Mineral Suite Research Articles

Behaviour of steel fibre reinforced concrete with wood ash as partial replacement

Nowadays in view of sustainable development it is very much important to reduce the usage of building materials that creates negative impact on environment. There is a necessity to reduce the production of cement content in order to reduce the CO2 content in the atmosphere and which may be achieved by introducing Mineral Admixtures in concrete. This also improves the quality of concrete. Wood ash is found to be one of the suitable mineral admixtures as it has got high pozzolanic activity. But strength of concrete decreases with increase in percentage of wood ash. The aim of this study is to enhance the strength of Steel Fibre Reinforced Concrete (SFRC) in which cement is partially replaced with wood ash. This research work presents the experimental investigation to evaluate the compressive strength and flexural strength with the addition of wood ash from 0 to 20% with increment of 5% in steel fibres reinforced concrete. From the experimental results, for the optimum 10% wood ash achieving considerable benefits in compressive strength and flexural strength.

Mineralogy and geochemistry of Lobé River sediments, SW Cameroon: Implications for provenance and weathering

The Lobé River (LR) watershed basement rock, Ntem Complex (NC), south Cameroon is covered by a thick lateritic soil. To better constrain the geology of the basement rock, textural, mineralogical and bulk geochemical (major, trace, and rare earth elements) analyses were undertaken on the recent stream sediments from the LR. The aims of this study were to investigate the provenance of sediments and to determine the weathering intensity of the source area. The ternary (Al2O3–TiO2–Zr) and binary (Th/Sc–Zr/Sc) diagrams suggested high sediment recycling and sorting, indicating that the bulk hydraulic energy of the LR controls the sediment texture. Despite the diagenetic processes of K-metasomatism observed on the A-CN-K plot, the (A-K)-C-N plot, Chemical Index of Alteration (CIA), and Plagioclase Index of Alteration (PIA) indicate that the studied sediments and their source areas underwent a high degree of chemical weathering. The heavy mineral suites imply heterogeneous provenance, including igneous, metamorphic and sedimentary source rocks. The ternary diagrams and Co/Th, La/Sc, Sc/Th, Cr/V, and Y/Ni elemental ratios indicate mostly felsic source rocks with lesser contribution from mafic components. The comparison of chondrite normalized REE patterns of LR sediments with potential source rocks reveals that the sediments were derived from the Precambrian basement rocks composed of tonalitic, trondhjemitic, and granodioritic suites, with remnants derived from Archean Greenstone Belt.

Evolution of Ephemeral Phosphate Minerals on Planetary Environments

The detection of ammonium-bearing compounds in meteorites, comets, and in Earth’s geologic record is challenging due to the volatilization of ammonia during heating. Struvite (MgNH4PO4·6H2O) is an ammonium-bearing phosphate mineral considered to be relevant to the origin of organophosphates on the early Earth, and it is possible that this mineral may have formed on the early Earth and in meteorites in favorable environments. However, in contrast to other phosphate minerals such as those within the apatite mineral group, there is little evidence of struvite on the early Earth and no detection of it in meteorites, where such high-N (nitrogen) and low-H2O conditions may be more commonplace. Here, we demonstrate that struvite quickly loses ammonia and transforms into a new suite of minerals; hence, this mineral is ephemeral. This ephemerality is demonstrated by the thermal decomposition reactions of struvite that lead to the mineral newberyite (MgHPO4·3H2O), an acidic phosphate mineral. Both struvite and newberyite transform into magnesium pyrophosphate and magnesium triphosphate, which are the final products of thermal decomposition (T > 200 °C). However, magnesium pyrophosphate itself reacts with calcium-bearing minerals such as calcite or gypsum and transforms into orthophosphate minerals and polyphosphate salts. Such reactions could have occurred in meteorites as well as on the early Earth. The present research helps identify how ephemeral—but prebiotically relevant—minerals may be lost from the geologic record, but still could have played a role in the development of life.

Measuring solar neutrinos over gigayear timescales with paleo detectors

Measuring the solar neutrino flux over gigayear timescales could provide a new window to inform the Solar Standard Model as well as studies of the Earth's long-term climate. We demonstrate the feasibility of measuring the time-evolution of the $^8$B solar neutrino flux over gigayear timescales using paleo detectors, naturally occurring minerals which record neutrino-induced recoil tracks over geological times. We explore suitable minerals and identify track lengths of 15--30 nm to be a practical window to detect the $^8$B solar neutrino flux. A collection of ultra-radiopure minerals of different ages, each some 0.1 kg by mass, can be used to probe the rise of the $^8$B solar neutrino flux over the recent gigayear of the Sun's evolution. We also show that models of the solar abundance problem can be distinguished based on the time-integrated tracks induced by the $^8$B solar neutrino flux.

Platinum group elements in lamprophyre, picrobasalt, gabbro and basalts of the Phenai Mata and nearby areas: implications for Fe–Ni–Cu–PGE mineralization in the Deccan Large Igneous Province

Abstract Among the basaltic large igneous provinces (LIPs) world over, the Deccan Large Igneous Province (DLIP) is considered barren of metalliferous sulfide deposits, and especially platinum group minerals (PGMs). The tholeiitic basaltic magmas of the DLIP were found to lack sulfur saturation at all stages of its evolution. However, we found some incidences of Fe–Ni–platinum group element (PGE) mineralization in the cumulate gabbros of the Phenai Mata Igneous Complex (PMIC), as well as intrusive dykes of lamprophyre, picrobasalt and basalt in adjoining areas. To examine the metal potential of the gabbros, we adopted the following approach: (a) whole-rock PGE analysis of selected rocks; (b) preconcentration of the samples by communition, sieving and gravity-magnetic separation, followed by froth floatation, Ni-sulfide fire assay and geochemical analysis of the concentrates; and (c) direct scanning of samples using an electron probe microanalyser (EPMA). The geochemical proxies – namely, Pd/Ir, Cu/Ir, Ni/Pd and Ni/Cu – indicate that PMIC has distinct geochemical signatures compared to other parts of the DLIP. The results have further indicated an interesting suite of minerals comprising metal sulfides of Fe–Cu–Zn–Pb–Co–Ni. This metal-rich suite in the otherwise ‘barren’ Deccan Trap tholeiites is a result of accidental fertilization of metals into their sulfides due to the mixing of crustal sulfur.

Technical note: Analytical protocols and performance for apatite and zircon (U–Th) ∕ He analysis on quadrupole and magnetic sector mass spectrometer systems between 2007 and 2020

Abstract. Apatite and zircon (U–Th) / He thermochronological data are obtained through a combination of crystal selection, He content measurement by crystal heating with analysis using noble gas mass spectrometry, and measurement of U, Th, and Sm contents by crystal dissolution as well as solution analysis using inductively coupled plasma mass spectrometry (ICP-MS). This contribution documents the methods for helium thermochronology used at the GEOPS laboratory, Paris-Saclay University, between 2007 and the present that allow apatite and zircon (U–Th) / He data to be obtained with precision. More specifically, we show that the He content can be determined with precision (at 5 %) and accuracy using a calibration of the He sensitivity based on the Durango apatite, and its use also appears crucial to check for He and U–Th–Sm analytical problems. The Durango apatite used as a standard is therefore a suitable mineral to perform precise He calibration and yields (U–Th) / He ages of 31.1 ± 1.4 Ma with an analytical error of less than 5 % (1σ). The (U–Th) / He ages for the Fish Canyon Tuff zircon standard yield a dispersion of about 9 % (1σ) with a mean age of 27.0 ± 2.6 Ma, which is comparable to other laboratories. For the long-term quality control of the (U–Th) / He data, attention is paid to evaluating the drift of He sensitivity and blanks through time as well as that of (U–Th) / He ages and Th / U ratios (with Sm / Th when possible), all relying on the use of Durango apatite and Fish Canyon Tuff zircon as standards.

Effect of Exogenously Applied Methyl Jasmonate on Yield and Quality of Salt-Stressed Hydroponically Grown Sea Fennel (Crithmum maritimum L.)

Salt stress is one of the main limiting factors for plant growth and crop yield. Halophytes have been postulated as a new food source since they are able to grow under saline environments and have suitable minerals and bioactive compounds. See fennel Crithmum maritimum L. is a facultative halophyte moderately tolerant to salinity. This study was carried out in order to determine the effect spraying methyl jasmonate (MeJa) on the leaves had on the growth and nutritional quality of NaCl-treated sea fennel plants grown in a hydroponic system. For that, the seedlings were treated with (a) 0.5 mM MeJa, (b) 150 mM NaCl, and (c) 0.5 mM MeJa + 150 mM NaCl. The results showed that NaCl reduced the shoot biomass of baby leaf plants, but the addition of MeJa enabled partial recovery. At the same time, when compared with the plants treated only with NaCl, MeJa favoured the Ca and K uptake and translocation to the leaves of saline-treated plants. However, MeJa did not reduce Na levels. In all treatments, nitrate and nitrite ions were in the range of the acceptable daily intake (ADI) and essential fatty acid content was elevated, although the addition of MeJa to NaCl-treated plants reduced linolenic and linoleic acid contents as compared to the plants treated only with NaCl. Total phenolic compounds were not recovered by MeJa after their decrease by salinity and no differences in antioxidant activity was found between treatments. However, all the plants maintained their antioxidant nutritional properties and increased total flavonoids after MeJa spraying to NaCl-treated plants. These results showed that MeJa spraying alleviated the negative effects of salt stress in C. maritimum grown in floating systems, improving the growth of their edible parts and increasing the total flavonoid and mineral content without affecting the total antioxidant capacity of the plant.

Multi-Proxy Provenance Analyses of the Kingriali and Datta Formations (Triassic–Jurassic Transition): Evidence for Westward Extension of the Neo-Tethys Passive Margin from the Salt Range (Pakistan)

The Salt Range, in Pakistan, preserves an insightful sedimentary record of passive margin dynamics along the NW margin of the Indian Plate during the Mesozoic. This study develops provenance analyses of the Upper Triassic (Kingriali Formation) to Lower Jurassic (Datta Formation) siliciclastics from the Salt and Trans Indus ranges based on outcrop analysis, petrography, bulk sediment elemental geochemistry, and heavy-mineral data. The sandstones are texturally and compositionally mature quartz arenites and the conglomerates are quartz rich oligomictic conglomerates. Geochemical proxies support sediment derivation from acidic sources and deposition under a passive margin setting. The transparent heavy mineral suite consists of zircon, tourmaline, and rutile (ZTR) with minor staurolite in the Triassic strata that diminishes in the Jurassic strata. Together, these data indicate that the sediments were supplied by erosion of the older siliciclastics of the eastern Salt Range and adjoining areas of the Indian Plate. The proportion of recycled component exceeds the previous literature estimates for direct sediment derivation from the Indian Shield. A possible increase in detritus supply from the Salt Range itself indicates notably different conditions of sediment generation, during the Triassic–Jurassic transition. The present results suggest that, during the Triassic–Jurassic transition in the Salt Range, direct sediment supply from the Indian Shield was probably reduced and the Triassic and older siliciclastics were exhumed on an elevated passive margin and reworked by a locally established fluvio-deltaic system. The sediment transport had a north-northwestward trend parallel to the northwestern Tethyan margin of the Indian Plate and normal to its opening axis. During the Late Triassic, hot and arid hot-house palaeoclimate prevailed in the area that gave way to a hot and humid greenhouse palaeoclimate across the Triassic–Jurassic Boundary. Sedimentological similarity between the Salt Range succession and the Neo-Tethyan succession exposed to the east on the northern Indian passive Neo-Tethyan margin suggests a possible westward extension of this margin.

Hydrothermal titanite U–Pb age and geochemistry as a reliable chronometer and genetic tracer for quartz vein-type tungsten deposit at Qipangou of Qinling orogenic belt, Central China

Although quartz vein-type deposits are extremely common worldwide, their formation age is difficult to determine due to the lack of suitable minerals for precise isotope dating. In this article, we report a case study from the large Qipangou quartz vein-type tungsten deposit (57,400 t@ 1.08–1.09 wt% WO3) in the South Qinling polymetallic ore belt, Shaanxi Province, Central China, in which the mineralization event was precisely dated using hydrothermal titanites that are co-genetic with ore minerals. Our results show that although granite is absent in the Qipangou mining district, the titanite U–Pb ages of 194.2 ± 3.6 Ma (sample 18QPG-29) and 198.6 ± 2.1 Ma (sample 18QPG-31) corresponded with that of regional granites and other W–Mo deposits (approximately 200–190 Ma) in the ore field, suggesting a temporal link between this quartz vein-type deposit and granitic magmatism in the region. This study represents the first hydrothermal quartz-vein tungsten deposit analysis using in situ U–Pb isotope dating of titanite, and the results indicate that titanite U–Pb dating can be a potential method for constraining the age of this type of deposits. Based on petrography and mineral assemblage, titanite can be classified as two types. Compositional differences between these two types likely indicate different fluid sources, the release of elements into the local fluid system during alteration such as the decomposition of rutile and hydrous mineral phases like phlogopite, and the addition of components from host sedimentary strata.

Selection of a Suitable Rock Mixing Method for Computing Gardner’s Constant Through a Machine Learning (ML) Approach to Estimate the Compressional Velocity: A study from the Jaisalmer sub-basin, India

The frequent variability of petrophysical properties makes hydrocarbon exploration challenging in carbonate reservoirs. Nowadays, quantitative interpretation (QI) is an essential part of hydrocarbon exploration in a complex reservoir, which needs adequate rock physics data at the well level. However, sometimes the relevant data are not available in earlier discovered oil and gas fields. We observed that the old oil and gas fields in the onshore parts of India have a scarcity of density and compressional velocity (Vp) data at the well level. Gardner's empirical expression provides the scope to estimate Vp from acquired density data and vice versa. However, there are two constants in this relationship, and these are different for different saturation cases of the reservoir due to different mineralogical content in the reservoir rock. The current study aims to identify suitable rock mineral mixing methods and their related uncertainty for estimating Gardner's constants. This uncertainty leads to the estimation of the degree of unwanted flexibility for Vp measurement. Improper selection of the rock mineral mixing method generates uncertainties during the fluid substitution model, mainly where available data are limited. A machine learning (ML) approach based on the naive Bayes algorithm was adopted in this study to select the appropriate rock mineral mixing method from a limited data set. The study was performed in a carbonate reservoir in an onshore sedimentary basin of western India. The ML study shows that the Reuss rock mineral mixing method is suitable for the computation of Gardner's constant in different saturation models for this carbonate reservoir, with less uncertainty.

Characterizing magnesite heavy-media separation screenings as promising technogenic raw materials

Introduction. This article discusses the possibility of using technogenic raw materials for the production of magnesia and magnesium oxide. The analysis of domestic industry supply with magnesite and magnesian raw materials is presented. Man-made minerals, such as magnesite screenings, produced in the course of heavy-media separation of ore, are noted to be a promising source of this type of raw material. It has been established that this type of raw material is poorly studied. Research methodology. The applied research methods were substantiated to establish the amount and form of magnesium oxide in the magnesite screenings of the Satka deposit. Results and discussion. A significant amount of both current and accumulated screenings at the site in Satka and their chemical composition allow us to consider them as a promising technogenic raw material for magnesium oxide production. The work has determined the distribution of magnesium oxide by size classes. On the basis of elemental analysis, it was decided to recognize the object under study as a suitable mineral for processing. The thermogravimetric analysis of magnesite screenings made it possible to establish the forms of magnesium oxide in the material. Conclusions. Analysis of the results obtained allows us to assert the possibility of processing the studied technogenic raw materials, but the presence of magnesium oxide in the composition of solid solutions with calcium carbonate predetermines the use of chemical enrichment methods.

Methods for determination of the source of iron in precontact Inuit and Dorset culture artifacts from the Canadian Arctic

The period during which Dorset Culture peoples and precontact Inuit used iron was widespread and overlapped the appearance of the Norse in Greenland. In Greenland and Arctic Canada, three sources of iron in artifacts have been reported: terrestrial native iron, Norse wrought iron and meteoritic iron from the Cape York iron meteorite. We investigated the source of iron from fourteen samples of iron artifacts recovered from one precontact Inuit and three Dorset culture sites. Polished mm-scale samples mounted in polyester resin blocks yielding a roughly rectangular 1 × 2 mm cross section to preserve as much of each sample as possible were examined. Petrographic examinations by reflected light microscopy and SEM observation coupled with energy-dispersive analysis revealed the presence of Widmanstätten structure (an intergrowth of kamacite and taenite), a suite of minerals comprising kamacite, taenite, daubreelite and schreibersite and nickel-content at iron meteorite levels indicating all fourteen samples were unambiguously of meteoritic origin. With the meteoritic origin confirmed, Goldstein’s (1965) model relating half-width of the kamacite lamellae in the Widmanstätten patterns to the Ni-content of the lamellae was used to determine whether the meteoritic iron originated from the Cape York meteorite. A test of the method used the mean kamacite bandwidth and the bulk Ni-content of the Cape York mass Savik I, which demonstrated the validity of the basis of the method. Using the experimentally-derived relation between kamacite half-width of the bands and composition of the kamacite, the nickel-content of the kamacite lamellae ranged from 6.13 to 6.61 wt% Ni. These compositions are consistent with bandwidths that are narrower than the mean for Cape York, the anticipated source. The discrepancy may be attributed to flattening of the kamacite lamellae by cold working in the manufacture of the artifacts. As well, it has been shown that a range of bandwidths is typical in large iron meteorites such as Cape York. Thus, this method cannot definitively identify Cape York as the source of the meteoritic iron in the fourteen samples; however, the results can serve to identify meteoritic artifacts if the material that has not been intensively cold worked and if sufficient bandwidths can be measured in order to establish a mean thickness.

Iron isotope fractionation in reduced hydrothermal gold deposits: A case study of the Wulong gold deposit, Liaodong Peninsula, East China

Abstract Iron isotope fractionation in hydrothermal systems is a useful diagnostic tool for tracing ore-forming processes. Here, we report on the Fe isotopic compositions of a suite of hydrothermal minerals from ores (pyrite, pyrrhotite, and quartz) from the Wulong gold deposit, Liaodong Peninsula, East China. Pyrites from quartz sulfide ores show a δ56Fe (56Fe/54Fe in the sample relative to IRMM-14) range from +0.11 ± 0.03‰ to +0.78 ± 0.03‰ (2SD), and pyrrhotites from the same vein are isotopically lighter than the pyrites, varying between −0.85 ± 0.01‰ and −0.07 ± 0.00‰. This result is consistent with theoretical predictions of equilibrium fractionation and published mineral compositions. For the first time, to our knowledge, we report the Fe isotopes of hydrothermal quartz that records the isotopic compositions of the ore-forming fluids. Two quartz separates in the quartz-sulfide vein yield δ56Fe values of −0.02 ± 0.02‰ and +0.07 ± 0.07‰. Our Fe isotope fractionation calculations show that pyrrhotite with light Fe isotopes crystallized first from the ore-forming fluids, which indicates a relatively reduced condition for the initial ore-forming fluids. Then the remaining fluids with heavy Fe isotopes precipitated pyrites with positive δ56Fe values, and their mineral crystallization sequence records an increase of oxygen fugacity during mineralization. Gold deposits in Wulong and Jiaodong share many similar geological characteristics. The pyrites from the Wulong deposit have higher δ34S values (+0.5 to +4.1‰) than the pyrrhotites (–1.2 to +1.2‰). Pyrites from the Jiaodong gold deposits show a wide range of both positive and negative δ56Fe values as well as high δ34S values, whereas those from the Wulong deposit have a relatively narrow range of positive δ56Fe values and near-zero δ34S values. The differences in Fe isotopes may be due to early precipitation of pyrrhotite with light Fe isotopes under a relatively low oxygen fugacity environment in the Wulong deposit, resulting in pyrite precipitated from the remaining fluids with heavy isotopes. The sulfur isotope variations between Wulong and Jiaodong gold deposits reflect differences in their source regions rather than oxygen fugacities. In addition, we have compiled Fe isotopic compositions of pyrites and pyrrhotites from different types of ore deposits to investigate their Fe isotopic behavior in magmatic-hydrothermal systems. Pyrite grains show a wide range of δ56Fe values. Positive pyrite δ 56Fe values reflect an equilibrium isotope effect, whereas negative pyrite δ56Fe values may be due to kinetic isotope effects or to a mixture of sedimentary host rocks. Pyrrhotite grains show similar negative δ56Fe values, and they have a strong influence on the Fe isotope systematics in magmatic and hydrothermal systems. Our data show that Fe isotopes can be used to trace precipitation orders of pyrite and pyrrhotite and oxygen fugacity evolution in relatively reduced hydrothermal deposits.

Secondary Sulfates from the Monte Arsiccio Mine (Apuan Alps, Tuscany, Italy): Trace-Element Budget and Role in the Formation of Acid Mine Drainage

A suite of sulfate minerals from the Monte Arsiccio mine (Apuan Alps, Northern Tuscany, Italy), previously identified by using both X-ray diffraction and micro-Raman spectroscopy, was studied through inductively coupled plasma mass spectrometry (ICP-MS), in order to determine their trace-element content. Several elements (Tl, Rb, As, Sb, Co, Ni, Cu, Zn, and Cr) were found above the detection limits. Among them, some are important from an environmental perspective and may reach relatively high concentrations (e.g., Tl = 1370–2988 μg/g; As = 505–1680 μg/g). Thus, these sulfates may act as transient sinks for some of these potentially toxic elements, as well as for sulfate ions and acidity. Indeed, dissolution experiments revealed the ability of these secondary minerals to produce a significant pH decrease of the solutions, as well as the release of Fe, Al, and K as major ions. This work discusses the relation between the budget of trace elements and the crystal chemistry of sulfate minerals and provides new insights about the environmental role played by the sulfate dissolution in controlling the quality of water in acid mine drainage systems.

A triple oxygen isotope perspective on the origin, evolution, and diagenetic alteration of carbonatites

Carbonatites are unique magmatic rocks that are essentially composed of carbonates, and they usually host a diverse suite of minor and accessory minerals. To provide additional insights on their petrogenesis, triple oxygen isotope analyses were carried out on carbonatites from sixteen localities worldwide in order to assess the behaviour of oxygen isotopes (mass-dependent fractionation) during their formation. The study evaluates the mineralogical differences, i.e., calcite, dolomite, ankerite, and Na-carbonates, and the mode of emplacement (intrusive or extrusive) in the mantle-derived carbonatites to further constrain the triple oxygen isotopic composition (Δ′17O) of the upper mantle. Δ′17O values in the intrusive calcite carbonatites vary between −0.003 to −0.088‰ (n = 20) and −0.024 to −0.085‰ (n = 5) in the dolomite varieties. We surmise that the magnitude of isotopic fractionation in the different carbonate phases during their formation is similar and thus, the observed variations are independent of mineralogy and may be related to alteration in the rocks. Taking the samples that classify as primary igneous carbonatites altogether, the average Δ′17O value of the mantle is estimated as −0.047 ± 0.027‰ (1SD, n = 18) which overlaps those of other mantle rocks, minerals and xenoliths, indicating that the mantle has a relatively homogenous oxygen isotope composition. Two ankerite carbonatites have identical Δ′17O values as calcite but a few samples, together with pyroclastic tuffs have significantly lower Δ′17O values (−0.108 to −0.161‰). This deviation from mantle Δ′17O signature suggests diagenetic alteration (dissolution and recrystallisation) and mixing of carbonate sources (juvenile and secondary carbonates) which is consistent with the high δ18O and clumped isotope (Δ47) values recorded in the pyroclastic and ankeritic rocks. In summary, diagenetic alteration driven by fluid-rock interaction at low temperatures, sub-solidus re-equilibration with magmatic waters, and the incorporation of secondary carbonates altogether facilitate the alteration of original isotopic compositions of carbonatites, obliterating their primary mantle signatures.

English

Some improved genotypes of cocoa tree (Theobroma cacao L.), have shown in standard study conditions of absence or a very low response to the induction of somatic embryos. This is the case of the recalcitrant genotypes C8 and C15, partially recalcitrant genotypes C14 and C16. This study aims to improve the production of somatic embryos of recalcitrant genotypes. Staminodes and petals excised from the immature buds of the five genotypes C1, C8, C14, C15 and C16 were used as plant material. These floral explants were cultured on different media containing two type of mineral salts such as potassium sulphate (K2SO4) at concentrations 18, 27, 36 and 45 mM and magnesium sulphate (MgSO4) whose concentrations used are 5, 10, 15 and 20 mM. Calli induction was obtained in the five (05) genotypes at percentages ranging from 50 to 100% with staminodes and from 61 to 100% with petals on all media. The transfer of the callogenic explants on the developmental medium allowed the induction of embryogenic calli and somatic embryos after 84 days only with petal explants. The most important PEC and NSE were obtained with two mineral salts concentrations, 27 mM K2SO4 and 15 mM MgSO4 for all genotypes and varied to 20 to 40%. Potassium sulphate (K2SO4) at 27 and magnesium sulphate (MgSO4) at 15 mM are the concentrations of the most suitable mineral salts to overcome recalcitrance of cocoa genotypes.   Key words: Recalcitrant, Theobrama cacao, improved genotypes, mineral salts, somatic embryogenesis.

Quantification of radionuclide distribution and migration during Cu-(Fe)-sulphide mineral processing by alpha particle autoradiography

Understanding the movement of radionuclides (RNs) between different mineral hosts during processing of base metal ores is critical for accurate modelling of RN deportment and optimisation of processes designed to reduce or eliminate RNs. Here, we demonstrate that spatially resolving quantitative alpha particle autoradiography combined with backscatter electron imaging and energy dispersive X-ray spectroscopy (EDS) can establish the correlation between alpha-emitting RNs (notably 226Ra and 210Po, daughters of the abundant 238U decay series) and certain minerals, in different stages of processing. This is achieved by locating the RNs to a specific mineral grain, the species of which can subsequently be identified using EDS. The mineralogy of RN-associated grains can then be compared with the mineral suite and relative abundances of the species within the sample, by relating how often each mineral is associated with alpha decay-events. In the processing of uranium-bearing copper ores, migration of alpha-emitting RN daughters of the 238U series were observed, and these RNs were demonstrated to correlate strongly with barite, bornite and covellite over other coexisting minerals.

Minerals As Electrode Materials for Ca-Based Rechargeable Batteries: Evaluation of the Pyroxene, Garnet, Melilite and Double Carbonate Groups

Rechargeable lithium-ion batteries dominate the consumer electronics and electric vehicle markets. However, concerns on Li availability have prompted the development of alternative high energy density electrochemical energy storage systems. Rechargeable batteries based on a Ca metal anode can exhibit advantages in terms of energy density, safety and cost. The development of rechargeable Ca metal batteries requires the identification of suitable high specific energy cathode materials. This work focuses on Ca-bearing minerals because they represent stable and abundant compounds. Suitable minerals should contain a transition metal able of being reversibly reduced and oxidized, which points to several major classes of silicates and carbonates. A recent work [1] discusses their electrode characteristics based on crystal chemistry analysis and density functional theory (DFT) calculations. The results indicate that upon Ca deintercalation, compounds such as pyroxene, garnet and double carbonate minerals could display high theoretical energy densities (ranging from 780 to 1500 Wh/kg) with moderate structural modifications. As a downside, DFT calculations indicate a hampered Ca mobility in their crystal structures with energy barriers for Ca migration exceeding 2 eV. More recent investigations found a lower energy barrier of 1 eV in the group of melilite with formula Ca2MSi2O7, where Ca ions are in a square antiprism coordination polyhedron and M is a transition metal ion in tetrahedral coordination.Acknowledgements: Authors are grateful for financial support from European Union H2020-FETOPEN funded project CARBAT-766617.[1] Torres, Luque, Tortajada, Arroyo-de Dompablo, Scientific Reports 9, 9644 (2019).

Controls on development of different mineral assemblages in gabbro and basalt during subduction metamorphism

Coexisting fine-grained (meta-volcanic) and coarse-grained (meta-plutonic) mafic rocks in a high-pressure (P)/low-temperature (T) complex (Sivrihisar, Turkey) preserve different prograde, peak, and retrograde mineral assemblages, providing an opportunity to evaluate controls on mineral assemblages in metabasites that experienced the same P–T conditions. Fine-grained metabasalts are garnet-bearing lawsonite blueschist and eclogite with similar assemblages that vary on a mm- to cm- scale in mode of glaucophane vs. omphacite. In contrast, metagabbro consists of a disequilibrium mineral suite of relict igneous clinopyroxene partially replaced by omphacite or hydrous phases (lawsonite + tremolite or glaucophane) in a matrix of fine-grained lawsonite, omphacite, tremolite, white mica, very rare garnet, and retrograde minerals (e.g., epidote, albite, and titanite), with later chlorite and calcite. Pseudosection modeling predicts similar peak P–T conditions (490–530 °C, 1.8–2.0 GPa) for both glaucophane-rich (blueschist) and omphacite-rich (eclogite) layers of the metabasalt and similar to slightly higher conditions (490–600 °C, 1.9–2.5 GPa) for metagabbro. The range of modelled H2O content at peak P–T conditions in metabasalt (2.0–5.4 wt%) is significantly lower than in metagabbro (6.4–8.7 wt%) due to the higher modal abundance of hydrous minerals in the latter. At the relatively similar peak P–T conditions, metagabbro experienced different reaction histories from coexisting metabasalt, thereby developing distinctive HP/LT mineral assemblages and modes (e.g., scarce garnet) owing to its more Mg-rich bulk composition (XMg = 0.58–0.84 vs. 0.50), higher H2O content, and coarser grain-size. This study is the first petrologic analysis of Sivrihisar metagabbro and the first systematic study of H2O content in metabasites from this locality, which is one of the best-preserved examples of lawsonite eclogite and blueschist in the world.

Tourmalines as a Tool in Provenance Studies of Terrigenous Material in Extra-Carpathian Albian (Uppermost Lower Cretaceous) Sands of Miechów Synclinorium, Southern Poland

The mature transgressive Albian quartz sands in the Miechów Synclinorium contain a poor (<1%) heavy mineral suite consisting of tourmaline, rutile, garnet, staurolite, ilmenite, zircon, monazite, kyanite, and gahnite. The other minerals, especially those containing Fe and Ti (e.g., biotite), are subordinate. Over 512 tourmaline grains from seven outcrops in the Miechów Segment were analysed using electron probe microanalysis (EPMA). The majority of grains belong to the alkali tourmaline group in which the X-site is dominated by Na (0.4 to 0.9 apfu). Detrital tourmalines are mainly dravite with a prevalent schorl end-member with average XMg values over 0.6. Apart from Mg and Fe, the other Y-site cations rarely exceed 0.1 apfu. Fluorine content is usually below the detection limit. Their chemical composition suggests that most tourmaline grains were sourced from Al-rich and Al-poor metapelites/metapsammites. The main source rocks for the Albian sands were rocks from low- to medium-grade metamorphism, probably from Al-rich quartz-muscovite schist and/or muscovite rich gneisses. Additional minor source rocks were granites and pegmatites coexisting with them. A comparison of the examined tourmaline to tourmaline from possible source areas indicates that these areas were located in the eastern part of the Bohemian Massif and/or eastern Sudetes.