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Eskolaite crystals were discovered in the course of Scanning Electron Microscopy (SEM) studies of the regolith sample, which was delivered from the continental area between Serenitatis and Tranquilitatis Maria during the Apollo 17 mission. The finding was compared with an analogue sampled from Mare Crisium (Luna 24 mission). A condensate-impact origin of eskolaite is assumed for both findings. It was demonstrated that the eskolaite of the Apollo 17 probe is genetically and morphologically identical to the eskolaite from the Luna 24 probes.

The AlN/Si(111) epitaxial structures were synthesized by coalescence overgrowth of AlN nanocolumns using PA MBE technique. Such epitaxial structures can be used as a buffer layer for obtaining high quality AlN and GaN layers. Structural, electrical and chemical properties of these samples were studied. For the first time it was demonstrated that the etching of the obtained type of AlN/Si(111) structures in KOH can become a promising method for obtaining high quality free-standing AlN and GaN.

A new method for nanopit formation by molecular-beam epitaxy (MBE) on different silicon substrates has been investigated. The dependence of the shape and depth of the nanopits on substrate orientation and doping type has been studied. The samples with an array of nanopits with 25 nm depth and (2-6)·108 cm−2 density for subsequent monolithic selective growth of quantum dots (QD) have been created.

The presence of condensate glass was established for the first time in natural terrestrial impact glasses. Its existence was previously predicted on the basis of shock evaporation experiments. Condensate glass was found in the irghizites of the Zhamanshin crater. Its characteristic features were described, including a combination of high silica content with the presence of nanoscale crystalline nuclei and typical globular morphology under TEM.

The presence of condensate glass, which had been forecasted exclusively based on experiments on shock evaporation, was first discovered in natural terrestrial impact glasses. The condensate glass was found in irghizites and zhamanshinites of the Zhamanshin crater. The glass characteristics, a combination of a high silica content and the occurrence of nanosize crystalline nuclei, as well as the typical globular morphology, were determined by means of transmission electron microscopy.

A new mineral phase was discovered in the course of studies at the Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry (IGEM) of fine-grained fractions of the lunar regolith delivered to the Earth by the Luna 16, Luna 20, and Luna 24 automatic stations. The grain of native niobium was identified in the regolith sample from the Mare Crisium. Presumably, this phase was formed during the fractioning process in a gas–plasma cloud under an impact event on the Moon.

The results of examining fragments of impact glasses of the regolith samples from Mare Fecunditatis delivered to the Earth by the Luna 16 Soviet automatic station are presented. Nanosize inclusions of native iron and titanium were found in the samples by means of transmission electron microscopy (TEM). It is shown that these inclusions are constituted of single-crystalline formations. The high-pressure phase of native ω-titanium was discovered naturally for the first time. The data testifying to the high heterogeneity of the glass matrix of regolith grains are presented. Possible mechanisms of the formation of nanocrystals of the treated native phases are discussed.

Minerals of the Fe-As-S system are the main components of Au ores in many hydrothermal deposits, including Carlin-type Au deposits, volcanogenic massive sulfide deposits, epithermal, mesothermal, sedimentary-hosted systems, and Archean Au lodes. The “invisible” (or refractory) form of Au is present in all types of hydrothermal ores and often predominates. Knowledge of the chemical state of “invisible” Au (local atomic environment/structural position, electronic structure, and oxidation state) is crucial for understanding the conditions of ore formation and necessary for the physical-chemical modeling of hydrothermal Au mineralization. In addition, it will help to improve the technologies of ore processing and Au extraction. Here we report an investigation of the chemical state of “invisible” Au in synthetic analogs of natural minerals (As-free pyrite FeS 2 , arsenopyrite FeAsS, and lollingite FeAs 2 ). The compounds were synthesized by means of hydrothermal (pyrite) and salt flux techniques (in each case) and studied by X-ray absorption fine structure (XAFS) spectroscopy in a high-energy resolution fluorescence detection (HERFD) mode in combination with first-principles quantum chemical calculations. The content of “invisible” Au in the synthesized lollingite (800 ± 300 ppm) was much higher than that in arsenopyrite (23 ± 14 ppm). The lowest Au content was observed in zonal pyrite crystals synthesized in a salt flux. High “invisible” Au contents were observed in hydrothermal pyrite (40–90 ppm), which implies that this mineral can efficiently scavenge Au even in As-free systems. The Au content of the hydrothermal pyrite is independent of sulfur fugacity and probably corresponds to the maximum Au solubility at the experimental P-T parameters (450 °C, 1 kbar). It is shown that Au replaces Fe in the structures of lollingite, arsenopyrite, and hydrothermal pyrite. The Au-ligand distance increases by 0.14 A (pyrite), 0.16 A (lollingite), and 0.23 A (As), 0.13 A (S) (arsenopyrite) relative to the Fe-ligand distance in pure compounds. Distortions of the atomic structures are localized around Au atoms and disappear at R > ~4 A. Chemically bound Au occurs only in hydrothermal pyrite, whereas pyrite synthesized without hydrothermal fluid contains only Au°. The heating (metamorphism) of hydrothermal pyrite results in the decomposition of chemically bound Au and formation of Au° nuggets, which coarsen with increasing temperature. Depending on the chemical composition of the host mineral, Au can play a role of either a cation or an anion: the Bader atomic partial charge of Au decreases in the order pyrite (+0.4 e) > arsenopyrite (0) > lollingite (−0.4 e). Our results suggest that other noble metals (platinum group elements, Ag) can form a chemically bound refractory admixture in base metal sulfides/chalcogenides. The content of chemically bound noble metals can vary depending on the composition of the host mineral and ore history.

Gold and silver contents in Noril’sk ore are controlled by the amount of sulphides and bulk Cu grade. Relative concentrations, re-calculated to 100 % sulphide, depend on type of ore: they are higher for disseminated ore than for massive ore and are the highest for low-sulphide platinum ore. Gold occurs mainly as high-fineness Au–Ag alloy in pyrrhotite-rich ore, whereas silver enters chalcopyrite mainly as solid solution. Increase in Cu grade correlates with an increase in the concentration of silver in chalcopyrite. Gold and silver form discrete minerals such as Au–Cu alloys, Au–Ag alloys, tellurides, sulphides, selenides, sulphobismuthides, Ag and Ag–Pd chlorides in Cu-rich ores; they also enter the structures of complex platinum-group minerals. The Au–Ag mineralisation is related to the post-magmatic hydrothermal stage under temperature conditions of 350–50 °C. Silver entered crystallizing chalcopyrite in solid solution in the late-magmatic stage, while all of the gold and the remainder of the silver and some platinum-group elements were transported predominantly as chloride and hydrosulphide complexes in hydrothermal fluids.

The n+-GaN epilayers were synthesised by PA MBE on the SiO2 patterned GaN/c-Al2O3 templates, grown by MOCVD. Formation of the polycrystalline GaN atop of the SiO2 mask during PA MBE was observed. It was found that macroscopic voids at the interface polycrystalline GaN/SiO2/n-GaN template appeared during the PA MBE process. The polycrystalline GaN film was completely removed by etching in hot aqueous KOH solution. Hall measurements have shown that the value of electron concentration in n+-GaN contact layer is about ne∼4.6×1019 cm-3.

AfricaAabsStractThe lateral variation in platinum-group mineral (PGM) assemblages in the magmatic constituents of the Platreef, Bushveld Complex, have been investigated using whole-rock PGE data, scanning electron microscope observations and electron-microprobe data on the PGM. The Platreef comprises a series of mafic–ultramafic sills together with interlayers and xenoliths of metamorphosed sedimentary rocks variably mineralized in PGE, Ni and Cu. In the Central Platreef, the zone with the highest exploitable PGE grade (referred to as PGE reef) occurs at the top of the sequence and is hosted by feldspathic pyroxenite partially replaced by feldspathic harzburgite down-dip. Elevated PGE contents are also related to zones of massive and disseminated chromitites that occur as discontinuous layers within the top reef and at the bottom of the Platreef close to the footwall contact. The harzburgite-hosted reef and chromitites contain PGE mineralization with a high PGE tenor, enriched in Rh and Ru that is taken to indicate proximity to a feeder zone for the Platreef. Textural relationships show that an early succession of laurite ± PGE sulfarsenides ± sperrylite crystallized at a high temperature from a hot magma that was unsaturated with respect to sulfide. Once sulfide saturation was achieved, cooperite and eutectic mixtures of Pt3Fe, Pt sulfide and Fe–Ni–Cu sulfides exsolved first from the sulfide liquid. With decreasing temperature, sperrylite and hollingworthite continued crystallizing across a wide range of conditions from early magmatic to hydrothermal and formed a series of solid solutions and exsolution products. The composition of the PGM assemblages changes along strike within a discrete magmatic layer, and the variation is a function of both the footwall and magmatic rock lithologies. The proportions of Pt–Pd sulfide, Pt–Fe alloy and Rh–Ir–Ru minerals are the most useful in discriminating between different magmatic facies and associated mineralization, whereas Pt–Pd bismuthotellurides are more widespread, and their abundance is dependent on the PGE grade. Early magmatic crystallization of Rh–Ir–Ru-rich PGM distinguishes the PGE profile characteristic of harzburgite and chromitite from the PGE profile typical of the pyroxenite-hosted PGE mineralization that has exsolved from the PGE-rich sulfide liquid.

In addition to traditional degassing of the melt in the subsurface magma chambers of the “dormant” El’brus volcano, alsodegassing through pores and microcracks that occur in the top of magma chambers has also been detected. It is proven by studies of compactness, porosity, and permeability of the rocks. The speeds at which gases (H, He, H2S, CO2, F, and Cl) pass through gneiss and volcanic rocks were estimated. Magma chambers on the ground surface are expressed in stable thermal anomalies revealed by night-time thermal sounding from an NOAA satellite. The presence of magma chambers at depths of 2–12 km was proven by magnetotelluric sounding [Sobisevich et al., 2003] and gravity studies. In addition to occasional “columns” of bright-white fluorescence above the thermal anomalies, aerosol “clouds” and hydrogen flows were detected by lidar and hydrogen surveying [Alekseev et al., 2007, 2009]. Observation at the same sites detected steam outbursts occurring periodically, the snow-ice cover thaws and the smell of hydrogen sulfide is felt. Geochemical characteristics of degassing were studied by snow sampling from up to 1 m deep pits. They were taken within contours of the thermal anomalies, above active fault zones, in the sites of bright-white fluorescence “columns,” and on a new fumarole locality. It is shown that the degassing of melt was accompanied by the gas transporting many elements (Li, B, Si, P, S, Ca, Zn, Pb, Mo, Ba, W, Hg, Ag, U, Th, I, Au, and Pt) in a fine-grained state (a few microns or possibly nanometers) with an active participation of F and Cl. Native platinum, chalcopyrite, halite, sylvite, barite, gypsum, zircon, opal, chlorinated organics, etc. were for the first time discovered in the Mt. El’brus area using electron microscope studies of solid residue from dehydrated snow samples. “Hidden” ore mineralization genetically related to degassing of melts enriched in ore elements may be supposedly found in paleo- and present-day areas of volcanic activity.

The formation conditions and age of the Sukhoi Log gold deposit are considered on the basis of new isotopic-geochemical data. The U-Pb isotopic study of zircon and monazite from high-grade ore and host black slates at the Sukhoi Log deposit was carried out with SIMS technique using a SHRIMP II instrument. Two generations of monazite are distinguished on the basis of optical and scanning electron microscopy, cathodoluminescence, and micro X-ray spectroscopy. Monazite I is characterized by black opaque porphyroblasts with microinclusions of minerals pertaining to metamorphic slates and structural attributes of pre- and synkinematic formation. Monazite II occurs only within the ore zone as transparent crystals practically free of inclusions and as rims around monazite I. The REE contents are widely variable in both generations. Porphyroblastic monazite I differs in low U and Th (0.01–0.7 wt % ThO2) contents, whereas transparent monazite II contains up to 4 wt % ThO2. The average weighted U-Pb isotopic age of monazite I is 650 ± 8.1 Ma (MSWD = 1.6; n = 9) and marks the time of metamorphism or catagenesis. The U-Pb age estimates of synore monazite II cover the interval of 486 ± 18 to 439 ± 17 Ma. Zircons of several populations from 0.5 to 2.6 Ga in age are contained in the ore. Most detrital zircon grains have porous outer rims composed of zircon and less frequent xenotime with numerous inclusions of minerals derived from slates. The peaks of 206Pb/238U ages in the most abundant zircon populations fall on 570 and 630 Ma and correspond to the age of newly formed metamorphic mineral phases. The discordant isotopic ages indicate that the U-ThPb isotopic system of ancient detrital zircons was disturbed 470–440 Ma ago in agreement with isotopic age of monazite II and the Rb-Sr whole -rock isochron age of black slates (447 ± 6 Ma). The new data confirm the superimposed character of the gold-quartz-sulfide mineralization at the deposit. Black shales of the Khomolkho Formation of the Bodaibo Synclinorium were affected by metamorphism over a long period; the peaks of metamorphism and catagenesis are dated at 570 and 650–630 Ma. The high-temperature ore formation was probably related to a hidden granitic pluton emplaced 450–440 Ma ago, that is, 200 Ma later than the events of greenschist metamorphism. Hercynian granitoid magmatism (320–270 Ma) did not exert a substantial effect on the U-Th-Pb isotopic system in accessory minerals from the ore and could not have been a major source of ore-forming fluids.

In the course of examining the regolith samples delivered to the Earth by the Luna 16, Luna 20, and Luna 24 Soviet automatic stations, it was found by means of transmission and scanning electron microscopy that the lunar glasses are in general characterized by micro-heterogeneity exhibited both in their composition and in the structure. Moreover, the condensate glass film on the surface of metallic iron grains plays an isolating and protective role preventing oxidation, including under long-term storage under the Earth’s atmosphere.

New data on accessory mineral phases found in ashes of the erupting Karymskii Volcano as micro-dispersed particles of native metals (Al, Fe, and Zn), intermetallic compounds, sulfides and oxides of iron, and carbonaceous substances are presented. Dominating submicron particles of native Al and Fe are largely confined to coarse-grained ash fractions; this is supported by extensive observations. The co-occurrence of iron oxide and sulfide particles of the same size possibly indicates extremely heterogeneous conditions of gas transport reactions during the eruption. The presence of native metals and carbonaceous compounds may attest to periods of a highly reducing environment in the fluid system supplying Karymskii Volcano.

This paper reports new findings of native molybdenum and iron from Mare Crisium. Native tin, copper, and nickel were detected for the first time in this area of the lunar surface. Native tantalum and indium, intermetallic compound Ta2Mo, and barium titanate Ba2TiO4 were found for the first time on the Moon. The latter two phases were observed for the first time in nature. It was shown that the investigated mineral phases correspond to different genetic groups (preimpact, impact, and postimpact mineral assemblages), which is in general typical of lunar regolith. Based on the morphological features of the identified mineral phases, the history of the formation of impact glass particles was reconstructed in part. They were probably affected by at least three impact events. It was concluded that the peculiar molybdenum geochemical anomaly observed in a group of orange impact glass fragments was not related to the impactor material but rather to the intrinsic enrichment in molybdenum of lunar rocks (target) in the area of the impact events. It was supposed that this enrichment could be of exhalative (fumarole) nature.

Abramovite, a new mineral species, has been found as fumarole crust on the Kudryavy volcano, Iturup Island, Kuriles, Russia. The mineral is associated with pyrrhotite, pyrite, wurtzite, galena, halite, sylvite, and anhydrite. Abramovite occurs as tiny elongated lamellar crystals up to 1 mm long and 0.2 mm wide (average 300 × 50 μ m), which make up chaotic intergrowths in the narrow zone of fumarole crust formed at ∼600°C. Most crystals are slightly striated along the elongation. The new mineral is silver gray, with a metallic luster and black streak. Under reflected light, abramovite is white with a yellowish gray hue. It has weak bireflectance; anisotropy is distinct without color effects. The chemical composition (electron microprobe) is as follows, wt %: 20.66 S, 0.98 Se, 0.01 Cu, 0.03 Cd, 11.40 In, 12.11 Sn, 37.11 Pb, 17.30 Bi; the total is 99.60. The empirical formula calculated on the basis of 12 atoms is Pb1.92Sn1.09In1.06Bi0.89(S6.90Se0.13)7.03. The simplified formula is Pb2SnInBiS7. The strongest eight lines in the X-ray powder pattern [d, A (I)(hkl)] are 5.90(36)(100), 3.90(100)(111), 3.84(71)(112), 3.166(26)(114), 2.921(33)(115), 2.902(16)(200), 2.329(15)(214), 2.186(18)(125). The selected area electron diffraction (SAED) patterns of abramovite are quite similar to those of the homologous cylindrite series minerals. The new mineral is characterized by noncommensurate structure composed of regularly alternated pseudotetragonal and pseudohexagonal sheets. The structure parameters determined from the SAED patterns and X-ray powder diffraction data for pseudotetragonal subcell are: a = 23.4(3), b = 5.77(2), c = 5.83(1) A, α = 89.1(5) °, β = 89.9(7)°, γ = 91.5(7)°, V = 790(8) A3; for pseudohexagonal subcell: a = 23.6(3), b = 3.6(1), c = 6.2(1) A, α = 91(2)°, β = 92(1)°, γ = 90(2)°, V = 532(10) A3. Abramovite is triclinic, space group P(1). The new mineral is named in honor of Russian mineralogist Dmitry Abramov. The type material of abramovite has been deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow.

This paper discusses the results of examining solid geyserite specimens from two present-day Kamchatkan hydrothermal systems: from geysers of the Academy of Sciences and from the Eastern Thermal Field in the caldera of the Uzon Volcano. These studies were performed using methods of IR spectroscopy, XR spectral analysis, and electron microscopy. Three types of geysers were discriminated: underwater, subaerial, and those that originated under the ground surface. All geyserite varieties consist of amorphous opal, and differences between them are caused by the shape, dimensions, and distribution character of silica aggregates. Most examined geyserites enclose silicified microfossil remnants.

The isotopic (δD, δ18O, δ13C, and 87Sr/86Sr) and geochemical characteristics of hydrothermal solutions from the Mid-Atlantic Ridge and the material of brucite-carbonate chimneys at the Lost City hydrothermal field at 30°N, MAR, were examined to assay the role of the major factors controlling the genesis of the fluid and hydrothermal chimneys of the Lost City field. The values of δD and δ18O in fluid samples indicates that solutions at the Lost City field were produced during the serpentinization of basement ultramafic rocks at temperatures higher than 200°C and at relatively low fluid/rock ratios (

Minerals of the system ZnS–CdS formed between 400 and 725°C in active fumaroles at the Kudriavy volcano, Iturup Island, Russia, were studied using scanning electron microscopy with energy dispersion, X-ray diffraction and with an electron microprobe. The composition of these minerals varies widely: Zn 2.46–57.7, Cd 2.38–69.5, Fe 0.72–13.6 wt.%, and thus covers almost the entire ZnS–CdS series. Two types of solid solutions occur: cubic, from 0 to ∼8 mol.% CdS, and hexagonal, from α17 to 100 mol.% CdS, separated by a two-phase transition zone. Three different mechanisms of substitution account for the range of composition: Zn-for-Fe in sphalerite, Zn-for-Cd in wurtzite–greenockite, and Cd-for-Fe in greenockite. The incorporation of Cu and In, up to 2.92 and 4.75 wt.%, respectively, is noted in sphalerite, and up to 1.27 wt.% Cu and 2.75 wt.% In, respectively, in minerals of the wurtzite–greenockite series. Both elements evidently occur as the roquesite component in solid solution. Zinc-rich species are metal-deficient, whereas Cd-rich species are sulfur-deficient. The range of nonstoichiometry in minerals of the system ZnS–CdS studied is in the order of 2.6 at.%, or 0.05 apfu S. We conclude that there is not a complete solid-solution between wurtzite and greenockite in the temperature range studied owing to a phase transition in ZnS and a change in the structure type. Phase relations for the temperature range studied proved to be identical with those established for synthetic compounds. In a fumarolic environment, crystals of Cd-rich sulfides of the system ZnS–CdS precipitate mainly at lower temperatures (400°C) than those of Zn (up to 725°C).

The top part of a lateritic profile including laterites in sensu stricto, bauxites and even zones of clay minerals (кaolinite, halloysite, montmorillonite), contains plentiful traces and products of interaction of a substratum with live organic substance and mortmasses. The surface of laterites is hidden under the cover of trees and bushes and the dense felt like a film weaved from filamentous fungus, roots of vegetation, and fossilized microorganisms. Dying off, they turned into biofilms, which is replaced with biominerals such as gibbsite-Al (OH)3, goethite-HFeO2, hematite-α-Fe2O3, and halloysite-Al4(OH)10[Si4O8](OH)2 · 4H2O. A zone of a biological pedoturbation is completely processed by the burrowing organisms. Earlier it was represented that they make only mechanical impact on rocks. We revealed that burrowing organisms, including worms, mill all minerals of a substratum, passing it through the digestive path, and satiate it with biochemically active substances. It causes dissolution of all minerals except rutile—TiO2. Gibbsite, when passed through a digestive path, recrystallizes and forms surprisingly beautiful and perfect idiomorphic crystals filling the burrows of the worms and covering their walls. We managed to find the paradoxical phenomenon: passing of worms through large (2–4 cm) quartz crystals. The entrances are surrounded with a biofilm similar to slimes and turned into units of crystals of hematite. The described phenomena are established on numerous bauxite deposits of India, Guinea, and Brazil of the modern tropic and on the ancient deposits of Siberia.

Leach resistance of neptunium-doped garnet- and murataite-based ceramics with calculated compositions (in wt.%: 38 Fe2O3, 21 Gd2O3, 16 NpO2, 15 ZrO2, 10 CaO and 55 TiO2, 10 Mn2O3, 10 CaO, 10 NpO2, 5 ZrO2, 5 Al2O3, 5 Fe2O3 respectively was studied. The samples were prepared from pre-activated oxide mixtures by sintering/melting in platinum ampules at 1450 °C. The murataite ceramic is composed of predominant murataite structure phases with five- (5C) and eight-fold (8C) elementary fluorite unit cell and minor rutile (≤5% of total bulk). The garnet-based sample is a polyphase ceramic and consists of major garnet phase, interstitial Fe2O3 and Ca-Fe-phase, and rare grains of (Ca,Zr,Np)O2-phase (cubic solid solution) included in the larger garnet grains. The edge of the garnet grains is enriched with Np as compared with their rim by approximately 1.5−2 times. Np leach-rates were measured using an ANS_16.1 test. Np leach rate from the murataite-based ceramic reduced significantly from 2.44×10-6 g/(cm2 day) within the first 2 hours of leaching to 3.41×10-9 g/(cm2 day) at 672 hours of leaching. At the same time for the garnet-based ceramic corresponding values were 1.49×10-5 g/(cm2 day) and 1.77×10-6 g/(cm2 day), respectively. Higher leach rates at early periods are due to the dissolution of trace phases and Np release from defect surfaces. Leach rate values at later periods of leaching are characteristic of the “equilibrium” leach rate of the element (Np). Much higher Np leaching from the garnet ceramic may be due to 1) higher concentration of Np at the edge of the garnet grains with a relatively low chemical durability; 2) leaching of Np traces from highly soluble minor Np-Zr-rich phase.

The distribution of gold in high-temperature fumarole gases of the Kudryavy volcano (Kurile Islands) was measured for gas, gas condensate, natural fumarolic sublimates, and precipitates in silica tubes from vents with outlet temperatures ranging from 380 to 870°C. Gold abundance in condensates ranges from 0.3 to 2.4 ppb, which is significantly lower than the abundances of transition metals. Gold contents in zoned precipitates from silica tubes increase gradually with a decrease in temperature to a maximum of 8 ppm in the oxychloride zone at a temperature of approximately 300°C. Total Au content in moderate-temperature sulfide and oxychloride zones is mainly a result of Au inclusions in the abundant Fe–Cu and Zn sulfide minerals as determined by instrumental neutron activation analysis. Most Au occurs as a Cu–Au–Ag triple alloy. Single grains of native gold and binary Au–Ag alloys were also identified among sublimates, but aggregates and crystals of Cu–Au–Ag alloy were found in all fumarolic fields, both in silica tube precipitates and in natural fumarolic crusts. Although the Au triple alloy is homogeneous on the scale of microns and has a composition close to (Cu,Ni,Zn)3(Au,Ag)2, transmission electron microscopy (TEM) shows that these alloy solid solutions consist of monocrystal domains of Au–Ag, Au–Cu, and possibly Cu2O. Gold occurs in oxide assemblages due to the decomposition of its halogenide complexes under high-temperature conditions (650–870°C). In lower temperature zones (

Rock displacement in some sites of coal mines is accompanied by changes in the permeability and fil� tering structure of the host rock massif. Transforma� tion of a massif resulting from the appearance of such hydrogeological channels significantly affects the con� ditions and environmental impact of mining; such a channel provides water flow through it and is called a “zone of water conducting displacement cracks” (ZWCDC). The maximal changes take place at the sites of a collapsed mine roof. The operational practice has revealed the ability to keep the minimal increment in through permeability of a dividing rock mass within the ZWCDC and to pre� serve the zones of minimal permeability values within the massif. These conclusions, supplemented with the studies of cracked structures based on equivalent material models, were also reported in [1] and became standard for Russian norms regarding the determination of coal extraction conditions near water objects.

Le gisement de Uzelginsk, dans le secteur sud des Ourales, en Russie, est un exemple d'un amas classique de sulfures massifs a faible degre d'alteration de type Ouralien. Dans le minerai pyritique a Cu-Zn, l'or sepresente de deux facons, soit l'or dit "invisible", dans les sulfures, et l'or dans une expresion mineralogique, par exemple l'or natif ou sous forme de tellurures. Les concentrations de l'or et des elements du groupe du platine (EGP) dans les sulfures de ce gisement ont ete etablies par activation neutronique et par analyses par voie humide, avec determinations chromatographiques et par ICP-MS en parallele. La plupart de l'or est invisible dans la pyrite et la chalcopyrite, entre 0.7 et 20 ppm, et entre 1 et 18 ppm, respectivement. La sphalerite montrant une emulsion d'inclusions tres fines de chalcopyrite contient entre 1.8 et 10.6 ppm Au. La teneur en or de la sphalerite pure, telle que detectee par activation neutronique, se situe entre 0.3 et 3 ppm. La tennantite serait l'hote principal de l'argent; la tennantite a faible teneur en fer (0.1-0.6% Ag, poids) est la variante dominante, tandis que la tennantite riche en Ag (jusqu'a 8.4%) est rare. Nous signalons un enrichissement notable en EGP (jusqu'a 354 ppb Pt, 1220 ppb Pd et 707 ppb Rh) dans les concentres de mineraux lourds des zones mineralisees en or, par rapport aux seuils assez faibles des EGP dans le minerai en general. Le metamorphisme du minerai sulfure a cause la redistribution des metaux autres que le fer, en particulier les metaux precieux, et la formation d'inclusions submicrometriques d'un alliage Au-Ag et de composes de l'or impliquant Te, Se, S, As, Sb et Hg. Certains des EGP pieges dans la pyrite sont donc repartis dans les rejets au cours du traitement; le reste de la fraction EGP a ete precipite par le fluide hydrothermal lors du metamorphisme, et a enrichi les produits de la paragenese tardive. La precipitation des sulfures aeu lieu a des conditions favorables a l'incorporation de l'or en solution solide dans ces mineraux, a une temperature relativement elevee, entre 250° et 380°C. L'association des metaux natifs (or, argent, tellure, rhenium), des tellurures et des sulfosels marque le stade ultime des processus hydrothermaux, entre 165° et 190°C.

During the study of tea-colored impact glass fragments from the sample of lunar regolith delivered to Earth by the Luna 24 automatic station by transmission electron microscopy, the composition variations of the previously described high-carbonaceous film, the presence of at least three composition types of glasses, and unusual nanospherulites with Zn-B-N-O composition were discovered. As a part of a nonuniform high-carbonaceous oxygen-bearing film, sites enriched in either Na, S, Si, or Ca were detected. All these sites, as well as the whole film, are electron-amorphous; however, crystalline graphite was also found. Two types of nanospherulites are composed of amorphous ZnO and regular interstratifications of crystalline ZnO and amorphous boron layers with insignificant participation of adsorbed nitrogen. It is supposed that the formation of zinc-boron nanospherulites was caused by a fast-flowing explosive process and probably was modulated by high-frequency acoustic oscillations in a cloud of evaporated high-temperature ionized gas during the impact event.