Vol CLIII, No 1 (2024)

The paper is dedicated to the 140^th anniversary of W. Ostwald’s birth and to the centenary of publishing of the Russian edition of his book «World of neglected dimensions», which changed ideas about micro- and nanoworld. We briefly observed results of the first and second stages of research breakthrough into the world of micro- and nanosized particles. This recently discovered understudied world between separate atoms and molecules and between minerals is called a protomineral world. This world is suggested to be called a new «World of neglected dimensions» by analogy with W. Ostwald’s book. The key objects of the protomineral world are precrystalization clusters in mineral-forming environments named «hidden» phase clusters or quatarons. We showed that the future investigation of structural forms of formation and existence of the protomineral matter would be connected with the use of the free electron laser and instruments of attosecond physics.

Thermodynamic analysis is carried out for the model systems: (1) Na–Ca–Mg–A1–Si–CO₂–H₂O and (2) Ca–Mg–A1–Si–CO₂–H₂O. In each systems the mineral equilibria involving dolomite, calcite, spinel, corundum, pargasite, hydroxylclinohumite, and diaspore are considered. A diagram of the multisystem in coordinates ${\mathrm{\mu }}_{{\mathrm{H}}_2\mathrm{O}}-{\mathrm{\mu }}_{{\mathrm{CO}}_2}$ is constructed. Analysis showed a significant influence of chemical potentials of water and carbon dioxide in the mineral-forming medium on stability of corundum and spinel in marbles. The conditions of the spinel formation during metamorphism of protolith consisting of carbonate sediments with evaporites lenses and terrigenous material (smectites, bauxites, etc.), are considered in detail. The conditions of the replacement of spinel by corundum during retrograde metamorphism are determined depending on the mole fraction of CO₂ in the fluid and temperature at pressure of 5 kbar.

In plastically deformed harzburgite and dunite of the Idzhim mafic-ultramafic massif, which is part of the Kurtushiba ophiolite belt of the Western Sayan and is one of largest massifs of this belt, platinum group minerals (PGM) were identified for the first time. They were found in pentlandite, awaruite and nickel arsenides (NiS, Ni₂S) in form of finely dispersed inclusions, the diagnosis of which, due to their small size, was carried out only qualitatively. Native osmium, Ir-bearing osmium, native ruthenium, garutiite, tetraferroplatinum, unnamed (Pt,Ir)Fe and (Ni,Cu,Pd,Pt)_2-3Fe phases, zaccarinite, Ir-bearing erlikmanite and unnamed sulfides with crystal chemical formula Me₂S were quantitatively identified and characterized. All PGM grains found are predominantly localized either in peripheral parts of grains of sulfides, awaruite and wairauite, or in silicate matrix in immediate vicinity of these minerals. The platinum group elements (PGE) content and their distribution in restite ultramafic rocks was apparently controlled by partial melting of primary peridotite substrate. During partial melting, the extraction of sulfur and Pt-group platinoides (Pt, Pd, Rh) into the silicate melt led to a decrease in S₂ fugacity and the accumulation of Ir-group platinoides (Os, Ir, Ru) in monosulfide solid solution (mss), from which subsequently primary Os-Ir-bearing pentlandite crystallized. The subsequent transformation of this sulfide led to appearance of PGE-containing awaruite and nickel arsenides, as well as to everything discovered diversity of identified PGM.

Barium-bearing micas (BaO content from 1.2 to 18.7 wt %) were found in hydrothermally altered ijolites and alkaline syenite of the Sredneziminsky ijolite-syenite-carbonatite massif (Eastern Siberia, Russia). It occurs in the products of low-temperature replacement of cancrinite, in association with natrolite, analcime, calcite, diaspore/boehmite, celsian, and strontianite. Ba-bearing micas are represented by grains up to 1 mm, heterogeneous in chemical composition. The amount of Ba increases in the marginal parts of grains; enrichment of some layers in mica grains with barium is also observed. The main isomorphic substitution in muscovite corresponds to the scheme K⁺+Si⁴⁺↔Ba²⁺+^IVAl³⁺. The empirical formula of barium-richest areas in one of the mica grains is (Ba_0.54–0.56Sr_0–0.09K_0.46)_{∑1.02–1.06}Al_1.98–2.01(Si_2.37–2.40Al_l.60–1.63)_∑4.00 O₁₀(OH_1.70–2.00F_0–0.30)_∑2.00, which corresponds to ganterite. The maximum content of BaO in the majority of muscovite grains of the Sredneziminsky massif is 14.0–14.9 wt % that is equal to 0.41‒0.44 apfu Ba. It is assumed that the source of barium in the hydrothermal solution was orthoclase containing 0.5–0.9 wt % BaO which underwent albitization at the post-magmatic stage. The widespread occurrence of sulfides in the rocks indicates low oxygen fugacity, which prevents the formation of barite and is favorable to the formation of Ba-bearing muscovite and celsian.

Ikorskyite KMn³⁺(Si₄O₁₀)·3H₂O is new mineral from agpaitic pegmatite of the Kukisvumchorr Mt. (Khibiny Massif, Russia). The mineral forms radial aggregates of light-brown crystals growing on separate quartz crystals or on romanèchite crusts in association with barite, donneite-Y, strontionite, natrolite, vinogradovite, manganoneptunite and organic matter. The mineral is monoclinic, space group P2₁/c. a = 5.0714(3), b = 8.2731(5), c = 13.3740(11) Å, β = 93.730(5)°, V = 559.93(5) ų. The eight most intense lines of the diffractogram are: (I-d[Å]-hkl): 55-7.04-011; 41-4.318-110; 100-4.185-11-1; 24-3.956-021; 28-3.339-004; 19-3.095-014; 30-3.014-113; 70-2.939-12-2. The crystal structure of ikorskyite belongs to a new structure type of minerals and inorganic compounds and belongs to the palygorskite group. The mineral is named in honor of Serafim Veniaminovich Ikorsky (1927–2016), a well-known specialist in the field of organic matter and gases research of the Kola alkaline province.

The article is devoted to the 155^th anniversary of the birth of Professor A. P. Gerasimov (1869–1942), Secretary (1914–1935), Honorary Member (1940) and Chairman (1936–1942) of the All-Russian Mineralogical Society, who died in evacuation in Sverdlovsk. His letters, found in the archive of Professor D. P. Grigoriev, kept in the Russian Mineralogical Society, are published: to A.N. Krishtafovich from Petrograd to Vladivostok (05.05.1921), to D.P. Grigoriev from Essentuki to Sverdlovsk (26.03.1942), to relatives from Essentuki (07.06.1942), as well as an autobiography (01.06.1942), and obituaries from the newspaper «The Ural Worker» (12.11.1942). The letters show the living and working conditions of the Geological Committee in Petrograd during the Civil War and of the Leningrad Mining Institute in evacuation during the World War II. The aim of the article is to restore the history of domestic science as fully as possible. The article is aimed at historians of science, as well as teachers, graduate students and students of geological faculties of universities.

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