Mineralogical Journal-Ukraine最新文献

{"title":"ENIGMATIC STONE SPHEROIDS FROM SCYTHIAN BURIAL AT KRASNYI PODOL OF UKRAINE: PETROGRAPHIC CHARACTERISTIC, PLACE OF MINING AND PROCESSING METHODS","authors":"M. Daragan, O. Mytrokhyn","doi":"10.15407/mineraljournal.43.03.104","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.03.104","url":null,"abstract":"The results of a petrographic investigation of 80 stone spheroids from a Scythian burial near the village of Krasnyi Podol are presented. The results indicate that all the stone spheroids were made from the same type of metamorphic rocks, namely actinolitites. The petrographic characteristics of the actinolitites indicate that the initial raw material was obtained from a single deposit. The Middle-Dnieper Region of the Ukrainian Precambrian Shield is considered as the probable place for their mining. The authors do not exclude that the natural outcrops of actinolitites could initially have had spherical jointing due to the processes of physical weathering. This jointing provided an opportunity to obtain roughly spherical blanks directly at the mining site. But most of the studied stone spheroids have got their spherical shape by artificial firing. The latter manifests itself in the surface desquamation and oxidation of the outer parts of the stone blanks. At least some of the stone blanks were ground to varying degrees after the firing. Stone abrasive materials were used for this purpose. The listed facts allow us to postulate that stone spheroids found in the Krasnyi Podol burial illustrate the successive stages of their processing. The owner of the stone spheroids likely possessed special knowledge regarding their mining, production and use.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synthetic Co-Existing Wadsleyite β-(Mg,Fe)2SiO4 and Ringwoodite γ-(Mg,Fe)2SiO4: an Optical Absorption Spectroscopy Study","authors":"M. N. Taran","doi":"10.15407/mineraljournal.43.04.003","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.04.003","url":null,"abstract":"The synthetic high-pressure α- and β-modification of (Mg1–xFex)2SiO4, wadsleyite and ringwoodite, respectively, were studied by optical absorption spectroscopy at ambient and hydrostatic high-pressure conditions. In addition, the effects of thermal annealing on the crystals were investigated. Under hydrostatic compression up to ~13 GPa and then consequent released to atmospheric pressure there were changes in the spectra and related changes in the crystal color. This is a clear indication that some Fe2+ was oxidized to Fe3+. The spectra of both ringwoodite and wadsleyite change after annealing in air at temperatures up to 300 °C. The intensities of electronic spin-allowed bands of Fe2+ decrease and the intensity of the charge-transfer electronic transition O2– → Fe3+, as given by the low-energy absorption edge in the UV region, increases. These crystal-chemical changes are shown by a weakening of the blue (ringwoodite) and green (wadsleyite) colors and a concomitant increase in yellowish tints. The effects of Fe2+ oxidation to Fe3+, upon decompression from high pressures as well as through annealing at relatively low temperatures, can cause the disintegration of both phases. Thus, both minerals have not yet been reliably identified at near surface Earth conditions after originating from deep-seated volcanism or deep subduction zone processes.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67125948","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microdiamonds from the Zeleny Yar Neogene Placer (the Ros'-Tikych Megablock of the Ukrainian Shield)","authors":"V. Kvasnytsya","doi":"10.15407/mineraljournal.43.02.003","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.02.003","url":null,"abstract":"We studied a collection of microdiamonds from the Zeleny Yar Neogene placer on the Ros’-Tikych megablock of the Ukrainian Shield, which consists of 102 microdiamonds, with crystal sizes 0.2-0.5 mm, using crystal morphology, photoluminescence, infrared and Raman spectroscopy, isotopic composition of carbon and helium of microdiamonds. Crystal forms are dominantly octahedra, others are cubes, combinational crystals {111}+{110}+{100}, cube-octahedra, and transitional forms {111}+{110}; rhombic dodecahedrons are rare. Many microdiamonds are damaged crystals and their fragments. Up to 20% of the studied microdiamonds are yellow, green, pink-purple, brown, gray, and black. The most colored crystals are among the cubes. Up to 70% of the studied microdiamonds are blue, green, yellow and orange in ultraviolet light. Many of the microdiamonds, especially cubes and crystals of the combinational form {111}+{110}+{100}, have an orange photoluminescence (center at 575 nm). 50% of the crystals are nitrogen-free crystals of type IIa. Nitrogen crystals of type Ia amount to 45% (among them 29 % of subtype IaA, 11% of subtype IaAB and 5% of subtype Iab) and 5% of type Ib. The content of nitrogen ranges from 57 to 612 at. ppm with an average nitrogen content of 224 at. ppm. The centers B2 (lines 1358-1380 cm–1) and hydrogen centers (3107 cm–1, 1405 cm–1) were recorded in IR spectra of some microdiamonds. The Raman line ranges from 1331.25 cm–1 to 1331.75 cm–1 with FWHM from 2.04 cm–1 to 4.47 cm–1. The carbon isotopic composition of microdiamonds shows a very wide range from –26.74 to –3.55‰ δ13C PDB. The content of helium isotopes for the studied crystal is 73.42 × 10–12 cm3/g of 3He and 0.265 × 10–6 cm3/g of 4He. Given the wide range of values of the isotopic composition of carbon δ13C, relatively high nitrogen content and cubic form of many crystals, it is possible to predict the eclogite association as the mantle crystallization medium of the Zeleny Yar microdiamonds. The location of the parent rocks of the microdiamonds is assumed to be the Berdychiv uplift of the Podolia block of the Ukrainian Shield.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126249","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Iron- and Nickel Enriched Olivine from Phlogopite Harzburgite of the Bug Granulite Complex (Ukrainian Shield)","authors":"S. Lobach-Zhuchenko, Yu. S. Egorova, S. Skublov, V. Sukach, O. Galankina","doi":"10.15407/MINERALJOURNAL.43.01.016","DOIUrl":"https://doi.org/10.15407/MINERALJOURNAL.43.01.016","url":null,"abstract":"An abundance of the trace elements has been determined in olivine of the Archean spinel-bearing phlogopite harzburgite enclave (sample UR17/2) from the Bug granulite complex of the Ukrainian Shield by SIMS analysis. Major elements were analyzed in the olivine by SEM-EDS and EPMA analysis. The olivine shows a homogeneous chemical composition: MgO — 45.20—45.64 wt.%, FeO — 13.66—14.23 wt.%, with Fo85—86 and Fe/Mn ratio of 68.3—68.6 which corresponds to the ratio of 60—70 in olivine of peridotites. Ni content in the UR17/2 olivine ranges from 4730 to 5612 ppm, which is higher than in olivine from mantle peridotites, high magnesium OIB and Hawaiian picrites. The olivine has average content of Ti — 20.6 ppm, Nb — 0.03 ppm, Zr — 0.32—0.60 ppm, the low total REE (0.1—0.5 ppm). The olivine crystallization temperature, calculated using an Al-in-olivine thermometer, corresponds to ~ 900°C. Enrichment in Fe and Ni is the main feature that distinguishes the UR17/2 olivine from other mantle-derived olivine. Сomposition of the UR17/2 olivine and host harzburgite indicates an influence of T, P, the oxygen fugacity and composition of parent magma on the partition coefficients of Fe and Ni. Сomposition and structure (degree of polymerization) of magma are the main factors responsible for the olivine enrichment by iron and nickel.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67125598","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Paramagnetic Centers of Mineral Component in Annealed Bone Tissue","authors":"N. Bagmut, T. Kalinichenko, A. Brik, N. O. Dudchenko, M. Kalinichenko","doi":"10.15407/mineraljournal.43.04.018","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.04.018","url":null,"abstract":"The mineral components of powdered samples of cortical dense bone tissue of domestic animals (pig and cow) were studied by electron paramagnetic resonance (EPR). Bone tissue was heated in a temperature range 600-1000 ºС in an oven and then held for more than one year at room temperature. This was done to allow short-lived defects to decay and to let the mineral structures stabilize. In these heat-treated samples, within the limits of the sensitivity of the experiments, no EPR signals were detected, but after irradiation with X-rays, multicomponent EPR signals appeared. Spectra vary depending on the heating temperatures. Paramagnetic centers related to РО32–, NO42–, CO2–, CO33– and O– groups are observed. The g-factor of spectroscopic splitting and amplitude of ultrafine interaction of the indicated paramagnetic centers in the spectra were determined. Due to different relaxation behavior of the paramagnetic centers, and hence their saturation effects, the form of the total EPR signals significantly depends on the microwave power level at which the spectra are recorded. Therefore, EPR signals were recorded at high (5 mW) and low (0.13 mW) microwave power levels. The temperature dependency of EPR signal amplitude was determined for some paramagnetic centers in the range of 600-1000 ºС. The EPR signal properties of the heated bone samples and synthetic hydroxylapatites were compared. The spectra indicate that phosphates in bone tissue have a more complex structure than simple synthetic hydroxylapatite. The results of this work can be used to create synthetic analogs of bone tissue, to help in the manufacturing of implants that are used to treat bone tissue, and to study the processes related to the assimilation of mineralogic-based implants by living bone tissue.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67125996","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Again About the \"Magmatic\" Nature of Topaz Crystals From Chamber Pegmatites of Volyn (Ukrainian Shield)","authors":"D. Voznyak, V. Belskyi","doi":"10.15407/mineraljournal.43.04.087","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.04.087","url":null,"abstract":"Various aspects of the genesis of primary fluid inclusions (0.01-1.0 sometimes up to 2 mm) with a large number of mineral inclusions in topaz crystals from chamber pegmatites of Volyn were analyzed. The data could be interpreted in two fundamentally different ways. The first argues for crystals grown in a magmatic melt; the second for an aqueous solution, with a density close to critical. The essence of the discrepancy is the reliability of the identification of the nature of mineral phases in the primary inclusions, if they are crystals captured during growth (xenogenic) or daughter crystals from the fluid. The xenogenic origin of the phases is indicated by the following observations: 1) The location of the mineral inclusions on the growing faces of the topaz crystals depends on the orientation of the crystal’s axis [001] relative to the horizontal plane. It determines the faces on which small mineral phases could be deposited from an aqueous suspension during the growth of topaz crystals. The studied crystals are dominated by individuals in which the mineral inclusions are located on the growing faces {011}, {021}, (001) (and others) of the crystal head. During growth, they were approximately in an upright position. 2) The filling of primary fluid inclusions is not constant. The volume of mineral phases in the inclusions varies from 40 to 95%, often 70-75%, the rest of the volume is gas and aqueous solution. Liquid-gas (liquids ˂ 40%) inclusions without or with < 5% solid phases are very rare. In addition, the ratio between the volumes of different mineral phases in the inclusions is not constant. 3) Light rims (Becke lines) around the inclusions record a change in the refractive indices (caused by a different chemical composition) of topaz when inclusions are acquiring the equilibrium form of the negative crystal. 4) The xenogenic nature of the mineral phases of the primary fluid inclusions in topaz is indirectly confirmed by the value of the fluid pressure (260-300 MPa)of the magmatic melt (determined by the method of homogenization of these inclusions), as it denies the possibility of chamber pegmatite formation at depths of 9-11 km. Thus, the peculiar mineral inclusions were deposited on the face of growing topaz crystals of small mineral phases from a turbid aqueous suspension, which boiled violently. We conclude that topaz crystals in chamber pegmatites of Volyn grew in aqueous solution at a temperature of 380-415ºС and a pressure of 30-40 MPa.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Features of Heavy Metals Distribution in Environmental Components of Urban Park Landscapes of Kyiv City","authors":"I. Kuraieva, T. Koshliakova, K. Vovk, K. Zlobina","doi":"10.15407/mineraljournal.43.02.058","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.02.058","url":null,"abstract":"We investigated the impact of the urban environment on the park ecosystems in Kyiv. As representatives of vegetation the species Taraxacum officinale Wigg. and Tilia cordata Mill., were chosen. The content of heavy metals (Cu, Pb, Zn, Ni, Mn, Cr, and Cd) in soil and leaf samples within the ecosystems of the parks Feofaniya, Kyiv Polytechnic Institute, Mariyinsky, Pushkin, and Nyvky was measured. The highest level of soil contamination with heavy metals was found in the areas of parks located near highways and public transport stops. The most polluted park was the Kyiv Polytechnic Park, and the least polluted Feofaniya Park. High levels of metals found in soil samples did not always coincide with their highest levels in the biomass of the studied plants leaves. We found that, according to the phytotoxicological classification of metals by the biological absorption coefficient (BAC) by plants within the studied park ecosystems, Cu, Pb, Zn, Ni, Mn, and Cr belong mainly to the elements of low absorption (hazard class IV) except for Mariyinsky Park, where Zn according to the BAC value belongs to the elements of moderate absorption (hazard class III). The order of amount of metal bioaccumulation in plants obtained by us show a fairly wide range for different park ecosystems, which confirms the principle of ecological congruence (compliance), according to which the living components of an ecosystem have developed appropriate adaptations coordinated by the abiotic environment. In order to identify additional ways of migration of heavy metals to the ecosystem of Feofaniya Park, hydrochemical data from the surface of the first aquifer, circulated within the study area, were involved. It has been suggested that the increased concentrations of Cu, Pb, Zn, Ni, and Mn in the soils of Feofaniya Park are connected with the Pirogivsky landfill, and the groundwater discharged into the park ponds serves as the main way of migration of pollutants to the natural environment, in particular to the soil-plant system. Our results confirm the need to involve biogeochemical data for ecological assessment of the urban environment and early diagnosis of negative influence, when the plants have not yet manifested morphological and anatomical abnormalities.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67125975","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DIAMONDS OF UKRAINE: RESULTS AND GOALS","authors":"V. Kvasnytsya","doi":"10.15407/mineraljournal.43.03.025","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.03.025","url":null,"abstract":"Diamonds from Ukraine were studied in terms of their separation into their geological and genetic types, distribution and occurrence, the ages of their host rocks, and their nature in Proterozoic and Neogene age sediments. The diamonds are variable in morphology, internal structure, concentration and degree of aggregation of nitrogen centers, carbon isotopes and mineral inclusions. Placer diamonds, primarily from Neogene sands, are anomalous in many respects. They are mostly extremely small, polyhedral, and morphologically diverse showing octahedral, rhombic dodecahedral and cubic forms and they have various colors. In addition to the large heterogeneity in nitrogen concentrations, many diamonds are characterized by a low degree of aggregation of nitrogen centers, which indicates short mantle residence times. Depending on the nitrogen impurity content, the degree of aggregation of nitrogen centers and the possible temperatures of crystallization, several types of diamonds are distinguished in the studied sedimentary placers. According to new isotope-geochemical data, placer diamonds are characterized by a wide range of carbon isotopic composition. This may indicate isotopic inhomogeneity of diamond carbon, different modes of formation and chemical variability in their source regions. Impact diamonds from meteorite craters and Neogene sedimentary deposits of Ukraine are paramorphoses from graphite with similar morphological, isotopic and structural characteristics. The goals of future research of Ukrainian diamonds are discussed.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogical Search Signs for Assessment of Prospects of Diamond Capacity of Ukraine (by Physiographical and Photoluminescent Data)","authors":"O.Yu. Palkina, O. Falkovich","doi":"10.15407/MINERALJOURNAL.43.01.068","DOIUrl":"https://doi.org/10.15407/MINERALJOURNAL.43.01.068","url":null,"abstract":"Some important questions concerning the application of methods of searches of diamond deposits on direct search signs - finds of diamonds are considered and indicator minerals of kimberlites (IMK). The probable reasons for the low efficiency of the dressing-mineralogical method in the search for diamond deposits in Ukraine are named. The article is based on materials of research of diamonds found in different age placers of Ukraine (~1300 crystals); diamonds from kimberlites of the Arkhangelsk province (~6000 crystals); diamonds from metamorphic rocks of the Kazakhstan deposit Kumdy-Kol (~200 crystals); Yakut province (~600 crystals from root springs and ~700 from placers). A physiographic description was made for all these crystals and the intensity and color of photoluminescence (PhL) were recorded. For some crystals, about 600 spectra were taken at a temperature of 77 K. For diamonds of the \"Dniester\" type and some highly defective diamonds from Ukrainian placers, data from Raman spectroscopy are given. The material on indicator minerals of kimberlites is partly the result of our research, partly attracted from literature sources. Finds of diamonds in terrigenous deposits of Ukraine, their territorial and age, possible sources of income are analyzed. The comparison of diamonds from terrigenous deposits of Ukraine with diamonds of indigenous deposits of different genetic type is performed. For comparison, we studied diamonds that were obtained (with their complete removal from the gross technological samples) from some kimberlite pipes of the Arkhangelsk province. We performed a physiographic description and established the particle size distribution and morphological distribution in these pipes. Based on these studies, convincing conclusions were drawn about the signs of the industrial diamond-bearing capacity of kimberlite bodies in this province. The study of a large number of diamonds extracted from Neogene and other placers of Ukraine allowed usto perform a comparative study not only on the morphology and color of photoluminescence but also on the frequency of photoluminescence centers (spectra were taken at 77K). These diamonds were compared with crystals from the industrial kimberlite bodies of the Arkhangelsk and Yakut provinces. It was established which physical properties of Ukrainian diamonds are close to the properties of kimberlite diamonds and how they differ, contrasting features of diamond sets of different genetic types were determined. It has been established that diamonds found in the deposits of the Bilokorovichi world have signs of kimberlite, and the nature of their surfaces, a set of PhL centers, indicates a long stay in sedimentary reservoirs of different ages. A study of diamonds and IMK, which were found on the territory of the Kirovohrad block of the Ukrainian Shield (USh), revealed that the known area of Gruzka has prospects and is worth further mineral and technological testing. The chemical composition of probable ","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"MACROCHONDRULES IN SOME CHONDRITES: 2. GENETIC ASPECTS","authors":"V. Semenenko, A. Girich, K. O. Shkurenko, N. Kychan","doi":"10.15407/mineraljournal.43.03.054","DOIUrl":"https://doi.org/10.15407/mineraljournal.43.03.054","url":null,"abstract":"An electron microscopic and microprobe study of the macrochondrules from the chondrites Allende CV3, Krymka LL3.1, Saratov L4, \"Velyka Balka\" L4-5 and Château-Renard L6 allow to clear some aspects of their formation. The main of them are following: 1) The texture and mineral composition of the majority of the macrochondrules does not differ from those of ordinary chondrules, thus indicating a similarity in formation conditions, 2) It is shown for the first time that the SiO2/MgO and FeO/(FeO+MgO) ratios of the fine-grained rims of the macrochondrules and one`s of chondrules in the Krymka meteorite are well correlated. This indicates to their coexistence in the same dusty environment of the protoplanetary nebula, 3) The unique characteristics of the two firstly found macrochondrules allowed us to detail conditions of their formation and existence in the protoplanetary nebula. A polyzonal graphite-bearing macrochondrule from the Krymka meteorite formed by accretional growth in a mineralogically variable dusty environment. Its complex evolutional history involved remelting and selective evaporation of the macrochondrule surface layer, accretion of an environmental dust, late formation of a fine-grained rim and migratory intrusion of an organic protomaterial and finally a metamorphic event that produced graphite. The melted surface of a macrochondrule from the Allende chondrite was notably affected by high-energy processes and instantaneous cooling in the protoplanetary nebula, 4) The rarity of macrochondrules in chondrites compared to typical chondrules is probably related to their priority destruction. This was caused by permanent movement and collision between them and other solid objects in the pre-agglomeration period of meteorite development.","PeriodicalId":53834,"journal":{"name":"Mineralogical Journal-Ukraine","volume":null,"pages":null},"PeriodicalIF":0.2,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67126162","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}