Mineralogical Journal

3-15

Authors: Rainer Thomas, Paul Davidson, Adolf Rericha, Dmytro K. Voznyak

In this contribution, we show that in miarolitic pegmatites during the crystallization of water-rich melts, samples of these mineral-forming melts were trapped in the form of water-rich melt inclusions, preserved primarily in quartz. The bulk concentration of water and the temperature are the system-determining parameters since from their analysis it follows that these melt inclusions depict pseudo-binary solvus curves in the coordinates of temperature and water concentration. Furthermore, using reduced coordinates (H2O/H2Ocrit vs. T/Tcrit) most melt inclusions of the studied pegmatites plot very well in a standardized and reduced solvus curve. The existence and formation of such uniform solvus curves is an expression of crystallization processes under nearly equilibrium conditions. However, many trace and some principal elements of the melt inclusions trapped near the solvus crest [H2O/H2Ocrit from 0.5 to 1.5 and T/Tcrit > 0.95] show unusual distributions, with very well-defined Gaussian and/or Lorentzian curves, characterized by defined area, width, offset, and height. This has been shown in many natural examples obtained from pegmatites. Only the offset values represent nearequilibrium conditions and corresponding element concentrations, which are equivalent to the regional Clarke number (Clarke number or Clark is the relative abundance of a chemical element, typically in the Earth’s crust). We interpret these distributions as explanation for some extraordinary-chemical properties in this critical region: principally extremely high diffusion rates, low dynamic viscosity and extremely low surface tension. Near the critical point, we have both space and time-related non-equilibrium and equilibrium processes close together. Furthermore, we can show that the Gaussian and Lorentzian distribution are first approximations of the specific element distribution because at the critical point the enrichment of some elements reaches such an extent that the Gaussian and/or Lorentzian curves degenerate into a vertical line (are asymptotic to the concentration axis), which is determined by the maximum solubility of a species in the supercritical melt-water system. The highest concentration of Be, as an example, was observed in Ehrenfriedersdorf melt inclusions: 71490 ppm Be.

32-40

Authors: V.M. Kvasnytsya

The size and shape of diamond crystals of different origin are analyzed. Diamonds with a size of less than about 0.5 mm are classified as microcrystals. Diamonds found in meteorites typically show non-faceted anhedral crystals of various sizes. Only the Canyon Diablo iron meteorite has cubic microcrystals of unclear crystallogenesis. Nano, micro- and macro-sized crystals of diamond in meteorites are usually aggregate in nature. The release of diamond polyhedra in meteorites is limited by the too small size of its crystals in chondrites and by its solid-phase transformation from very fine-grained diamond and graphite in ureilites and octahedrites. The size and shape of diamond crystals found in meteorite impact craters are determined by the nature of the source carbon material. The process of solid-phase transformation of graphite or other carbon-bearing materials (e.g., coal, plant remains) to diamond in meteorite craters does not allow euhedral crystal to be formed. At the same time, in the case of diamonds formed from impacts, on the (0001) faces of impact apographitic diamonds, polyhedra of nano-microdiamonds crystallize from the gas phase. These crystals are often form autoepitaxially, because they crystallize in an oriented manner on the lonsdaleite -diamond matrix. Diamonds found in metamorphic rocks, ophiolites and modern volcanites show faceted microcrystals. A wide range of sizes, from 0.1 mm to 10 cm, is characteristic of faceted diamond crystals from kimberlites, lamproites and lamprophyres. Diamond crystals from different mantle rocks acquire a multifaceted shape after reaching certain embryo sizes — the most likely appearance of diamond polyhedra larger than 40-50 nm. Octahedra forms are dominant for natural diamond crystals of different sizes and origin.

56-70

Authors: N.O. Kryuchenko, E.Ya. Zhovinsky, P.S. Paparуga

Presented are the results of studies of the chemical composition of the waters of mountain rivers and their tributaries of the Ugolsk-Shyrokoluzhansk protected massif of the Carpathian Biosphere Reserve (CBR) — the Velyka Ugolka river and its left tributary — the Kamensky stream; the Mala Ugolka river and its right tributary — the Vezhansk stream; the Luzhanka river and its left tributary — the Vonyacha Zvoryna stream. According to the results of statistical processing of the chemical composition of the waters, the average content of the salt composition was established — SO42–, Cl–, Ca2+, Mg2+, HCO3–, Na+ + K+, total dissolved solids (mineralization) and pH values. Based on the results of many years of research (2003-2019), the ionic composition of the waters was determined and the similarity of the Velyka and Mala Ugolka rivers (hydrocarbonate-calcium waters) and the difference between the Luzhanka river (hydrocarbonate-sodium waters) were revealed. The main difference in the composition of the waters of the river. Luzhanka has a low content of magnesium and calcium, with an increased content of sodium and potassium, the pH value is 7.04, while in other rivers it is 7.10-7.5. A direct relationship was established between HCO3 and mineralization (from lower to higher): the Luzhanka river — the Velyka Ugolka river — the Mala Ugolka river. The natural factors of the formation of the chemical composition of waters are identified — the composition of rocks and atmospheric precipitation (snow), climate and relief. It was revealed that the main factor influencing the formation of river waters is the composition of rocks: flysch with a predominance of sandstone (Luzhanka river), flysch with a predominance of limestone (Velyka and Mala Ugolka rivers). According to the standards for drinking water, there is an insufficient content of calcium and magnesium (Luzhanka river) and in all rivers — sulfates, chlorides, sodium. Recommendations are given to the population on replenishing the diet with microelements, which are not enough for the physiological needs of the body in the case of using river waters as drinking.