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Vermiculite

About: Vermiculite is a research topic. Over the lifetime, 2320 publications have been published within this topic receiving 37142 citations.


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Journal ArticleDOI
01 Mar 2012-Geoderma
TL;DR: In this article, the authors used X-ray diffraction (XRD), cation exchange capacity (CEC) determination, and high-resolution transmission electron microscopy (HRTEM) to investigate the Jiujiang red earth.

55 citations

Journal ArticleDOI
TL;DR: In this article, changes which occur during the natural weathering of biotite in granite gneiss and associated soils are measured by microanalysis and illustrated by SEM, and their formation in different parts of Biotite flakes taken from different locations within the soil profile is described.
Abstract: A B S T R A C T : Changes which occur during the natural weathering of biotite in granite gneiss and associated soils are measured by microanalysis and illustrated by SEM. Biotite weathers through a series of interstratified minerals to vermiculite and/or smectite phases which decompose rapidly to kaolinite. Both vermiculite and smectite phases appear to be dioctahedral, on the basis of chemical compositions derived from microprobe data. Weathering products are first apparent on the edges of laminae, where interstratified minerals are formed at right angles to both the edge face and the cleavage. Weathering soon develops along cleavage planes, initially most strongly near the edges of flakes, but then permeating extensively into the body of flakes and subdivided segments. The orientation of interstratified minerals and kaolinite within cleavages is parallel to the cleavage. Oxidation of Fe in biotite causes internal stresses which are relieved by physical deformation of the crystals. This accelerates chemical decomposition, particularly along cleavage planes. At an advanced stage of weathering when decomposition is active at many cleavages, biotite deteriorates to very finely divided, wafery remnants consisting of thin laminae separated by more open layers of particulate clay. Parts of the thin laminae remain relatively unweathered and have the same chemical composition as the original biotite immediately after oxidation. These relatively unweathered layers within the laminae have X-ray diffraction (XRD) characteristics of trioctahedral illite and they persist when the biotite remnants are broken up into clay (Fordham, 1989b). Other decomposition products are also formed. Some occur in sufficient bulk (at the microanalytical scale) to be identified directly by microprobe, but the chemical composition of others must be estimated by graphical procedures (Fordham, 1989a). These additional decomposition products of biotite are the subject of the present paper. Their formation in different parts of biotite flakes taken from different locations within the soil profile is described, and the weathering sequence as a whole is discussed. Microanalyses were performed on both thin sections and whole specimens, and the products are illustrated by scanning electron microscopy (SEM).

55 citations

Journal ArticleDOI
TL;DR: In this paper, the authors used activated vermiculite for the assessment of the environmental impact of biodegradable polyurethane (PU) based plastic material and showed that the vermicule test method is also suitable to perform ecotoxicological studies.

55 citations

Journal ArticleDOI
TL;DR: In this article, an analysis of 18 soil samples from China, representing Great Soil Groups of varying degree of weathering from Desert Soils to a Latosol were analyzed by fractionation at 5, 2, 0.2, and 0.08 µ, and application of X-ray diffraction and elemental analysis procedures.
Abstract: Eighteen soil samples from China, representing Great Soil Groups of varying degree of weathering from Desert Soils to a Latosol were analyzed by fractionation at 5, 2, 0.2, and 0.08 µ, and application of X-ray diffraction and elemental analysis procedures. In the weighted mean of these fractions of Pedocals, illite constituted 35%; of Pedalfers, vermiculite (5–12%) and kaolinite (11–50%) were more abundant; of Podsolic soils, vermiculite (5–12%) and kaolinite (11–21%) were abundant, and illite was also still important (15–23%); of the Latosols, gibbsite (25%) and hematite (23%) were dominant, but kaolinite, vermiculite, and illite were present. Montmorinic dioctahedral illite was found in the Desert soils and shows a young stage of soil weathering. The content of the montmorin series was low in most of the soils studied, attributed to drier cool climates than in the regions of the United States where it commonly occurs. The weathering mean is suggested for use in the measurement of the degree of soil mineral weathering. The weathering mean ranges from 2.5 to 11.0 for the soils of China examined.

55 citations

Journal ArticleDOI
TL;DR: In this article, the weathering of chlorite in hydrothermally-altered basalt was studied with XRD, TEM and electron microprobe to determine the type and orientation of secondary minerals.
Abstract: The weathering of chlorite in hydrothermally-altered basalt was studied with XRD, TEM and electron microprobe to determine the type and orientation of secondary minerals Optical examination indicated chlorite assemblages to have altered in two distinct microsites: one microsite near micro-fissures traversing the regolith units, and the other away from the continuous passages In this paper, weathering mechanisms and products of chlorite present in microsites distant from the micro-fissures are reported In all the regolith units the original chlorite grain remained intact and was pseudomorphed by secondary products In the saprock, chlorite altered to corrensite with possible random interstratifications of chlorite and corrensite and corrensite and vermiculite In the saprolite, corrensite altered to vermiculite Parallelism of two axes of the products with the host indicated topotactic alteration In the fine saprolite, vermiculite was found to alter to kaolinite via a randomly interstratified kaolinite-vermiculite stage with a high proportion of kaolinite Goethite crystallized in between packets of kaolinite, vermiculite and kaolinite-vermiculite Though the disruption of the crystal structure of vermiculite is necessary in its alteration to kaolinite, the reaction was such as to maintain parallelism of the c axis The alteration of chlorite to vermiculite was characterized by the loss of Mg and Fe and minor Al, all ions considered to be lost from the brucite-like sheet of chlorite The Fe released during the alteration of vermiculite to kaolinite is likely to have migrated to micropores to form goethite The presence of interstratifications of the end-members of layer silicates involved in the reaction sequence suggests that interstratifications are common during layer silicate weathering in environments where space is limited and consequently solution and ionic transport passages are restrictive

55 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202395
2022223
202163
202068
2019104
2018101