The nanoscale elastic properties of moist clay minerals are not sufficiently understood. The aim of the present study was to understand the fundamental mechanism for the effects of water and pore size on clay mineral (K+-smectite) elastic properties using the General Utility Lattice Program (GULP) with the minimum energy configurations obtained from molecular dynamics (MD) simulations. The simulation results were compared to an ideal configuration with transversely isotropic symmetry and were found to be reasonably close. The pressures computed from the MD simulations indicated that the changes due to water in comparison to the dry state varied with the water content and pore size. For pore sizes of around 0.8–1.0 nm, the system goes through a process where the normal pressure is decreased and reaches a minimum as the water content is increased. The minimum normal pressure occurs at water contents of 8 wt.% and 15 wt.% for pore sizes of around 0.8 nm and 1 nm, respectively. Further analyses of the interaction energies between water and K+-smectite and between water and water revealed that the minimum normal pressure corresponded to the maximum rate of slope change of the interaction energies (the second derivative of the interaction energies with respect to the water content). The results indicated that in the presence of water the in-plane stiffness parameters were more correlated to the pressure change that resulted from the interplay between the interactions of water with K+-smectite and the interactions of water with water rather than the water content. The in-plane stiffness parameters were much higher than the out-of-plane parameters. Elastic wave velocities for the P and S waves (VP and VS) in the dry K+-smectite with a pore size of ~1 nm were calculated to be 7.5 and 4.1 km/s, respectively. The P and S wave velocity ratio is key in the interpretation of seismic behavior and revealed that VP/VS = 1.64–1.83, which were values in favorable agreement with the experimental data. The results might offer insight into seismic research to predict the mechanical properties of minerals that are difficult to obtain experimentally and can provide complimentary information to interpret seismic surveys that can assist gas and oil exploration.

Illite polytypes are used to elucidate the geological record of formations, such as the timing and provenance of deformations in geological structures and fluids, so the ability to characterize and identify them quantitatively is key. The purpose of the present study was to compare three X-ray powder diffraction (Q-XRPD) methods for illite polytype quantification for practical application to directly date clay-rich fault rocks and constrain the provenance of deformation-related fluids in clay-rich brittle rocks of the upper crust. The methods compared were WILDFIRE© (WF) modeling, End-member Standards Matching (STD), and Rietveld whole-pattern matching (BGMN®). Each technique was applied to a suite of synthetic mixtures of known composition as well as to a sample of natural clay gouge (i.e. the soft material between a vein wall and the solid vein). The analytical uncertainties achieved for these synthetic samples using WF modeling, STD, and Rietveld methods were ±4–5%, ±1%, and ±6%, respectively, with the caveat that the end-member clay mineral used for matching was the same mineral sample used in the test mixture. Various particle size fractions of the gouge were additionally investigated using transmission electron microscopy (TEM) to determine polytypes and laser particle size analysis to determine grain size distributions. The three analytical techniques produced similar 40Ar/39Ar authigenesis ages after unmixing, which indicated that any of the methods can be used to directly date the formation of fault-related authigenic illite. Descriptions were included for pre-calculated WF illite polytype diffractogram libraries, model endmembers were fitted to experimental data using a least-squares algorithm, and mixing spreadsheet programs were used to match end-member natural reference samples.

Recently, studies on the use of polymer nanomaterial composites as pour-point depressants (PPD) have drawn much attention, but the crystallization properties and improved rheological performance of waxy crude oils using nanoclay-based composite PPDs have rarely been reported. In this paper, montmorillonite (Mnt) was first organically modified using octadecyltrimethylammonium chloride (C21H46NCl, or stearyltrimethylammonium chloride) in aqueous solution. Then, the organically modified Mnt (OMnt) material was dispersed into a polyoctadecylacrylate (POA) matrix to prepare a POA/OMnt composite PPD by melt blending. The composition, structure, and morphology of Mnt, OMnt, and the POA/OMnt composite PPDs were investigated. The results showed that the OMnt and POA were compatible and that the OMnt was exfoliated into several sheets in the POA matrix. Subsequently, the isothermal crystallization kinetics of the POA/OMnt composite PPDs showed that small amounts of OMnt had a dramatic impact on POA chain motion during crystallization and facilitated POA crystallization. After it was added to a waxy crude oil, the POA/OMnt composite PPDs produced better rheological properties and performance than identical concentrations of the neat POA. The POA/OMnt composite PPDs can act as wax nucleation sites for wax molecule precipitation and result in larger and more compact wax crystal flocs, which adversely affect the formation of a wax crystal network and, thus, favor the improvement of waxy crude oil rheology.

The high-density siliciclastic minerals (e.g. zircon) in the coarse fractions (>44 mm, informally known as grit) of the mined Georgia kaolins are potential and significant sources of the rare-earth elements (REE). The abundances and provenance of the REE signature have not been studied extensively for the Georgia kaolins. The objective of the present study was, therefore, to define the contribution of these heavy minerals (e.g. zircon) to the REE inventory of the coarse fractions of Georgia kaolins. Heavy-mineral subfractions separated from the coarse fractions contained 1647 mg/kg REE from the Jeffersonville Member of the Lower Tertiary Huber Formation and 5012 mg/kg REE from the Buffalo Creek Kaolin Member of the Upper Cretaceous Galliard Formation, respectively. These heavy-mineral subfractions were enriched 10–100 times in the heavy rare-earth elements (HREE, Gd—Lu,), Hf, and Zr relative to the concentrations of these elements in Upper Continental Crust. The heavy-mineral subfractions comprised 5% of the coarse fractions (grit) of these two kaolin-producing formations. The heavy-mineral subfractions consisted of zircon, anatase, rutile, kaolinite, and minor amounts of muscovite, trace ilmenite, and staurolite. The large concentrations of REE were obtained by separating the dense heavy minerals from the coarse fraction (grit) obtained during the typical production of kaolin-group minerals (kaolinite) from kaolin ore. The amount of zircon (estimated from the 6–11 wt.% Zr) and the absence of monazite did not explain the high concentrations of REE in the heavy-mineral subfractions. The large amounts of REE could have resulted from the sorption of REE released during weathering reactions, or from the presence of small amounts (0.025 wt.%) each of monazite and xenotime in addition to the presence of zircon. This heavymineral subfraction represented a novel domestic resource of extractable REE, especially the HREE, of a grade as high as 0.50 wt.% total REE.

As a common mineral phase on Earth and Martian regolith, natural rutile was reported as a potential candidate for use as a Fenton catalyst in this study. The influences of Fe and V in various chemical states on the generation of reactive oxygen species (ROSs) and the catalytic activity of rutile were examined. A series of rutile samples with various surface and bulk states of Fe and V were obtained initially by hydrogen annealing of natural rutile at ~773–1173 K. X-ray diffraction, electron paramagnetic resonance spectra, and X-ray photoelectron spectroscopy demonstrated that the atomic fractions of Fe(III) and V(V) decreased sharply with increasing temperature, along with the accumulation of surface Fe(II) and bulk V(III). All as-prepared materials showed enhanced Fenton degradation efficiency on methylene blue (MB) compared with P25-TiO2, and the treated samples exhibited up to 3.5-fold improvement in efficiency at pH 3 compared to the untreated sample. The improved efficiency was attributed mainly to Fenton catalysis involving Fe(II) and V(III). The dissolved Fe2+ played a crucial role in the homogeneous Fenton reaction, while the bound V(III) favored adsorption primarily and may have facilitated heterogeneous Fenton reaction and the regeneration of Fe2+. The pH regulated the reaction mechanism among homogeneous (pH = 3) and heterogeneous (pH = 3.7) Fenton catalysis and physical adsorption (pH = 5, 6). The aim of the present study was to improve the understanding of the potential role of natural rutile with advanced oxidation functions in Earth systems and even on Mars, which also provide an inspiration for screening natural rutile and any other similar, Earth-abundant, low-cost minerals for environmental application.

Zinc (Zn) is widely known as an essential trace element for fish and new ways to supply it to them are needed. Palygorskite (Pal) is a natural silicate clay mineral and the palygorskite structure contains nano-channels, which are filled with water and exchangeable ions. Zn-bearing palygorskites (Zn-Pal) prepared using ion exchange have attracted attention due to the durable antibacterial properties that limit pathogens and as a potential new Zn source for livestock. The present study was conducted to evaluate the effects of Zn-Pal supplementation on the growth performance, nutrient retention, meat quality, Zn accumulation, and intestinal Zn transporter protein gene expression in blunt snout bream Megalobrama amblycephala. The fish were fed a basal diet without an exogenous Zn source and the basal diet was supplemented with 125 mg/kg Zn as Zn sulfate (ZnSO4) or 35, 80, or 125 mg/kg Zn as Zn-Pal. Each diet was tested using three replicates for 7 weeks. The results showed that dietary Zn-Pal supplementation quadratically (P<0.05) increased growth performance, nutrient retention, total and Cu/Zn superoxide dismutase activity, Zn content in scales, and intestinal Zn transporter protein gene expression. The muscular cooking loss in blunt snout bream decreased with the optimum Zn-Pal Zn level of 35 mg/kg. Compared to the fish treated with ZnSO4, the fish supplemented with 35 mg/kg as Zn-Pal exhibited similar growth performance and nutrient retention (P>0.05), increased mRNA expression of the metal-response element-binding transcription factor-1 in the intestine (P<0.05), and decreased cooking loss of muscle (P<0.05).The results suggested that 35 mg/kg Zn supplementation as Zn-Pal could improve the growth performance and body composition, increase nutrient retention and tissue Zn concentrations, enhance the muscle water-holding capacity, and enhance antioxidant status in blunt snout bream. The Zn-Pal was more efficient and could be used as an alternative Zn source to ZnSO4 in the diet of blunt snout bream.

The oil sands of western Canada represent the third largest hydrocarbon deposit in the world. Bitumen, a very heavy petroleum, is recovered from mined oil sands using warm water extraction followed by separation treatments to isolate the bitumen product. The high energy, water use, as well as tailings remediation challenges associated with the warm water extraction process raise major environmental concerns. Non-aqueous extraction using organic solvents at room temperature has been investigated extensively as an alternative to the warm water extraction process. The main challenge to the large-scale implementation of non-aqueous extraction is the retention of solvent in the tailings. The objective of this work was to present and validate a computational model for the interaction of solvents used in non-aqueous extraction with minerals, such as the abundant and adsorbent clay mineral kaolinite. The model system contained a periodically extended kaolinite platelet immersed in a solvent and all were treated at the atomic level using the 3D Reference Interaction Site Model with the Kovalenko-Hirata closure approximation (3D-RISM-KH) molecular theory of solvation. The solvent solvation free energy of interaction with kaolinite as well as site-specific adsorption energies and kinetic barriers for desorption were computed based on the solvent site density distribution functions. Moreover, the lateral and integrated density distributions were computed to analyze the organization of solvent at kaolinite surfaces. The integrated density distribution profiles were correlated with experimental adsorption isotherms. The results showed very strong adsorption of ethanol and weak adsorption of hydrocarbon solvents on kaolinite, which were in qualitative agreement with experimental solvent extraction reports. The model and these findings are valuable in understanding the mechanism of solvent retention in tailings after non-aqueous extraction and highlight the action of hydroxylated cosolvent additives to enhance extraction using nonpolar solvents.

Infrared (Visible-Near Infrared-Shortwave Infrared (VNIR-SWIR)) spectroscopy is a cost-effective technique for mineral identification in the field. Modern hand-held spectrometers are equipped with on-board spectral libraries that enable rapid, qualitative analysis of most minerals and facilitate recognition of key alteration minerals for exploration. Spectral libraries can be general or customized for specific mineral deposit environments. To this end, careful collection of spectra in a controlled environment on pure specimens of key minerals was completed using the National Mineral Reference Collection (NMC) of the Geological Survey of Canada. The spectra collected from specimens in the ‘Kodama Clay Collection’ were processed using spectral plotting software and each new example was validated before being added to a group of spectra considered for incorporation into the on-board library of the handheld ASD-TerraSpec Halo near-infrared (NIR) mineral identification instrument. Spectra from an additional suite of mineral samples of the NMC containing REE, U, Th, and/or Nb are being prepared for a new, publicly available spectral library. These minerals commonly occur in carbonatite or alkali intrusive deposits, and as such will assist in the exploration for critical metals.