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The x-ray identification and crystal structures of clay minerals
01 Jan 1961-
About: The article was published on 1961-01-01 and is currently open access. It has received 966 citations till now. The article focuses on the topics: Clay minerals.
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TL;DR: In this paper, a mixture of microcrystalline boehmite and amorphous aluminosilicate was formed, altering to kaolinite in solutions with MHCl = 0.003 at 245 and 230°C.
22 citations
01 Oct 1964
TL;DR: The 25° sorption isotherms of a polyoxyethylated n-dodecanol with 14 ethylene oxide units (C12EO14) on sodium and calcium montmorillonite were determined.
Abstract: The 25° sorption isotherms of a polyoxyethylated n-dodecanol with 14 ethylene oxide units (C12EO14) on sodium and calcium montmorillonite were determined. Sorption “complexes” of the two clays were also prepared with C12EO30, n-dodecanol, polyethylene glycol and polypropylene glycol.
X-ray powder diagrams show that the sorbed organic molecules are intercalated with their chains parallel to the montmorillonite lamellae, in layers one or two molecules thick. Sodium montmorillonite sorbs C12 EO14 and C12EO30 in excess of close-packed double layers: the excess detergent is occluded in interstices and absorbs moisture at 85% relative humidity to the same extent as the bulk detergents. The double layer complexes are not swelled by water; the single layer complexes sorb a single layer of water molecules at 85% relative humidity. Apparent densities of the sorbed organic molecules decrease with increasing EO content while bulk densities increase. This is explained in terms of chain flexibility and polarity.
22 citations
TL;DR: The term rodingite has been extended to include any metasomatic rock, of basic or ultrabasic parentage, consisting of clinopyroxene, which may be derived from the parent, garnet derived wholly by metascale process, and possibly other metamodel products such as prehnite, serpentine, chlorite, and xonotlite as discussed by the authors.
Abstract: SUMMARY. Xenoliths of eucritic gabbros in an alpine-serpentinite body at Wairere have been altered to rodingites and xonotlite about their margins by bydrothermal metasomatism at temperatures between 43o-47o ~ A chemical analysis and the optical properties of the xonotlite are reported, the textures of the rocks are described, and the metasomatic process is discussed. A LENSOID mass of serpentinite is continuously exposed over some 650 m along the trace of the NNE.-trending Waipa Fault at Wairere (38~ 33" S., 175 ~ 2' E.) south of Te Kuiti (Fleming, 1948; O'Brien, I97O). Extensive quarrying of the deposit has revealed the presence of numerous highly-altered xenoliths of gabbro ranging in size from hand specimens to about 12o m a and exhibiting strongly grooved and slickensided surfaces. The original composition of the majority of specimens examined was close to that of a eucrite but hydrothermal alteration has not only destroyed the original texture of the rock but also resulted in saussuritization and albitization of the feldspars. About the margins of several xenoliths, rodingites have formed and veins and layers of xonotlite occur both within and around many of the gabbros (fig. I). Dr. P. Marshall, in Bell, Clarke, and Marshall (I 911), proposed the name 'rodingite' for certain 'grossularite-diallage' phases associated with the Dun Mountain massif. His definition was based upon the rock occurring at the type locality in the upper reaches of the Roding River, Nelson. Lauder (I965, p. 485) redefined rodingite to include '... all leucocratic vein and dike rocks in ultrabasic terrains that contain considerable amounts of grossular, diopside and serpentinite and may contain a greater or less amount of prehnite, vesuvianite and perhaps other minerals'. Considerable mineralogical variation exists in rodingites and Lauder's definition is felt to be too restrictive. If a strictly mineralogical and textural definition is required the criteria given by Marshall are probably sufficient but for the purposes of this discussion the term has been extended to include any metasomatic rock, of basic or ultrabasic parentage, consisting of clinopyroxene, which may be derived from the parent, garnet derived wholly by metasomatic process, and possibly other metasomatic products such as prehnite, serpentine, chlorite, and xonotlite. Specimen numbers quoted in the text are those of the University of Auckland Geology Department rock and thin section collection. Petrography
22 citations
TL;DR: In this article, the co parameter of graphite is used for geothermometric estimations, at low-grade metamorphic conditions and at high-temperature conditions.
Abstract: This paper examines the potential use of the variation of the co parameter of graphite with temperature for geothermometric estimations. Two examples are presented in which graphite geothermometry, at low-and high-temperature conditions, is tested against other widely used geothermometers. The results obtained indicate that, at low-grade metamorphic conditions, the co parameter of graphite is affected by other factors besides the temperature, so graphite geothermometry (based on co) can only be used in such rocks for qualitative estimations. For temperatures above 500 °C, when the fully ordered graphite appears, there is a close correlation between the temperature estimations based on the structural ordering of graphite and from mineral-exchange geothermometry. The temperature calculations based on the co parameter of graphite are not influenced by factors (such as pressure or retrometamorphism) that clearly affect the exchange equilibria. Thus, graphite thermometry is a useful tool, for temperatures above 500 °C.
22 citations
TL;DR: The effects of NaOAc removal of carbonates, HzOz removal of organic materials, and sodium citrate-bicarbonate-dithionite (SCBD) removal of iron oxides upon the X-ray powder diffraction (XRD) characteristics of clay minerals present within weathered volcanic ash deposits were examined as discussed by the authors.
Abstract: The effects of NaOAc removal of carbonates, HzOz removal of organic materials, and sodium citrate-bicarbonate-dithionite (SCBD) removal of iron oxides upon the X-ray powder diffraction (XRD) characteristics of clay minerals present within weathered volcanic ash deposits were examined. All pre- treatments of samples derived from the Ae and Bhf horizons containing volcanic ash resulted in dramatic increases in XRD peak intensities, while the treatment of IIC-horizon samples resulted in subdued XRD peak intensities. Also, the chemical treatments produced an apparent increase in the amount of expandable clay minerals within the Ae horizon, due probably to the hydrolysis and removal of interlayer A1 z+ when H~O~ and SCBD were used. Hence, poorly ordered and pedogenicaUy modified vermiculite or vermiculite/ montmorillonite interstratifications became "weathered" by H + attack and AP § removal in a manner sim- ilar to the natural processes which take place in the acid and eluvial A horizon. In addition, possible XRD peak modification due to the dilution of crystalline clay concentrations 'by amorphous clay-size material appeared to be subordinate to the laboratory-induced chemical alteration of the weathered clay minerals.
22 citations