Hasil untuk "Mineralogy"

Gabriela Ligeza, Tomaso R. R. Bontognali, Tomaso R. R. Bontognali et al.

ExoMars is an astrobiology program led by the European Space Agency, which foresees the launch of a rover that will look for signs of past life on Mars. CLUPI, a close-up imager part of the rover’s payload, is designed for capturing high-resolution images of geological samples. Ensuring that each CLUPI image contains a maximum of relevant scientific information is crucial for optimizing the scientific return of the instrument and for the daily tactical planning of the rover’s activities. This study focuses on identifying the preferred lighting conditions for close-up image acquisition in the area that will be explored by the rover: Oxia Planum. To identify lithologies potentially occurring in this region, we conducted a comprehensive review of past publications on Oxia Planum’s mineralogy and geology and analysed image repositories from previous rover missions to guide our selection of samples relevant to the ExoMars mission. These samples were chosen either because we anticipate their presence at the landing site or because they represent highly interesting targets in a mission primarily aimed at finding potential evidence of past microbial life. The samples were categorized into five groups: 1) clastic sedimentary rocks, 2) rocks with Fe-Mg phyllosilicates, 3) igneous rocks, 4) evaporites, carbonates and morphological biosignatures, and 5) rocks with various sedimentary structures. For each group, we identified diagnostic textures visible in CLUPI images. The rocks were photographed using a CLUPI analogue camera under Mars - simulated lighting conditions, varying the proportion of direct and indirect light to mimic morning, evening, and mid-day conditions on Mars, as well as during dust storm conditions. We demonstrated that strategically capturing images at different times of the day under specific illuminations enhances the likelihood of detecting diverse rock textures and relevant structures. Moreover, the images produced in our simulations constitute a reference dataset of Oxia-analogue samples. Thereby, they support the exploration strategy for CLUPI and will help the science team in the decision-making process and data interpretation during the prime mission on Mars.

Yasheng Li, Zhi Wen, Wei Ma et al.

Adsorption is a key mechanism governing water vapor diffusion in lunar regolith. To investigate this process, we conducted experiments under simulated lunar conditions—Knudsen diffusion conditions—using three soil types with varying water vapor adsorption heats and specific surface areas. Results show that soils with higher adsorption heat and larger surface area captured more water vapor. Lower temperatures enhanced water retention across all soil types. In samples with underlying ice, upward migration of water vapor was hindered by adsorption onto soil particles, reducing water loss. Montmorillonite, with its superior adsorption properties, retained the most water under all test conditions. These findings suggest that cold lunar regoliths with high adsorption capacity may act as a favorable reservoir for water accumulation.

Hussain Shendy, G.A. Khater, Mohamed G. Shahien et al.

The preparation of affordable glass-ceramic materials by induced crystallization of glass-based mica schists and other natural raw materials (dolomite & limestone), as well as magnesite as a mine waste, was investigated for the first time. Five glass batches were designed based on the eutectic composition of the diopside-anorthite ratio with increasing the enstatite content from 0–40 wt.% within the quaternary CaO–MgO–Al2O3–SiO2 system. After melting at 1400 to 1500 °C, casting into discs & rod shapes, and annealing process, the prepared glasses were subjected to careful heat treatment schedules. Several techniques were used to characterize the applied raw materials, glass, and glass-ceramic materials such as X-ray Fluorescence (XRF), Differential Thermal Analysis (DTA), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Polarizing-light Microscopy. The produced glass-ceramic from the glass batch with 30 wt% enstatite that was nucleated at 750 °C /2h followed by crystallization at 950 °C /h, displayed the well-developed product on the level of volume crystallization and pore formation.

Rodrígues-Navarro Carlos

Lime mortars and plasters have been used as building materials since the origins of pyrotechnology in the Levant ca. 12,000-14,000 years ago, and currently are experiencing a revival as compatible and sustainable materials in heritage conservation and modern construction. Extensive research has recently explored ways to improve their properties, particularly using Nature as an inspiration. Such a biomimetic approach is enabling the functionalization of lime mortars and plasters via different strategies that are reviewed here and include accelerated setting via enzymatic-like catalyzed carbonation, increased toughness via inter- and intracrystalline additive incorporation, modification of surface wettability and enhanced self-cleaning ability via surface microtexturing and photoactive nanoparticle incorporation, anti-biofouling capacity, increased radiative cooling, or self-healing properties.

Shiteng Qin, Sheng Dou, Yang Hu et al.

This study investigates the challenges faced in the grinding and classification process of a polymetallic magnetite ore from Anhui, particularly focusing on low classification efficiency, significant over-grinding, and decreased metal recovery rates. By analyzing the mineralogical properties of the ore, specifically mineral composition, intergrowth relationships, intergrowth particle size, and liberation degree, with an emphasis on magnetite, chalcopyrite, cobalt minerals, and precious metal minerals, this research aims to identify the underlying causes of these issues. Subsequent single-factor experiments were conducted to assess the effects of magnetic field strength and grinding parameters on the enrichment of magnetite and chalcopyrite. Under optimal processing conditions, with a magnetizing current of 0.25 A and a grinding fineness of 65% passing through a 200-mesh sieve, the application of butyl xanthate as a collector during mixed rough flotation achieved a copper recovery rate of 89.54%. Building on these findings, the study further discusses the impact of various process flow optimizations on grinding, classification operations, and the recovery of target minerals. Additionally, it evaluates the advantages and disadvantages of different processing methods in practical applications and ultimately proposes a suitable mineral processing flow for intermediate to deep ore deposits.

Lingyun Zhao, Peng Xia, Yong Fu et al.

The lithofacies and thermal maturity of the over-mature Lower Cambrian marine shale in the Northern Guizhou Region, and their impacts on reservoir properties in this shale were analyzed by combining geochemistry, mineralogy, and gas adsorption methods. Ten lithofacies were identified, and the dominant lithofacies in the studied shale are lean-total organic carbon (TOC) argillaceous-rich siliceous shale (LTAS), medium-TOC siliceous shale (MTSS), and rich-TOC siliceous shale (RTSS). Since the gas generation potential of organic matter was weak, meso- and macro-pores were compressed or filled during the thermal evolution stage with a vitrinite reflectance (RO) range of 3.0%–4.0%. The controlling factors for methane adsorption capacity in the shale samples are significantly influenced by TOC content rather than thermal maturity. Among the RTSS, MTSS, and LTAS samples, RTSS exhibits the highest favorability for preserving hydrocarbon gas, followed by MTSS. The shale types in this study play a significant role in determining the properties of shale reservoirs, serving as an effective parameter for evaluating shale gas development potential. The RTSS and MTSS with a RO range of 2.0%–3.0% stand out as the most favorable target shale types for shale gas exploration and development.

Hassan Tumwiine, Mubashir Aziz, Umair Ali et al.

Soil improvement using chemical admixtures has been extensively investigated in the recent past and these admixtures are abundantly being used on various construction projects. However, there is a need to elucidate the long-term performance of stabilized geomaterials under aggressive pore fluid environments such as high salinity of groundwater in coastal areas. This study presents the effects of the concentration of pore fluid salinity on the post-stabilization behavior of cement-treated Marl specimens to brine solution from Sabkha deposits and rejected water from a water treatment plant. Unconfined compressive strength (UCS), mineralogy, chemical, and microstructural evaluations have been carried out in this regard. minerals like albite and muscovite completely leached out of the samples after 28 days of soaking in a saline environment. A new mineral Attapulgite was formed at various concentration levels of the pore fluid. Significant changes in the chemical composition were also observed in various phases of the experiments. Moreover, at all salinity levels, the UCS initially increased to a maximum of 75 % which later reduced to a value less than the original strength whereas the elastic modulus (E50) increased as the soaking period progressed. Lastly, it is emphasized that the engineering properties of treated soils exposed to aggressive pore fluids should be carefully assessed for a reliable prediction of the long-term performance of geotechnical structures.

F. Caso, A. Petroccia, S. Nerone et al.

<p>Despite the fact that rock textures depend on the 3D spatial distribution of minerals, our tectono-metamorphic reconstructions are mostly based on a 2D visualisation (i.e. thin sections). This work compares 2D and 3D investigations of petrography and microstructures, modal abundances, and local bulk rock composition and their implication for <span class="inline-formula"><i>P</i></span>–<span class="inline-formula"><i>T</i></span> estimates, showing the pros and cons and reliability of 2D analysis. For this purpose, a chloritoid–garnet-bearing mica schist from the Dora-Maira Massif in the Western Alps has been chosen. In particular, for 2D a thin section scan has been combined with chemical X-ray maps, whereas for 3D the X-ray computerised axial microtomography (<span class="inline-formula">µ</span>CT) has been applied. Two-dimensional investigations are readily accessible and straightforward but do not consider the entire rock volume features. Conversely, the rise of 3D techniques offers a more comprehensive and realistic representation of metamorphic features in the 3D space. However, they are computationally intensive, requiring specialised tools and expertise. The choice between these approaches should be based on the research aims, available resources, and the level of detail needed to address specific scientific questions. Nevertheless, despite differences in the modal distribution, the estimated bulk rock compositions and relative thermodynamic modelled phase fields show similarities when comparing the 2D and 3D results. Also, since different thin section cut orientations may influence the results and consequent interpretations, three different cuts from the 3D model have been extrapolated and discussed (i.e. XZ, YZ, and XY planes of the finite-strain ellipsoid). This study quantitatively corroborates the reliability of the thin section approach for tectono-metamorphic reconstructions, still emphasising that 3D visualisation can help understand rock textures.</p>

Q. Bollaert, M. Chassé, G. Morin et al.

<p>The mineralogy of niobium (Nb) is characterized by multicomponent oxides such as AB<span class="inline-formula">₂</span>O<span class="inline-formula">₆</span>, A<span class="inline-formula">₂</span>B<span class="inline-formula">₂</span>O<span class="inline-formula">₇</span>, ABO<span class="inline-formula">₄</span>, and ABO<span class="inline-formula">₃</span> in which Nb is incorporated in the B site. Such complex crystal-chemistry prevents their unambiguous identification in ore deposits such as hydrothermal rocks and laterites which exhibit complex and fine-grained textures. The understanding of the processes controlling Nb ore deposit formation in various geological settings is therefore limited, although Nb is a critical element. In this study, we use X-ray absorption spectroscopy (XAS) at the Nb K-edge to investigate the local atomic-scale structure around Nb in a large set of natural and synthetic minerals of geological and technological importance. Our X-ray absorption near-edge structure (XANES) data at the Nb K-edge show three major features of variable position and intensity and then can be related to the local distortion and coordination number of the Nb site. Shell-by-shell fits of the extended X-ray absorption fine structure (EXAFS) data reveal that the NbO<span class="inline-formula">₆</span> octahedra are distorted in a variety of pyrochlore species. At least two distinct first shells of O atoms are present while reported crystallographic data yield regular octahedra in the same minerals. Next-nearest Nb–Nb distances in pyrochlore and Nb-bearing perovskite mirror a corner-sharing NbO<span class="inline-formula">₆</span> network, whereas the two Nb–Nb distances in columbite are typical of edge- and corner-sharing NbO<span class="inline-formula">₆</span> octahedra. Such a resolution on the Nb site geometry and the intersite relationships between the next-nearest NbO<span class="inline-formula">₆</span> octahedra is made possible by collecting EXAFS data under optimal conditions at 20 K and up to 16 Å<span class="inline-formula">⁻¹</span>. The local structure around substituted Nb<span class="inline-formula">⁵⁺</span> in Fe<span class="inline-formula">³⁺</span>, Ti<span class="inline-formula">⁴⁺</span>, and Ce<span class="inline-formula">⁴⁺</span> oxides suffers major changes relative to the unsubstituted structures. The substitution of Nb<span class="inline-formula">⁵⁺</span> for Ti<span class="inline-formula">⁴⁺</span> in anatase leads to the increase in the interatomic distances between Nb and its first and second Ti<span class="inline-formula">⁴⁺</span> neighbors. The substitution of Nb<span class="inline-formula">⁵⁺</span> for Ce<span class="inline-formula">⁴⁺</span> in cerianite reduces the coordination number of the cation from eight to four, and the Nb–O bonds are shortened compared to Ce–O ones. In hematite, Nb<span class="inline-formula">⁵⁺</span> occupies a regular site, whereas the Fe<span class="inline-formula">³⁺</span> site is strongly distorted suggesting major site relaxation due to charge mismatch. The sensitivity of XANES and EXAFS spectroscopies at the Nb K-edge to the local site geometry and next-nearest neighbors demonstrated in this study would help decipher Nb speciation and investigate mineralogical reactions of Nb minerals in deposit-related contexts such as hydrothermal and lateritic deposits.</p>

Christiane L. Schnabel, Maria-Christin Jentsch, Sabrina Lübke et al.

IntroductionSevere equine asthma (SEA) is a common, chronic respiratory disease of horses characterized by hyperreactivity to hay dust which has many similarities to severe neutrophilic asthma in humans. SEA-provoking antigens have not been comprehensively characterized, but molds and mites have been suggested as relevant sources. Here, we identified relevant antigen candidates using immunoproteomics with IgG isotype-binding analyses.MethodsProteins from Dermatophagoides pteronyssinus (Der p) were separated by two-dimensional gel electrophoresis followed by immunoblotting (2D immunoblots) resulting in a characteristic pattern of 440 spots. After serum incubation, antibody (Ig)-binding of all Ig (Pan-Ig) and IgG isotypes (type-2-associated IgG3/5, type-1-associated IgG4/7) was quantified per each spot and compared between asthmatic and healthy horses’ sera (n=5 per group).ResultsIg binding differences were detected in 30 spots. Pan-Ig binding was higher with asthmatics compared to healthy horses’ sera on four spots, and IgG3/5 binding was higher on 18 spots. Small IgG4/7 binding differences were detected on 10 spots with higher binding with asthmatics’ sera on four but higher binding with healthy horses’ sera on six spots. Proteins from the spots with group differences including mite and yeast proteins were identified by liquid chromatography mass spectrometry. The latter likely originated from the feeding substrate of the Der p culture. Prioritized antigen candidates amongst the proteins identified were Der p 1, Der p 11, group 15 allergens, myosin heavy chain, and uncharacterized Der p proteins. Additionally, yeast enolases, alcohol dehydrogenase (ADH), phosphoglycerate kinase (PGK), glyceraldehyde-3-phosphate dehydrogenase, and heat shock proteins were prioritized. Eleven antigen candidates were tested for confirmation by ELISAs using the respective proteins separately. Differences in asthmatics vs. healthy horses’ serum Ig binding to Der p 1, Der p 18, and three yeast enzymes (enolase, ADH, and PGK) confirmed these as promising antigens of immune responses in SEA.DiscussionAntigens with relevance in SEA were newly identified by immunoproteomics, and yeast antigens were considered for SEA for the first time. Serum IgG3/5 binding to relevant antigens was increased in SEA and is a novel feature that points to increased type-2 responses in SEA but requires confirmation of the corresponding cellular responses.

H. Kroll, H. U. Bambauer, H. Pentinghaus

<p>In feldspars, mean tetrahedral T–O bond lengths (T <span class="inline-formula">=</span> Al,Si) are the standard measure of the tetrahedral Al content. However, for a sophisticated assessment of the Al,Si distribution, factors have to be accounted for (1) that cause individual T–O bond lengths to deviate from their tetrahedral means and (2) that cause mean tetrahedral lengths to deviate from values specified by the Al content. We investigated low albite, <span class="inline-formula">Na[AlSi₃O₈]</span>, from six X-ray crystal structure refinements available in the literature. The Al,Si distribution of low albite is fully ordered so that Al,Si–O bond length variations result only from bond perturbing factors. For the <i>intra</i>-tetrahedral variation <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><mtext>T–O</mtext><mo>≡</mo><mtext>T–O</mtext><mo>-</mo><mo>〈</mo><mtext>T–O</mtext><mo>〉</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="103pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="de4a18840c900a64a92c51c9eeb720fa"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ie00001.svg" width="103pt" height="13pt" src="ejm-32-427-2020-ie00001.png"/></svg:svg></span></span>, only two factors turned out to be effective: (1) the sum of bond critical point electron densities in the Na–O and T–O bonds neighbouring the T–O bond under consideration and (2) the fractional <span class="inline-formula"><i>s</i></span>-bond character of the bridging oxygen atom. This model resulted in a root mean square (rms) value for <span class="inline-formula">ΔT–O</span> of only 0.002 Å, comparable to the estimated standard deviations (esd's) routinely quoted in X-ray and neutron structure refinements. In the second step, the <i>inter</i>-tetrahedral differences <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><mi mathvariant="normal">Δ</mi><mo>〈</mo><mtext>T–O</mtext><mo>〉</mo><mo>≡</mo><mo>〈</mo><mtext>T–O</mtext><mo>〉</mo><mo>-</mo><mo>〈</mo><mo>〈</mo><mtext>T–O</mtext><mo>〉</mo><mo>〉</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="124pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="6abfb304be1d8b97681671ce7a3bdf5f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ie00002.svg" width="124pt" height="13pt" src="ejm-32-427-2020-ie00002.png"/></svg:svg></span></span> were considered. Here, apart from the tetrahedral Al content, the only size-perturbing factor is the difference between the tetrahedral and the grand mean fractional <span class="inline-formula"><i>s</i></span>-characters. The resulting rms value was as small as 0.0003&thinsp;Å.</p> <p>From this analysis, Al site occupancies, t, can be derived from observed mean tetrahedral distances, <span class="inline-formula">〈T–O〉_obs</span>, as </p><div class="disp-formula" content-type="" id="Ch1.Ex1"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M9" display="block" overflow="scroll" dspmath="mathml"><mrow><mstyle class="stylechange" displaystyle="true"/><mi mathvariant="normal">t</mi><mo>=</mo><mn mathvariant="normal">0.25</mn><mo>(</mo><mn mathvariant="normal">1</mn><mo>+</mo><msub><mi>n</mi><mrow class="chem"><mi mathvariant="normal">An</mi></mrow></msub><mo>)</mo><mo>+</mo><mfenced open="(" close=")"><mrow><mo>〈</mo><mtext>T–O</mtext><msub><mo>〉</mo><mrow class="chem"><mi mathvariant="normal">adj</mi></mrow></msub><mo>-</mo><mo>〈</mo><mo>〈</mo><mtext>T–O</mtext><mo>〉</mo><mo>〉</mo></mrow></mfenced><mo>/</mo><mn mathvariant="normal">0.12466</mn><mspace linebreak="nobreak" width="0.125em"/><mo>(</mo><mn mathvariant="normal">17</mn><mo>)</mo><mo>,</mo></mrow></math><div><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="256pt" height="16pt" class="svg-formula" dspmath="mathimg" md5hash="fe07b7a1b3c638e07d3983e3abcfb650"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ue00001.svg" width="256pt" height="16pt" src="ejm-32-427-2020-ue00001.png"/></svg:svg></div></div> <p>with the observed distance <span class="inline-formula">〈T–O〉_obs</span> adjusted for the influence of the fractional <span class="inline-formula"><i>s</i></span>-character, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M12" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>〈</mo><mtext>T–O</mtext><msub><mo>〉</mo><mrow class="chem"><mi mathvariant="normal">adj</mi></mrow></msub><mo>=</mo><mo>〈</mo><mtext>T–O</mtext><msub><mo>〉</mo><mrow class="chem"><mi mathvariant="normal">obs</mi></mrow></msub><mo>+</mo><mn mathvariant="normal">0.1907</mn><mo>(</mo><mn mathvariant="normal">51</mn><mo>)</mo><mspace width="0.125em" linebreak="nobreak"/><mo>[</mo><mo>〈</mo><msub><mi>f</mi><mi>s</mi></msub><mrow class="chem"><mo>(</mo><mi mathvariant="normal">O</mi><mo>)</mo></mrow><mo>〉</mo><mo>-</mo><mo>〈</mo><mo>〈</mo><msub><mi>f</mi><mi>s</mi></msub><mrow class="chem"><mo>(</mo><mi mathvariant="normal">O</mi><mo>)</mo></mrow><mo>〉</mo><mo>〉</mo><mo>]</mo></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="245pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="76271aee603b405952b6274f3466ce59"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ie00003.svg" width="245pt" height="15pt" src="ejm-32-427-2020-ie00003.png"/></svg:svg></span></span>. This equation served to determine the site occupancies of 16 intermediate to high albites and one analbite from their mean tetrahedral distances. It was found that the individual site occupancies t<span class="inline-formula">₁</span>0, t<span class="inline-formula">₁</span>m and t<span class="inline-formula">₂0=</span> t<span class="inline-formula">₂</span>m all vary linearly with the difference <span class="inline-formula">Δt₁=</span> t<span class="inline-formula">₁0−</span> t<span class="inline-formula">₁</span>m. <span class="inline-formula">Δt₁</span>, in turn, varies linearly with the length difference, <span class="inline-formula">Δ</span>tr[110], between the unit cell repeat distances [<span class="inline-formula">1∕2<i>a</i></span>, <span class="inline-formula">1∕2<i>b</i></span>, 0] and [<span class="inline-formula">1∕2<i>a</i></span>, <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M25" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">1</mn><mo>/</mo><mn mathvariant="normal">2</mn><mi>b</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="35pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="2fda8e0b28ae904e7551963328325caf"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ie00004.svg" width="35pt" height="14pt" src="ejm-32-427-2020-ie00004.png"/></svg:svg></span></span>, 0]. Then, from the <span class="inline-formula">Δ</span>tr[110] indicator, values of <span class="inline-formula">t</span> were obtained as </p><div class="disp-formula" content-type="" specific-use="align"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M28" display="block" overflow="scroll" dspmath="mathml"><mtable columnalign="left" displaystyle="true"><mtr><mtd><mrow><mstyle displaystyle="true" class="stylechange"/><msub><mi mathvariant="normal">t</mi><mn mathvariant="normal">1</mn></msub><mn mathvariant="normal">0</mn></mrow></mtd><mtd><mrow><mstyle class="stylechange" displaystyle="true"/><mo>=</mo><mo>(</mo><mn mathvariant="normal">1</mn><mo>-</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mo>)</mo><mo>+</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mspace linebreak="nobreak" width="0.125em"/><mo>(</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">1</mn></msub><mo>+</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">2</mn></msub><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">Δ</mi><mrow class="chem"><mi mathvariant="normal">tr</mi><mo>[</mo><mn mathvariant="normal">110</mn><mo>]</mo></mrow><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mstyle displaystyle="true" class="stylechange"/><msub><mi mathvariant="normal">t</mi><mn mathvariant="normal">1</mn></msub><mrow class="chem"><mi mathvariant="normal">m</mi></mrow></mrow></mtd><mtd><mrow><mstyle class="stylechange" displaystyle="true"/><mo>=</mo><mo>(</mo><mn mathvariant="normal">1</mn><mo>-</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mo>)</mo><mo>-</mo><mo>(</mo><mn mathvariant="normal">1</mn><mo>-</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mo>)</mo><mspace linebreak="nobreak" width="0.125em"/><mo>(</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">1</mn></msub><mo>+</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">2</mn></msub><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">Δ</mi><mrow class="chem"><mi mathvariant="normal">tr</mi><mo>[</mo><mn mathvariant="normal">110</mn><mo>]</mo></mrow><mo>)</mo></mrow></mtd></mtr><mtr><mtd><mrow><mstyle displaystyle="true" class="stylechange"/><msub><mi mathvariant="normal">t</mi><mn mathvariant="normal">2</mn></msub><mn mathvariant="normal">0</mn></mrow></mtd><mtd><mrow><mstyle class="stylechange" displaystyle="true"/><mo>=</mo><msub><mi mathvariant="normal">t</mi><mn mathvariant="normal">2</mn></msub><mrow class="chem"><mi mathvariant="normal">m</mi></mrow><mo>=</mo><mo>(</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mo>-</mo><mn mathvariant="normal">0.5</mn><mo>)</mo><mo>-</mo><mo>(</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">0</mn></msub><mo>-</mo><mn mathvariant="normal">0.5</mn><mo>)</mo><mspace linebreak="nobreak" width="0.125em"/><mo>(</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">1</mn></msub><mo>+</mo><msub><mi mathvariant="normal">b</mi><mn mathvariant="normal">2</mn></msub><mspace width="0.125em" linebreak="nobreak"/><mi mathvariant="normal">Δ</mi><mrow class="chem"><mi mathvariant="normal">tr</mi><mo>[</mo><mn mathvariant="normal">110</mn><mo>]</mo></mrow><mo>)</mo><mo>,</mo></mrow></mtd></mtr></mtable></math><div><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="248pt" height="46pt" class="svg-formula" dspmath="mathimg" md5hash="cfecd6185490c16477e2a53bb9fd506f"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="ejm-32-427-2020-ue00002.svg" width="248pt" height="46pt" src="ejm-32-427-2020-ue00002.png"/></svg:svg></div></div> <p>with b<span class="inline-formula">₀=0.7288(16)</span>, b<span class="inline-formula">₁=0.1103(59)</span> and b<span class="inline-formula">₂=3.234(32)</span>&thinsp;Å<span class="inline-formula">⁻¹</span>.</p> <p>Finally, from an expression that converts the <span class="inline-formula">Δ2<i>θ</i>(131)</span> measure of order into <span class="inline-formula">Δ</span>tr[110] and thus into site occupancies, it was possible to obtain from the unique suite of bracketed high-pressure experiments performed<span id="page428"/> on albites by Goldsmith and Jenkins (1985) the evolution with equilibrium temperature of the thermodynamic order parameter <span class="inline-formula"><i>Q</i>_od</span> and of the individual Al site occupancies t at a pressure of 1&thinsp;bar. For that purpose, since the Goldsmith and Jenkins experiments were performed at <span class="inline-formula">≈18</span>&thinsp;kbar, a procedure was devised that accounts for the effect of pressure on the state of order. At 1&thinsp;bar, low albite is stable up to 590&thinsp;<span class="inline-formula">^∘</span>C, where it begins to disorder, turning into high albite above 720&thinsp;<span class="inline-formula">^∘</span>C. The highly though not fully disordered monoclinic state (monalbite) is reached at 980&thinsp;<span class="inline-formula">^∘</span>C, 1&thinsp;bar, and 1055&thinsp;<span class="inline-formula">^∘</span>C, 18&thinsp;kbar, respectively. Eventually, when applying the determinative equations given above to low microcline, full order is predicted as in low albite.</p>

Valentina Esposito, Franco Andaloro, Simonepietro Canese et al.

The geological, biological and geochemical features of a particular field of hydrothermal vents, discovered in the Panarea Volcanic Complex during a research survey carried out in 2015, are described for the first time. The site, located at 70-80 m depth off the South-western coast of the islet of Basiluzzo, was named Smoking Land for the presence of a large number of wide and high active chimneys and was characterized in terms of dissolved benthic fluxes, associated macrofauna and megafauna communities and preliminary mineralogy and geochemistry of chimney structures. On the whole field, a total of 39 chimneys, different in size and shape, were closely observed and described; 14 of them showed emission of low temperature hydrothermal fluids of marine origin characterized by acidified chemical conditions. The CTD and benthic chamber measurements highlighted that the Smoking Land is able to form a sea water bottom layer characterized by variable acidity and high DIC and trace elements concentrations; these characteristics weaken moving away from the chimney mouths. The SEM-EDS analysis of the collected solid samples revealed a chimney structure principally composed by amorphous and low crystalline Fe-oxyhydroxides of hydrothermal origins. The ROV explorations revealed a wide coverage of red algae (Peyssonnelia spp.) colonized by the green algae Flabiella petiolata and by suspension feeders, mainly sponges, but also bryozoans, and tubicolous polychaetes. Although novent-exclusive species were identified, the benthic communities found in association to the chimneys included more taxa than those observed in the surrounding no-vent rocky areas. These first findings evidence a submarine dynamic habitat where geological, chemical and biological processes are intimately connected, making the Smoking Land an important site in terms of marine heritage that should be safeguarded and protected.

Aldjia Bouzeboudja, Bachir Melbouci, Ouardia Bouzeboudja

The grains can be of very diverse nature (size, shape, mineralogy, etc), indeed even if each grain is a fairly simple object, the set of grains is a very complex system in which the geometrical and physical properties of the grains, their forces and their orientations play a crucial role in their mechanical behavior. The measurement of their shape in soil mechanics has historically required the use of standards and diagrams to which the different grains can be compared. However, these methods are approaches and remain insufficient and incomplete for the actual measurement of their form and the understanding of their behavior remains a task far from being completed. This work is in this context and proposes to analyze the shape and size of the grains with the fractal theory using the Box Counting method. It also makes it possible to study their influence on the crushing of the grains of the calcareous material under the effect of the cyclic loading-unloading during the oedometer test. The obtained results show that the variation of the fractal dimension, corresponding to the crushing effect of the grains, is strongly influenced by their shape, their size, their particle size distribution and the variation in the number of loading-unloading cycles.

Jennifer S Le Blond, Peter J Baxter, Dhimiter Bello et al.

<h4>Background</h4>Podoconiosis, non-filarial elephantiasis, is a non-infectious disease found in tropical regions such as Ethiopia, localized in highland areas with volcanic soils cultivated by barefoot subsistence farmers. It is thought that soil particles can pass through the soles of the feet and taken up by the lymphatic system, leading to the characteristic chronic oedema of the lower legs that becomes disfiguring and disabling over time.<h4>Methods</h4>The close association of the disease with volcanic soils led us to investigate the characteristics of soil samples in an endemic area in Ethiopia to identify the potential causal constituents. We used the in vitro haemolysis assay and compared haemolytic activity (HA) with soil samples collected in a non-endemic region of the same area in Ethiopia. We included soil samples that had been previously characterized, in addition we present other data describing the characteristics of the soil and include pure phase mineral standards as comparisons.<h4>Results</h4>The bulk chemical composition of the soils were statistically significantly different between the podoconiosis-endemic and non-endemic areas, with the exception of CaO and Cr. Likewise, the soil mineralogy was statistically significant for iron oxide, feldspars, mica and chlorite. Smectite and kaolinite clays were widely present and elicited a strong HA, as did quartz, in comparison to other mineral phases tested, although no strong difference was found in HA between soils from the two areas. The relationship was further investigated with principle component analysis (PCA), which showed that a combination of an increase in Y, Zr and Al2O3, and a concurrent increase Fe2O3, TiO2, MnO and Ba in the soils increased HA.<h4>Conclusion</h4>The mineralogy and chemistry of the soils influenced the HA, although the interplay between the components is complex. Further research should consider the variable biopersistance, hygroscopicity and hardness of the minerals and further characterize the nano-scale particles.

N.P. Safina, L.Ya. Kabanova, D.A. Kuznetsov et al.

Sulfide ores from the Luchistoe copper occurrence, which are metamorphosed under thermal influence of the Mazar granitic intrusion, are similar in mineralogy and petrography with metamorphosed ores from the VHMS and copper scarn deposits of the Urals. The massive, disseminated, and banded ores with dominant pyrite and chalcopyrite are distinguished according to the textural features. The presence of the high-Fe sphalerite (up to 12 wt. % Fe), galena, molybdenite, pyrrhotite, rutile-ilmenite aggregates, and magnetite is typical of massive ores. The disseminated and banded ores are characterized by aggregates of ilmenite and rutile, ilmenite and Ti-magnetite, apatite, monazite-(Ce), and xenotime-(Y). The absence or insignificant amount of pyrrhotite, the presence of pyrite with graphical microstructures, and high-temperature exsolution structures of ilmenite+magnetite (T = 600–700 °C) are typical features of the ores studied. The disseminated and banded ores host hornblende, biotite, antophyllite, and cordierite, which reflect the processes of hornfels formation.

Francisco Souza Fadigas, Nelson Moura Brasil do Amaral Sobrinho, Lucia Helena Cunha dos Anjos et al.

Soils formed from the Barreiras Group sediments, located mainly along the coast of Brazil Northern and Northeastern regions, generally present low concentrations of iron oxides and total organic carbon, high quantities of quartz in the sand fraction, and kaolinitic clay mineralogy. The objective of the present study was to quantify the pseudo total concentrations of Cd, Co, Cu, Cr, Mn, Ni, Zn and Fe in Xhantic Udox and Xhantic Udult soils derived from these sediments. The reference sites were covered by native vegetation and located in the States of Pará and Amapá, Brazil. Multiple linear regression analysis was applied to determine correlations between soil parameters and the levels of these metals. The best correlation was obtained between Fe, Mn, clay, and silt contents, and Cd, Co, Cu, Zn, Cr, Ni. A correlation between pH and these metal levels was not found. Clay and sand contents showed a negative inverse correlation with the metal levels,of same magnitude but with a different sign; this was the reason for excluding one of the parameters in the regression model. In general, the contents of the elements were lower than those found in soils formed from other parent materials. The Mn content was included in the model of multiple linear regression for Cd and Co, due to its association with these last metals. Silt level showed to have a significant influence in the equations for Cr and Co, which is attributed to the presence of clay minerals and Fe and Mn oxides in ferruginous and clay aggregates of silt size. The equations obtained in this paper, are useful to predict, in general terms, the amounts of those heavy metals in an unknown soil sample, if the soil material were not contaminated or affected by land usage. Thus, they may be applied to evaluate soil contamination by the studied heavy metals.<br>Solos formados a partir de sedimentos do Grupo Barreiras apresentam, em geral, baixos teores de ferro, mineralogia caulinítica, elevadas quantidades de quartzo na fração areia e pequena quantidade de carbono orgânico. Determinaram-se os teores de Cd, Co, Cr, Ni e Zn extraídos com água régia, em bloco digestor, em Argissolos Amarelos e Latossolos Amarelos sob vegetação natural do Pará e Amapá. Regressão linear múltipla foi utilizada para correlacionar os parâmetros de solo e os teores desses metais. Melhores correlações foram obtidas entre Fe, Mn, argila, silte e Cd, Co, Cu, Zn, Cr, Ni. Não foi encontrada correlação entre o pH e os teores de metais. Argila e areia apresentaram correlação inversa com os metais, porém de mesma magnitude, sendo necessária a exclusão de uma delas no modelo de regressão. Em geral, os teores dos elementos estudados foram inferiores aos encontrados em solos formados a partir de outros materiais de origem. O Mn foi incluído no modelo de regressão linear múltipla do Cd e Co, em função de sua associação com esses metais. O silte foi significativo nas equações para Cr e Co, o que pode ser devido à presença de minerais de argila e óxidos de Fe e Mn em agregados ferruginosos e argilosos de tamanho silte. Estas equações podem ser úteis quando se deseja conhecer, em termos gerais, quais as quantidades que determinada amostra teria se o solo em questão não estivesse contaminado ou sujeito a uso antrópico, podendo ser utilizadas na avaliação da contaminação do solo por estes metais.

Hans-Juergen Gursky, Gerardo Orozco-Melgar, Allan Pierra-Conde et al.

Esta investigación tuvo el propósito de comprobar cambios en la dinámica erosiva–acumulativa en Cayo Moa Grande, con base en un análisis fotogeológico temporal. Se usaron fotos aéreas, correspondientes al proyecto K-10 del año 1972, a escala aproximada 1:36 000, e imágenes obtenidas de Google Earth en el año 2007. Para la valoración espacial de los cambios se implementó como herramienta de trabajo un sistema de información geográfica que permitió sectorizar las fotos aéreas; mediante la superposición de la línea de costa para los diferentes años analizados y calculando la tasa de punto final, se determinan las principales transformaciones geodinámicas del cayo en un periodo de 35 años. Los procesos de erosión y sedimentación en Cayo Moa Grande se manifiestan de forma rápida y se registran principalmente en los últimos 50 años, alcanzando un avance máximo en las últimas tres décadas. Tales procesos han modificado la configuración de la línea de costa con la acumulación de sedimentos en la parte occidental y central del cayo y un intenso proceso erosivo en la porción oriental del mismo.

S. Gehor

M. R. Krbetschek, J. Götze, G. Irmer et al.