卷 CLIII, 编号 5 (2024)
ARTICLES
About the age of granite of the famous Thunderstone pedestal of the monument to Peter the Great “The Bronze Horseman” in Saint Petersburg
摘要
The age of the Thunderstone granite, which is the pedestal of the Bronze Horseman monument to Peter the Great in Saint Petersburg, is dated at ~1595 Ma. This age was obtained by U-Pb dating of accessory zircon separated with a jewelry gravel from the biotite flakes. The study was carried out on a secondary ion microprobe SIMS SHRIMP-IIe at the Center of Isotopic Research of the Karpinsky Institution (Saint Petersburg). 15 local U-Pb isotopic analyses were performed on 12 zircon crystals. It is not yet possible to recognize the source of the Thunder Stone, since granites of the same age have not yet been found either in the Vyborg batholith (1665—1615 million years), or in the Salminsky batholith (1547—1535 million years), or in other granite intrusions located in the proximity of Saint Petersburg. Thus, the Thunder Stone seems to confirm the historically established idea about its uniqueness and hints that its homeland should be sought among the manifestations of the yet unidentified phases of Early Riphean granitoid magmatism in the nearest regions.



Mineral composition and parameters of metamorphism of granulite in the Khapchan orogenic belt (Anabar shield)
摘要
The calculation of temperature and pressure of metamorphic mineral formation was carried out by methods of mineral thermobarometry for granulites of the Khapchan Group. Peak metamorphism conditions were hidden by a post-culmination partitioning of Fe and Mg between minerals at the retrograde stage of metamorphism. The maximum temperature and pressure obtained with the winTWQ are 820—855 °C and 6.6—7.0 kbar. The retrograde stage of metamorphism was characterized by a synchronous decrease in temperature and pressure down to 560 °C and 3 kbar. It is embodied in a composition of biotite: Ti, Sr, and REE contents in this mineral are lowered when temperature is decreased. The rare-element composition of garnets with a well-defined negative Eu anomaly and high value of SmN/GdN ratio is typical for low-calcium garnets of granulite facies.



МИНЕРАЛЫ И ПАРАГЕНЕЗИСЫ МИНЕРАЛОВ
Mustard gold in the Evevpenta epithermal gold-silver ore occurrence (Kamchatka)
摘要
The paper describes the occurrence of so-called mustard gold, which forms independent grains and rims that replace calaverite (AuTe2) in the adularia-quartz veins of the Evevpenta epithermal ore occurrence in Kamchatka, Russia. Four types of mustard gold were identified: (1) pure mustard gold, (2) mustard gold containing areas and veinlets of homogeneous native gold, (3) mustard gold with remnants of Ag sulfides (Au-Ag), and (4) mustard gold intergrown with oxygen-containing compounds of Fe and Mn. It is hypothesized that the mustard gold at the Evevpenta formed as a result of calaverite (AuTe2) replacement during the late hydrothermal stage. We propose that the chemical composition of mustard gold serves as its distinguishing feature and can indicate the geological and genetic types of gold deposits.



Mineral association of the terrigenous-volcanogenic strata of the Kontozero volcano-plutonic complex (Kola Peninsula, Russia)
摘要
The article presents the results of a study of mineral assemblages in effusive rocks (meimechite and foidites) of the terrigenous-volcanogenic stratum of the Kontozero volcano-plutonic complex. The earliest rock, meimechite, was crystallized in the temperature range 1505—1595 °C and consist of the diopside + magnetite + phlogopite matrix with olivine (Fo84—92) phenocrysts; accessory minerals are ulvöspinel, chromite, titanite, ilmenite, and calcite. The meimechite formation led to a significant decrease in the MgO concentration and an increase in SiO2 and CaO contents and Fe2O3/FeO ratio in the magmatic melt, which determined the nature of the mineral assemblages in foidites. Thеsе rocks followed meimechite and formed at temperatures of 1325—1330 °C. In foidites, diopside crystallized in the form of phenocrysts, and previously formed olivine reacted with the melt to form symplectite intergrowths of diopside and magnetite. An increase in SiO2 and CaO contents as well as Fe2O3/FeO ratio in the sequence meimechite → foidites led to a change in the assemblage of titanium-bearing minerals. In foidites, the diversity of such minerals increases; they form zonal segregations in which, from core to rim, minerals replace each other in the following sequence: magnetite → perovskite → titanite → andradite (shorlomite).



Noble мetal and polymetal mineralization of the Mesoproterozoic Spiridon-Ty peridotite–shonkinite massif in the Kola Peninsula
摘要
This article presents the results of studies of noble metal and polymetal mineralization from the zone of late superimposed carbonatization in phlogopite peridotites of the Mesoproterozoic peridotite-shonkinite massif Spiridon-Ty. These rocks are characterized by high concentrations of noble metals (Au up to 0.51 ppm and Ag up to 18 ppm) and polymetals (Cu up to 1.55 wt %; Pb up to 0.17 wt %; Zn up to 0.15 wt %). It has been established that the ore mineralization is sulfide-sulfosalt with native Cu, Ag, and Au. Sulfides and sulfosalts are represented by bornite, chalcopyrite, covellite, galena, sphalerite, tennantite, and gersdorfite. It was determined that the primary noble metal and polymetal mineralization was formed under the following conditions: T ≈ 395—280 °C, lgfS2 ≈ 10–6.5—10–9.9 atm, lgfO2 ≈10–37 atm and pH of the hydrothermal solution ≈ 5.5—7.8. Covellite is an intermediate mineral in the oxidation of primary sulfide minerals and was formed at T ≈ 190—110 °C and lgfS2 ≈ 10–10—10–12 atm. Native copper is a late oxidation mineral of sulfide minerals and formed at T ≤ 110 °C and lgfS2 ≤ 10–31 atm. The results obtained allow us to consider the potassium alkaline-ultrabasic massifs of the Kola alkaline province as a possible source of noble metal and polymetal ores.



Purpurite from spodumene pegmatite of Kolmozero deposit, Kola Peninsula, Russia
摘要
Purpurite Mn3+(PO4) from the spodumene pegmatite of the Kolmozero deposit, Kola Peninsula, Russian Arctic, was studied comprehensively, which allowed to obtain the data about its morphology, mineral assemblage, chemical composition and crystal structure. The Raman spectrum of the mineral was also obtained. Purpurite occur as powdery aggregates on crystal surfaces and cleavage planes of lithiophilite and spodumene, as well as patches among of secondary mineral masses filling the cavities in pegmatite. Purpurite from Kolmozero has high iron content with Mn/(Mn+Fe) ≈ 0.55. Its composition is close to the isomorphic heterosite Fe3+(PO4). The crystal structure of natural purpurite has been studied for the first time in this work. Purpurite is orthorhombic, space group Pbnm, unit cell parameters: a = 4.7783(3), b = 9.7417(5), c = 5.8388(4) Å, V = 271.79(3) Å3, R1 = 2.42 %. The crystal structure of purpurite is based upon layers of vertex-sharing octahedra (Mn3+, Fe3+)O6 that linked via PO4 tetrahedra. The (Mn3+, Fe3+)O6 octahedra are strongly distorted.



Mineralogical Crystallography
Isomorphism in vanadinite. 1. Chemical variation and solid solutions
摘要
The chemical composition of hundred vanadinite specimens from 17 occurrences worldwide was studied by electron microprobe and the new and literature data on its chemical composition were summarized. Vanadinite is a supergene mineral: no reliable data indicating that vanadinite may be hypogene have been found, although its analogue is synthesized in a wide temperature range: from 25 to 1000 °C. The overwhelming majority of vanadinite specimens have a composition close to the ideal formula, Pb5(VO4)3Cl. Phosphorus and/or arsenic-rich vanadinite (> 0.5 apfu P and/or As) is rare, as well as a Cr-bearing variety of this mineral. According to the data available today, isomorphism between V, As and P in natural vanadinite–pyromorphite–mimetite system is incomplete unlike synthetic system Pb5(T5+O4)3Cl (T = V, P, As) in which full miscibility occurs, even at low temperatures. For the vanadinite–mimetite series, the compositional range from V3.00As0.00 to As2.15V0.85 has been recorded while the vanadinite–pyromorphite series is so far represented almost only by the vanadinite part: from V3.00P0.00 to P1.50V1.50. Two new finds of the so-called endlichite (an intermediate member of the vanadinite–mimetite series with a V: As ratio of ~1:1, data on which were previously based only on wet chemical analyses published in 1885) were made. The calcium content in all vanadinite samples studied in this work does not exceed 0.2 apfu, and the contents of other elements with atomic numbers >8, excepting Pb, Ca, V, P, As and Cl, are below their detection limits by electron microprobe.



Cation ordering in zvyaginite: new data on composition and structure
摘要
A new modification of zvyagignite from agpaitic pegmatite at Mt. Kuamdespakhk, Lovozero massif, Kola Peninsula, was studied. It is triclinic, space P-1. a = 5.4141(2), b = 7.1410(6), c = 12.0831(12) Å, α = 104.963(8), β = 95.294(6), γ = 90.048(5)°, V = 449.24(6) Å3. This zvyaginite modification is formed by natural cation exchange reaction 2Na+ ↔ □ + Zn2+ and inherit unit cell parameters from epistolite. This modification of zvyaginite is considered as disordered, or zvyaginite-1Tc, in contrast to the previously known modification with doubled unit cell volume (ordered modification, or zvyaginite-2Tc) In the disordered modification of zvyaginite Zn2+ incorporates exclusively at the octahedral layer, whereas the formation of ordered zvyaginite can be associated with a greater exchange completeness, when Zn2+ incorporates at heteropolyhedral layer, where it’s even a small admixture is sufficient to change the geometry of Si2O7 groups and doubling of unit cell parameters. Variations in the chemical composition of zvyaginite allow us to propose for it a generalized formula Na2-хZnNb2Ti(Si2O7)2[(OH)2+xO2-x]⸱4H2O (0 ≤ x ≤ 1).



CHRONICLES
Recipients of the N. I. Koksharov Medal of the Russian Mineralogical Society
摘要
Information is provided about the recipients of the 2024 N. I. Koksharov Medal of the Russian Mineralogical Society: L. Z. Reznitsky, Senior Researcher at the Institute of the Earth’s Crust of the Siberian Branch of the Russian Academy of Sciences, and Chen Jinhua, Professor at Guangxi University (China). L. Z. Reznitsky is a researcher of the mineralogy of peculiar Cr-V-containing metamorphic rocks of the Southern Baikal region and the co-author of the discovery of 15 new mineral species. Chen Jinhua is a specialist in the field of mineral flotation, including the active use of quantum chemical modeling methods.



XX International Meeting on Crystal Chemistry, X-Ray Diffraction and Spectroscopy of Minerals and VI International Conference on Organic Mineralogy
摘要
Information is provided about the XX International Meeting on Crystal Chemistry, X-ray Diffraction and Spectroscopy of Minerals, and VI International Conference on Organic Mineralogy that was held on June 17—21, 2024 in St. Petersburg on the basis of St. Petersburg State University. The meetings were attended by about 200 specialists from Russia, as well as from Belarus, Azerbaijan, Iran (in person), Germany, India, Italy, Canada, France (in absentia). A brief overview of the topics of plenary and sections reports are presented.


