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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: The results of X-ray diffraction, DTA, and chemical tests are presented for some chlorites typical of the Flagstaff Hill area as mentioned in this paper, which is notable for the large variety of chlorite types occurring in considerable quantities.
Abstract: The results of X-ray diffraction, DTA, i.r. spectroscopy, and chemical tests are presented for some chlorites typical of the Flagstaff Hill area. The area is notable for the large variety of chlorite types occurring in considerable quantities. Chlorite, in this area, is found as veins, as pseudomorphs, and as individual crystals. Textures vary from massive, fine-grained aggregates to books which are more than 20 mm in width. Crystals more than 5 mm in size occur in parallel groupings at rock interfaces. Judging from 45 chlorite samples studied, sheridanite is most abundant; clinochlore and ripidolite are common. Penninite and its Cr-chlorite equivalent are less abundant. The parent rock is an irregularly shaped ultramafic body surrounded by low-grade schists and located very close to a granodiorite stock. The original ultramafic rocks have been highly altered by metamorphism and metosomatism into assemblages comprised mainly of serpentine, talc, hornblende, and chlorite with relics of olivine, pyroxene, and other less abundant original minerals. Much of the exposed rock is essentially monomineralic, mostly consisting of various polytypes of serpentine. Preliminary investigation indicates that the area merits much more study because of the opportunity for readily observing the various chlorite types and determining their genesis, alteration sequences and weathering characteristics. The area, being easily accessible, could also serve as an adequate source for samples to be used as reference standards.
48 citations
TL;DR: In this paper, seven samples from the Arundel area of Sussex were treated with acetic acid and the residues analysed to determine their mechanical and mineralogical compositions, and it was shown that the sand and silt fractions of the residues consist mainly of flint and opaline silica, collo- phane, limonite, and quartz, and the clay fractions consist of montmorillonite, mica, quartz and apatite.
Abstract: Seven samples, representative of all zones of the Upper Chalk in the Arundel area of Sussex, were treated with acetic acid and the residues analysed to determine their mechanical and mineralogical compositions. The sand and silt fractions of the residues consist mainly of flint and opaline silica, collo- phane, limonite, and quartz, and the' clay fractions consist of montmorillonite, mica, quartz, and apatite. Authigenic apatite and quartz occur in the clay and silt and authigenic alkali feldspar in the silt. The montmorillonite may also be authigenic. A necessary preliminary to any investigation of drift deposits or soils on the English Chalk is a knowledge of the composition of the insoluble residue of the Chalk left after dissolution under atmospheric conditions. The early work of Hume (1893) and Double (1927) on the Chalk of the south coast of England and East Anglia respec- tively, showed that HCl-insoluble residues were composed almost entirely of clay, and that the small amounts of sand contained limonite, pyrite, glauconite, and a range of detrital minerals including quartz, feldspar, zircon, tourmaline, mica, garnet, hornblende, rutile, chlorite, augite, chalcedony, magnetite, jasper, epidote, andalu- site, staurolite, sphene, and kyanite. In addition to these minerals Cayeux (1890, 1891a, b, 1897) recorded anatase, brookite, apatite, and corundum in the Chalk of northern France. The use of hydrochloric acid, even in very dilute solution, is liable to remove minerals that might be expected in natural chalk residues; for this reason, Perrin (1956, 1957, 1964) and Avery et al. (1959) used buffered acetic acid. Both made accurate mechanical analyses of the residues and showed that montmorillonite and mica are the dominant constituents of the insoluble clay fraction. Brown & Oilier (1956) used the same treatment for samples of Middle and Upper Chalk from the Chilterns and found abundant collophane in the sand fraction and an apatite-like mineral in the silt and clay. Young (1965) identified mont- morillonite, illite, kaolinite, chlorite (or vermiculite), and apatite in the clay fractions of acetic acid-insoluble residues from the Lower Chalk of the Leatherhead (Fetcham Mill) borehole, but found only montmoriUonite, illite, and apatite in the Middle and Upper Chalk.
48 citations
TL;DR: In this paper, hollow alumina microspheres were obtained from emulsified boehmite sols by an ion extraction method, and a tentative mechanism for the formation of the hollow micro-spheres was presented.
Abstract: Hollow alumina microspheres were obtained from emulsified boehmite sols by an ion extraction method. The viscosity and the equivalent alumina content of the sols were found to affect the characteristics of the derived microspheres. High-viscosity sols produced broken microspheres. A temperature of about 400–500 °C for boehmite to γ-Al2O3 transformation in the gel microspheres was observed by differential thermal analysis and X-ray diffraction. Complete crystallization of the gel microspheres to α-Al2O3 occurred at 1200 °C. A tentative mechanism for the formation of the hollow microspheres is presented.
47 citations
TL;DR: In this article, an extra-solar system origin for either mafic population is possible, though similarly lacking in evidence, and about 15% of the olivines, randomly distributed with respect to iron content, retain particle track evidence of a precompaction irradiation.
47 citations
TL;DR: In this article, a detailed analysis of the relationship between temperature and state of hydration of the vermiculite close to equilibrium at atmospheric pressure was rendered possible by use of low heating rates in combination with a fast recording position-sensitive detector.
Abstract: Dehydration and rehydration of a phlogopitic Ca-vermiculite were studied by thermoanalysis (TG, DSC) and by in situ X-ray powder diffractometry. A detailed analysis of the relationship between temperature and state of hydration of the vermiculite close to equilibrium at atmospheric pressure was rendered possible by use of low heating rates in combination with a fast recording position-sensitive detector. The results reveal the existence of a number of distinct states of hydration characterized by basal spacings of 1.515, 1.493, 1.473, 1.188, 1.176 and 0.95 nm. In confirmation of results obtained earlier with Mg-vermiculite, regular interstratification occurred at dehydration during the transition between two- to one- and between one- to zero-layer hydrates showing integral series of 001 reflections with basal spacings of 2.67 and 2.11 nm, respectively.
47 citations