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:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Abstract The structural–morphological types and localization conditions of talc occurrences in the Beloretsk district of the Western Urals talc province are discussed. The talc mineralization is represented by low-iron talcites and talc stones in the Riphean clastic–carbonate complexes of the Bashkirian Meganticlinorium. Prospective talc objects in the Beloretsk district are classified as apocarbonate

Abstract—In the section of the sedimentary cover of the East European Platform, the new Sabantuy chromite ore occurrence was revealed. It is localized in Upper Kazanian sandstones of the erosional terrace above the floodplain of Malaya Berkutla Creek in the south-west of the Republic of Bashkortostan. The article presents the first results of geological, lithological, and mineralogical–geochemical

Abstract—An experimental study was carried out on the dissolution of natural octahedral diamonds from the Internatsionalnaya and Yubileinaya kimberlite pipes (Yakutia) in an Fe–S melt at 4 GPa and 1450–1500°C with different sulfur contents (10–25 wt %). It was found that with an increase in sulfur content in the iron melt, the degree of diamond dissolution sharply decreases. The stationary (final)

Abstract The distribution of index minerals of the hydrothermal arsenide process of the formation of Ni‒Co–As (±U–Ag), Co–S–As (±Au–W), and Cu–Co–As (±Sb–Ag) quartz–carbonate veins of deposits of the Bou Offro–El Graara ore belt (Morocco) are discussed. The Co arsenide objects of the Bou Azzer ore cluster with typical low-temperature Ni–Co–As (U–Ag) deposits of the five-element hydrothermal type are

Abstract—The paper describes indicator minerals of kimberlites found on the southern side of the Vilyui syneclise in the Markha River basin, a tributary of the Lena River. It is shown that indicator minerals—pyrope and picroilmenite—derive from Middle Paleozoic kimberlites, very likely diamondiferous. Methods are proposed for further studies on determining the prospects for the diamond content of the

Abstract Gold and silver mineralogy is studied in ores of the Biksizak base-metal deposit (South Urals, Russia). This is a skarn-related carbonate replacement mineralization typical for marginal zones of porphyry-epithermal systems. The variability of precious metals minerals is established. Native gold (fineness 853 to 939) in assemblage with chalcopyrite and sphalerite is the most abundant. A telluride

Abstract The Mociços Cu-deposit is part of a cluster of ancient copper mines in the Sousel-Barrancos metallogenic belt in the Ossa-Morena Zone at the SW Iberia. The orebodies develop along NNW-SSE quartz-carbonate-sulfides veins with pyrite and chalcopyrite as the main sulfide phases, and ore emplacement has been attributed to copper remobilization from the metasedimentary host-rocks, though no detailed

Abstract— The Dudica deposit is located in the southern part of the Republic of North Macedonia (RNM), not far from the border with Greece in the Kozuf–Aridean volcanic region. The deposit is genetically associated with the Neogene igneous event (≥6 Ma, K/Ar), which is manifested at the intersection of northeast trending faults with the northwest trending Vardar fault zone. The REE spectrum of volcanic

Abstract— The sulfur isotope composition of single sulfide grains has been studied taking into account their paragenetic sequence in the samples collected from three hydrothermal fields (Logatchev, Krasnov, and Rainbow), located in the northern part of the Mid-Atlantic Ridge. The δ34S values of sulfides are +3.9 to +6, +7.1 to +9.8, and +2.1 to +8.4 ‰ in the Logatchev, Krasnov, and Rainbow fields,

Abstract— The major objective of the study investigation was to find the physicochemical conditions for U, Nb, and Ta mobilization into the solution from acidic melts similar in composition to rhyolitic inclusions in quartz at the unique Streltsovka Mo–U field (Eastern Transbaikalia). The experiments were performed with model homogeneous leucogranite glass (wt %): 72.18 SiO2, 12.19 Al2O3, 1.02 FeO

Abstract Preore metasomatites of epithermal gold–silver deposits are formed by various types of hydrothermal solutions—from highly acidic and oxidized (argillization, alunitization, secondary quartzites) and moderately acid (sericitization) to rather reduced and alkaline (adularia). The possible processes creating highly acid mineralizing fluids at shallow depths are: (a) the condensation of the acid

Abstract—More than 10 t of gold have been mined within the Vagran placer cluster (Northern Urals), and the identified primary sources are limited to single noneconomic ore occurrences. Our research has established the heterogeneity of placer gold, which reflects the multistage history of the cluster’s development and the diversity of bedrock mineralization owing to which placer deposits were formed

Abstract—Gold and silver are capable of forming stable natural compounds with different elements. For gold 36 minerals are known: 10 in the class “Native metals, intermetallic compounds” and 26 in the class “Sulfides (selenides, tellurides, arsenides, antimonides, bismuthides).” For silver, 194 minerals are registered in the MMA, presented in 8 classes. Compared to gold in the class “Native metals

Abstract New data on the geological structure and ore-bearing structural parageneses of the Uryakh gold ore field are presented. The formation of the deposit occurred in dynamic shear regime along ore-controlling deep-seated faults of the Syulban fault system and faults of the system transverse to it. The interaction of two duplex shear systems resulted in the block structure of the ore field. Tectonophysical

Abstract The Varvarinskoye copper–gold deposit, large in terms of Au and small in terms of Cu, was discovered in 1979 in the western part of the Torgai trough in Kazakhstan. It is composed of Devonian volcanosedimentary and intrusive rocks. Ore zones with a thickness from a few meters to a few tens of meters have been identified against a background of disseminated ore mineralization. They are composed

Abstract A study of the composition of fluid inclusions in ore minerals of the Davenda Mo–porphyry deposit and the Aleksandrovskoe sulfide–quartz–gold ore deposit, as well as of fluid inclusions in minerals of igneous rocks, showed that ore-forming fluids inherit the salt and gas composition of magmatic fluids generated during crystallization of ore-bearing rocks of the Amudzhikan–Sretensky Igneous

Abstract The Lipovka and Alabashka ruby occurrences in the Central Urals hosted in marble of the Murzinka–Adui Anticlinorium are considered. The field works were carried out; the chemical compositions of rocks and minerals and oxygen isotopic composition of corundum and silicates were determined; and micas were dated by the K–Ar method. These occurrences are similar in geological environment and mineral

AbstractIndividual fluid inclusions in quartz from ore veins of the Askold gold deposit, which was previously attributed to the epithermal type, are studied for the first time. It is established that gold mineralization of Askold Island derived from ore-forming fluids of carbon dioxide–water–salt composition, with a salt concentration of 2.8–4.1 wt % NaCl equiv and a high carbon dioxide concentration

AbstractOscillatory zoning in tennantite-(Fe) crystals found in carbonate–sulfide aggregates at the Darasun gold deposit has been studied. Similar elements have been distinguished in zoned crystals: core, “identical oscillatory rhythm,” rhythms with crystallographic and wavy oscillatory zoning, and rim with poorly defined fine oscillatory zoning. Oscillatory zoning is due to considerable variations

Abstract—The formation of present-day seafloor sulfide deposits is accompanied by their continuous oxidation and crystallization of insoluble Fe oxyhydroxides, which absorb metals (including heavy metals) (Fallon et al., 2017). Due to the high sorption ability of Fe oxyhydroxides, it is suggested that the removal of metals during submarine oxidation into ambient seawater is insignificant (Fallon et

Abstract—The limited literature data on gold-bearing albite–pyroxene rodingites are summarized for the Agardag ultramafic massif in southern Tuva. These data are supplemented by new mineralogical, geochemical, thermobarogeochemical, and isotopic–geochemical results in order to reveal the physicochemical mineral formation conditions and sources of ore matter and fluids on gold deposition in rodingites

AbstractThe article discusses the features of the composition, age, and genesis of gold–antimony mineralization of the East Sayan based on the example of the largest Tumannoe ore occurrence. It is shown that objects of this type are rare in the considered region. In the course of studies, it was found that stibnite, pyrite, and arsenopyrite predominate in ores; Bi minerals (tetradymite, cobaltite,

AbstractThe Valunistoe Au–Ag deposit is the third largest among epithermal deposits in Chukotka after the Kupol and Dvoinoe. It is located at the western closing of the East Chukotka flank zone of the Okhotsk-Chukotka volcanic belt. Volcanic domes (Pravogornenskaya, Zhil’ninskaya, Shakhskaya, Valunistaya, Shalaya, and Oranzhevaya, each is 3–6 km in diameter) have the main ore-controlling significance

AbstractExhalation ore mineralization is developing in the crater part of the active Kudryavy volcano. Lithogeochemical sampling results have revealed that Re, Au, Ag, As, Bi, Cd, Cu, Ge, In, Mo, Pb, S, Sb, Se, Sn, Te, Tl, W, Zn, Rb, and Cs accumulate in solid fumarole formations. These elements are transported by high-temperature volcanic gases and are deposited in mineral phases in the near-surface

AbstractBased on 5000 analyses of geological prospecting samples from four alunite deposits (Began’, Ukraine; Haft Sanduq, Iran; Bolshaya Kremenyukha and Kachar, Kazakhstan) and 6000 microprobe analyses of alunite, the features of changes in three parameters of alunite quartzite composition have been studied: (1) alunite content, (2) mole fraction of K in alunite, and (3) correspondence of the amount

Abstract—The recognition of the Fouta Djallon–Mandingo territory as an independent bauxite province is substantiated. It is confined to the morphostructure of the same name within a single geotectonic structure, the sedimentary cover of the Sahara Platform, in the tropical monsoon climate zone in West Africa. The bauxite exploration history, reserve and resource estimates, and production dynamics in

AbstractThe distributions of niobium mineral deposits and their resources on the geological time scale are analyzed. The sampling list includes 45 mineral deposits with their individual resources estimated not less than 105 tons of Nb2О5. The classification of deposits used includes three types, namely, alkaligranitic, foidic, and carbonatitic. The geohistorical variability in niobium metallogeny is

Abstract—Geochronological studies have been conducted for ore-hosting rocks (quartz rhyolites, felsitic rhyolites, porphyry granites) of some U deposits of the Yakshi-Yangistau complex within the Balkashino ore center of the Northern Kazakhstan uranium province. According to geological maps of various scales, the rocks were traditionally ascribed to the Early–Middle Devonian (quartz and felsitic rhyolites)

Abstract—This paper considers examples of “hydrogenic” commercial uranium deposits termed as “sandstone-hosted” in the English literature and characterized by so-called “reduced-type alterations.” In addition to the case when they are absent at the deposit, a few characteristic alterations are identified in different ratios, such as rock bleaching, iron redistribution, argillization, carbonatization

Abstract—Various hypotheses, including alternative ones, have been put forward in the literature about the sources of ore substance and ore-forming fluids in the deposits of the Streltsovka ore field, which hosts the world’s largest uranium reserves, in excess of 250 000 t U: (1) uranium transport by ascending flow of ore-forming fluids that have separated from a deep subcrustal or intracrustal uranium-bearing

Abstract—The characteristic features of the manifestations of acid magmatism and metasomatic hydrothermal alteration processes in Southeastern Transbaikalia, an important mining region in Russia, are discussed. The zoned or beltlike distribution of the ores of various metals, uranium in particular, and other mineral deposits is due to the general evolutionary trends of the geodynamic regimes of the

Abstract—The distribution of major gold deposits in the Earth’s history is discussed. The primary heterogeneity of the Archean crust in terms of gold mineralization is demonstrated. Characteristics of the main auriferous metallogenic epochs are given. The predominant associations of the orogenic gold deposits with volcanogenic massive sulfide and copper–nickel deposits during the early periods of the

AbstractThe global distribution of tantalum deposits and their resources on the geological time scale is analyzed. The analysis is based on the data for 65 deposits of the world with a resource estimate from 2000 t of Ta2O5, which are classified into five types: pegmatitic, granitic, alkaligranitic, foidic, and carbonatitic. Placers and ore-bearing weathering crusts are taken into account with their

AbstractHeterogeneous rhythmic–zonal aggregates of tennantite-IV partly or completely replacing early homogeneous Zn-tetrahedrite-I grains and euhedral (Fe–Zn)-tennantite-I crystal were found in ores of the Darasun gold deposit. The different stages of fahlore replacement were observed. This initiates at grain boundaries and is terminated by a complete transformation into pseudomorphic, newly formed

Abstract—The paper completes a series of works about the unique Schlema-Alberoda deposit. The data on sources of vein and ore minerals and their relation to the processes of regressive alteration of rocks from the contact metamorphism zone are refined. The correlation between stages of mineral formation and their directed change are shown. A general scheme for the sequences in formation stages of the

Abstract—The first results of optical microscopy, cathodoluminescence (CL), ultraviolet fluorescence (UV), electron-probe microanalysis (EPMA), and laser-ablation inductively-coupled plasma-mass spectrometry (LA-ICPMS) study of scheelite from quartz–molybdenite and quartz–carbonate–sulfide veins and veinlets (porphyry type), as well as the magnetite–sulfide massive, veinlets, and disseminated (skarn

AbstractThe Neoarchean subalkaline magmatism of the Keivy structure is expressed in the formation of the volcanoplutonic latite–monzonite–granite association (LMGA). The formation of LMGA magmas is assumed to occur due to melting of metasomatically altered mafic rocks during intrusion into the lower crust of basaltic melts initial for rocks of the dike complex and gabbro–labradorite massifs. The alkaline

AbstractThree hundred thirty-six diamonds from deposits of the Rassolninskaya depression and 144 crystals from recent alluvial placers of the Krasnovishersky district were studied by IR absorption and photoluminescence spectroscopy. It is shown that crystals from the Rassolninskaya depression have a close-to-normal distribution for the nitrogen concentration. The average nitrogen content is 725 ppm

AbstractSulfide-free mineral assemblages with the chalcophile element minerals from occurrences associated with altered rocks of Pelagonian massif, Republic of North Macedonia have been studied. The inputting sequence of various ore-forming constituents has been revealed on the basis of morphological features, zoning of the spinel-group minerals, and the högbomite supergroup minerals. Conclusions about

AbstractMagnetoplumbite-group minerals from various paragenetic assemblages, including a xenolith of altered garnet lherzolite from the Obnazhennaya kimberlite pipe in Yakutia, sulfide-free metasomatic Pb–Zn–Sb ore from the Pelagonian massif in the Republic of North Macedonia, and some other metasomatic occurrences have been studied with electron microprobe, as well as using IR and Raman spectroscopy