Geohimiâ

The formation of nanophase metallic iron (npFe0) in lunar regoliths, which is observed in the condensate films on the surface of mineral grains and in agglutinate glasses, is one of the signs of “space weathering” on the Moon under the influence of solar wind and micrometeorite bombardment. The paper presents the results of laser experiments simulating micrometeorite “impact” on basalt, olivine, pyroxene and some other types of targets. Numerous iron nanospherules that are often arranged into chains and clusters were found in the molten products of the “impact”. The experiments showed that npFe0 can be formed without the participation of implanted solar wind ions (hydrogen ions) as a reducing agent, as well as without iron condensation from shock-formed vapor. Similar clusters of nanophase metallic iron and chain structures are observed in the impact glasses of the lunar regolith and asteroid particles.

The paper presents analysis of the crystal morphology of two similarly shaped interpenetration twins of cubic crystals: the Chinese Lantern diamond (Arkhangelsk diamond mining province, provided for this study by courtesy of the ALROSA company) and a diamond crystal from Brazil, which has been studied in much detail by A.E. Fersman. Comparison of data on these diamonds, which were obtained using original methodological techniques for interpreting morphological indications of crystal growth and dissolution, revealed a number of crystal morphological features of crystals characteristic of regular accretions of this type. In addition to tetragonal pits characteristic of the cuboids, ribbon-shaped, jagged, and drop-shaped relief features typical of surface dissolution, a new type of symmetrical sawtooth microrelief associated with etching of octahedral layers of cuboid growth was discovered on the diamond from the Arkhangelsk province. In accordance with the height and direction of the steps of the relief pattern, the development sequence of the aforementioned types of microrelief is determined according to the increase in the depth of dissolution and the degree of change in the curvature of the surface of the tetrahexahedron on twin cuboids. The genesis of the characteristic equatorial sharp ridge of octahedron faces encircling the twinning plane was revealed. It is demonstrated to has been formed in relation to an early stage of the systematic coalescence of fibrous diamond cuboids and to be a determining condition of its development, first as a interpenetration twin of flat-faced octahedral crystals. Crystal morphological similarities between indications of dissolution on curved tetrahexahedra from kimberlites of the Arkhangelsk pipes and placer sources in Brazil and the north of the Yakutian diamond-bearing province is discussed.

The results of geochemical studies of soils and anthropogenic grounds within the territory of the large Pioneer gold ore deposit developed in the Amur Region are presented. Using the enrichment indices for the soil and ground cover of the Pioneer deposit territory, the following pollutant elements were determined: As, Sb, Mo, Bi, W, S, Cd, and Pb. Using the methods of mathematical statistics, the background contents of As, Sb, Bi, Mo, W, S, Cd, and Pb in the technogenically transformed territory at the sampling time accounted for 63, 8.84, 0.69, 3.54, 4.19, 529, 0.11, and 36.5 mg/kg, respectively. The exceedance of background values for As, Sb, Bi, Mo, W, and S is caused by the natural metallogenic features of the territory. It has been established that the sources of metal emissions into the environment are mining facilities and structures of the mining complex: quarries, waste dumps, heap leaching areas, gold extraction plant, and tailings dumps.