The calibration for LA-ICP-MS was performed using cellulose-matrix matched standards with 13C normalization. Tree ring series except for Ginkgo sp. showed that the accumulation rates of Pb and Cd were higher between 1992 and 1999. Other elements, such as Fe, Cr, Mn, Cd, Zn, and Sr, showed a variation in the rings, likely due to the different physiological processes of element uptake and radial mobility. Concentrations of Pb and Cd in the annual rings of Pinus sp. corresponded to the metal monitoring data for the ambient air with the correlation coefficients of 0.879 and 0.579, respectively. Moreover, Cd in Platanus sp. and Pb in Salix sp. showed a positive correlation to ambient metal concentration compared to Chamaecyparis sp. and Ginkgo sp. Therefore, caution should be taken to select candidate elements as well as tree species to reconstruct the ambient air metal pollution history by measuring the concentration of metal in the tree ring. Full article
(This article belongs to the Section Environmental Mineralogy and Biogeochemistry)
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20 pages, 9388 KiB  
Article
TLS and SfM Approach for Bulk Density Determination of Excavated Heterogeneous Raw Materials
by Peter Blistan, Stanislav Jacko, Ľudovít Kovanič, Julián Kondela, Katarína Pukanská and Karol Bartoš
Minerals 2020, 10(2), 174; https://doi.org/10.3390/min10020174 - 14 Feb 2020
Cited by 24 | Viewed by 3706
Abstract
A frequently recurring problem in the extraction of mineral resources (especially heterogeneous mineral resources) is the rapid operative determination of the extracted quantity of raw material in a surface quarry. This paper deals with testing and analyzing the possibility of using unconventional methods [...] Read more.
A frequently recurring problem in the extraction of mineral resources (especially heterogeneous mineral resources) is the rapid operative determination of the extracted quantity of raw material in a surface quarry. This paper deals with testing and analyzing the possibility of using unconventional methods such as digital close-range photogrammetry and terrestrial laser scanning in the process of determining the bulk density of raw material under in situ conditions. A model example of a heterogeneous deposit is the perlite deposit Lehôtka pod Brehmi (Slovakia). Classical laboratory methods for determining bulk density were used to verify the results of the in situ method of bulk density determination. Two large-scale samples (probes) with an approximate volume of 7 m3 and 9 m3 were realized in situ. 6 point samples (LITH) were taken for laboratory determination. By terrestrial laser scanning (TLS) measurement from 2 scanning stations, point clouds with approximately 163,000/143,000 points were obtained for each probe. For Structure-from-Motion (SfM) photogrammetry, 49/55 images were acquired for both probes, with final point clouds containing approximately 155,000/141,000 points. Subsequently, the bulk densities of the bulk samples were determined by the calculation from in situ measurements by TLS and SfM photogrammetry. Comparison of results of the field in situ measurements (1841 kg∙m−3) and laboratory measurements (1756 kg∙m−3) showed only a 4.5% difference in results between the two methods for determining the density of heterogeneous raw materials, confirming the accuracy of the used in situ methods. For the determination of the loosening coefficient, the material from both large-scale samples was transferred on a horizontal surface. Their volumes were determined by TLS. The loosening coefficient for the raw material of 1.38 was calculated from the resulting values. Full article
(This article belongs to the Section Mineral Processing and Extractive Metallurgy)
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