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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 article, the authors measured the adsorption isotherm, titration curve and zeta-potential of the hematite surface association, and showed that the surface association is consistent with the hemi-micelle theory.
10 citations
TL;DR: A B S T R A C T: A smectite formed by weathering of mica in a laterite pallid zone at Boddington, Western Australia has been investigated by analytical electron microscopy as mentioned in this paper.
Abstract: A B S T R A C T: A smectite formed by weathering of mica in a laterite pallid zone at Boddington, Western Australia has been investigated by analytical electron microscopy. The evidence suggests that this mineral has the chemical composition and swelling properties of ideal beidellite but is anomalous in containing abundant non-exchangeable K. This K balances half of the layer charge that arises mostly from tetrahedral substitution of A13+ for Si 4+, with the K + occupying one sixth of the sites occupied by K in mica.
10 citations
TL;DR: The Lower Palaeozoic Naqus Formation of Gebel Gunna in the Sinai Peninsula is conformably underlain by the Araba Formation and unconformably overlain by the Cenomanian Malha Formation.
10 citations
TL;DR: Beck et al. as discussed by the authors found that the surface skin of the black zone, less than 1 µm thick, commonly consists of well oriented thin clay and biotite flakes coated with amorphous hydrous Mn-Fe oxides.
Abstract: Black coated fracture surfaces are common in the saprolites of the Southeast United States. Many of the surfaces are polished and striated indicating movement has occurred; others show no evidence of movement. The black zone is commonly 1-2 mm thick. The surface skin of the black zone, less than 1 µm thick, commonly consists of well oriented thin clay and biotite flakes coated with amorphous hydrous Mn-Fe oxides. The underlying material is not oriented parallel to the fracture surface. The clay is an iron-rich tabular halloysite which formed from biotite. The Mn occurs as 0.1 µm ovoids thin coatings and micro-nodules. Some black surfaces contain a high concentration of rare earth elements, particularly cerium. Both the Mn and Fe were released from the biotite during acid weathering (saprolite pH 5). Much of the Fe was precipitated in the vicinity of the biotite. The more mobile Mn migrated to pre-existing fractures and voids where the pH of circulating ground waters was sufficiently high (pH 7) to cause precipitation. All features indicate movement along the fractures has been extremely gentle and is probably due to settling or stress release rather than tectonic activity. The "black coating" has intrigued me since I moved to the S.E.. I am grateful to the Duke Power Company for supporting much of this study, C. H. Gardner of Law Engineering Testing Company aided in the sample collecting and was most helpful in defining the problem. Dr. K. C. Beck and G. A. Cooke kindly provided the chemical analyses.
10 citations
TL;DR: In this paper, the evolution of some properties of halloysite with heat treatment (temperature range 110°C-1000°C) has been studied and the influence of the temperature on the surface properties (surface area, acid surface centres and porosity) are also studied.
10 citations