pdf № 344, August

DOI: 10.19110/geov.2023.8.1

The results of the study of native gold of the Timan-Northern Ural region using X-ray diffraction analysis (Debye-Scherrer diffractometric method, single crystal registration) have been presented. It was established that the structural characteristics of gold were different depending on the nature of gold-bearing objects. The structure of typical placer gold was an aggregate of randomly distributed microcrystallites. In this case, only solid annular lines of reflexes of the planes of the crystal lattice of gold were visible on the photodebagrams. The formation of this microcrystalline structure in gold was conditioned by exogenous mechanical deformations resulting from its occurrence in dynamic environments (water, wind activity, etc.).

The structure of the autigenic gold of ore occurrences was characterized by a suboriented ordering of crystals (texturization). On the photodebagrams of this gold, intermittent dashed lines and nodes of reflections from the planes of the crystal lattice of the metal were observed. The frequency of occurrence of gold with this structure on primary ore objects varied from several units to several tens of percent. According to the authors, the findings of native gold with the structures of the ordering of its grains as part of accretions or aggregates of microcrystallites were a sign of the extreme proximity of this gold to its root source, which was important at predicting of gold content and searching for gold deposits.

Keywords: native gold, X-ray diffraction (Debye-Scherrer method), Kyvvozhskoye gold-placer field, Middle Timan.

Download full text

DOI: 10.19110/geov.2023.8.2

The study of the processes and products of biomineral formation in various organs and tissues is of general scientific interest for solving practical issues related to the physiological functioning of living organisms.

The object of the study was multiple pigment gallstones removed from the gallbladder in people living in the Komi Republic. The purpose of the work was a comprehensive study of the composition and structure of pigment gallstones, as well as a comparative analysis of the studied samples with natural organic carbon-containing mineraloids.

The following methods were used during the study methods: X-ray diffraction (Shimadzu XRD-6000), IR-spectroscopic (InfraLum FT-02), thermal (TGA/DSC 3+), mass spectrometry (Elan-6100), chemical (EA-1110), atomic emission (Optima-4300 DV). The cleavages of the samples were studied by a scanning electron microscope with an X-Max energy-dispersive attachment (VEGA3 TESCAN) and atomic force microscope (Ntegra Prima (NT-MDT)).

As a result of the studies, it was established that pigment gallstones contained an amorphous organic and mineral component – calcium bilirubinate, calcium carbonate (calcite, aragonite), calcium phosphate (magnesium-containing hydroxylapatite). Thermal-oxidative destruction of samples occured in the high-temperature region (500 ºC and above). Pigment gallstones belonged to formations with low carbon content. Microminerals in the samples were represented by classes of oxides, chlorides, silicates, carbonates and oxalates. Detailed studies of the nanostructure of pigment gallstones showed that it was represented by globule-like particles, the size and order of which varies. We newly revealed that pigment gallstones, according to a number of criteria, were similar to natural organic carbon-containing mineraloids.

Keywords: gallstones, pigment, bilirubin, biomineral, mineraloid.

Download full text

DOI: 10.19110/geov.2023.7.3

Sergevanite with idealized formula (Na₁₂KH₃O)[Ca₃(Mn₂Ca)](Na₂Fe)Zr₃Ti_0.5Si_25.5 O₇₂OH^₂.(H₂O)₂ (Z = 3) — a low calcium eudialyte group mineral from Lovozero alkaline complex was investigated repeatedly using obtained earlier the X-ray diffraction data. Its crystal structure with 174 sites was refined in the frame of trigonal primitive cell to R = 4.7 % on the base of 5613 averaged independent reflections with F > 3s(F). The unit-cell parameters were: a = 14. 2179(1), c = 30.3492(3) Å, V = 5313.1(1) Å3, space group P3. More detailed, close to real, cations distribution on sites was established. Studied sergevanite was the second mineral of eudialyte group with lowering symmetry from rhombohedral (R3) to trigonal (Р3).

Keywords: sergevanite, eudialyte group, crystal structure, isomorphism, key sites, primitive cell.

Download full text

DOI: 10.19110/geov.2023.7.4

The article continues the series on the history of geology and is devoted to the Natural Science Museum of the St. Petersburg Mining University, namely its mineral collection. From the letters found by the author in the archive of Professor D. P. Grigoriev’s archive, kept in the Russian Mineralogical Society we can learn, interesting information about the circumstances of the acquisition of certain collections and exhibits, and about people worthy to remain in the history of mineralogy. At the same time, wide connections of D. P. Grigoriev with industrial and academic organisations and his active work on the creation and dissemination of the doctrine of mineral ontogeny, which eventually became a section of the university course of mineralogy, were revealed. The letters were accompanied by photographs from the same archive. The aim of the article was to cover the history of Russian mineralogy as fully as possible, including the role of organisations and individuals, and to reconstruct details of their biographies. Some of the problems discussed in the letters are still relevant today. The reader's attention should be attracted by the names of statesmen Prince G. Orbeliani, Prime Minister of India J. Nehru, Emperor of Ethiopia H. Selassie, mineralogists A. E. Fersman, G. N. Vertushkov, Yu. S. Kobya­shev, name of the Ural historical deposits Gumeshevka and Vatikha, enterprise «Russian precious stones» mentioned in one context. The article is timed to coincide with the 250th anniversary of the Mining Museum.

Keywords: D. P. Grigoriev, St. Petersburg Mining University, Mining Museum, personal archives, history of mineralogy.

Download full text