Scientific articles
Peer-reviewed research on crystallography, geochemistry and mineral formation.
Thermocatalytic transcarbonation with diethyl carbonate for valorization of glycerol : recycling siliceous bauxite residue waste components and exploring the potential of sodalite hydroxide reservoir
Bauxite residues contain katoites and desilication products (sodalite and cancrinite), which are excellent candidates for Earth-abundant heterogeneous base catalysts from industrial waste sources. For the first time, they were tested in synthetizing the renewable and promising fuel or fuel additive glycerol carbonate for the purpose of recycling glycerol by-products from biodiesel production. Incorporation of silicate was found to enhance the previously established excellent catalytic activity of tricalcium aluminate (Si-free katoite). Performance of sodalites containing four different cage an...
Mckelveyite group minerals – Part 5: Bainbridgeite-(NdCe), Na 2 Ba 2 NdCe(CO 3 ) 6 ●3H 2 O, a new neodymium and cerium-dominant species from Mont Saint-Hilaire, Canada
Abstract. The new mckelveyite group mineral bainbridgeite-(NdCe), ideally Na2Ba2NdCe(CO3)6⚫3H2O, was found at Mont Saint-Hilaire, Quebec, Canada. It occurs in two distinct environments: (1) in a “carbonate pegmatite” as pale-yellow or orange barrel-shaped short prismatic crystals up to 2 mm in size, where bainbridgeite-(NdCe) forms thin rims while the core is composed of bainbridgeite-(YCe), and (2) in a hornfels rock as white or pale-grey tabular saucer-shaped crystals up to 0.5 mm in size. It has a white streak, a vitreous lustre, and no cleavage. Dcalc is 3.49 g cm−3. Bainbridgeite-(NdCe)...
Geometallurgical Diagnosis of Gold Loss in Refractory Quartz-Vein Gold Tailings Using Automated Mineralogy: A Case Study of the Baolun Gold Mine, Hainan Province, China
To enhance gold recovery from tailings of a quartz-vein gold deposit in Hainan, China, this study systematically characterized the chemical composition, mineral composition, and process mineralogical characteristics of gold particles using inductively coupled plasma optical emission spectrometry (ICP-OES), Advanced Mineral Identification and Characterization System (AMICS), and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS). The results show that the tailings have an average gold grade of 0.44 g/t, and the gold occurs predominantly as native gold (average fineness a...
Multistage metasomatism during experimental reaction of axinite-(Fe) with F-, Cl-, OH-, Si-bearing fluids at 600 °C, 200 MPa and 800 °C, 500 MPa
Abstract Many studies have shown that geological processes, such as metamorphism and metasomatism, consist of multiple superimposed events developing over various timescales, with each stage overprinting the previous one and thus complicating reconstruction of the complete history. Here, we report the use of a natural calcium aluminum borosilicate mineral axinite-(Fe) [(Ca 2 Fe 2+ Al 2 BSi 4 O 15 (OH)], which occurs in skarn deposits, as a starting material in a series of experiments representing various metasomatic processes. The fluids used include NaF+H 2 O, NaCl+H 2 O, KCl+H 2 O, CaCl 2 +H...
Scandium mineralogy in Bayan Obo deposit, north China: Tracing magmatic to hydrothermal enrichment pathways
Abstract As a rare metal essential for aerospace and clean energy technologies, scandium (Sc) has a low abundance and dispersed occurrence in the Earth’s crust. The Bayan Obo carbonatite-hosted deposit, the world’s largest REE deposit, hosts significant Sc resource distributed across distinct types of Fe-Nb-REE ore, primarily disseminated, banded, massive, and vein-type ores. Previous studies attributed Sc enrichment at Bayan Obo dominantly to hydrothermal processes, as direct mineralogical evidence for magmatic-stage enrichment remained elusive. This study integrates whole-rock geochemistry,...
Hydrothermal quartz genesis revealed by the combination of SEM charge contrast maps, FTIR mapping, and LA-ICP-MS trace element geochemistry
Abstract. Magmatic–hydrothermal ore deposits, such as pegmatites, are an increasingly important source of metals and critical elements for the development of green-energy resources. The geochemical processes at the magmatic–hydrothermal transition influence the degree of element enrichment in these ores. Quartz is a mineral that grows throughout the complete crystallization sequence of granitic pegmatites. Tracking the systematics of trace element incorporation into the quartz crystal structure throughout the magmatic–hydrothermal pegmatite evolution may offer unprecedented insights into pegma...
Complex dielectric permittivity of clay minerals: impact of clay mineralogy, porosity, and ionic concentration
Permittivity can be one of the non-destructive methods to monitor many properties of soils. The objective of this study was to provide a comprehensive understanding of the permittivity of clay minerals through the measurement of permittivity and electrical conductivity as a function of water content, ionic concentration and clay mineralogy. It was found that swelling clay shows a wide variation in real and imaginary permittivity as a function of water content at low ionic concentration. In addition, the variation of permittivity was a strong function of swelling potential where Ca-montmorillon...
Boron coordination in haplogranite glasses
Abstract. The coordination of boron in silicate melts has been extensively studied in synthetic industrial glasses but rarely in natural volcanic glasses or their synthetic analogues. Because coordination is a controlling factor in the boron isotope exchange between melts and coexisting phases, it is important to close this knowledge gap. We synthesized a set of boron-rich (2 wt % and 5 wt % B2O3) haplogranite glasses with water content from 0 wt % to 7 wt % and a variable alumina–alkali ratio, expressed by the aluminum saturation index (ASI), the molar ratio of Al2O3 / (CaO + Na2O + K2O). Bor...
MINERALOGIA E GÊNESE DE SOLOS ÂNDICOS EM AMBIENTE ALTOMONTANO NO SUL DO BRASIL
A confirmação de solos com propriedades ândicas no Brasil e a escassez de estudos sistemáticos motivam a caracterização mineralógica desses materiais em ambientes altomontanos do Sul do país. Este trabalho caracteriza a fração argila de dez perfis com propriedades ândicas distribuídos ao longo da escarpa da Formação Serra Geral (RS–SC). Amostras de horizontes superficiais e subsuperficiais foram analisadas por difração de raios X em lâminas orientadas, após remoção de óxidos por ditionito-citrato-bicarbonato e tratamentos com Mg, Mg+etileno glicol e K (25–550 °C). Foram estimadas proporções re...
Evolution of the epithermal mineralization in the Pukanec deposit, Štiavnické vrchy Mts. (Slovakia)
Abstract The Pukanec deposit belongs to the historically significant ore field of epithermal Au-Ag mineralization in the Middle Miocene Štiavnica andesite stratovolcano (Western Carpathians, Slovakia). Up to now, the Ag and Au carriers were not properly identified so far. In this paper, we present mineralogical, paragenetic, and geochemical aspects of the ore mineralization and fluid properties for the Pukanec deposit. Five subsequent mineralization stages were recognized, comprising (1) pyrite stage with quartz, K-feldspar, pyrite, and Au-Ag alloys, (2) base-metal stage with pyrite, Au/Ag all...
Yttrotungstite-(Nd), a new mineral species from the Nyakabingo tungsten mine, Kigali, Rwanda
Abstract. Yttrotungstite-(Nd), NdW2O7(OH)(H2O), is a new mineral species discovered in the Nyakabingo tungsten mine, Kigali, Rwanda. The mineral occurs in the oxidized zones of the deposit, where it forms tiny yellow-orange tabular crystals associated with anthoinite and hydrokenoelsmoreite. The crystals are transparent, reach a length of a maximum of 100 µm, and frequently form radiated groups. The dominant form is {010}, and a twinning has been observed parallel to (001). The streak of yttrotungstite-(Nd) is white, the lustre is vitreous, and the mineral is non-fluorescent. The Mohs hardness...
Petrogenesis of isolated high-silica rhyolites in Iceland
Abstract High-silica rhyolites (HSRs) are rhyolites containing > 75 wt% SiO 2 on an anhydrous basis. In this contribution we have studied four Icelandic isolated occurrences away from central volcanoes (i.e., Icelandic volcanoes with a well-developed volcanic plumbing system): three in active rift zones (Mælifell, Ketilhyrnur and Prestahnúkur) and one in a flank/off-rift zone (Sultarfell). With no established central volcano, in which magmas can evolve by fractional crystallisation in its plumbing system, we propose that these high-silica volcanic rocks are the product of partial melting of to...
Electron microanalysis of minerals: the advantages and pitfalls of wavelength-dispersive spectroscopy for mineral characterization
Accurate determination of mineral chemical composition is essential for various aspects of geoscience, including economic geology, geochemistry, thermodynamic modelling, mineralogy, etc. With the increasing complexity of the rules for mineral definitions, accurate chemical analysis has become crucial for proper mineral classification. Electron microanalysis is the most widely used technique, employing energy-dispersive (EDS) and wavelength-dispersive (WDS) spectroscopies. While EDS enables rapid, simultaneous acquisition of X-ray spectra, its analytical performance is limited by relatively poo...
How new minerals are discovered and how they are validated
This article provides practical advices on how to move from an unknown mineral phase to a valid new mineral species officially approved by the Commission on New Minerals, Nomenclature, and Classification of the International Mineralogical Association (IMA CNMNC). The first step is to make sure that the unknown phase is truly new and has natural origin, realistically assess chances to obtain a complete set of analytical data required for its approval as a new mineral, and assemble a team of professionals to conduct the relevant analytical works. Based on the research results, a proposal (“check...
Topomineralogical forecast of hydrothermal mineralization in the Zirabulak-Ziaetdi region (Uzbekistan)
The paper presents a method of topomineralogical forecast of hydrothermal mineralization, which is based on the presence of typical minerals, and an example of its application for the forecasting the hydrothermal mineralization in the Zirabulak-Ziaetdi region of the Republic of Uzbekistan. For this region, the mineralization level of identified geologically homogeneous blocks is assessed and they are compared with reference blocks with known deposits. Theoretically possible types of ore deposits in various rocks are plotted in stratigraphic-mineralogical columns.
Application of electron backscattered diffraction to solving petrological problems on example of ultramafic rocks
Electron backscatter diffraction (EBSD) is a modern high-precision method for studying the microstructural features of a wide range of crystalline materials. This paper examines EBSD application for natural ultramafic rocks including surface preparation, analysis, and post-processing in HKL Channel and MTEX software. The EBSD data are compared with those measured using classical microstructural study of transparent minerals on a universal Fedorov stage. The main EBSD advantages include high localization and rapid data acquisition, automation, objectivity, and a wide range of the studied materi...
Rapakivi microstructure in a 3.3 Ga rhyolite
Abstract The rapakivi microstructure has been widely studied in granites, but few investigations have focused on volcanic rocks, especially Paleoarchean types. The Contendas Rhyolite (CR), approximately 3.3 billion years old, is a rare example of a Paleoarchean volcanic rock with preserved rapakivi microstructure. This work provides a microstructural description, results of energy-dispersive X-ray spectrometry (EDS) analyses, and electron-backscatter diffraction (EBSD) studies of the rapakivi feldspars in the CR. Petrographic analysis shows that the microstructure features a single, thick rim...
Influence of errors of geochemical analyses on genetic geodynamic and geological conclusions
The influence of analytical errors of geochemical analyses on genetic conclusions is typically underestimated by researchers. The composition of rocks or minerals, as a rule, is shown on diagrams as a point, actually with no size, however, all analyses should be presented on diagrams as fields rather than points. The larger the analytical error, the larger the field. It is shown that all genetic geochemical diagrams, interpretations, and conclusions are senseless with analytical errors of ~30 % and more, because the area of the “point” (more precisely, the field) of a single analysis in this c...
The role of single-crystal X-ray diffraction in the description of new mineral species
The discovery and formal approval of a new mineral species require the integration of chemical, crystallographic, and structural information. Among the available analytical techniques, single-crystal X-ray diffraction (hereafter SCXRD) remains the most powerful method for determining the crystal structure of crystalline materials and, in turn, of minerals. In recent decades, advances in instrumentation and analytical methods have greatly expanded the capability of SCXRD, allowing reliable structure determination even from extremely small crystals and this is impacting the number of new mineral...
Structure analysis of new mineral species: current state and perspectives
A brief overview of X-ray diffraction techniques currently used for the structural investigation of new minerals is provided, focusing mostly on X-ray diffraction from single crystals, which remains the most widely used method, and on the emerging field of electron diffraction methods that are expected to overtake, to some extent, the role of X-ray diffraction methods.
Application of LA-ICP-MS method in study of mineralogy of microfacies of massive sulfide deposits
The paper analyzes potential and limitations of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) during study of mineralogy of sulfide facies and microfacies from massive sulfide deposits. Using point LA-ICP-MS analysis and LA-ICP-MS micromapping for the mineralogical and geochemical zoning of chimneys and mineralized biomorphs, we evaluate the formation conditions of mineral and trace element associations in sulfides for various types of massive sulfide deposits and substantiate hydrothermal-sedimentary models of chemical element differentiation. The analysis of pulse t...
Methods of studying detrital zircons
This paper provides an overview of detrital zircon study methods from sample collection to the interpretation of geochronological and geochemical data. Detrital zircon geochronology is used to identify potential provenances and migration routes of terrigenous material, to correlate coeval deposits, and to determine the maximum depositional age. Large datasets are used for regional and global geodynamic reconstructions. Different stages of detrital zircon study affect the results and their interpretation. Sample collection and preparation, formation of the zircon sampling, selection of analytic...
Petrology and Mineralogy of Serpentinite Rock from the Mawat Ophiolite Complex in Zagros Suture Zone, Betwat Area, NE Iraq
الهدف من هذا البحث هو لدراسة صخور السربنتين في معقد ماوات من خلال استخدام الملاحظات الحقلية والبتروغرافية والمعدنية لتحديد التركيب المعدني والأصل والموضع التكتوني لكتلة الصخور فوق القاعدية من معقد ماوات الاوفيولايتي في منطقة زاغروس شمال شرقي العراق. وكانت عينات الصخور الخاضعة لعملية التحول الى سربنتين بالكامل تتميز بتجمع معدني من السربنتين مع بقايا من المعادن الاصلية مثل الأوليفين والبيروكسين، اضافة الى معادن أخرى ثانوية مثل الأمفيبول والتالك والكلواريت والكرومايت والماكنتايت. يظهر معدن السربنتين في ثلاثة أنواع هي (الكريسوتايل والليزاردايت والأنتيكورايت). المعدن الأكثر شيوعًا هو الأنتيكورايت،...
A mineralogy-driven machine learning framework for optimizing LC 3 -based 3D-printed cementitious composites with an integrated, end-to-end python-based design tool
Abstract This study presents a framework for developing low-carbon, printable limestone–calcined clay cement (LC 3 ) using locally available clays in Oman that primarily contain kaolinite, illite, and montmorillonite. A dataset of 287 formulations using varying the proportions of these components and limestone, with each mix experimentally tested for compressive strength, flexural strength, and static yield stress to link mechanical performance with printability. Two supervised machine learning models: Gaussian process regression (GPR) and a shape-constrained generalized additive model, were t...