Showing papers on "Vermiculite published in 1973"
TL;DR: In this paper, it is proposed that vermiculite derives from a series of reactions whose relative rates often result in an abundance of vermiculate, and that these relative reaction rates are slow for mica dissolution, rapid for K removal, and slow for vermicule dissolution.
Abstract: Stability determinations were made by solubility methods on two trioctahedral mica-derived vermiculites. The phlogopite-derived vermiculite was found to be unstable under acid solution conditions, where stabilities of montmorillonite, kaolinite and gibbsite had previously been determined. An attempt was next made to locate a possible montmorillonite-vermiculite-amorphous silica triple point. This triple point involved conditions of alkaline pH, high pH4SiO4 and high Mg2+. These are conditions where phlogopite and biotite-derived vermiculites are most likely to control equilibria if they are stable minerals. The montmorillonite-vermiculite-amorphous silica samples went to the montmorillonite-magnesite-amorphous silica triple point, leaving no stability area whatsoever for the vermiculites. These large particle-size, trioctahedral, mica-derived vermiculites appear to be unstable under all conditions of room T and P. Arguments are presented indicating that micas are unstable in almost all weathering environments. A hypothesis is proposed that mica-derived vermiculites result from the unique way in which unstable micas degrade in these environments. It is proposed that vermiculite derives from a series of reactions whose relative rates often result in an abundance of vermiculite. These relative reaction rates are slow for mica dissolution, rapid for K removal and other reactions pursuant to vermiculite formation, and slow for vermiculite dissolution. In chemical terms, mica-derived vermiculites may be considered fast-forming unstable intermediates.
46 citations
TL;DR: In this paper, X-ray diffraction analysis of mixed alkylammonium-exchanged smectite revealed segregation of different ion species into randomly ordered layers, which is explained by the hydration properties of cations as well as the energy requirements of layer expansion.
Abstract: X-ray diffraction analysis of mixed alkylammonium-exchanged smectite revealed segregation of different ion species into randomly ordered layers. Vermiculite, however, showed segregation into crystallites, a behavior attributed to clay inhomogeneity. Ion segregation is explained by the hydration properties of cations as well as the energy requirements of layer expansion. Quaternary ammonium ions of different size were used to exchange ethylammonium-clays, and the effectiveness, as well as steric hindrance, of cation size in ion exchange was demonstrated. Layer charge density was related to the degree of ease of large cation adsorption. Basal spacing in suspension was found to be important in determining the preference of vermiculite for certain cations, while more freely-expanding, lower layer charge smectite did not demonstrate this phenomenon.
32 citations
TL;DR: In this paper, the Gray Brown Podzolic soil, derived from granite in Greece, is presented and discussed, where morphological, chemical, and mineralogical properties of the soil are discussed.
Abstract: Morphological, chemical, and mineralogical properties of a Gray Brown Podzolic soil, derived from granite in Greece, are presented and discussed. Certain analytical data concerning this soil, namely the CEC and clay content, are incompatible, and this incompatibility could not, for some time, be explained. Thus, the clay content and the CEC of the B22t, B3, and C horizons were 20.8, 11.0, and 5.4 percent and 47.7, 50.5, and 47.8 me/100 g of soil, respectively, while the organic matter content was lower than 1 percent. This incompatibility has been explained and the observed high CEC values accounted for with accuracy, when it was found that not only the clay but also the coarse fractions of this soil contained high CEC material, namely a trioctahedral vermiculite and montmorillonite, the latter being present in small quantities only. The trioctahedral vermiculite was found in percentages ranging from 2.7 to 28.8 in the sand and 10.4 to 29.6 in the silt, and dominated the clay fraction (26.6 to 31.3 percent).
10 citations
TL;DR: Vermiculite, the geological name for a group of hydrated laminar minerals, has industrial application in areas previously restricted to the use of asbestos, and was injected into the pleural cavity of rats for assessment of its tumorigenicity.
Abstract: Hunter, B., and Thomson, C. (1973).British Journal of Industrial Medicine,30, 167-173. Evaluation of the tumorigenic potential of vermiculite by intrapleural injection in rats. Vermiculite, the geological name for a group of hydrated laminar minerals, has industrial application in areas previously restricted to the use of asbestos. In this assessment of its tumorigenicity, Rhodesian chrysotile asbestos or vermiculite was injected into the pleural cavity of rats. Mesotheliomata developed in 48% of the rats treated with asbestos. No tumours occurred which were associated with the vermiculite injections.
9 citations
TL;DR: An unusual chlorite has been collected from amygdales in Miocene volcanic rock found at Taiheizan, Akita Prefecture, Japan as mentioned in this paper, which is identified as a highly chloritic vermiculite with a small proportion of imperfect hydroxy interlayer.
Abstract: An unusual chlorite has been collected from amygdales in Miocene volcanic rock found at Taiheizan, Akita Prefecture, Japan. The mineral shows subtle variations from other chlorites and related minerals. These are: (a) no apparent expansion with water or ethylene glycol, (b) negligible or no collapse after NH4-saturation or heating at about 300~ (c) a slow decrease in the basal spacing on heating from approximately 400~ to 760~ (d) a small amount of low temperature or capillary water and (e) a DTA curve with a vermiculite-like system of peaks. The mineral is identified as a highly chloritic vermiculite with a small proportion of imperfect hydroxy interlayer.
5 citations
Journal Article•
TL;DR: In this paper, the authors studied the sorption and fixation of cesium in dilute solutions by vermiculite saturated with Na or K, and found that the larger amount of sorbed Cs was extracted by KCl rather than with any other extractants.
4 citations
Journal Article•
TL;DR: In this article, the authors studied the clay mineral distribution in a region extending from Palampur to Mandi and Sarkaghat in northwest India using standard X-ray diffractometer techniques.
Abstract: Clay mineral distribution in Dharmsala sediments over a region extending from Palampur to Mandi and Sarkaghat in northwest India was studied using standard X-ray diffractometer techniques. Lower Dharmsala sediments show uniform clay mineral distribution over the region and contain partially degraded illite and chlorite with minor amounts of kaolinite. Upper Dharmsala sediments seem to vary in clay mineralogy from one part of the region to another. They are characterized by the presence of illite, chlorite and vermiculite at Palampur-Baijnath. The clay minerals are mainly degraded illite, vermiculite and expandable mixed layers at Jogindernagar-Mandi and Rewalsar areas. Upper Dharmsala clays at Sarkaghat consist of montmorillonite, expandable mixed layers and minor amounts of highly degraded chlorite. Differences in clay mineral distribution over the region is explained here by variations in the characters of source rocks, weathering intensity, sediment transport, drainage and topography. The present findings are compatible with information obtained from paleocurrent investigalions.
2 citations
2 citations
01 Jan 1973
TL;DR: In this paper, the authors measured the layer charge of micas by /sup 235/U fission particle tracks (thermal neutron activated) by a development of a unique method of UO/sup 2 +/ saturation at pH 2.4 and removal of excess salts physically.
Abstract: Determination of layer charge of micas by /sup 235/U fission particle tracks (thermal neutron activated) was completed by a development of a unique method of UO/sup 2 +/ saturation at pH 2.4 and removal of excess salts physically. The U content and age-dating of soil micas was also accomplished by fission particle counting. Thermodynamic metastability of micaceous vermiculite in soils with reversible mica-vermiculite reactions were found to result in extremely tenacious natural fixation of Cs/sup +/ in soil fine fractions and weathering rock, a model for /sup 137/Cs/sup +/ retention. Visual models for Cs/sup +/ fixation were obtained as structural layer images of micaceous vermiculite wedges in clays, including kaolinites. Diverse divalent cations were found to adsorb specifically (i.e., in lM NaNO/sub 3/) on hydrous oxides of Fe and Al, materials common in soils and capable of ''holding up'' /sup 90/Sr/sup 2 +/, /sup 45/Ca/sup 2 +/, and other fission products from free movement in groundwaters. Aerosol size quartz (1 to 10 ..mu..m), from dusts containing Cs/sup +/ fixing micaceous vermiculites, was characterized by oxygen isotopic ratio analysis and the ratios found useful in tracing dust provenance. Quartz of chert origin was revealed electron microscopically as clusters of fine subhedralmore » crystals. Of the 20 elements measured in Cretaceous shales La, Sm, Ba, and Hf showed trends in concentration from igneous shore line to central basin, correlative with change in oxygen isotopic ratio.« less
1 citations