Solvent-pore interactions in the Eagle Ford shale formation.

The effect of solvent extraction on pore space was examined on a suite of samples from the Eagle Ford Shale Formation with varying lithologies and maturities. Several solvents ─toluene, cyclohexane, methanol, dichloromethane, and hydrochloric acid─ were contacted with shale samples, extracting the compatible organic matter. The porosity in these extracted shale samples was compared to unmodified samples.

Clay mineral diversity and abundance in sedimentary rocks of Gale crater, Mars.

Clay minerals provide indicators of the evolution of aqueous conditions and possible habitats for life on ancient Mars. Analyses by the Mars Science Laboratory rover Curiosity show that ~3.5-billion year (Ga) fluvio-lacustrine mudstones in Gale crater contain up to ~28 weight % (wt %) clay minerals.

Silicic volcanism on Mars evidenced by tridymite in high-SiO2 sedimentary rock at Gale crater.

Tridymite, a low-pressure, high-temperature (>870 °C) SiO2 polymorph, was detected in a drill sample of laminated mudstone (Buckskin) at Marias Pass in Gale crater, Mars, by the Chemistry and Mineralogy X-ray diffraction instrument onboard the Mars Science Laboratory rover Curiosity The tridymitic mudstone has ∼40 wt.% crystalline and ∼60 wt.% X-ray amorphous material and a bulk composition with ∼74 wt.

Mineralogy, provenance, and diagenesis of a potassic basaltic sandstone on Mars: CheMin X-ray diffraction of the Windjana sample (Kimberley area, Gale Crater).

The Windjana drill sample, a sandstone of the Dillinger member (Kimberley formation, Gale Crater, Mars), was analyzed by CheMin X-ray diffraction (XRD) in the MSL Curiosity rover. From Rietveld refinements of its XRD pattern, Windjana contains the following: sanidine (21% weight, ~Or); augite (20%); magnetite (12%); pigeonite; olivine; plagioclase; amorphous and smectitic material (~25%); and percent levels of others including ilmenite, fluorapatite, and bassanite. From mass balance on the Alpha Proton X-ray Spectrometer (APXS) chemical analysis, the amorphous material is Fe rich with nearly no other cations-like ferrihydrite.

The origin and implications of clay minerals from Yellowknife Bay, Gale crater, Mars.

The Mars Science Laboratory (MSL) rover Curiosity has documented a section of fluvio-lacustrine strata at Yellowknife Bay (YKB), an embayment on the floor of Gale crater, approximately 500 m east of the Bradbury landing site. X-ray diffraction (XRD) data and evolved gas analysis (EGA) data from the CheMin and SAM instruments show that two powdered mudstone samples (named John Klein and Cumberland) drilled from the Sheepbed member of this succession contain up to ~20 wt% clay minerals. A trioctahedral smectite, likely a ferrian saponite, is the only clay mineral phase detected in these samples.

The first X-ray diffraction measurements on Mars.

The Mars Science Laboratory landed in Gale crater on Mars in August 2012, and the Curiosity rover then began field studies on its drive toward Mount Sharp, a central peak made of ancient sediments. CheMin is one of ten instruments on or inside the rover, all designed to provide detailed information on the rocks, soils and atmosphere in this region. CheMin is a miniaturized X-ray diffraction/X-ray fluorescence (XRD/XRF) instrument that uses transmission geometry with an energy-discriminating CCD detector.

Isotope ratios of H, C, and O in CO2 and H2O of the martian atmosphere.

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C, (18)O/(16)O, (17)O/(16)O, and (13)C(18)O/(12)C(16)O in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established ~4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing.

Release of beryllium from mineral ores in artificial lung and skin surface fluids.

Exposure to some manufactured beryllium compounds via skin contact or inhalation can cause sensitization. A portion of sensitized persons who inhale beryllium may develop chronic beryllium disease (CBD). Little is understood about exposures to naturally occurring beryllium minerals.

Physicochemical characteristics of aerosol particles generated during the milling of beryllium silicate ores: implications for risk assessment.

Inhalation of beryllium dusts generated during milling of ores and cutting of beryl-containing gemstones is associated with development of beryllium sensitization and low prevalence of chronic beryllium disease (CBD). Inhalation of beryllium aerosols generated during primary beryllium production and machining of the metal, alloys, and ceramics are associated with sensitization and high rates of CBD, despite similar airborne beryllium mass concentrations among these industries. Understanding the physicochemical properties of exposure aerosols may help to understand the differential immunopathologic mechanisms of sensitization and CBD and lead to more biologically relevant exposure standards.

Pretreatment technique for siderite removal for organic carbon isotope and C:N ratio analysis in geological samples.

A method for the removal of siderite from geological samples to determine organic carbon isotope compositions using elemental analysis isotope ratio mass spectrometry is presented which includes calculations for % organic carbon in samples that contain diagenetic carbonate. The proposed method employs in situ acidification of geological samples with 6 N HCl and silver capsule sample holders and was tested on modern peach leaf samples (NIST 1547) and ancient lacustrine samples from Valles Caldera, New Mexico. The in situ acidification technique eliminates potential errors associated with the removal of soluble organic material using standard acid decanting techniques and allows for removal of the less soluble siderite, which is not efficiently removed using vapor acidification techniques.

Characteristics of dusts encountered during the production of cemented tungsten carbides.

Inhalation of cobalt (Co) and tungsten carbide (WC) particles, but not Co or WC alone, may cause hard metal disease, risk of which does not appear to be uniform across cemented tungsten carbide (CTC) production processes. Inhalation of Co alone or in the presence of WC may cause asthma. Hypothesizing that aerosol size, chemical content, heterogeneity, and constituent compaction may be important exposure factors, we characterized aerosols from representative CTC manufacturing processes.

Novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of graphite.

We report a novel crystalline carbon-cage structure synthesized from laser-driven shock wave loading of a graphite-copper mixture to about 14+/-2 GPa and 1000 +/- 200 K. Quite unexpectedly, it can be structurally related to an extremely compressed three-dimensional C60 polymer with random displacement of C atoms around average positions equivalent to those of distorted C60 cages. Thus, the present carbon-cage structure represents a structural crossing point between graphite interlayer bridging and C60 polymerization as the two ways of forming diamond from two-dimensional and molecular carbon.

Magnesium sulphate salts and the history of water on Mars.

Recent reports of approximately 30 wt% of sulphate within saline sediments on Mars--probably occurring in hydrated form--suggest a role for sulphates in accounting for equatorial H2O observed in a global survey by the Odyssey spacecraft. Among salt hydrates likely to be present, those of the MgSO4*nH2O series have many hydration states. Here we report the exposure of several of these phases to varied temperature, pressure and humidity to constrain their possible H2O contents under martian surface conditions.