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Abstract—Layer-by-layer chemical and mineralogical analysis was carried out to consider the evolution of the Fe-Mn crusts in different tectonic settings in the South Atlantic Ocean. The ferromanganese crust in the rift valley of the Mid-Atlantic Ridge was formed owing to the hydrothermal-hydrogenetic supply. The formation of crust in the Transform Fracture zones of the Angola Basin was related to the halmyrolysis of magmatic rocks and subsequent hydrogenetic supply, which affected the proportions of goethite and vernadite, the Mn/Fe ratio, and Ce anomaly, as well as the content of some elements (Co, Cu, Al, REE). It is revealed that the Fe-Mn crusts taken in the abyssal part and on the seamount top in the Cape Basin are hydrogenetic in origin and consist of vernadite significantly enriched in Co, Ce, Tl, and Pt. The relationship of trace elements with manganese minerals is estimated by leaching of crusts by reagents, which either completely dissolve manganese oxyhydroxides (1 M NH2OH · HCl + 25%CH3COOH) or no (3.5 N H2SO4). It was shown that 100% Co and only 28% Ce are incorporated in the manganese minerals, while REE, Y, Sr, and U form a sorption complex of oxhyhydroxides. To estimate the chemical peculiarities of the hydrogenetic Fe-Mn crusts of the Atlantic Ocean, they were compared with the crusts of the Pacific Ocean. It is shown that the crusts of the Pacific Ocean have higher manganese and cobalt contents. The additional manganese could be derived from a hydrothermal source. [ABSTRACT FROM AUTHOR]

The authors present the results of chemical and mineralogical analyses of urban dusts collected in the spring seasons of 2015 and 2016 in three different parks of the Cracow agglomeration. The parks are located in the city centre, in the Nowa Huta industrial district and in a new housing development situated around 9 km west of the city centre. Mineralogical instrumental analyses included the SEM, FTIR and XRD methods and revealed that the dusts of Cracow are highly amorphous and contain significant amounts of hydrocarbons, whereas quartz, feldspars, kaolinite and gypsum are their crystalline phases. Chemical analyses were carried out using the ICP-MS method on aqua regia extracts of the starting samples. The contents of selected toxic elements are: As 5–123; Cd 1–14; Pb 56–258; Zn 486–1891 mg/kg and Fe 0.74–4.02 wt%. The health risk of these elements imposed on the residents of Cracow frequently visiting the three urban parks was assessed on the basis of the health quotient index HQ. At its values exceeding 1, adverse health effects are probable in humans. The HQ values calculated for As and Tl contained in the Cracow Park dusts in the case of adults are 3.42E−01 and 3.00E−01, respectively. They are significantly higher (one order of magnitude) in the case of children 3.19E+00 and 2.27E+00, respectively. [ABSTRACT FROM AUTHOR]

The new mineral roymillerite PbMg(SiAlO)(SiO)(BO)(CO)(OH)O, related to britvinite and molybdophyllite, was discovered in a Pb-rich assemblage from the Kombat Mine, Grootfontein district, Otjozondjupa region, Namibia, which includes also jacobsite, cerussite, hausmannite, sahlinite, rhodochrosite, barite, grootfonteinite, Mn-Fe oxides, and melanotekite. Roymillerite forms platy single-crystal grains up to 1.5 mm across and up to 0.3 mm thick. The new mineral is transparent, colorless to light pink, with a strong vitreous lustre. Cleavage is perfect on (001). Density calculated using the empirical formula is equal to 5.973 g/cm. Roymillerite is optically biaxial, negative, α = 1.86(1), β ≈ γ = 1.94(1), 2 V (meas.) = 5(5)°. The IR spectrum shows the presence of britvinite-type tetrahedral sheets, $${\text{CO}}_{3}^{2 - }$$ , $${\text{BO}}_{3}^{3 - }$$ , and OH groups. The chemical composition is (wt%; electron microprobe, HO and CO determined by gas chromatography, the content of BO derived from structural data): MgO 4.93, MnO 1.24, FeO 0.95, PbO 75.38, BO 0.50, AlO 0.74, CO 5.83, SiO 7.90, HO 1.8, total 99.27. The empirical formula based on 83 O atoms pfu (i.e. Z = 1) is PbMgMnFeBAlCSiHO. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is triclinic, space group P $$\bar{1}$$ , with a = 9.315(1), b = 9.316(1), c = 26.463(4) Å, α = 83.295(3)°, β = 83.308(3)°, γ = 60.023(2)°, V = 1971.2(6) Å. The crystal structure of roymillerite is based built by alternating pyrophyllite-type TOT-modules Mg(OH)[(Si,Al)O] and I-blocks Pb(OH)O(CO)(BO,SiO). The strongest lines of the powder X-ray diffraction pattern [ d, Å (I, %) ( hkl)] are: 25.9 (100) (001), 13.1 (11) (002), 3.480 (12) (017, 107, −115, 1-15), 3.378 (14) (126, 216), 3.282 (16) (−2-15, −1-25), 3.185 (12) (−116, 1-16), 2.684 (16) (031, 301, 030, 300, 332, −109, 0-19, 1-18), 2.382 (11) (0.0.-11). Roymillerite is named to honor Dr. Roy McG. Miller for his important contributions to the knowledge of the geology of Namibia. [ABSTRACT FROM AUTHOR]

Acid-base accounting (ABA) is a static test used to evaluate pre-mining drainage quality of ores with interpretations based on a reference 3-data point model. The method is often complemented with a kinetic test to ensure certainty of results. The challenges associated with both methods compel companies to rely on only the ABA test, thereby compromising on the long-term drainage quality. This paper validates a proposed 4-data point model that was used to establish a 20% increase in the alkaline amendment of ores at the AngloGold Ashanti Obuasi Mine in Ghana. The validation was done using model limits, the robustness of coefficient of determination and model factor sequence variation. Acidification trends and mineralogical data evaluation of tailings were used to characterise pH buffer trends in mine drainage. The modified 4-data point model, which incorporates a vital kinetic test factor into the ABA model, provides a criterion for the adjustment of carbonate amendment value to improve acid neutralisation in the drainage; this would reduce (1) cost of experimentation, (2) turnaround time for analyses, (3) complexities associated with both test methods. From the XRD data, alunite and goethite are present in tailings to provide sustained pH buffering in drainage beyond the scope of the modified model, while the characterised pH buffer trend could be used for monitoring drainage quality. [ABSTRACT FROM AUTHOR]

Changes in mineralogical, chemical, and mechanical properties of a rock mass during the weathering process allow calibrating the degree of weathering. Based on those properties, various weathering indices can be used as tools for this purpose. This study focuses on using chemical weathering indices that represent the chemical behaviour of a rock mass and their relationship with other properties for better evaluation of weathering grades. Metamorphic rocks that undergo weathering due to both chemical and operational means at Smanalawewa hydropower station in Sri Lanka, where tropical climate exists, were selected for this study. Among the chemical weathering indices calculated, the product index, Ruxton ratio, silica-titania index, alumina-titania index, chemical weathering index by Sueoka, and S/SAF index change consistently with progressive weathering. They correlate well with the weathering potential index, Miura index, bulk density, and point load strength. Among the six indices mentioned, the product index, Ruxton ratio, silica-titania, and alumina-titania indices have been recognised as better measures to classify metamorphic rocks in Sri Lanka for chemical means. Since there is a good correlation with physical and mechanical properties, the chemical weathering index and S/SAF index also appear to be better indices in the same context. Weathering potential, Parker, and modified weathering potential indices, which are widely used, show minor fluctuations during weathering. On the contrary, the chemical index of weathering and chemical index of alteration fluctuate with progressive weathering. These changes exhibit the influence of bulk mineral composition of the rock, where aluminium rich minerals are present. This study clearly shows that chemical weathering indices of a particular rock mass are more reliable when they correlate well with physical and mechanical properties. [ABSTRACT FROM AUTHOR]

At present, the dealkalization and comprehensive utilization of red mud is a worldwide problem. Studies on the settling performance and phase transformation of red mud by HCl, CaO, and HO leaching are limited. In this study, the characteristics of red mud were systematically analyzed. The average sizes of graded and initial red mud were 4.11 and 9.20 μm, respectively. X-ray diffraction (XRD), X-ray fluorescence spectra (XRF), and thermogravimetry-differential scanning calorimetry (TG-DSC) results indicated the different mineralogical phases, composition, and thermal behavior. The addition of HCl could neutralize the alkalization in the red mud slurry, and CaO could replace the Na and K. Notably, the pH of the red mud slurry had no obvious change with the increase in water washing times in a certain pH. Interestingly, soluble Al and Fe were not detected in the HCl-red mud and CaO-red mud. In addition, the settling ratio was used to express the settling performance of the red mud slurry. Their interaction mechanisms were proposed, which may include phase transformation and the changing of the size and surface area. The research provided a better understanding of the phase transformation and settling performance in the treatment of red mud by HCl, CaO, and HO leaching. [ABSTRACT FROM AUTHOR]

Metacarbonates of the Moldanubian Zone (Bohemian Massif, Czech Republic) were studied to obtain qualitative and quantitative mineralogical-petrographic as well as stable isotopic data for the purpose of stone provenance studies, potentially applicable in material research studies of cultural heritage artefacts. Twenty-six samples from twelve different historical quarries, as well as two samples from historical artefacts, were analysed by both mineralogical-petrographic and geochemical methods including: polarizing microscopy, cathodoluminescence, scanning electron microscopy with microanalysis, petrographic image analysis, powder X-ray diffraction, and isotope ratio mass spectrometry. The petrographic characteristics allowed for the discrimination of groups of (1) calcitic marbles, (2) dolomitic marbles, and (3) carbonate-silicate rocks. These groups exhibit characteristic features such as (1) the presence/abundance of major rock-forming minerals, (2) grain geometric characteristics (specifically, mean carbonate grain size and index of grain size homogeneity), and (3) the presence of specific accessory phases. The content of non-carbonate minerals, some rock fabric parameters, as well as the carbon and oxygen isotope data exhibited significant variability, even within a single quarry in the case of some impure marbles and carbonate-silicate rocks. Although the carbon and oxygen isotopic ranges displayed overlaps among the quarries studied, the isotopic signatures throughout the Moldanubian Zone allowed for discrimination of a group of white calcitic marbles with high carbon and oxygen depletion, as well as white dolomite-calcitic marble with higher carbon isotope values when compared with other marble resources of the Bohemian Massif. A combination of the isotopic signature with detailed mineralogical-petrographic characteristics seems to provide sufficient information for discrimination of the Moldanubian marbles from one another. The provenance of the Vrchotovy Janovice artefact is very probably from the Rabí quarry, among the Moldanubian marbles. The provenance of the artefact from the Prague Klementinum was not definitively assigned; however, the Nehodiv quarry was considered its probable source locality. [ABSTRACT FROM AUTHOR]

Mineralogical and chemical investigations (<2μm clay separates) of shale samples from the Neogene-age Surma Group obtained from four wells (Habiganj-11, Shahbazpur-1, Titas-11, Titas-15) in the Bengal basin, Bangladesh, were carried out in order to reveal the clay mineral composition as reservoir exploration and exploitation requires a good understanding of the clay minerals. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-Ray fluorescence spectrometry (XRF). Mineralogically, the sub-surface Surma Group shales comprise predominantly quartz, plagioclase, illite, chlorite, kaolinite, with lesser amounts of K-feldspar, dolomite and smectite, and minor to trace amounts of calcite, siderite and pyrite. The chemical composition of the <2 μm clay separates also suggests an illite and chlorite-rich composition. With increasing burial depth, the Surma Group shales are enriched in illite. The gradual decreasing of the smectite clays with depth and ultimate disappearance at greater depths (≥ 3000 m) may have been responsible for the presence of the diagenetic illite. Based on the mineralogical composition it is most likely that the illite-chlorite associations together with quartz and feldspar were predominantly detrital in origin and thus reflect the presence of a rapidly-rising source terrain not subjected to intense weathering. [ABSTRACT FROM AUTHOR]

Data on the mineralogical composition of clay in soils of solonetzic complexes of the Priobskoe Plateau and the Kulunda and Baraba lowlands have been generalized. The parent materials predominating in these regions have loamy and clayey textures and are characterized by the association of clay minerals represented by dioctahedral and trioctahedral mica-hydromica, chlorite, kaolinite, and a number of irregular interstratifications. They differ in the proportions between the major mineral phases and in the qualitative composition of the minerals. Mica-hydromica and chlorites with a small amount of smectitic phase predominate on the Priobskoe Plateau and in the Kulunda Lowland; in the Baraba Lowland, the portion of mica-smectite interstratifications is higher. An eluvial-illuvial distribution of clay fraction in solonetzes is accompanied by the acid-alkaline destruction and lessivage of clay minerals, including the smectitic phase in the superdispersed state. This results in the strong transformation of the mineralogical composition of the upper (suprasolonetzic) horizons and in the enrichment of the solonetzic horizons with the products of mineral destruction; superdispersed smectite; and undestroyed particles of hydromica, kaolinite, and chlorite from the suprasolonetzic horizons. A significant decrease in the content of smectitic phase in the surface solodic horizons of solonetzic complexes has different consequences in the studied regions. In the soils of the Priobskoe Plateau and Kulunda Lowland with a relatively low content (10-30%) of smectitic phase represented by chlorite-smectite interstratifications, this phase virtually disappears from the soils (there are only rare cases of its preservation). In the soils of the Baraba Lowland developed from the parent materials with the high content (30-50%) of smectitic phase represented by mica-smectite interstratifications, the similar decrease (by 10-20%) in the content of smectitic phase does not result in its complete disappearance. However, the smectitic phase acquires the superdispersed state and the capacity for migration. [ABSTRACT FROM AUTHOR]

Deep saline aquifers in sedimentary basins are considered to have the greatest potential for CO geological storage in order to reduce carbon emissions. CO injected into a saline sandstone aquifer tends to migrate upwards toward the caprock because the density of the supercritical CO phase is lower than that of formation water. The accumulated CO in the upper portions of the reservoir gradually dissolves into brine, lowers pH and changes the aqueous complexation, whereby induces mineral alteration. In turn, the mineralogical composition could impose significant effects on the evolution of solution, further on the mineralized CO. The high density of aqueous phase will then move downward due to gravity, give rise to 'convective mixing,' which facilitate the transformation of CO from the supercritical phase to the aqueous phase and then to the solid phase. In order to determine the impacts of mineralogical compositions on trapping amounts in different mechanisms for CO geological storage, a 2D radial model was developed. The mineralogical composition for the base case was taken from a deep saline formation of the Ordos Basin, China. Three additional models with varying mineralogical compositions were carried out. Results indicate that the mineralogical composition had very obvious effects on different CO trapping mechanisms. Specific to our cases, the dissolution of chlorite provided Mg and Fe for the formation of secondary carbonate minerals (ankerite, siderite and magnesite). When chlorite was absent in the saline aquifer, the dominant secondary carbon sequestration mineral was dawsonite, and the amount of CO mineral trapping increased with an increase in the concentration of chlorite. After 3000 years, 69.08, 76.93, 83.52 and 87.24 % of the injected CO can be trapped in the solid (mineral) phase, 16.05, 11.86, 8.82 and 6.99 % in the aqueous phase, and 14.87, 11.21, 7.66 and 5.77 % in the gas phase for Case 1 through 4, respectively. [ABSTRACT FROM AUTHOR]

The object studied is Shaimerden oxidized zinc ore deposit containing zinc, lead, copper, iron, calcium, magnesium, aluminum, manganese and silicon. Chemical and mineralogical composition of the ore are investigated. It is established that ore coarse fraction contains more zinc carbonate and less zinc silicate compared with undersize particles. In addition, ore coarse fraction is richer in residual forms (nontronite, sphalerite) hardly soluble in sulphuric acid solution. Thermodynamic analysis of probable transformations during leaching is carried out, kinetics of coarse fraction and undersize particles of ore leaching is studied, and Pourbaix diagrams are plotted for analysis of processes occurring at a phase interface during leaching of oxidized zinc ore. Studies for stripping oxidized zinc ore are carried out on large (-20+1 mm) and small (-1+0 mm) fractions. Optimum leaching parameters are established for fine and coarse ore fractions: sulfuric acid concentration and process temperature and duration (C(HSO) = 150-160 g/liter, temperature 60°C, leaching time 60 min). Dependences are determined for the degree of zinc extraction into solution on sulphuric acid concentration, temperature, and leaching duration for coarse and fine ore factions. [ABSTRACT FROM AUTHOR]

Large volumes of borate resources exist in Bolivia, with the most important being the Rio Grande deposit, located close to the Salar of Uyuni. Here, borates occur in beds and lenses of variable thickness. A mineralogical and thermal characterization of borates from the Rio Grande was made using XRD, FTIR, SEM and DTA-TG. The deposit is mainly composed of BO, CaO and NaO, with minor contents of MgO and KO. Some outcrops are constituted by pure ulexite aggregates (NaCaBO(OH)·5HO) of fibrous morphology; in other cases, gypsum, calcite and halite also are present. The thermal decomposition of ulexite begins at 70 °C and proceeds up to ~550 °C; this decomposition is attributed to dehydration and dehydroxylation processes in three steps: at 115, 150-300 and 300-550 °C. The last mass loss of 1-5 % at 800 °C is due to the removal of Cl from the decomposition of halite. DTA shows two endothermic events related to the removal of water; in the first, NaCaBO(OH)·5HO evolved from NaCaBO(OH)·3HO, at 108-116 °C; in the second, NaCaBO(OH) is formed at 180-185 °C and NaCaBO (amorphous) is formed at 300-550 °C. The exothermic peak (658-720 °C) is related to the crystallization of NaCaBO. A small endothermic peak appears due to the halite melting. Later, another endothermic event (821-877 °C) appears, which is related to the decomposition of NaCaBO into a crystalline phase of CaBO and amorphous NaBO. The XRD pattern evidences that, at 1050 °C, CaBO still remains in the crystalline state. [ABSTRACT FROM AUTHOR]

A new mineral ferricoronadite with the simplified formula Pb(Mn Fe )O was discovered in the orogenetic zone related to the 'Mixed Series' metamorphic complex near the Nežilovo village, Pelagonian massif, Republic of Macedonia. Associated minerals are franklinite, gahnite, hetaerolite, roméite, almeidaite, Mn-analogue of plumboferrite, zincohögbomite analogue with Fe > Al, zincochromite, Zn-bearing talc, Zn-bearing muscovite, baryte, quartz and zircon. Ferricoronadite is a late hydrothermal mineral forming veinlets up to 8 mm thick in granular aggregate predominantly composed by zinc-dominant spinels. The new mineral is opaque, black, with brownish black streak. The luster is strong submetallic to metallic. The micro-indentation hardness is 819 kg/mm. Distinct cleavage is observed on (100). Ferricoronadite is brittle, with uneven fracture. The density calculated from the empirical formula is 5.538 g/cm. In reflected light, ferricoronadite is light gray. The reflectance values [ R / R , % ( λ, nm)] are: 28.7/27.8 (470), 27.6/26.6 (546), 27.2/26.1 (589), 26.5/25.5 (650). The IR spectrum shows the absence of HO and OH groups. According to the Mössbauer spectrum, all iron is trivalent. The Mn K-edge XANES spectroscopy shows that Mn is predominantly tetravalent, with subordinate Mn. The chemical composition is (wt%; electron microprobe, Mn apportioned between MnO and MnO based on the charge-balance requirement): BaO 5.16, PbO 24.50, ZnO 0.33, AlO 0.50, MnO 9.90, FeO 11.45, TiO 4.19, MnO 44.81, total 100.84. The empirical formula based on 8 cations Mn + Fe + Ti + Al + Zn pfu is PbBa(MnFeMnTiAlZn)O. The crystal structure was determined using single-crystal X-ray diffraction data. The new mineral is tetragonal, space group I4/ m, a = 9.9043(7), c = 2.8986(9) Å, V = 284.34(9) Å, Z = 1. In ferricoronadite, double chains of edge-sharing (Mn, Fe, Ti)-centered octahedra are connected via common vertices to form a pseudo-framework with tunnels containing large cations Pb and Ba. The strongest lines of the powder X-ray diffraction pattern [ d, Å ( I, %) ( hkl)] are: 3.497 (33) (220), 3.128 (100) (−130, 130), 2.424 (27) (−121, 121), 2.214 (23) (240, −240), 2.178 (17) (031), 1.850 (15) (141, −141), 1.651 (16) (060), 1.554 (18) (−251, 251). Ferricoronadite is named as an analogue of coronadite Pb(Mn Mn )O with the major charge-compensating octahedral cation Fe instead of Mn. [ABSTRACT FROM AUTHOR]

The northwestern Guizhou in the Yangtze Craton of south China has a tremendous potential of shale gas resource. In this paper, we present results from major and trace elements, total organic carbon, mineralogical composition analysis and petrophysical parameters to characterise shale weathering features. Further, the differences of black shale between underground and outcrops have also been presented to examine the changes of black shale after weathering. Our results show that the trace elements of shale have varying degrees of loss in the weathering leaching process, both in Niutitang shale and Longmaxi shale, the loss of B, V, Ni, Cu, Zn and Ba is obvious, but the element migration quantity in the former is greater than in the latter. Decomposition of minerals such as pyrite, feldspar and calcite result in the leaching of Na, Ca, Mg and Fe. The loss rate of total organic carbon (TOC) in black shales ranges from 18% to 70% with an average of 43%; moreover, the loss of organic carbon in samples with high TOC content is larger than in those samples with low TOC content. Results following the testing of porosity and permeability show that porosity increases significantly after weathering but permeability changes little. Furthermore, the increment of porosity is greater in the Niutitang shale (with more sulphide minerals) than in the Longmaxi shale, suggesting that the oxidation of sulphide minerals may have led to the formation of an acidic environment, causing the other minerals in the black shale to weather more quickly, thus resulting in increased porosity. The content of clay minerals in the core samples is slightly lesser than the outcrop samples, but the TOC content in the core samples is greater and has a larger specific surface area. This suggest that the TOC content played a decisive role on the specific surface area of shale. In addition, changes in the black shale caused by the weathering process mainly depend on the mineral composition and the TOC content in shale. In this study, we try to establish relations between outcrop samples and core samples, in order to better understand the underground characteristics of shale reservoir. [ABSTRACT FROM AUTHOR]

Mineralogical composition of geological formations has a great effect on the groundwater quality, as it may result in the generation of harmful chemicals in groundwater leading to deterioration of concrete lining of tunnels. The present study investigates the future problems of the corrosiveness of concrete due to groundwater chemistry along Tabriz metro line 2 (TML2) in Iran. Having a length of 22 km, this subway entirely passes in an underground route along a general W-E direction. According to the geological map of the area and field survey, east part of the tunnel is excavated within marl-shale deposits with gypsum, and anhydrite and coal belonging to upper red formation and Baghmisheh formation. These formations have the greatest impact on deterioration of groundwater quality, as the values of EC, TDS, SO, and Cl significantly increased in TML2 at the east part. In this regard, EC, Cl, and SO increased roughly from 502 to 29,700 µs cm, from 71 to 5753 ppm, and from 51 to 8309 ppm, respectively, while TDS increased to 26,200 ppm. Marls existing in the study area including yellow, green, and gray/black marls, have the potential of corrosion because of containing aggressive substances, such as sulfate, chloride, and a high percentage of organic matter. Thus, it can be concluded that the groundwater in the east part is highly aggressive, and deterioration of concrete lining of the tunnel is expected in the near future. [ABSTRACT FROM AUTHOR]

Graphite is found dispersed in high-grade metapelitic rocks of the Anatectic Complex of Toledo (ACT) and was mined during the mid twentieth century in places where it has been concentrated (Guadamur and la Puebla de Montalbán mines). Some samples from these mines show variable but significant alteration intensity, reaching very low-T hydrothermal (supergene) conditions for some samples from the waste heap of the Guadamur site (<100 °C and 1 kbar). Micro-Raman and XRD data indicate that all the studied ACT graphite is of high crystallinity irrespective of the degree of hydrothermal alteration. Chemical differences were obtained for graphite δC composition. ACT granulitic graphite shows δC values in the range of −20.5 to −27.8 ‰, indicating a biogenic origin. Interaction of graphite with hydrothermal fluids does not modify isotopic compositions even in the most transformed samples from mining sites. The different isotopic signatures of graphite from the mining sites reflect its contrasted primary carbon source. The high crystallinity of studied graphite makes this area of central Spain suitable for graphitic exploration and its potential exploitation, due to the low carbon content required for its viability and its strategic applications in advanced technologies, such as graphene synthesis. [ABSTRACT FROM AUTHOR]

Effects of impurities (SO, NO and O) from the extraction processes of the power plants in the scCO fluids are studied with an experimental approach combining geochemical alteration in high p, medium T autoclaves, compressional tests in a heated triaxial testing device as well as geochemical and mineralogical analyses before and after the influences of distinct scCO fluids on 140 × 70 mm sized samples of reservoir sandstones from the North German Basin (with carbonate cementation, silicate cementation and a combined silicate-carbonate cementation). On the background of variable lithological compositions, the attempt was made to normalize the scattering geomechanical data by the pure CO-behavior measurement data to achieve a direct impression of any differences due to the impurities. Changes in the chemical composition of the saline fluids were systematically measured during the scCO alteration experiments in the autoclave systems at distinct pT conditions. The development of the silica concentrations and of the pH value in the fluid solution during alteration showed a clear dependency on the fluid composition. Through systematical analysis of changes on the mineral surfaces using SEM microscopy images before and after scCO + impurities alteration experiments or triaxial compression tests, corrosion effects were detected, but no differences which could be directly related to differences in the fluid composition could be identified. In all the types of sandstones, visible or measurable changes on mineral surfaces and pore fluid composition, respectively, take place as an interaction of rock with fluids of scCO with and without impurities. Changing deformability and compressive strength of the rocks are the most apparent consequences due to these compositional changes. It is supposed that the chemical fluid differences are responsible for these changes. Also a specific distribution of the different fluids in the ambient pore space is indicated with even undetected consequences for the fluid influence on stress transmission and distribution within the grain structure. All work was performed within the project 'CO purity for capture and storage (COORAL)' supported by the German Federal Ministry for Economic Affairs and Energy. [ABSTRACT FROM AUTHOR]

In Covasna area from Romania, some heterogeneous metallurgical waste (slag) has been identified by archaeological excavations. This paper presents the analytical investigations of such an iron material, performed by inductively coupled plasma atomic emission spectrometry, energy dispersive X-ray fluorescence, X-ray diffraction and thermal analyses. From mineralogical point of view, the samples collected from the artefact are dominated by fayalite and almandine. Also, the slag has an iron-dominated composition, with magnetite, tridymite and quartz, too. Meanwhile, the ratios SiO/AlO and KO/MgO are rather low (1.2-2), these being further proof for assigning the sample to a slag one. Because CaO, MgO, and KO have low concentrations, it may be concluded that another material has been used to melt the mineral than the usually used wood and coal, most probably charcoal. The presence of vanadium is a proof of iron production from magnetite ore or hematite. Glass factor (G factor) of the monolithic samples has low values, corresponding to almandine-fayalite-tridymite-glass composite. The performed thermal analyses materialized into valuable information regarding the composition of the analysed materials. [ABSTRACT FROM AUTHOR]

The introduction of wastes from the production of foam glass into clay-containing mixtures promotes the formation of a strong porous fragmentary structure in a composite material. The influence of textural and structural characteristics of composites on their physical and mechanical properties is examined. [ABSTRACT FROM AUTHOR]

Presents detailed mineralogical and phase characteristics of trachybasalt, mugearite, trachydacite, and comendite samples from Nemrut Volcano in eastern Turkey, estimates of mineral formation conditions, and analyses of glasses from melt inclusions in olivine and rock matrix. Based on the analysis of the mineralogy and geochemistry of the rocks and mass balance calculations, the most feasible models of mugearitic and benmoreitic magma formation were proposed. The crystallization conditions of olivine, feldspar, and Fe-Ti oxides (titanomagnetite and ilmenite) were determined. Titanomagnetite and ilmenite were formed under the following conditions: 960-922°C, $\Delta \log _{f_{O_2 } } $ NNO from −1.54 to −0.73 in the mugearite, 940-890°C, $\Delta \log _{f_{O_2 } } $ NNO from −1.46 to −0.79 in the benmoreite, 870-845°C and $\Delta \log _{f_{O_2 } } $ NNO from −2.11 to −1.82 in the trachydacite, and 705-667°C, $\Delta \log _{f_{O_2 } } $ NNO from −2.48 to −2.18 in the comendite. Feldspars crystallized at 1150-950°C in the trachybasalt, 920-800°C in the benmoreite, and 760-720°C in the comendite. The temperature of melt inclusion entrapment in olivine ( Fo) from the trachybasalt, mugearite, benmoreite, and trachydacite was estimated as 1270-860°C. Except for the trachybasalt, partly resorbed phenocrysts and/or xenocrysts were observed in all the samples, which indicates their formation under nonequilibrium conditions. Mass balance calculations for rock compositions (FC, AFC, and FCA models) and mineralogical observations suggest that the magmas or melts of mugearitic and benmoreitic compositions could be produced by the fractional crystallization of trachybasaltic melt (mass fraction of melt F = 0.63-0.79), which assimilated a small amount of crustal material, as well as by the mixing of trachybasaltic ( F = 0.16-0.45) and trachydacitic ( F = 0.45-0.58) magmas in the presence of excess olivine, plagioclase, magnetite, and apatite (totaling 10-24 wt %). Pre-caldera comendites are enriched in Fe (4-5 wt % FeO) and trace elements compared with post-caldera comendites (2-3 wt % FeO). The analysis of the geochemical data and mass balance calculations indicated that the post-caldera benmoreitic magma could not be produced by the fractionation of trachybasaltic melt. This magma and corresponding post-caldera benmoreites have anomalously low Ba (46-54 ppm) and Sr (203-269 ppm) contents, which could not be obtained in the models of fractional crystallization of trachybasaltic melt accompanied by crustal assimilation. The compositions of post-caldera benmoreites and hybrid rocks of trachydacitic composition showing evidence for magma mixing (presence of xenocrysts from benmoreitic and comenditic magmas and compositionally variable glasses) were best reproduced by mixing trachybasaltic ( F = 0.7-0.5) and low-Fe comenditic ( F = 0.3-0.5) melts. Magma chambers with low-Fe comenditic melts appeared during the post-caldera stage owing to the fractional crystallization of pre-caldera trachytic and trachyte-comenditic magmas. Perhaps, the repeated eruptions of low-Fe comendites in the caldera and 'rift' zone of Nemrut Volcano were related to the injection of benmoreitic magma into these chambers. [ABSTRACT FROM AUTHOR]

The characterization of the quality and storage capacity of geological underground reservoirs is one of the most important and challenging tasks for the realization of carbon capture and storage (CCS) projects. One approach for such an evaluation is the upscaling of data sets achieved by laboratory CO batch experiments to field scale. (Sub)-microscopic, petrophysical, tomographic, and chemical analytical methods were applied to reservoir sandstone samples from the Altmark gas field before and after static autoclave batch experiments at reservoir-specific conditions to study the relevance of injected CO on reservoir quality. These investigations confirmed that the chemical dissolution of pore-filling mineral phases (carbonate, anhydrite), associated with an increased exposure of clay mineral surfaces and the physical detachment and mobilization of such clay fines (illite, chlorite) are most appropriate to modify the quality of storage sites. Thereby the complex interplay of both processes will affect the porosity and permeability in opposite ways-mineral dissolution will enhance the rock porosity (and permeability), but fine migration can deteriorate the permeability. These reactions are realized down to ~µm scale and will affect the fluid-rock reactivity of the reservoirs, their injectivity and recovery rates during CO storage operations. [ABSTRACT FROM AUTHOR]

We examine the fine-scale variations in mineralogical composition, geochemical alteration, and texture of the fault-related rocks from the Phase 3 whole-rock core sampled between 3,187.4 and 3,301.4 m measured depth within the San Andreas Fault Observatory at Depth (SAFOD) borehole near Parkfield, California. This work provides insight into the physical and chemical properties, structural architecture, and fluid-rock interactions associated with the actively deforming traces of the San Andreas Fault zone at depth. Exhumed outcrops within the SAF system comprised of serpentinite-bearing protolith are examined for comparison at San Simeon, Goat Rock State Park, and Nelson Creek, California. In the Phase 3 SAFOD drillcore samples, the fault-related rocks consist of multiple juxtaposed lenses of sheared, foliated siltstone and shale with block-in-matrix fabric, black cataclasite to ultracataclasite, and sheared serpentinite-bearing, finely foliated fault gouge. Meters-wide zones of sheared rock and fault gouge correlate to the sites of active borehole casing deformation and are characterized by scaly clay fabric with multiple discrete slip surfaces or anastomosing shear zones that surround conglobulated or rounded clasts of compacted clay and/or serpentinite. The fine gouge matrix is composed of Mg-rich clays and serpentine minerals (saponite ± palygorskite, and lizardite ± chrysotile). Whole-rock geochemistry data show increases in Fe-, Mg-, Ni-, and Cr-oxides and hydroxides, Fe-sulfides, and C-rich material, with a total organic content of >1 % locally in the fault-related rocks. The faults sampled in the field are composed of meters-thick zones of cohesive to non-cohesive, serpentinite-bearing foliated clay gouge and black fine-grained fault rock derived from sheared Franciscan Formation or serpentinized Coast Range Ophiolite. X-ray diffraction of outcrop samples shows that the foliated clay gouge is composed primarily of saponite and serpentinite, with localized increases in Ni- and Cr-oxides and C-rich material over several meters. Mesoscopic and microscopic textures and deformation mechanisms interpreted from the outcrop sites are remarkably similar to those observed in the SAFOD core. Micro-scale to meso-scale fabrics observed in the SAFOD core exhibit textural characteristics that are common in deformed serpentinites and are often attributed to aseismic deformation with episodic seismic slip. The mineralogy and whole-rock geochemistry results indicate that the fault zone experienced transient fluid-rock interactions with fluids of varying chemical composition, including evidence for highly reducing, hydrocarbon-bearing fluids. [ABSTRACT FROM AUTHOR]

Asbestiform minerals, namely serpentine (chrysotile) and amphiboles (tremolite-actinolite) as well as others of fibrous habit (sepiolite) from Argentine deposits were characterised to assess their biological hazard. Materials currently used as asbestos substitutes were also assessed (glass fibre and ceramic fibre). Studies with laboratory animals were conducted. Sixty mice (30 females and 30 males), 8 weeks old, were used following the good practices in the care and handling of laboratory animals. They were split into six groups of ten mice each (5 females and 5 males), designated as control, tremolite, glass fibre, chrysotile, sepiolite and ceramic fibre, and were exposed by inhalation to these previously ground materials. The animals were examined throughout the experiments to see how they responded to the inhaled substances to establish the effects of inhalation at the time of exposure and once they had been killed. The respiratory tract (trachea, bronchi and lungs) of the animals exposed to the different materials was examined in tissue sections. Differences in the amount of connective tissue in the lungs and the presence of alveolar macrophages were observed in the animals exposed to tremolite, chrysotile and sepiolite, as compared to the control group. It was concluded that, of all the materials used, amphiboles caused greater damage and an incipient development of carcinogenesis. The other ones, especially chrysotile, produced connective tissue thickening. [ABSTRACT FROM AUTHOR]

The chemical-mineralogical composition of local leucocratic granites from the Kargaliiskoe ore deposit was studied. Petrographic and scanning electron microscopic analyses were used to investigate the microstructure. Leucocratic granite consists mainly of the minerals microcline, albite, and quartz; it is a valuable nonmetalliferous ceramic raw material, which can replace imported deficit feldspar materials use in ceramic bodies. [ABSTRACT FROM AUTHOR]

Zircons extracted from the nepheline and feldspar crystals of miaskitic and feldspar pegmatites, respectively, are analyzed with the SHRIMP method for the first time. The early (Silurian) zircons coincide in age (432 Ma), composition, and mineralogical peculiarities with early zircons from miaskites. It is concluded that the pegmatite melt is a derivative of the miaskite melt. Permian (240-260 Ma) metamorphic zircons are widespread in pegmatites and miaskites. Zircons from these rocks are characterized by genetic commonality. [ABSTRACT FROM AUTHOR]

A study was conducted to understand the hydrogeological processes dominating in the North 24 Parganas and South 24 Parganas based on representative 39 groundwater samples collected from selected area. The abundance of major ions was in the order of Ca > Na > Mg > K > Fe for cations and HCO > PO > Cl > SO > NO for anions. Piper trilinear diagram was plotted to understand the hydrochemical facies. Most of the samples are of Ca-HCO type. Based on conventional graphical plots for (Ca + Mg) vs. (SO + HCO) and (Na + K) vs. Cl, it is interpreted that silicate weathering and ion exchange are the dominant processes within the study area. Previous studies have reported quartz, feldspar, illite, and chlorite clay minerals as the major mineral components obtained by the XRD analysis of sediments. Mineralogical investigations by SEM and EDX of aquifer materials have shown the occurrence of arsenic as coating on mineral grains in the silty clay as well as in the sandy layers. Excessive withdrawal of groundwater for irrigation and drinking purposes is responsible for fluctuation of the water table in the West Bengal. Aeration beneath the ground surface caused by fluctuation of the water table may lead to the formation of carbonic acid. Carbonic acid is responsible for the weathering of silicate minerals, and due to the formation of clay as a product of weathering, ion exchange also dominates in the area. These hydrogeological processes may be responsible for the release of arsenic into the groundwater of the study area, which is a part of North 24 Parganas and South 24 Parganas. [ABSTRACT FROM AUTHOR]

Interaction of igneous rocks with river (rain) water in the systems granite-water, basalt-water, and dunite-water open with respect to carbon dioxide ( PCO = 10, 10, and 10 bar) and oxygen ( PO from 10 to 10 bar) is numerically simulated at 25 and 50°C and a mass ratio of water and rock R/W ≤ 10. Equilibrium simulations indicate that, first, the differences in the mineralogical composition of the transformation products of the igneous rocks are insignificant, and second, Cu extraction from minerals of the rocks is optimal at Eh from +200 to −100 mV. Simulations of the systems with regard for the dissolution rates of minerals indicate that the chemical weathering time of the rocks is few hundred thousands years. [ABSTRACT FROM AUTHOR]

Two extreme groups of alluvial gold placers (lost and preserved 'live' relation to the primary sources) are distinguished by the character of this relation and mineralogical-geochemical peculiarities. The content of the invisible gold in the first ones is close to the regional background (first mg/t) in contrast to its anomalous (exceeding the local background for several orders of magnitude) amount in placers of the second type. The invisible gold composes the geochemical dispersion flows combined with the placer. The placers of this type are important forecast criterion of the assessment of the nearby areas for the primary gold. [ABSTRACT FROM AUTHOR]

Background: Because dacryoliths occur at low frequency, few studies have focused on their composition. We aimed to present findings from morphological, chemical, and mineralogic analysis of 86 dacryoliths. Methods: We studied 86 dacryoliths obtained during 832 dacryocystorhinostomies (DCR) performed for postsaccal obstruction. We examined the samples with atomic infrared spectrometry (80 samples), amino acid analysis (17 samples), scanning electron microscopy, and an electron microprobe with an energy dispersive detector (seven samples). Results: Dacryoliths were found in 86/832 DCRs (10.3 %), mostly in patients with primary acquired nasolacrimal duct obstruction. All the dacryoliths were soft, composed of organic material, including proteins and mucoproteins, with approximately 20 % amino acid content. There were no 'hard' dacryoliths composed of calcium phosphate. The stones were composed of lobes and lobules built on an amorphous core material with small cavities, probably as a result of various chemical processes that produced a gaseous product. The most frequent elements found in inorganic inclusions were silicon, magnesium, sulfur, potassium, calcium, sodium, and chlorine. Also, some particles had high contents of bismuth, titanium, iron, and organic fibers. The fibers found in the core of dacryoliths suggested a potential origin from cotton swabs used in cosmetics. Conclusion: Dacryoliths are composed almost exclusively of organic material, including proteins and mucoproteins, with approximately 20 % amino acid content. [ABSTRACT FROM AUTHOR]

Gem-quality alexandrite, hiddenite and kunzite, elbaite and topaz minerals were characterized through a multi-methodological investigation based on EMPA-WDS, LA-ICP-MS, and laser-induced breakdown spectroscopy (LIBS). With respect to the others, the latter technique enables a simultaneous multi-elemental composition without any sample preparation and the detection of light elements, such as Li, Be and B. The criteria for the choice of minerals were: (a) the presence of chromophore elements in minor contents and/or as traces; (b) the presence of light lithophile elements (Li, Be and B); (c) different crystal chemistry complexity. The results show that LIBS can be employed in mineralogical studies for the identification and characterization of minerals, and as a fast screening method to determine the chemical composition, including the chromophore and light lithophile elements. [ABSTRACT FROM AUTHOR]

Tailings deposits generated from mining activities represent a potential risk for the aquatic environment through the release of potentially toxic metals and metalloids occurring in a variety of minerals present in the tailings. Physicochemical and mineralogical characteristics of tailings such as total concentrations of chemical elements, pH, ratio of acid-producing to acid-neutralizing minerals, and primary and secondary mineral phases are very important factors that control the actual release of potentially toxic metals and metalloids from the tailings to the environment. The aims of this study are the determination of geochemical and mineralogical characteristics of tailings deposited in voluminous impoundment situated near the village of Markušovce (eastern Slovakia) and identification of the processes controlling the mobility of selected toxic metals (Cu, Hg) and metalloids (As, Sb). The studied tailings have unique features in comparison with the other tailings investigated previously because of the specific mineral assemblage primarily consisting of barite, siderite, quartz, and minor sulfides. To meet the aims, samples of the tailings were collected from 3 boreholes and 15 excavated pits and subjected to bulk geochemical analyses (i.e., determination of chemical composition, pH, Eh, acid generation, and neutralization potentials) combined with detailed mineralogical characterization using optical microscopy, X-ray diffraction (XRD), electron microprobe analysis (EMPA), and micro-X-ray diffraction (μ-XRD). Additionally, the geochemical and mineralogical factors controlling the transfer of potentially toxic elements from tailings to waters were also determined using short-term batch test (European norm EN 12457), sampling of drainage waters and speciation-equilibrium calculations performed with PHREEQC. The tailings mineral assemblage consists of siderite, barite, quartz, and dolomite. Sulfide minerals constitute only a minor proportion of the tailings mineral assemblage and their occurrence follows the order: chalcopyrite > pyrite > tetrahedrite > arsenopyrite. The mineralogical composition of the tailings corresponds well to the primary mineralization mined. The neutralization capacity of the tailings is high, as confirmed by the values of neutralization potential to acid generation potential ratio, ranging from 6.7 to 63.9, and neutral to slightly alkaline pH of the tailings (paste pH 7.16-8.12) and the waters (pH 7.00-8.52). This is explained by abundant occurrence of carbonate minerals in the tailings, which readily neutralize the acidity generated by sulfide oxidation. The total solid-phase concentrations of metal(loid)s decrease as Cu > Sb > Hg > As and reflect the proportions of sulfides present in the tailings. Sulfide oxidation generally extends to a depth of 2 m. μ-XRD and EMPA were used to study secondary products developed on the surface of sulfide minerals and within the tailings. The main secondary minerals identified are goethite and X-ray amorphous Fe oxyhydroxides and their occurrence decreases with increasing tailings depth. Secondary Fe phases are found as mineral coatings or individual grains and retain relatively high amounts of metal(loid)s (up to 57.6 wt% Cu, 1.60 wt% Hg, 23.8 wt% As, and 2.37 wt% Sb). Based on batch leaching tests and lysimeter results, the mobility of potentially toxic elements in the tailings is low. The limited mobility of metals and metalloids is due to their retention by Fe oxyhydroxides and low solubilities of metal(loid)-bearing sulfides. The observations are consistent with PHREEQC calculations, which predict the precipitation of Fe oxyhydroxides as the main solubility-controlling mineral phases for As, Cu, Hg, and Sb. Waters discharging from tailings impoundment are characterized by a neutral to slightly alkaline pH (7.52-7.96) and low concentrations of dissolved metal(loid)s (<5-7.0 μg/L Cu, <0.1-0.3 μg/L Hg, 5.0-16 μg/L As, and 5.0-43 μg/L Sb). Primary factors influencing aqueous chemistry at the site are mutual processes of sulfide oxidation and carbonate dissolution as well as precipitation reactions and sorption onto hydrous ferric oxides abundantly present at the discharge of the impoundment waters. The results of the study show that, presently, there are no threats of acid mine drainage formation at the site and significant contamination of natural aquatic ecosystem in the close vicinity of the tailings impoundment. [ABSTRACT FROM AUTHOR]

The present study focuses on the mineralogical and geochemical patterns of mining and ore-processing wastes from some occurrences in the Eastern Carpathians; its aim is to identify the main factors and processes that could lead to the pollution of the environment. In this respect, the following types of solid waste were investigated: efflorescent salts developed on the surface of rock blocks from a quarry, ore-processing waste from two tailings ponds, and salt crusts developed at the surface of a tailings pond. The potential risks emphasized by these preliminary investigations are the following: (1) the risk of wind-driven removal and transport of the waste from the surface of tailings ponds, given that fine grains prevail (up to 80 %); (2) the risk of tailings removal through mechanical transport by water, during heavy rainfall; (3) the appearance of hydrated sulfates on the rock fragments from the mining waste, sulfates which are highly susceptible to the generation of acid mine drainage (pH < 4); (4) the high amount of toxic elements (Pb, Cd, Cu, Zn, As, etc.) that acid mine drainage leachates contain; and (5) the development of a salt crust on the flat, horizontal surfaces of the waste deposit, due to this very shape. Statistical data regarding the amount of both major and minor elements in the tailings have revealed two statistical populations for nearly all the toxic metals. This suggests that, beyond the effect that the tailings have upon the environment through their mere presence in a given area, there are alleged additional factors and processes which intensify the pollution: the location of the waste deposit relative to the topography of the area; the shape of the waste deposit; the development of low areas on the surface of the deposit, areas which favor the appearance of salt crusts; and the mineralogy of efflorescent aggregates. [ABSTRACT FROM AUTHOR]

Mineral phases and their content were determined in attic dust samples collected from 27 houses in the Tikveš Valley, Republic of Macedonia. By using quantitative X-ray diffraction, the principal mineral phases were determined to be the serpentinite group (chrysotile, lizardite) and amphibole group of minerals (ribecite, tremolite, actinolite) present in the attic dust samples from this region which are not common constituents of urban dust. Strong correlations existed between these mineral phases in the dust and those in ores processed at a ferronickel smelter plant situated in this region. Spatial distributions of specific mineral phases were made and were consistent with wind directions and predicted deposition (60-70 %) of dust emitted from the metallurgical plant. [ABSTRACT FROM AUTHOR]

This paper presents data on the effect of the mineralogical composition of gabbro-basalt rocks on the properties of mineral fibers and stone-cast materials prepared from them. We consider experimental and calculational approaches to determining the mineralogical composition of magmatic rocks, discuss possible origins of discrepancies in results, and demonstrate that the mineralogical compositions determined by physicochemical calculations can be used to roughly estimate the performance of natural raw materials in mineral-fiber production and stone casting. [ABSTRACT FROM AUTHOR]

Geochemical and mineralogical studies were conducted on the 12-m-thick weathering profile of the Kata Beach granite in Phuket, Thailand, in order to reveal the transport and adsorption of rare earth elements (REE) related to the ion-adsorption type mineralization. The parent rock is ilmenite-series biotite granite with transitional characteristics from I type to S type, abundant in REE (592 ppm). REE are contained dominantly in fluorocarbonate as well as in allanite, titanite, apatite, and zircon. The chondrite-normalized REE pattern of the parent granite indicates enrichment of LREE relative to HREE and no significant Ce anomaly. The upper part of the weathering profile from the surface to 4.5 m depth is mostly characterized by positive Ce anomaly, showing lower REE contents ranging from 174 to 548 ppm and lower percentages of adsorbed REE from 34% to 68% compared with the parent granite. In contrast, the lower part of the profile from 4.5 to 12 m depth is characterized by negative Ce anomaly, showing higher REE contents ranging from 578 to 1,084 ppm and higher percentages from 53% to 85%. The negative Ce anomaly and enrichment of REE in the lower part of the profile suggest that acidic soil water in an oxidizing condition in the upper part mostly immobilized Ce as CeO and transported REE downward to the lower part of the profile. The transported REE were adsorbed onto weathering products or distributed to secondary minerals such as rhabdophane. The immobilization of REE results from the increase of pH due to the contact with higher pH groundwater. Since the majority of REE in the weathered granite are present in the ion-adsorption fraction with negative Ce anomaly, the percentages of adsorbed REE are positively correlated with the whole-rock negative Ce anomaly. The result of this study suggests that the ion-adsorption type REE mineralization is identified by the occurrence of easily soluble REE fluorocarbonate and whole-rock negative Ce anomaly of weathered granite. Although fractionation of REE in weathered granite is controlled by the occurrence of REE-bearing minerals and adsorption by weathering products, the ion-adsorption fraction tends to be enriched in LREE relative to weathered granite. [ABSTRACT FROM AUTHOR]

The article investigates the Holocene sediments of Bol'shoe Alginskoe Lake located on the territory of Buryatia in the Barguzin depression in Transbaikalia, Russia and its connection with paleoclimate. It highlights the approach of paleoclimatic reconstructions based on detailed mineralogical and crystallochemical investigations of terrigenous and endogenic components of lake sediments. The authors combined the results of the investigations with data on the distribution of a number of geochemical indicators of the environment of mineral formation in the section.

The Bracco-Gabbro Complex (Internal Liguride ophiolite), that intruded subcontinental mantle peridotite, contains layers of chromitite that are associated with ultramafic differentiates. The chromitites and disseminated chromites in the ultramafics have Al contents similar to the Al-rich podiform chromitites [0.40 < Cr# = Cr/(Cr + Al) < 0.55]. TiO contents of the chromitites are unusually high and range up to 0.82 wt%. The calculated AlO and TiO content of the parental melt suggest that the melt was a MORB type. Geothermobarometrical calculations on few preserved silicate inclusions revealed formation temperatures between 970 and 820 °C under a relatively high oxygen fugacity (Δlog fO at +2.0-2.4). Chromitites were altered during the post-magmatic tectono-metamorphic uplift and the final exposure at the seafloor, as evidenced by the formation of ferrian chromite. The PGE contents of the chromitites and associated ultramafics are unusually low (PGEmax 83 ppb). The chondrite-normalized PGE spidergrams show positive PGE patterns and to some extent similarities with the typical trend of stratiform chromitites. No specific PGM have been found but low concentrations of PPGE (Rh, Pt, and Pd) have been detected in the sulphides that occur interstitially to or enclosed in chromite. Recently, it has been shown that the Internal Liguride gabbroic intrusions have formed by relatively low degrees of partial melting of the asthenospheric mantle. We conclude that the low degree of partial melting might be the main factor to control the unusual low PGE contents and the rather unique PGE distribution in the Bracco chromitites. [ABSTRACT FROM AUTHOR]

The article presents a study conducted in support of the Russian Foundation for Basic Research in Moscow, Russia to investigate detailed mineralogical and geochemical studies of one composite mantle xenolith around veins in the peridotite matrix and the metasomatic alteration of peridotitic minerals. It informs that xenoliths of peridotite represent material of the lithospheric mantle. It analyzed the data for other regions of the world and assumed that the thickness of the metasomatized area exceeds the sizes of the samples studied.

The mineralogical and micromorphological characteristics of Si-Fe-Mn oxyhydroxides from the dacite-hosted PACMANUS hydrothermal field were analyzed. The samples are poorly crystallized Si-Fe-Mn oxyhydroxides with minor birnessite, todorokite, nontronite, goethite, and opal-A. There are some microtextures which are rather like fossil microbes such as the filamentous silica and the hollow pipes. Flakes of nontronite crystals are found either forming a honeycomb texture or distributed on the surface of the hollow pipes. Nontronite is the product precipitated from low-temperature hydrothermal fluids, and microbes may play a role in its formation. Si-Fe-Mn oxyhydroxides have two kinds of nuclei: Si-Mn nuclei and Si nuclei, both enveloped by the similar Si-Fe outer layer, existing in the rod-shaped oxyhydroxide and spheroidal oxyhydroxide, respectively. In the Si-Mn nuclei, the concentration of SiO is between 39.32 wt% and 86.31 wt%, and MnO concentration is between 4.97 wt% and 27.01 wt%, but FeO concentration is very low (0.54 wt%-3.43 wt%). In the Si nucleus the concentration of SiO is 90.17 wt%, but concentration of MnO and FeO are low, with 0.06 wt% and 3.47 wt%, respectively. The formation of the Si-Mn nucleus is closely related to microbes, whereas the Si nucleus is of inorganic origin. [ABSTRACT FROM AUTHOR]

Detailed lithological study of tills was carried out at exposures along the Adz'va, Bol'shaya Rogovaya, and Seida rivers-northern tributaries of the Usa River-in the northeasternmost area of the Timan-Pechora-Vychegoda region. The results of grain size, mineralogical, and petrographic analyses coupled with measurements of orientation of elongated clasts in tills made it possible to substantiate the presence of three moraine horizons. Lithological features of the Pechora (Dnieper) and Polyarny (Ostashkovo) horizons of tills testify to the input of terrigenous material from Novaya Zemlya. The upper (middle Pleistocene) till, which is also as defined as the Vychegoda (or Moscovian) till, represents clastic material derived from the Polar and Subpolar Urals. Lithological properties have been defined for the stratification and correlation of tills. A chart of lithological criteria has been compiled for the subdivision and correlation of middle and upper Pleistocene tills in the Far Northeast of European Russia. [ABSTRACT FROM AUTHOR]

The Fakos porphyry Cu and epithermal Au-Te deposit, Limnos Island, Greece, is hosted in a ~20 Ma quartz monzonite and shoshonitic subvolcanic rocks that intruded middle Eocene to lower Miocene sedimentary basement rocks. Metallic mineralization formed in three stages in quartz and quartz-calcite veins. Early porphyry-style (Stage 1) metallic minerals consist of pyrite, chalcopyrite, galena, bornite, sphalerite, molybdenite, and iron oxides, which are surrounded by halos of potassic and propylitic alteration. Stage 2 mineralization is composed mostly of quartz-tourmaline veins associated with sericitic alteration and disseminated pyrite and molybdenite, whereas Stage 3, epithermal-style mineralization is characterized by polymetallic veins containing pyrite, chalcopyrite, sphalerite, galena, enargite, bournonite, tetrahedrite-tennantite, hessite, petzite, altaite, an unknown cervelleite-like Ag-telluride, native Au, and Au-Ag alloy. Stage 3 veins are spatially associated with sericitic and argillic alteration. Fluid inclusions in quartz from Stage 1 (porphyry-style) mineralization contain five types of inclusions. Type I, liquid-vapor inclusions, which homogenize at temperatures ranging from 189.5°C to 403.3°C have salinities of 14.8 to 19.9 wt. % NaCl equiv. Type II, liquid-vapor-NaCl, Type III liquid-vapor-NaCl-XCl (where XCl is an unknown chloride phase, likely CaCl), and Type IV, liquid-vapor-hematite ± NaCl homogenize to the liquid phase by liquid-vapor homogenization or by daughter crystal dissolution at temperatures of 209.3 to 740.5 °C, 267.6 to 780.8 °C, and 357.9 to 684.2 °C, respectively, and, Type V, vapor-rich inclusions. Stage 2 veins are devoid of interpretable fluid inclusions. Quartz from Stage 3 (epithermal-style) veins contains two types of fluid inclusions, Type I, liquid-vapor inclusions that homogenize to the liquid phase (191.6 to 310.0 °C) with salinities of 1.40 to 9.73 wt. % NaCl equiv., and Type II, vapor-rich inclusions. Mixing of magmatic fluids with meteoric water in the epithermal environment is responsible for the dilution of the ore fluids that formed Stage 3 veins. Eutectic melting temperatures of −35.4 to −24.3 °C for Type I inclusions hosted in both porphyry- and epithermal-style veins suggest the presence of CaCl, MgCl, and/or FeCl in the magmatic-hydrothermal fluids. Sulfur isotope values of pyrite, galena, sphalerite, and molybdenite range from δS = −6.82 to −0.82 per mil and overlap for porphyry and epithermal sulfides, which suggests a common sulfur source for the two styles of mineralization. The source of sulfur in the system was likely the Fakos quartz monzonite for which the isotopically light sulfur isotope values are the result of changes in oxidation state during sulfide deposition (i.e., boiling) and/or disproportionation of sulfur-rich magmatic volatiles upon cooling. It is less likely that sulfur in the sulfides was derived from the reduction of seawater sulfate or leaching of sulfides from sedimentary rocks given the absence of primary sulfides in sedimentary rocks in the vicinity of the deposit. Late-stage barite (δS = 10.5 per mil) is inferred to have formed during mixing of seawater with magmatic ore fluids. Petrological, mineralogical, fluid inclusion, and sulfur isotope data indicate that the metallic mineralization at Fakos Peninsula represents an early porphyry system that is transitional to a later high- to intermediate-sulfidation epithermal gold system. This style of mineralization is similar to porphyry-epithermal metallic mineralization found elsewhere in northeastern Greece (e.g., Pagoni Rachi, St. Demetrios, St. Barbara, Perama Hill, Mavrokoryfi, and Pefka). [ABSTRACT FROM AUTHOR]

The article focuses on the solidified gel of uranium oxide found in rock samples, which exhibits signs of natural nuclear reactions (NNR), that underwent mineralogical examination in zone reactor Z-13. It mentions that reactor zone Z-13 of the Oklo deposit and the adjacent area in Gabon occurred in sandstone located in dolerite dyke, which influenced the texture, structure and mineral composition of ores. It states that the solidified structure of nonrecrystallized pitchblende nodules were mineral radial-tubular colony separated by links. Furthermore, the solidified gel of uranium oxides reveals pressure decrease within the process of hydrothermal to form an ore.

Geochronological, mineralogical, and geochemical analyses have been focussed on the Mont-Lozère-Borne plutonic complex and surrounding rocks (Cévennes, French Massif Central) in which B-W-Sn and As-Au-Sb mineralization is encountered. Two main results are highlighted: (1) the existence of a 301-306 Ma magmato-hydrothermal event unrelated to the emplacement of the Pont-de-Montvert-Borne plutonic body at 316 Ma; (2) the magmatic and hydrothermal features are strongly associated, both in time and in space, thus demonstrating an intimate connection between mineralizing processes and magmatism in this part of the French Massif Central. We also show that mineralization and associated hydrothermal occurrences do not correspond to a simple and single geochemical signature and that a contamination model must be invoked in order to account for the complexity of isotopic results. This study demonstrates that the application of the O and H isotopic signatures as tracers of the source and nature of fluids in an orogenic context requires some specific care. Finally, a model of the tectonic-magmatic-hydrothermal evolution of the study area is suggested in which we discuss two alternative scenarios. The first one implies the existence of two different hydrothermal/mineralizing events (Bo-W-Sn and As-Au-Sb ones). The second one suggests the same source for all hydrothermal and mineralized structures. [ABSTRACT FROM AUTHOR]

Lavas erupted at the southern end of the intermediate Juan de Fuca ridge (Cleft segment) are mostly cogenetic and their chemical diversity results from melt evolution in an open magma system. In the present study, we apply a theoretical model allowing the time evolution of this periodically recharged and tapped magma chamber to be estimated. In our mathematical procedure, the melt quantity supplied to the reservoir varies through time following a sinusoidal function. The rare earth element concentrations in the refilling melt were calculated on the basis of the REE distribution in lavas. This theoretical composition is akin to that previously estimated for a Mg#70 MORB from mineralogical and chemical data. Then, we approached the temporal evolution of the reservoir using a set of suitable parameters deduced from the geometry of the crust and magma system beneath the Cleft segment. Particularly, we considered two end-members scenarios for the melt repartition through the magma reservoir beneath the Cleft segment: the 'gabbro glacier' model (crystal nucleation and growth occur within one single melt lens and crystals subside vertically and laterally) and the 'sheeted sill' model (crystallization takes place within a network of connected sills located at various depths within the crust). We estimated that the magma chamber is refilled every thousand years and that the melt resides approximately one hundred years within the reservoir. [ABSTRACT FROM AUTHOR]

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies. [ABSTRACT FROM AUTHOR]

Two texturally and chemically distinct types of tourmaline are found inside peraluminous granites of the Moslavačka Gora, Croatia: nodular tourmaline in the two-mica granite and disseminated tourmaline in the cross-cutting leucogranite dykes. Both tourmaline types belong to alkali tourmaline group, nodular tourmaline being dravite to schorl and disseminated tourmaline corresponding to schorl. Comparison of characteristic parameters of nodular (Nt) and disseminated tourmaline (Dt) shows significant differences in #Fe (0.40-0.65 for Nt vs. 0.74-0.85 in Dt) along with variations in the calculated X-site vacancy (0.22-0.37 pfu in Nt and 0.33-0.44 in Dt) and □/(□+Na) ratio (0.23-0.40 in Nt and 0.34-0.45 in Dt). Disseminated tourmaline from the MG leucogranites is regarded as an early crystallized magmatic phase, while the interstitial tourmaline from the cores of tourmaline nodules originated from more complex mineralogical and chemical interactions inside the two-mica granite melt. Major element gain (Mg) and loss (Fe, Ca, Na, K) for the 'idealized nodule' (34 vol. % core + 66 vol. % halo) when compared to the host granite shows that the nodule's volume is not a completely independent and closed system. Based on the observed characteristics, nodule's halo can be considered as a 'transitional zone' between the tourmaline-bearing core and the host granite, texturally and mineralogically related to the host two-mica granite, chemically being an integral part of the nodule's volume at the same time. [ABSTRACT FROM AUTHOR]