Geology and Characterization of Two Hydrothermal Nontronites from Weathered Metamorphic Rocks at the Uley Graphite Mine, South Australia

Keeling, John

doi:10.1346/ccmn.2000.0480506

Cited by 208 publications

(163 citation statements)

References 20 publications

Supporting

Mentioning

141

Contrasting

Unclassified

Order By: Relevance

“…However, as has been demonstrated here for synthetic nontronites, the NIR combination region clearly indicates the presence of only one band corresponding to δFe 3+ 2 -OH vibrations. Thus, assignment of this 841-850 cm −1 band in synthetic nontronite to a δFe 3+ 2 -OH bending mode as previously hypothesized by some authors for natural nontronites (Goodman et al, 1976;Keeling et al, 2000;Gates, 2005) is therefore inadvisable.…”

Section: Lattice Bandssupporting

confidence: 62%

Hydrothermal synthesis of dioctahedral smectites: The Al–Fe3+ chemical series. Part II: Crystal-chemistry

Petit

Decarreau

Gates

et al. 2015

Applied Clay Science

View full text Add to dashboard Cite

Section: Lattice Bandssupporting

confidence: 62%

Hydrothermal synthesis of dioctahedral smectites: The Al–Fe3+ chemical series. Part II: Crystal-chemistry

Petit

Decarreau

Gates

et al. 2015

Applied Clay Science

View full text Add to dashboard Cite

“…Compositions by ICP are from Actlabs; compositions by XRF were obtained at University of Massachusetts with the exception of the Totavi basalt, which is a LANL reference material. Reagent compositions (CaSO 4 as anhydrite and lithium tetraborate) are as-certified carbonate and iron oxyhydroxide (Keeling et al 2000) while KGa-2 has been reported to have 3 % anatase, 1 % crandallite, and traces of mica and/or illite (Chipera and Bish 2001). Our XRD analysis of the as-received NAu-2 sample shows presence of a trace amount of feldspar; anatase is present in the as-received KGa-2 ( Fig.…”

Section: Ceramic Synthesis Tests and Fabricationmentioning

confidence: 64%

Ceramic ChemCam Calibration Targets on Mars Science Laboratory

et al. 2012

View full text Add to dashboard Cite

The ChemCam instrument on the Mars Science Laboratory rover Curiosity will use laser-induced breakdown spectroscopy (LIBS) to analyze major and minor element chemistry from sub-millimeter spot sizes, at ranges of ∼1.5-7 m. To interpret the emission spectra obtained, ten calibration standards will be carried on the rover deck. Graphite, Ti metal, and four glasses of igneous composition provide primary, homogeneous calibration targets for the laser. Four granular ceramic targets have been added to provide compositions closer to soils and sedimentary materials like those expected at the Gale Crater field site on Mars. Components used in making these ceramics include basalt, evaporite, and phyllosilicate materials that approximate the chemical compositions of detrital and authigenic constituents of clastic and evaporite sediments, including the elevated sulfate contents present in many Mars sediments and soils. Powdered components were sintered at low temperature (800°C) with a small amount (9 wt.%) of lithium tetraborate flux to produce ceramics that retain volatile sulfur yet are durable enough for the mission. The ceramic targets are more heterogeneous than the pure element and homogenous glass standards but they provide standards with compositions more similar to the sedimentary rocks that will be Curiosity's prime targets at Gale Crater.

show abstract

“…The clay mineral used in this study is a nontronite from Southern Australia (25). Nontronite is a naturally occurring swelling dioctahedral clay mineral related to the montmorillonitebeidellite series in which most aluminum atoms are replaced by iron (III) ions.…”

Section: Resultsmentioning

confidence: 99%

Liquid–crystalline aqueous clay suspensions

Michot¹,

Bihannic²,

Maddi³

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

231

248

View full text Add to dashboard Cite

This article demonstrates the occurrence of a true isotropic͞nematic transition in colloidal Brownian aqueous suspensions of natural nontronite clay. The liquid-crystalline character is further evidenced by polarized light microscopy and small-angle x-ray scattering experiments in the presence and absence of modest external magnetic fields. The complete phase diagram ionic strength͞volume fraction then exhibits a clear biphasic domain in the sol region just before the gel transition in contrast with the situation observed for other swelling clays in which the sol͞gel transition hinders the isotropic͞ nematic transition. Small-angle x-ray scattering measurements of gel samples reveal strong positional and orientational orders of the particles, proving unambiguously the nematic character of the gel and, thus, clearly refuting the still prevalent ''house of cards'' model, which explains the gel structure by means of attractive interactions between clay platelets. Such order also is observed in various other swelling clay minerals; therefore, this very general behavior must be taken into account to reach a better understanding of the rheological properties and phase behavior of these systems.colloids ͉ liquid crystal ͉ phase transitions S welling clay minerals are layered compounds that bear a negative layer charge compensated by interlayer exchangeable cations whose valence and hydration properties control both swelling and colloidal behavior. One of the most important properties of swelling clay minerals is their ability to form yield stress materials when dispersed in water. This feature, extensively used in various industrial applications (drilling fluids, food industry, cosmetic industry, etc.), also plays a major role in many fundamental processes occurring at the Earth's surface, such as slipping processes in plate-boundary faults (1-4) or landslide triggering (5-9). For these reasons, numerous studies have focused on the rheology of aqueous clay suspensions with particular emphasis on yield stress, thixotropy, and aging (10-15). However, most studies neglect a key feature of clay minerals, i.e., their anisotropic shape. Actually, due to their high aspect ratio typically ranging between 25 and 1,000, these materials should very likely form liquid-crystalline phases (16), such as those observed for rod-like clay particles, such as imogolite in aqueous media (17), or organophilic sepiolite clay particles in nonaqueous solvents (18). A phase transition was indeed observed by Langmuir (19, ** ) as early as 1938 in suspensions of natural hectorite swelling clay. However, all subsequent studies failed to reproduce this crucial observation and give evidence of a clear thermodynamic liquid-crystalline order but instead revealed a dominant gel formation (20). Such behavior is observed for both highly polydisperse natural samples (21) and synthetic monodisperse ones (22). The structure and formation mechanisms of the gel are still under debate. Indeed, although some of the gel features indicate nematic ordering (23,24)...

show abstract

Geology and Characterization of Two Hydrothermal Nontronites from Weathered Metamorphic Rocks at the Uley Graphite Mine, South Australia

Cited by 208 publications

References 20 publications

Hydrothermal synthesis of dioctahedral smectites: The Al–Fe3+ chemical series. Part II: Crystal-chemistry

Hydrothermal synthesis of dioctahedral smectites: The Al–Fe3+ chemical series. Part II: Crystal-chemistry

Ceramic ChemCam Calibration Targets on Mars Science Laboratory

Liquid–crystalline aqueous clay suspensions

Contact Info

Product

Resources

About