pdf № 316, April

DOI: 10.19110/geov.2021.4.1

Odikhinchaite, a Sr-Mn-Nb-CO₃-dominant eudialyte-group mineral from the Khibiny alkaline complex has been investigated using the methods of electron probe microanalysis, X-ray diffraction, infrared and Mössbauer spectroscopy. The crystal structure was refined to R = 3.4 % in the anisotropic approximation of atomic displacements using 3815 independent reflections with F > 3s(F). The unit-cell parameters are: a = 14.2709(1), c = 30.023(1) Å, V = 5295.33(7) ų; the space group is R3m. The simplified formula of the mineral is (Z = 3): Na₁₁Sr₃(Mn²⁺,Fe²⁺,Fe³⁺)Ca₆Zr₃Nb[Si₂₅O₇₂(OH)](CO₃)Cl(OH,O)₄. The studied sample is the second find of this rare mineral worldwide, represented by a variety with high Fe content in the M2 micro-region, belonging to the taseqite — odikhinchaite solid-solution series. The significance of odikhinchaite as an indicator of a stage corresponding to maximum Sr activity in specific ultraagpaitic pegmatites is discussed.

Keywords: mineral, eudialyte group, odikhinchaite, crystal structure, IR spectroscopy, isomorphism, Khibiny alkaline complex.

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DOI: 10.19110/geov.2021.4.2

The petrographic features and conditions of the formation of metamorphosed mafic-ultramafic rocks of the Ampelshor complex, which are part of a small massif in the southern part of the Marunke u block of the Polar Urals (Peridotitovyi stream) and are controlled by tectonic thrust faults, have been studied. Muscovite-albite-clinozoisite-amphibole rocks (metabasites) and pyroxene-amphibole-chlorite (metautramafic) rocks are described. Structural, textural, and mineralogical features of metamagmatites indicate the hypabyssal nature of metabasite and plutonic nature of metaultramaphite. In metabasites, primary minerals are represented by relics of amphiboles (pargasite, edenite), and in metaultramaphites — by olivine and, possibly, clinopyroxene (augite, diopside). Magnesiohastingsite and chermakite in metautramafite were formed either at the late magmatic or metamorphic stages of rock transformation. The studied rocks underwent low-temperature changes (t — 468–380 °C, P — 2–3 kbar), corresponding to the greenschist metamorphic facies.

Keywords: P–T parameters, metabasites, metaultramafites, Polar Urals.

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DOI: 10.19110/geov.2021.4.3

It is shown that the origins of technological mineralogy in Russia are associated with the name of Academician V. M. Severgin, who at the end of the 18th century introduced the concept of «technological and economic» mineralogy. The stage of development of 1921—1955 is considered as important for the formation of the school of applied mineralogy. The next stage is the implementation of the principles of technological mineralogy in the practice of geological exploration and mining production and the creation of the Technological Mineralogy Commission of the All-Union Mineralogical Society by the beginning of 1983. The main directions of the development of technological mineralogy and the role of the published works of the commission are substantiated.

Keywords: technological mineralogy, methods, innovative technologies, metals, industrial minerals, georesources.

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DOI: 10.19110/geov.2021.4.4

The paper deals with the history of stromatolite studies in the Republic of Karelia and the compiling of a stromatolite collection at the Museum of Precambrian Geology, IG, KarRC, RAS, Petrozavodsk. Major stages in the study of Karelia’s Proterozoic stromatolites are presented, changes in the point of view of their origin are assessed and the exposition «Karelia’s and worldwide stromatolites» is described for the first time. Analysis of the history of Karelia’s widespread and accessible stromatolites and a review of the stromatolite collection at the museum are of scientific and educational interest.

Keywords: stromatolites, paleoproterozoic, microbial buildups, Museum of Precambrian Geology.

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