Albite Minerals Research Articles

Kandungan Mineral dan Struktur Kristal Batu Sekis

This study aims to determine the mineral content and crystal structure of schist rocks in South Lampung. The method used in this research is the X-ray diffraction method to see the lattice parameters and the crystal structure of the schist rocks. Based on data processing, information was obtained that two main minerals were found, namely quartz and albite minerals. In conclusion, the Albit minerals found in the two samples of rock crystal schists in South Lampung have the same crystal structure and lattice parameters, while the quartz minerals from the two samples have different crystal structures and lattice parameters.
 Keywords: Lampung, Schis, XRD, Crystal Structure

Secondary Ion Mass Spectrometry as an advanced tool for meteorite classification

A reliable classification of meteorites is of great importance in order to study the meteorite history. Secondary ion mass spectrometry is applied to collect a database of spectra for four meteorite classes, H chondrite, IAB iron, L chondrite, and achondrite and based on convolutional neural network to determine the meteorite class of un unknown sample. The focus of the presented analysis is on the Košice meteorite which is identified with following elements Li, B, Na, Mg, Al, Si, P, K, Ca, Ti, Cr, Mn, Fe, and Ni. Due to the high mass resolution of 7000, several isotopes of these elements are clearly identified. The Secondary ion mass spectrometry images provide also mineralogical analysis by revealing distributions of chemical composition. The minerals of albite, troilite, augite, and diopside are recognized. Using 88 reference spectra, the unknown sample is identified as the H chondrite based on calculated probability. Secondary ion mass spectrometry technique coupled with convolutional neural network proves to be the advanced tool to analyze meteorites, to classify them, and to determine a meteorite of unknown origin.

First Exploration on Electrochemical Activation of Low‐Cost Albite Mineral for Boosting Lithium Storage Capability

AbstractThe direct use of natural minerals for low‐cost energy storage is a promising solution toward large‐scale and affordable sustainable energy supply, but it is usually impeded by their inert electrochemical activity. In this work, electrochemically inert albite mineral layered particles are activated as a promising low‐cost anode material for electrochemical Li+ ion storage devices through a facile thermal reduction treatment technology. Via this strategy, partial SiO2 reduction within the albite mineral particles and a conductive carbon layer on the surface are simultaneously realized, which effectively addresses the issues of inactive lithium storage and poor electric conductivity of albite minerals. Via theoretical density functional theory calculations and molecular dynamics simulations, the activation mechanism of lithium storage achieved by silica reduction is understood. This innovatively activated albite mineral delivers a maximum specific capacity of >250 mAh g−1 based on a dominant surface‐driven capacitive storage mechanism, and demonstrates excellent capacity and cycling stability at high charging/discharging rates. This design opens a new pathway to address the current cost issue in energy devices, provides insights into producing cost‐effective anodes by using silica‐rich minerals, and gives an alternative solution for improving the chemical reactivity of inorganic natural minerals toward low‐cost and large‐scale energy storages.

Characterization of scoria rock from Arabian lava fields as natural pozzolan for use in concrete

The feasibility studies of using alternative cementitious materials (ACMs) in concrete construction are conducted using various characterization tests. Different samples of scoria rocks (SR) were procured from different regions of the Arabian Shield and investigated for use as ACMs. Various methods and characterization techniques were conducted. Characterization results revealed that the pozzolanic activity of SR in mortar does not correlate well with the sum of the main elemental oxides (SiO2+Al2O3+Fe2O3), as per the requirement of ASTM C618. Concrete mixtures containing 30% SR per cement weight were prepared and tested at 28 and 90 days to evaluate the performance of SR for construction applications. Furthermore, the mortar and concrete mixtures containing SR have shown a slow rate of pozzolanic activity at early ages. However, the development in compressive strength was enhanced at later ages dependent on the mineralogical compositions of SR. It is concluded that the improvement in strength could be corroborated based on the formation of tobermorite-like structures, as confirmed using XRD and thermal analyses. These structures result from the reaction of minerals of amorphous sodium aluminosilicate phase (albite minerals) in SR with portlandite liberated during cement hydration. Conclusively, SR reacts as a pozzolan not as a filler.

Hydrologic Transport of Dissolved Inorganic Carbon and Its Control on Chemical Weathering

Chemical weathering is one of the major processes interacting with climate and tectonics to form clays, supply nutrients to soil microorganisms and plants, and sequester atmospheric CO2. Hydrology and dissolution kinetics have been emphasized as factors controlling chemical weathering rates. However, the interaction between hydrology and transport of dissolved inorganic carbon (DIC) in controlling weathering has received less attention. In this paper, we present an analytical model that couples subsurface water and chemical molar balance equations to analyze the roles of hydrology and DIC transport on chemical weathering. The balance equations form a dynamical system that fully determines the dynamics of the weathering zone chemistry as forced by the transport of DIC. The model is formulated specifically for the silicate mineral albite, but it can be extended to other minerals, and is studied as a function of percolation rate and water transit time. Three weathering regimes are elucidated. For very small or large values of transit time, the weathering is limited by reaction kinetics or transport, respectively. For intermediate values, the system is transport controlled and is sensitive to transit time. We apply the model to a series of watersheds for which we estimate transit times and identify the type of weathering regime. The results suggest that hydrologic transport of DIC may be as important as reaction kinetics and dilution in determining chemical weathering rates.

Mineral Properties of Ruby Deposit in Monghsu, Myanmar

Monghsu has been very plentiful and well-known source of the high grade ruby, However it’s mineral properties has never been systematically described in the field. This work is aimed to understanding clearly the mineral properties of Monghsu ruby deposit. Six rock specimens were collected from a mine of ruby deposit in Monghsu for study through XRD and observation of hand specimens and thin sections. The ruby orebody is mainly composed of dolomite and minor calcite, phlogopite. The country rock is mainly muscovite, calcite and minor albite. Outside of calcite is consisting of albite, phlogopite and quartz. The specimens of ruby deposit show mainly following texture types: inequigranular crystalloblastic texture, mylonitic texture.

Characterization of Minerals Deposit Patimpeng Bone Regency, South Sulawesi through Petrographic

A research on the characterization of minerals from the Patimpeng District Bone Regency, South Sulawesi using petrographic analysis has been conducted. The aims of this study was to identify the minerals deposited in Patimpeng District. Specimens of rocks are grouped into 13 sections. Characterization of samples was conducted in microstructure laboratory, Department of Physics Universitas Negeri Makassar using Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy (SEM-EDS) and X-ray Diffraction (XRD). Based on XRD examinations on 13 samples, 9 samples containing albite mineral. The details of XRD analysis, namely; a) PAT_01 containing titanite 16%, albite 65%, hematite 2.9%, periclase 3.4%, and quartz 14%; b) PAT_04 containing thomsonite 18.1%, albite 62%, magnetite 18%, anatase 1.18%, and lime 1.36%; c) PAT_05 containing tetranatrolite 31%, albite 30%, diopside 26%, and magnetite13%; d) PAT_06 containing indialite 8.5%, albite 58%, clinochlore 23%, anatase 5.4%, and magnetite 4.7%; e) PAT_08 containing Thomsonite 42%, albite, 35%, anatase 2.2%, magnetite 7% and magnesium 14%; f) PAT_10 containing Clinochlore 31%, Sodium 5.2%, albite 55%, anatase 3.1%, hematite 1.75%, and magnetite 3.5%; g) PAT_11 containing clinochlore 19.8%, albite 55%, quartz 21.7%, anatase 1.76%, and magnetite 1.9%; h) PAT_12 containg cronstedtite 2,20%, albite 95.3%, anatase 0.88%, rutile 1,18% and magnetite 0.4%; i) PAT_13 containing ferrohornblende 5.8%, clinochlore 20.9%, periclase 11.9%, and albite 61%. Sample PAT_12 showed that weight percentage (wt%) of albite was dominant than other minerals. The results of petrographic analysis using X-ray mapping for the sample PAT_12 showed that the entire surface is covered with Si which overlap with Al, Fe, Ca, Na, Mg, and Sb.

The Role of Sandstone Mineralogy and Rock Quality in the Performance of Low-Salinity Waterflooding

Summary Recent field applications and laboratory studies have recognized that low-salinity waterflooding (LSW) is a potentially effective technique to achieve sufficient recovery in sandstone reservoirs. Researchers have noted that the impacts of clay content, rock permeability, and pore-throat radius are still unclear on the performance of LSW. This paper reports the results of coreflood, zeta-potential, X-ray-powder-diffraction (XRD), X-ray-fluorescence (XRF), scanning-electron-microscope (SEM), nuclear-magnetic-resonance (NMR), and high-pressure-mercury-injection experimental investigations on these parameters. The main objectives of this work are to examine the performance of LSW by use of four sandstone rocks during secondary- and tertiary-recovery modes; to investigate the role of clay content, rock permeability, and average pore-throat radius on the performance of LSW; and to evaluate the effects of mineral type, brine salinity, cation type, and pH on the zeta-potential measurements. Zeta-potential measurements were conducted for rock/brine interfaces to determine the suitable injection brine for the used sandstone rocks. Various brines were used, including seawater (SW), 20% diluted SW, 0.5 wt% NaCl, 0.5 wt% MgCl2, and 0.5 wt% CaCl2. Then, a set of comprehensive coreflood tests were conducted with Bandera, Parker, Gray Berea, and Buff Berea outcrop sandstone cores. The coreflood experiments were conducted with 6- and 20-in.-length and 1.5-in.-diameter outcrop cores at 185°F. Oil recovery, pressure drop, and pH were observed and analyzed after each coreflood experiment. On the basis of the results attained, the Parker, Bandera, Gray Berea, and Buff Berea sandstone cores showed additional oil recoveries of 4.3, 9.2, 13.3, and 17.1% of original oil in place (OOIP), respectively, through the injection of low-salinity brine (5,000 ppm NaCl) as the secondary recovery mode. The average pore-throat radius (rock quality) has a higher effect in the performance of LSW than in high-salinity waterflooding (HSW) on the secondary recovery mode. The incremental oil recovery (microscopic) for the LSW increased from 4.3 to 17% when the average pore-throat radius (R35) of the core increased from 1.4 to 8.5 µm. The total clay content and the clay composition are not the main factors that influence the LSW performance. The distribution of the clays seems to be playing a significant role. The measured zeta potentials of kaolinite and montmorillonite particles in 5,000 ppm NaCl brine at 77°F and pH 7 were −26.5 and −29.4 mV, respectively. The zeta-potential values indicated a stronger negative charge on muscovite and albite minerals of −33.8 and −31.5 mV, respectively. Zeta-potential values indicated a less-negative charge on the chlorite and illite particles than the other minerals. It seems that chlorite and illite contribute to a smaller electrical-double-layer expansion than those of kaolinite, feldspars, montmorillonite, and muscovite. On the other hand, the zeta-potential values of calcite and dolomite particles are 1.0 and −4.5 mV, respectively. The presence of dolomite and calcite would decrease the effect of the low-salinity brine to improve oil recovery.

Effect of Sodium Oxides in Ash Composition on Ash Fusibility

Ash fusibility is closely associated with ash slagging, which has great significance on efficiency and cleanliness of thermal conversion and coal utilization. Not being a dominant component of coal ash, Na2O is believed to be an inducement for slagging problems. In this study, for the realization of better understanding of the underlying mechanisms, the influence of Na2O on the ash fusibility was investigated from the perspectives of content variation and temperature rising. Experimental approaches, such as ash fusion temperature (AFT) test, X-ray diffraction (XRD), and scanning electronic microscope (SEM), were applied to quantify the ash fusibility and detect minerals’ transformation and surface morphology in ash melting. The ash melting process was simulated by a multicomponent system based on the FactSage database, which includes SiO2–Al2O3–Fe2O3–CaO–Na2O. This study also used Gibbs free energy theory to analyze the chemical reactions, mineral behaviors, and phase diagram and record the sodium migration in the melting process. In general, Na2O reduces the fusion temperatures of ash samples, which can be related to the performances of minerals albite, nepheline, and anorthite, as well as the eutectics they form.

Mineralogical and chemical composition analysis of some saudian raw materials

This work aims at studying the solid phase composition and chemical constitution of some mineralogical raw materials widespread in Gholaa and Osfan regions, Khulais Governorate, in the western area of the Kingdom of Saudi Arabia. Ten samples were investigated through their phase composition using X-ray diffraction (XRD). Four of which were selected for further investigations. The quantitative phase compositions of the selected samples were calculated from XRD data. Their chemical constitutions were determined using x-ray fluorescence technique (XRF). The microstructure of one selected sample was depicted using scanning electron microscope attached with EDAX unit to analyze elementary some selected crystals. Most of the investigated samples composed mainly of albite mineral (NaAlSiO3) and they are suitable for glass ceramic industries. One sample contains considerable contents of quartz (SiO2) and kaolinite (Al2O3.2SiO2.2H2O) in addition to albite; it is suitable for the cement, brick and ceramic industry. Some minerals were present in varying amounts in the samples namely; chlorite (Mg6Si4O10(OH)8), chamosite (Fe3Si2O5(OH)4), chabazite (CaSrAl silicate), biotite (H4K2Mg6Al2Si6O2), microcline (KAlSi3O8), montimorillonite (Mg.Al2O3.5SiO2.xH2O), hematite (Fe2O3) tremolite (Na0.11Ca1.69Mg4.6Fe0.48Al0.29Si7.82O22(OH)2), kaolinite (Al2Si2O5(OH)4) and anatase (TiO2). Based on their chemical and mineralogical compositions the raw materials are suitable for various chemical, mineralogical, and engineering applications.

Fluid Inclusion and Carbon‐Oxygen Isotope Studies of the Hujiayu Cu Deposit, Zhongtiao Mountains, China: Implications for Syn‐metamorphic Copper Remobilization

The Hujiayu Cu deposit, representative of the “HuBi‐type” Cu deposits in the Zhongtiao Mountains district in the southern edge of the North China Craton, is primarily hosted in graphite‐bearing schists and carbonate rocks. The ore minerals comprise mainly chalcopyrite, with minor sphalerite, siegenite [(Co, Ni)3S4], and clausthalite [Pb(S,Se)]. The gangue minerals are mainly quartz and dolomite, with minor albite. Four fluid inclusion types were recognized in the chalcopyrite‐pyrite‐dolomite‐quartz veins, including CO2‐rich inclusions (type I), low‐salinity, liquid‐dominated, biphase aqueous inclusions (type II), solid‐bearing aqueous inclusions (type III), and solid‐bearing aqueous‐carbonic inclusions (type IV). Type I inclusion can be further divided into two sub‐types, i.e., monophase CO2 inclusions (type Ia) and biphase CO2‐rich inclusions (with a visible aqueous phase), and type III inclusion is divided into a subtype with a halite daughter mineral (type IIIa) and a subtype with multiple solids (type IIIb). Various fluid inclusion assemblages (FIAs) were identified through petrographic observations, and were classified into four groups. The group‐1 FIA, consisting of monophase CO2 inclusions (type Ia), homogenized into the liquid phase in a large range of temperatures from −1 to 28°C, suggesting post‐entrapment modification. The group‐2 FIA consists of type Ib, IIIb and IV inclusions, and is interpreted to reflect fluid immiscibility. The group‐3 FIA comprises type II and IIIa inclusions, and the group‐4 FIA consists of type II inclusions with consistent phase ratios. The group‐1 and group‐2 FIAs are interpreted to be entrapped during mineralization, whereas group‐3 and group‐4 FIAs probably represent the post‐mineralization fluids. The solid CO2 melting temperatures range from −60.6 to 56.6° C and from −66.0 to −63.4° C for type Ia and type IV inclusions, respectively. The homogenization temperatures for type II inclusions range from 132 to 170°C for group‐3 FIAs and 115 to 219°C for group‐4 FIAs. The halite melting temperatures range from 530 to 562°C for type IIIb and IV inclusions, whereas those for type IIIa inclusions range from 198 to 398°C. Laser Raman and SEM‐EDS results show that the gas species in fluid inclusions are mainly CO2 with minor CH4, and the solids are dominated by calcite and halite. The calcite in the hosting marble and dolomite in the hydrothermal veins have δ13CV‐PDB values of −1.2 to 1.2‰ and −1.2 to −6.3‰, and δ18OV‐SMOW values of 14.0 to 20.8 ‰ and 13.2 to 14.3 ‰, respectively. The fluid inclusion and carbon‐oxygen isotope data suggest that the ore‐forming fluids were probably derived from metamorphic fluids, which had reacted with organic matter in sedimentary rocks or graphite and undergone phase separation at 1.4–1.8 kbar and 230–240°C, after peak metamorphism. It is proposed that the Hujiayu Cu deposit consists of two mineralization stages. The early stage mineralization, characterized by disseminated and veinlet copper sulfides, probably took place in an environment similar to sediment‐hosted stratiform copper mineralization. Ore minerals formed in this precursor mineralization stage were remobilized and enriched in the late metamorphic hydrothermal stage, leading to the formation of thick quartz–dolomite–sulfides veins.

A comparison between ab initio calculated and measured Raman spectrum of triclinic albite (NaAlSi3O8)

Albite is one of the most common minerals in the Earth's crust, and its polymorphs can be found in rocks with different cooling histories. The characteristic spectrum of vibration of the albite mineral reflects its structural Si/Al ordering. In this study, we report on the comparison between the Raman spectra measured on a natural and fully ordered (as deduced on the basis of single‐crystal X‐ray diffraction data) ‘low albite’, NaAlSi3O8, and those calculated at the hybrid Hartree–Fock/density functional theory level by employing the WC1LYP Hamiltonian, which has proven to give excellent agreement between calculated and experimentally measured vibrational wavenumbers in silicate minerals. All the 39 expected Ag modes are identified in the Raman spectra, and their wavenumbers and intensities, in different scattering configurations, correspond well to the calculated ones. The average absolute discrepancy is ~3.4 cm−1, being the maximum discrepancy |Δv|max ~ 10.3 cm−1. The very good quality of the WC1LYP results allows for reliable assignments of the Raman features to specific patterns of atomic vibrational motion. Copyright © 2015 John Wiley & Sons, Ltd.

Quantification of mass transfers and mineralogical transformations in a thrust fault (Monte Perdido thrust unit, southern Pyrenees, Spain)

In fold-and-thrust belts, shortening is mainly accommodated by thrust faults which are preferential zones for recrystallisation and mass transfer. This study focuses on a detachment fault related to the emplacement of the Monte Perdido thrust unit in the southern Pyrenees. The studied fault zone consists of a 10 m thick intensively foliated phyllonite developed within the Millaris marls, of Eocene age. The lithological homogeneity of the hanging wall and footwall allows us to compare the Millaris marls outside the fault zone with the highly deformed marls located in the fault zone and to quantify the chemical, mineralogical and volumetric changes related to deformation processes along the fault.The Millaris marls are composed of detrital quartz, illite, chlorite, minor albite and pyrite, in a micritic calcite matrix. In the fault zone, the cleavage planes are marked by clay minerals and calcite ± chlorite veins attest to fluid–mineral interactions during deformation.The mineral proportions in all samples from both the fault zone and Millaris marls have been quantified by two methods: (1) X-ray diffraction and Rietveld refinement, and (2) bulk chemical analyses as well as microprobe analyses to calculate modal composition. The excellent agreement between the results of these two methods allows us to estimate mineralogical variations using a modification of the Gresens' equation. During fault activation, up to 45 wt% of calcite was lost while the amounts of quartz and chlorite remained unchanged. Illite content remained constant to slightly enriched. The mineralogical variations were coupled with a significant volume loss (up to 45%) mostly due to the dissolution of micritic calcite grains. Deformation was accompanied by pressure solution and phyllosilicates recrystallisation. These processes accommodated slip along the fault. They required fluids as catalyst, but they did not necessitate major chemical transfers.

Mineralogy and major-element geochemistry of the lower Permian Greta Seam, Sydney Basin, Australia

The mineralogy of the high-volatile bituminous coals and associated strata from the Greta seam, Sydney Basin, Australia, has been evaluated in this study. Although the seam is not immediately overlain by marine strata, percolation of marine water into the original peat bed is indicated by the petrological, mineralogical and geochemical characteristics, which resemble those of coals with marine roof strata. The upper and lower sections of the seam have contrasting mineralogy. Pyrite typically comprises 40 to 56 wt% of the mineral assemblage in the marine-influenced upper part of the seam section. The lower part contains much less pyrite (typically <5 wt%, organic-free basis), and also relatively abundant dawsonite (up to 14 wt%, organic-free basis). The minerals within most coal plies are largely of authigenic origin. These include pyrite, siderite, clay minerals (mainly kaolinite and Na-rich mixed-layer illite/smectite), and quartz, most of which have a relatively early, syngenetic origin. Minor Ti-bearing minerals, anatase or rutile, and phosphate minerals, fluorapatite and goyazite, were probably also formed during early diagenesis. Other minerals have features that indicate late-stage precipitation. These include abundant cleat- and fracture-filling dawsonite, which may be the result of reactions between earlier-precipitated kaolinite and Na2CO3- or NaHCO3-bearing fluids. Minor albite may also be epigenetic, possibly precipitated from the same Ca–Al bearing fluids that formed the dawsonite. The most abundant detrital minerals in the Greta coals are quartz, poorly ordered kaolinite, illite and mixed-layer illite/smectite (I/S). These occur mainly in the floor, roof and other epiclastic horizons of the seam, reflecting periods of greater clastic influx into those parts of the original peat-forming environment. Detrital minerals are rare in the coals away from the epiclastic horizons, probably owing to almost complete sediment bypassing in the depositional system. Alternatively, any detrital minerals that were originally present may have been leached from the peat bed by diagenetic or post-diagenetic processes.

Source characterisation of road dust based on chemical and mineralogical composition

Road dust contain potentially toxic pollutants originating from a range of anthropogenic sources common to urban land uses and soil inputs from surrounding areas. The research study analysed the mineralogy and morphology of dust samples from road surfaces from different land uses and background soil samples to characterise the relative source contributions to road dust. The road dust consist primarily of soil derived minerals (60%) with quartz averaging 40–50% and remainder being clay forming minerals of albite, microcline, chlorite and muscovite originating from surrounding soils. About 2% was organic matter primarily originating from plant matter. Potentially toxic pollutants represented about 30% of the build-up. These pollutants consist of brake and tire wear, combustion emissions and fly ash from asphalt. Heavy metals such as Zn, Cu, Pb, Ni, Cr and Cd primarily originate from vehicular traffic while Fe, Al and Mn primarily originate from surrounding soils. The research study confirmed the significant contribution of vehicular traffic to dust deposited on urban road surfaces.

Structural Controls and Evolution of Gold-, Silver-, and REE-Bearing Copper-Cobalt Ore Deposits, Blackbird District, East-Central Idaho: Epigenetic Origins

The Cu-Co ± Au (± Ag ± Ni ± REE) ore deposits of the Blackbird district, east-central Idaho, have previously been classified as Besshi-type VMS, sedex, and IOCG deposits within an intact stratigraphic section. New studies indicate that, across the district, mineralization was introduced into the country rocks as a series of structurally controlled vein and alteration systems. Quartz-rich and biotite-rich veins (and alteration zones) and minor albite and siderite veinlets maintain consistent order and sulfide mineral associations across the district. Both early and late quartz veins contain chalcopyrite and pyrite, whereas intermediate-stage tourmaline-biotite veins host the cobaltite. Barren early and late albite and late carbonate (generally siderite) form veins or are included in the quartz veins. REE minerals, principally monazite, allanite, and xenotime, are associated with both tourmaline-biotite and late quartz veins. The veins are in mineralized intervals along axial planar cleavage, intrafolial foliation, and shears. Mineralized intervals are hosted by a variety of metasedimentary rocks, including three phyllitic units of Mesoproterozoic age and two schistose units. All of these units are S-tectonites in the footwall of a regional thrust fault. Specifically, the district lies within an oblique thrust ramp containing a series of structural horses (three domains) in a duplex system. The deposits span the three domains and are hosted by metamorphic rocks that range from lower amphibolite facies in the structurally upper domain to lower-middle greenschist facies in the lower domain (an inverted metamorphic sequence). Early quartz and biotite veins were introduced during progressive folding and prolonged peak metamorphic conditions and they underwent late-tectonic retrograde recrystallization and metamorphic mineral growth, to the same extent as the country rocks in each domain. Where little subsequent deformation occurred, early veins are discordant to bedding but, where folding was polyphase and fabrics are penetrative, mineralized zones are concordant with metamorphic compositional layering. Late quartz veins in the zones are associated with retrograde minerals and textures and are only locally deformed. 40 Ar/ 39 Ar dating of unoriented muscovite from the selvage of a late quartz vein yields a Late Cretaceous age of about 83 Ma, the time of retrograde metamorphism associated with introduction of late quartz veins. Textural data at all scales indicate that the host sites for veins and the tectonic evolution of both host rocks and mineral deposits were kinematically linked to Late Cretaceous regional thrust faulting. Heat, fluids, and conduits for generation and circulation of fluids were part of the regional crustal thickening. The faulting also juxtaposed metaevaporite layers in the Mesoproterozoic Yellowjacket Formation over Blackbird district host rocks. We conclude that this facilitated chemical exchange between juxtaposed units resulting in leaching of critical elements (Cl, K, B, Na) from metaevaporites to produce brines, scavenging of metals (Co, Cu, etc) from rocks in the region, and, finally, concentrating metals in the lower-plate ramp structures. Although the ultimate source of the metals remains undetermined, the present Cu-Co ± Au (± Ag ± Ni ± REE) Blackbird ore deposits formed during Late Cretaceous compressional deformation.

Water diffusion in basalt and andesite melts under high pressures

Water diffusion is one of the most important characteristics of many processes dealt with in magmatic geochemistry, petrology, and volcanology. We have experimentally examined water diffusion in Fe-free andesite and basalt melts (stoichiometric mixtures of the minerals albite + diopside + wollastonite) at 3 and 100 MPa, 1300×C, up to approximately 4 wt % water in the melts, and a total (lithostatic) pressure of 100 MPa on a high gas pressure apparatus equipped with a unique internal device. The experiments were conducted simultaneously with the use of two different methods: diffusion hydration and couples. Water solubility in the melts and water concentrations along the diffusion profiles (CH2O) were determined by quantitative IR microspectroscopy, using the Beer-Lambert law. A structural chemical model is proposed for calculating and predicting the concentration dependence of the molar absorption coefficient of the hydroxyl group and water molecules in andesite and basalt glasses. The diffusion coefficients of water (DH2O) are derived by the mathematical analysis of concentration profiles and the analytical solution of the second Fick diffusion law. Preliminary results indicated DH2O is roughly one order of magnitude higher in basaltic melts than in andesitic ones (at the same temperatures and PH2O) and significantly (exponentially) increases with increasing water concentrations in andesitic and basaltic melts. The newly obtained experimental data are proved to be fully consistent with the results obtained on the DH2O dependence on CH2O in melts of acid rocks (rhyolite and obsidian). The derived quantitative dependence between DH2O and melt viscosity is used to develope principles of a new method for predicting and calculating the temperature, concentration, and pressure dependences of DH2O in magmatic melts of the of acid-basic series (up to 3 wt % CH2O) at crustal T, P parameters.

Processing and interpretation of ASTER TIR data for mapping of rare-metal-enriched albite granitoids in the Central Eastern Desert of Egypt

ASTER level 1B (radiance at the sensor) TIR-bands and level 2B04 (surface emissivity) data were analyzed to detect four of 14 rare-metal-enriched albite granite, which are classified as I-type magnetite-series (G3 type) granites in the Central Eastern Desert of Egypt. Analysis of the shapes of laboratory emissivity spectrum of albite granite samples measured by portable emission spectrometer and albite mineral spectra from ASTER spectral library at the website of JPL of NASA showed that, albite granite samples has a higher emissivity in bands 12, 13 and 14 than in bands 10 and 11. To identify and map this type of granite, Quartz Index, as well as band ratios, band ratio combination and band combinations were used, based on the shapes of the analyzed emissivity spectrum of albite granite samples and albite mineral. The Quartz Index (QI) was high for quartz-rich/feldspar poor rocks and was low for K-feldspar or gypsum-rich rocks. Albite rich granites were detected as dark pixels in the QI image. The proposed band ratio b12/b11 clearly identified the albite granite bodies as dark regions. False color images of band combination of 14:12:10 and 12:13:11 in R:G:B clearly mapped the albite granite bodies as light brownish yellow and light greenish regions respectively. A new ASTER colored composite band ratio combination b12/b13:b11/b12:b14/b13 as R:G:B is applied successfully for mapping albite granite in the study area. This new combination clearly separated albite granite as pinkish magenta color. An ASTER scene covering the study area acquired on a different date was used to determine the effect of atmospheric and surface temperature conditions on the ratio and the mathematical band operation. The results indicated no significance differences.

Fractionation of alkali elements during laser ablation ICP-MS analysis of silicate geological samples

Data on elemental fractionation of alkali elements during laser ablation ICP-MS analysis of silicate reference glasses (NIST-610, BCR-2G, alkali element-doped andesite glasses) and crystalline mineral albite (NaAlSi3O8) are reported. Laser ablation ICP-MS and SIMS were used to determine differences in sample composition before and after laser interaction with the samples. The fractionation trends of the alkali elements are different from those of other lithophile elements, such as Ca and the rare earth elements (REEs). The rate of fractionation varies for different sample matrices and for different alkali elements in the same matrix. Data from SIMS analyses of the ejecta blanket deposited adjacent to the laser ablation crater in silicate NIST-610 glass and crystalline albite suggest a matrix dependent fractionation of alkali elements for different particle size fractions in the ablated aerosol. The extent of fractionation varies for different alkali elements and is independent of their ionic radii. Ion probe depth profiling into the bottom of laser craters showed laser ablation-induced chemical changes in the sample that involved alkali elements and major matrix elements including Si and Ca. This suggests that a combination of thermally-driven diffusion and size-dependent particle fractionation are responsible for the observed fractionation of alkali elements during laser ablation of silicate samples.

Defect properties of albite

Knowledge of the defect properties of Lunar and Mercurian minerals has recently become important, with the advent of models which attempt to explain the formation of the thin exosphere of these celestial bodies. Here, we have calculated the formation energies of sodium and oxygen vacancies in the mineral albite (NaAlSi3O8), as well as the Schottky defect energy for the removal of a Na2O unit. We have employed both the supercell and Mott–Littleton approaches, using Kohn–Sham density functional theory and classical interatomic potential methods. As well as reporting the defect energies and structures, we comment upon the relative merits of the methods used.