Subjects -> MINES AND MINING INDUSTRY (Total: 82 journals)
Showing 1 - 42 of 42 Journals sorted alphabetically
American Mineralogist     Hybrid Journal   (Followers: 16)
Applied Earth Science : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Archives of Mining Sciences     Open Access   (Followers: 3)
AusiMM Bulletin     Full-text available via subscription   (Followers: 1)
BHM Berg- und Hüttenmännische Monatshefte     Hybrid Journal   (Followers: 2)
Canadian Mineralogist     Full-text available via subscription   (Followers: 7)
CIM Journal     Hybrid Journal   (Followers: 1)
Clay Minerals     Hybrid Journal   (Followers: 9)
Clays and Clay Minerals     Hybrid Journal   (Followers: 5)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Contributions to Mineralogy and Petrology     Hybrid Journal   (Followers: 14)
Environmental Geochemistry and Health     Hybrid Journal   (Followers: 3)
European Journal of Mineralogy     Hybrid Journal   (Followers: 14)
Exploration and Mining Geology     Full-text available via subscription   (Followers: 3)
Extractive Industries and Society     Hybrid Journal   (Followers: 2)
Gems & Gemology     Full-text available via subscription   (Followers: 2)
Geology of Ore Deposits     Hybrid Journal   (Followers: 5)
Geomaterials     Open Access   (Followers: 3)
Geotechnical and Geological Engineering     Hybrid Journal   (Followers: 9)
Ghana Mining Journal     Full-text available via subscription   (Followers: 3)
Gold Bulletin     Hybrid Journal   (Followers: 2)
Inside Mining     Full-text available via subscription  
International Journal of Coal Geology     Hybrid Journal   (Followers: 4)
International Journal of Coal Preparation and Utilization     Hybrid Journal   (Followers: 2)
International Journal of Coal Science & Technology     Open Access   (Followers: 1)
International Journal of Hospitality & Tourism Administration     Hybrid Journal   (Followers: 16)
International Journal of Mineral Processing     Hybrid Journal   (Followers: 8)
International Journal of Minerals, Metallurgy, and Materials     Hybrid Journal   (Followers: 12)
International Journal of Mining and Geo-Engineering     Open Access   (Followers: 4)
International Journal of Mining and Mineral Engineering     Hybrid Journal   (Followers: 8)
International Journal of Mining Engineering and Mineral Processing     Open Access   (Followers: 6)
International Journal of Mining Science and Technology     Open Access   (Followers: 4)
International Journal of Mining, Reclamation and Environment     Hybrid Journal   (Followers: 6)
International Journal of Rock Mechanics and Mining Sciences     Hybrid Journal   (Followers: 9)
Journal of Analytical and Numerical Methods in Mining Engineering     Open Access   (Followers: 1)
Journal of Applied Geophysics     Hybrid Journal   (Followers: 18)
Journal of Central South University     Hybrid Journal   (Followers: 1)
Journal of China Coal Society     Open Access  
Journal of China University of Mining and Technology     Full-text available via subscription   (Followers: 1)
Journal of Convention & Event Tourism     Hybrid Journal   (Followers: 6)
Journal of Geology and Mining Research     Open Access   (Followers: 10)
Journal of Human Resources in Hospitality & Tourism     Hybrid Journal   (Followers: 9)
Journal of Materials Research and Technology     Open Access   (Followers: 2)
Journal of Metamorphic Geology     Hybrid Journal   (Followers: 17)
Journal of Mining Institute     Open Access  
Journal of Mining Science     Hybrid Journal   (Followers: 5)
Journal of Quality Assurance in Hospitality & Tourism     Hybrid Journal   (Followers: 6)
Journal of Sustainable Mining     Open Access   (Followers: 3)
Journal of the Southern African Institute of Mining and Metallurgy     Open Access   (Followers: 6)
Lithology and Mineral Resources     Hybrid Journal   (Followers: 4)
Lithos     Hybrid Journal   (Followers: 11)
Mine Water and the Environment     Hybrid Journal   (Followers: 6)
Mineral Economics     Hybrid Journal   (Followers: 2)
Mineral Processing and Extractive Metallurgy : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 14)
Mineral Processing and Extractive Metallurgy Review     Hybrid Journal   (Followers: 5)
Mineralium Deposita     Hybrid Journal   (Followers: 4)
Mineralogia     Open Access   (Followers: 2)
Mineralogical Magazine     Hybrid Journal   (Followers: 1)
Mineralogy and Petrology     Hybrid Journal   (Followers: 5)
Minerals     Open Access   (Followers: 2)
Minerals & Energy - Raw Materials Report     Hybrid Journal   (Followers: 1)
Minerals Engineering     Hybrid Journal   (Followers: 14)
Mining Engineering     Full-text available via subscription   (Followers: 7)
Mining Journal     Full-text available via subscription   (Followers: 4)
Mining Report     Hybrid Journal   (Followers: 3)
Mining Technology : Transactions of the Institutions of Mining and Metallurgy     Hybrid Journal   (Followers: 4)
Mining, Metallurgy & Exploration     Hybrid Journal  
Natural Resources & Engineering     Hybrid Journal  
Natural Resources Research     Hybrid Journal   (Followers: 5)
Neues Jahrbuch für Mineralogie - Abhandlungen     Full-text available via subscription   (Followers: 1)
Physics and Chemistry of Minerals     Hybrid Journal   (Followers: 4)
Podzemni Radovi     Open Access  
Rangeland Journal     Hybrid Journal   (Followers: 4)
Réalités industrielles     Full-text available via subscription  
Rem : Revista Escola de Minas     Open Access  
Resources Policy     Hybrid Journal   (Followers: 4)
Reviews in Mineralogy and Geochemistry     Hybrid Journal   (Followers: 5)
Revista del Instituto de Investigación de la Facultad de Ingeniería Geológica, Minera, Metalurgica y Geográfica     Open Access  
Rock Mechanics and Rock Engineering     Hybrid Journal   (Followers: 9)
Rocks & Minerals     Hybrid Journal   (Followers: 5)
Rudarsko-geološko-naftni Zbornik     Open Access  
Transactions of Nonferrous Metals Society of China     Hybrid Journal   (Followers: 9)
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Journal Cover
Geology of Ore Deposits
Journal Prestige (SJR): 0.54
Citation Impact (citeScore): 1
Number of Followers: 5  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 1555-6476 - ISSN (Online) 1075-7015
Published by Springer-Verlag Homepage  [2653 journals]
  • New Data for Malanite and Cuprorhodsite from Chromitites of the Bushveld
           Complex, South Africa
    • Abstract: The 3D-mineralogical technology was used to study a representative selection of grains of thiospineles from three groups of chromitite horizons (lower LG6, middle MG1/MG2 and upper UG2): 46 grains of malanite (4–42 μm) and 34 grains of cuprorhodsite (9–42 μm). Their microprobe analysis was performed (n = 61). The statistics for this selection of grains have resulted in the following formulas: for malanite, (Сu2+,Fe2+)(Pt3+Rh3+,Ir3+,Co3+,Ni3+Fe3+)2S4 and for cuprorhodsite, (Сu2+,Fe2+)(Rh3+,Pt3+,Ir3+,Fe3+)2S4. According to morphological properties and their relationship with platinum-group minerals (PGMs) and base metal sulfides, thiospinel can be attributed to the earliest primary PGMs in chromitites. The distribution of cuprorhodsite and malanite in chromitites was controlled by the Rayleigh fractionation of the primary sulfide melt in the process of formation of Bushveld chromitite horizons.
      PubDate: 2020-12-01
       
  • The Symmetry Statistics of Mineral Species in Various Thermodynamic
           Environments
    • Abstract: This paper generalizes the data on the symmetry of minerals in different Earth shells as a function of temperature, pressure, and the combined effects of both parameters. It is shown that the distribution of mineral species in the symmetry hierarchy, in particular, the existence of a monoclinic maximum and a triclinic minimum in the symmetry statistics of the world for minerals and inorganic compounds, is determined, first of all, by two diverse factors: the dynamic properties of the crystal lattice (the number of unit-cell parameters that are not fixed according to symmetry) and the efficiency of the crystal structure (the maximum number of admitted atomic positions according to the given point-to-point group). As the temperature increases, the symmetry of a substance usually becomes higher, with constantly increasing pressure making it lower, but increasing again with its reconstruction. The mutual increase of temperature and pressure with depth inside the Earth provides a stable increase of the average symmetry of rock, from a few units to the maximum value of 48 of the Dolivo-Dobrovolsky index. Due to the multiparametric nature of the mineral-symmetry statistics we will leave some fluctuations of this function without comment until their verification over time.
      PubDate: 2020-12-01
       
  • Agates from Paleoproterozoic Volcanic Rocks of the Onega Structure,
           Central Karelia
    • Abstract: Agate mineralization in Central Karelia, Northwest Russia is related to the Paleoproterozoic volcanic rocks of the Ludicovian Superhorizon (2.05–1.95 Ga) within the Onega structure. Agates and parental volcanic rocks were studied with optical and electron microscopy, electron microprobe, X-ray diffraction, Raman spectroscopy, and ICP-MS. It is shown that fine-grained quartz, and fibrous and fine-flake chalcedony are the major minerals in the agate structure. Inclusions of coarse-crystalline calcite, and microinclusions of chlorite, iron oxides and hydroxides, hydroxylapatite, epidote, mica (phengite), apatite, pyrite, chalcopyrite, titanite, and leucoxene are present in agates. The presence of contrast rhythms within agate amygdules is marked by compositional variation in impurity mineral phases and different microtextures of silica layers represented by different-grained aggregates of quartz, fine-flake and fibrous chalcedony, and quartzine. This indicates stage-by-stage mineral crystallization at variable temperatures and pressures during agate formation, which may also reflect the heterogeneity of the initial hydrothermal fluid. High concentrations of Ti, Cr, Mn, Ni, and Cu (10–120 ppm) and the low concentrations of Li, Co, Ga, Zn, Sr, Zr, Mo, and Sn (0.5–10 ppm) are characteristic of quartz–chalcedony agates. Calcite in agates is characterized by high concentrations of Mn (1253–6675 ppm), Sс, Ti, Ni, Sr, Y, La, Ce, and Nd (5–56 ppm). The chondrite-normalized REE distribution pattern in agates shows a decay profile from La to Lu and a negative Eu anomaly in some samples. Low contents of rare metals and REE in agates compared to parental volcanic rocks indicate a gradual chemical depletion of circulating fluids during agate formation.
      PubDate: 2020-12-01
       
  • The Niz’yavr Alkaline Pluton: Age, Isotope Characteristics, and
           Rare-Metal Mineralization
    • Abstract: The two phase Niz’yavr alkaline pluton is composed of alkali syenite and alkali quartz syenite. The crystallization age of alkali quartz syenite is 2656 ± 3 Ma. According to the isotope data (Rb–Sr, Sm–Nd), the pluton rocks are mantle-derived. The BSE mantle reservoir was the probable source for their melts, like other Neoarchean alkaline plutons in the Kola Province that belong to the association of alkaline gabbro, nepheline syenite, alkaline syenite, and granosyenite. The tantalum–niobium mineralization as pyrochlore identified in the pluton distinguishes the latter from other Neoarchean alkaline plutons in the province.
      PubDate: 2020-12-01
       
  • Modeling of Mineral Parageneses and Thermobarometry of Metavolcanic Rocks
           of the Ruker Group in the Southern Prince Charles Mountains, East
           Antarctica
    • Abstract: Diverse geological complexes that form the crystalline basement of the East Antarctic Platform crop out in the Prince Charles Mountains. The Ruker Group is a member of the metasedimentary complexes that make up the Paleoproterozoic through Neoproterozoic suprastructure of the Ruker Terrane. It is divided into two sequences consisting of highly deformed and greenschist facies metamorphosed sedimentary and volcanic rocks. The mineral and major element compositions of metavolcanic rocks have been studied and physicochemical modeling of mineral parageneses has been performed to reconstruct the P–T parameters of metamorphism. The dependence of the mineralogy of metabasic schists on the protolith composition and the ratio of components in the H2O–CO2 fluid involved in the phase reactions were analyzed. The calculated mole fraction of CO2 in the fluid equilibrated with carbonate-bearing parageneses is 0.13–0.27. It is assumed that chloritoid schist consists of metamorphosed laterites derived from basalt. Modeling and the data of chlorite–phengite thermobarometry indicate that the Ruker Group rocks were metamorphosed under conditions of the high-pressure part of the greenschist facies (300–450°C, 7–8 kb). These conditions are significantly higher than the stable continental geotherm and are close to those in the zone of a slow subduction geotherm. According to the available geological data, a similar geodynamic setting could be caused by the evolution of the Neoproterozoic intraplate sedimentary basin in connection with deep-sinking basement blocks as a result of tectonic aggregation during the closure of the basin.
      PubDate: 2020-12-01
       
  • Finding forms and Micro- and Nanoscale Assemblages of Gold as Indicators
           of Formation Conditions, Distribution, and Typification of Orogenic
           Deposits of Uzbekistan (South Tien Shan)
    • Abstract: —Gold deposits of the Kyzylkum and Nurata regions of Uzbekistan are confined to the South Tien Shan orogenic belt. They are hosted in black shales (Muruntau and Myutenbai); carbonate, terrigenous, and volcanogenic rocks (Kokpatas and Balpantau); and in intrusive units (Zarmitan zone). The age of gold mineralization is 280–290 Ma, which corresponds to the age of postcollisional granitoid magmatism. Gold is observed as micro- and nanoscopic particles and is a part of various minerals (Au2Bi, AuTe2, AuAg2Te3, AuAgS, AuAg2Se3, AuSb2, etc.), which form inclusions in pyrite, arsenopyrite, antimonite, and quartz. These minerals form regular micro- and nanoscopic assemblages, which are direct signs of prospecting and evaluating gold ores of the distinguished mineral-geochemical types.
      PubDate: 2020-12-01
       
  • Granite Systems with Rare-Metal Pegmatites
    • Abstract: For most rare-metal pegmatite fields, two generations of granitic pegmatites are documented, namely, beryll-bearing (often with tantaloniobates and muscovite, which are inseparable from vein granites of the leucogranite complex), and Na-Li (Li, Ta, Cs, Be, and Sn) (LCT-pegmatites). The latter, in turn, subdivide into (i) a “multicomponent rare-metal type” with pegmatite zoning and main mineralization (large crystals of spodumene, tantalates, beryll, cassiterite, pollucite, petalite, and amblygonite) in the central parts of the respective bodies (Koktogai, Bernic Lake, Bikita, Karibib, Varutrask, Vishnyakovskoe, and others) and (ii) “albite-spodumene pegmatites” that compose multiple extended dikes that are devoid of pegmatite zoning and are grouped into fields of up to 10–15 km or more in length (Kings Mountain, Zavitinskoe, Gol’tsovoe, Kolmozero, Polmos-Tundrovoe, Tastyg, and others). For a number of deposits (e.g., Zavitinskoe, Vasin-Myl’k, and Shukbyul’), the occurrence of multicomponent rare-metal pegmatites in the “heads” of feeding dikes of “albite–spodumene pegmatites” is established. Any attempt to identify parent granites for “albite–spodumene pegmatites” is a priori futile, because these are not pegmatites, but granites, although specific ones (in fact, spodumene granites of the Allakha type). The purely terminological correction, granite instead of pegmatite, surprisingly has both scientific and forecasting implications. The scientific implications imply that, first, the problem about parent granites is solved and, second, the “pegmatite” status of “albite–spodumene pegmatites” no longer debated. These pegmatites correspond to the particular, spodumene–rare-metal–granite stage in the history of magmatism of certain pegmatite-bearing areas (the end of this stage was marked by the formation of true multicomponent pegmatites that are characteristic of only this stage). Regarding the forecast implications, it can be supposed that such multicomponent deposits as Koktogai, Bernic Lake, Bikita, Karibib, and Vishnyakovskoe are underlain by a suite of dikes comprised by spodumene-bearing rare-metal granites (i.e., an independent Li deposit), and multicomponent pegmatites are differentiates of these granites.
      PubDate: 2020-12-01
       
  • On the Genesis of “White Granite” from the Kester Harpolith,
           Arga–Ynnakh–Khaya Pluton, East Yakutia
    • Abstract: —The problem of the origin of “white granite” in the Kester harpolith of the Arga–Ynnakh–Khaya Pluton is discussed. The morphology, occurrence, and nature of the intrusive contacts of the Kester harpolith prove its magmatic origin. The petrographic and petrochemical properties of “white granite” allow its identification as a postorogenic rare-metal high-phosphorus granite of the Li-F geochemical type. The magmatic genesis of the “white granite” texture is supported by statistical methods. The composition, typomorphic properties, ontogenetic features internal structure and relationship of accessory minerals indicate that the major accessories of the granite, that is, cassiterite, columbite, tantalite, “wolframoixiolite,” zircon, and ferberite, were formed at the late stage of the low-temperature rare-metal granitic melt. The Kester harpolith within the Arga–Ynnakh–Khaya granite pluton and the eponymous tin–rare-metal deposit genetically related to it are a part of the Far East Superprovince of rare-metal granites.
      PubDate: 2020-12-01
       
  • The Lu–Hf Isotope Composition of Zircon from Syenites of the Saharjok
           Alkaline Massif, Kola Peninsula
    • Abstract: Zircon crystals from the alkaline and nepheline syenites of the Saharjok massif, which were formed during the magmatic (2645 ± 7 Ma), hydrothermal (1832 ± 7 Ma), and metamorphic (1784 ± 22 Ma) crystallization stages, were studied. Zircon from alkaline syenites displays lower εHf and εNd values than zircon from ocean island basalts (OIB); these values indicate their affinity to mantle-derived protoliths, which are similar to CHUR in isotope composition. It is assumed that the Neoarchean Keivy alkaline province formed as a result of the plume–lithosphere interaction, induced by the upwelling of a Neoarchean plume, which facilitated metasomatic alteration and the subsequent partial melting of rocks of the subcratonic lithospheric mantle and the crust. The parental melts of the Saharjok massif could have been formed during the resumption of plume activity 20–30 million years after alkaline granite emplacement in the province by the selective melting of the metasomatized lithospheric mantle rocks.
      PubDate: 2020-12-01
       
  • New Data on Platinum Group Element Bearing Chromitites from the Kurtushiba
           Ophiolite, Western Sayan
    • Abstract: —Small grains of platinum group minerals (PGMs) have been found in chromitites of the Ergaksky and Kalninsky ultramafic massifs, which are marginal northeastern fragments of the Kurtushiba ophiolite belt in Western Sayan. Along with previously described PGMs, the Cu–Ru–Os solid solution, arsenic-bearing (As up to 3.6 wt %) laurite with minor Pt, Ni, and Co, platinum group element (PGE) sulfides of the MeS and Me3S4 types, sulfoarsenide with the high Rh content (12.7 wt %) in chromitites of the Ergaksky massif, and laurite and sulfoarsenides in chromitites of the Kalninsky massif were found for the first time. The PGM compositions indicate a high formation temperature of Ru–Os sulfide (1200–1250°C) in both massifs, as well as a high partial sulfur pressure during the formation of chromitites and syngenetic PGMs in the Ergaksky massif. The PGM assemblages were formed during several stages. The Os–Ir–Ru alloys and the laurite–erlichmanite series disulfides (predominantly partitioning Ru) are early; the Cu–Ru–Os alloys, sulfides (Ru,Fe)3S4, (Ru,Ni,Fe)S, and PGE sulfoarsenides are late and were crystallized under the influence of reductive fluids as a result of PGE remobilization and redeposition.
      PubDate: 2020-12-01
       
  • The Age of Monazite from the Ichet’yu Occurrence, Middle Timan (CHIME
           and LA–ICP–MS Methods)
    • Abstract: —A study of the morphology, composition, and age (by the CHIME and LA–ICP–MS methods) of monazite from the Ichet’yu occurrence, located in Middle Timan, revealed some principal differences in the typomorphic features and genesis of its two varieties. The common yellow monazite from this occurrence is monazite-(Ce), in which the content of La is higher than that of Nd. The time of its crystallization (recrystallization) is estimated by the CHIME method as 518 ± 40 Ma. Kularite (a grayish-brown globular variety of monazite, in which Nd is higher than La) was dated at 978 ± 31 Ma. The age of some kularite grains is 520 ± 27 Ma, which may be interpreted as the date of a hydrothermal event that resulted in the simultaneous recrystallization of both monazite and kularite. However, these two monazite varieties were formed in two completely different sources and were combined in the mineral parasteresis of the Ichet’yu occurrence. The CHIME age of monazite from the Ichet’yu occurrence that belongs to two intervals (500–600 and 960–1000 Ma) is consistent with the age determined in the same monazite grains using the LA–ICP–MS technique.
      PubDate: 2020-12-01
       
  • Belogubite, a New Mineral of the Chalcanthite Group from the Gaiskoe
           Deposit, South Urals, Russia
    • Abstract: Belogubite CuZn(SO4)2 ⋅ 10H2O, a new mineral of the chalcanthite group, is found in the Gai (Gaiskoe) massive sulfide deposit, South Urals, Russia. This mineral forms aggregates of blue grains up to 1 mm. It is optically biaxial (–), np = 1.512(2), nm = 1.525(2), ng = 1.531(2), 2V = 70(10)°. The chemical composition of the holotype sample is as follows (wt %): 1.12 MgO, 0.10 MnO, 3.15 FeO, 8.98 CuO, 18.02 ZnO, 32.49 SO3, and 36.75 H2O, total 100.61. The empirical formula is (Cu0.55Zn0.45)Σ1.00(Zn0.64Fe0.22Mg0.14Mn0.01)Σ1.01S1.99O7.98 ⋅ 10.02H2O. The crystal structure of belogubite is studied using the single crystal method, R = 0.016. The mineral is triclinic, P \({{\bar {1}}}{\text{.}}\) The unit cell parameters are: a = 6.2548(1), b = 10.6112(2), c = 6.0439(1) Å, α = 82.587(1), β = 109.625(1), γ = 104.848(1)°, V = 364.81(1) Å3, and Z = 1. The strongest reflections of the powder XRD pattern [dmeas., Å (I, %) (hkl) are: 5.73 (35) (100), 5.576 (47) (–110), 4.873 (100) (–111), 3.907 (31) (021), 3.719 (45) (0 –21), 3.229 (27) (111), 2.915 (25) (–221), and 2.684 (26) (130).
      PubDate: 2020-12-01
       
  • Wolframoixiolite in Lithium–Fluorine Granites of the
           Arga–Ynnakh–Khaya Pluton, Yakutia
    • Abstract: A complex of accessory W-bearing tantalo-niobates (columbite-(Fe), columbite-(Mn), tantalite-(Mn), microlite group minerals, and Ta-bearing rutile) involving “wolframoixiolite” has been found for the first time in Li–F granite and ongonite of the Arga–Ynnakh–Khaya Pluton in East Yakutia. The rocks that contain wolframoixiolite, as well as the composition and typical features of the mineral, are described: its high Fe concentration, the leading mineral-forming role of niobium, widely variable W and Ta contents, and paragenesis with W-bearing columbite-(Mn), Ta–Nb ferberite, lepidolite, and topaz. Wolframoixiolite from the Arga–Ynnakh–Khaya Pluton is formed by polymorphic transition of columbite-(Fe) at the late stage of Li–F granite crystallization. A review of accessory mineralization in rare-metal Li–F granites of Eurasia, taking the new finding into account, indicates that wolframoixiolite is a typical accessory phase in Li–F granites and may indicate rare-metal granite magmatism accompanied with tin–rare-metal mineralization.
      PubDate: 2020-12-01
       
  • Mineral Systems Based on the Number of Species-Defining Chemical Elements
           in Minerals: Their Diversity, Complexity, Distribution, and the Mineral
           Evolution of the Earth’s Crust: A Review
    • Abstract: —The chemical diversity of minerals can be analyzed in terms of the concept of mineral systems based on the set of chemical elements that are essential for defining a mineral species. Only species-defining elements are considered to be essential. According to this approach, all minerals are classified into ten types of mineral systems with the number of essential components ranging from 1 to 10. For all known minerals, only 70 chemical elements act as essential species-defining constituents. Using this concept of mineral systems, various geological objects may be compared from the viewpoint of their mineral diversity: for example, alkali massifs (Khibiny and Lovozero in Russia; Mont Saint Hilaire in Canada), evaporite deposits (Inder in Kazakhstan and Searles Lake in the United States), fumaroles of active volcanoes (Tolbachik in Kamchatka and Vulcano in Sicily, Italy), and hydrothermal deposits (Otto Mountain in the United States and El Dragon in Bolivia). Correlations between chemical and structural complexities of the minerals were analyzed using a total of 5240 datasets on their chemical compositions and 3989 datasets on their crystal structures. The statistical analysis yields strong and positive correlations (R2 > 0.95) between chemical and structural complexities and the number of different chemical elements in a mineral. The analysis of relationships between chemical and structural complexities provides strong evidence for the overall trend of a greater structural complexity at a higher chemical complexity. Following R. Hazen, four groups of minerals representing four mineral evolution stages have been considered: (I) “Ur-minerals,” (II) minerals from chondrite meteorites, (III) Hadean minerals, and (IV) contemporary minerals. According to the obtained data, the number of species-defining elements in minerals and their average contents increase regularly and significantly from stage I to stage IV. The analyzed average chemical and structural complexities in these four groups demonstrate that both are gradually increasing in the course of mineral evolution. The increasing complexity follows an overall trend: the more complex minerals were formed in the course of geological time, without replacing the simpler ones. The observed correlations between chemical and structural complexities understood in terms of the Shannon information suggest that chemical differentiation is the major force that drives the increase of mineral complexity over the course of geological time.
      PubDate: 2020-12-01
       
  • Prenucleus Clusters and Nonclassical Crystal Formation
    • Abstract: —The features of nonclassical nucleation of crystals, which are related to the formation of stable prenucleus clusters of an intermediate phase in a crystal-forming medium, are considered. These clusters (quatarons) are primary protomineral particles, whose crystallization is among the possible scenarios of their evolution. The formation conditions and typical properties of quatarons are discussed. The importance of experiments on direct observation of prenucleus clusters and other objects of protomineral world is shown.
      PubDate: 2020-12-01
       
  • The Defect-Impurity Composition of Diamond Crystals with 〈100〉 Growth
           Pyramids from Placers of the Krasnovishersk District, the Urals
    • Abstract: —The internal structure and spectroscopic features of cuboid diamonds from recent alluvial placers of the Krasnovishersk District (the Urals) have been investigated. Crystals were divided into four groups by their anatomy and spectroscopy: cuboids of the II group (according to the Yu.L. Orlov classification): cuboids with a transparent core and peripheral zone saturated with inclusions; crystals with mixed habit growth of 〈100〉 and 〈111〉 pyramids, and crystals with the sequential growth of 〈100〉 and 〈111〉 pyramids. In all studied crystals, the regenerative formation of the {111} face steps together with the formation of tetragonal pits on the cuboid surface was the last stage of growth. Local photoluminescence investigations have been carried out for all cubic diamond crystals of the Urals for the first time. It was established that luminescence bands at 926 and 933 nm are related to growth pyramids of 〈100〉 and 〈111〉, respectively. Bands with peaks at 800, 820.5, 840, 860, and 869 nm were revealed in the luminescence systems of the cuboids of II group. We note that the cuboid diamonds from different regions of the world have similar internal structures and spectroscopic features.
      PubDate: 2020-12-01
       
  • Chrome Spinels in Carbonate Veins of the Onguren Complex, Western Baikal
           Region
    • Abstract: Chrome spinels in carbonate veins of the Onguren Complex, East Siberia, Western Baikal region are predominantly ferrichromite and chrommagnetite (MgO ≤ 0.3 wt %, Mg# ≤ 0.04, Al2O3 ≤ 2.5 wt %; Cr# 0.91–1.00, Fe2+/Fe3+ 0.8–1.4) with a high ZnO content (0.9–4.6 wt %). In the calcite vein, titanian chrome-magnetite is transformed into Cr-bearing titanomagnetite, which decomposes into Ti-depleted magnetite and ilmenite at temperature of 970–1000°С and \({{f}_{{{{{\text{O}}}_{{\text{2}}}}}}}\) approximately of +0.5…+0.7 QFM. In the dolomite vein, ferrichromite and chrome-magnetite grains contain relict cores of subferrialumochromite (Al2O3 10.6–14.4 wt %, Cr# 0.63–0.73, Fe2+/Fe3+ 4.1–5.2, MgO ≤ 0.52 wt %) with elevated ZnO (3.7–5.1 wt %), TiO2 (3.2–4.1 wt %), and MnO (0.6–1.1 wt %). Ferrichromite and chrome-magnetite are formed during the high-temperature (>600°C) metamorphism of the vein. Superimposed deformations under greenschist facies conditions lead to the formation of magnetite rims around chrome-magnetite grains.
      PubDate: 2020-12-01
       
  • Polymorphism and Isomorphic Substitutions in the $${\text{Cu}}_{3}^{{2 +
           }}$$ ( T 5+ O 4 ) 2 Natural System with T = As, V, or P
    • Abstract: —In the \({\text{Cu}}_{3}^{{2 + }}\) (T5+O4)2 (T = As, V or P) natural system arsenates are trimorphous (lammerite, lammerite-β, and unnamed triclinic Cu3[(As,V)O4]2), as well as vanadates (mcbirneyite, pseudolyonsite, and borisenkoite), while phosphates are represented by a poorly studied lammerite-like Cu3[(P,As)O4]2 phase. In active oxidizing-type fumaroles related to the Tolbachik volcano in Kamchatka, Russia, all these minerals crystallized at temperature no lower than 250°C. The crystal structure of natural triclinic Cu3[(As,V)O4]2 was first studied on a single crystal from the Yadovitaya fumarole at Tolbachik; R = 4.89%. It is isostructural to stranskiite and mcbirneyite and crystallizes in the P-1 space group; the unit-cell parameters are: a = 5.0701(8), b = 5.4047(8), c = 6.3910(8) Å, α = 70.091(13), β = 86.828(12), γ = 68.399(15)°, V = 152.61(4) Å3, and Z = 1. This paper also contains new data on mcbirneyite (its novel As-enriched variety is characterized), lammerite, and lammerite-β. Original and previously published materials on natural members of the Cu3(T5+O4)2 system are summarized and isomorphism and other crystal chemical features of minerals belonging to this system are discussed in comparison with the data on related synthetic compounds.
      PubDate: 2020-12-01
       
  • The Mineral Composition of Paleoproterozoic Metamorphosed Massive Sulfide
           Ores in the Kola Region (A Case Study of the Bragino Ore Occurrence,
           Southern Pechenga)
    • Abstract: Many massive sulfide ore occurrences and deposits in the Kola region are located within the Paleoproterozoic Pechenga–Imandra–Varzuga rift belt (2.5–1.7 Ga). They are hosted by volcanosedimentary complexes of the South Pechenga (Bragino ore occurrence) and western Imandra–Varzuga structural zones (Pirrotinovoe Ushchel’e deposit, Tahtarvumchorr ore occurrence, etc.). The age of the massive sulfide ore was estimated at ca. 1.9 Ga. The ores and their host complexes underwent amphibolite-facies metamorphism, which accounts for their specific mineral composition. The types of ores in the Bragino ore occurrence are discussed, the mineral assemblages are listed, and the major ore minerals, that is, pyrrhotite, pyrite, sphalerite, marcasite, etc., are characterized.
      PubDate: 2020-12-01
       
  • The High-Temperature Behavior of Axinite-(Mn), Kornerupine, and
           Leucosphenite
    • Abstract: — In situ high-temperature powder X-ray diffraction (HTPXRD), differential scanning calorimetry (DSC), and thermogravimetry (TG) of three natural borosilicates have been performed in the temperature range of 25–1200°С. Axinite-(Mn) melts incongruently at 900°С with the formation of anorthite and bustamite. Leucosphenite decomposes at 850°С to form fresnoite and cristobalite. According to DSC data, kornerupine decomposes at 1177°С to form sapphirine, indialite, and spinel as the products of heating kornerupine. The values of the thermal expansion tensor and its orientation were determined using the HTPXRD data. The study showed that the three borosilicates expand weakly and almost isotropically. The average bulk thermal expansion coefficients are 21.3, 22.7, and 32.9 × 10–6°С–1 for axinite-(Mn), kornerupine, and leucosphenite, respectively. Leucosphenite has the maximum volumetric expansion, most likely due to the pronounced layered character of its crystal structure. The least symmetric structure of axinite-(Mn) has the maximum anisotropy of thermal expansion in the temperature range of 600–900°С.
      PubDate: 2020-12-01
       
 
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