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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, Na-beidellite, a member of the smectite group, was grown hydrothermally from a gel of composition 0.35NazO.
Abstract: Ahstract--Na-beidellite, a member of the smectite group, was grown hydrothermally from a gel of composition 0.35NazO.2.35A1zO3.7.3SiO2 in NaOH solutions at a pH between 7.5 and 13.5, a pressure of 1 kbar, and a temperature of 350"C. The synthetic Na-beidellite was characterized by means of scanning electron microscopy, X-ray powder diffraction, infrared spectroscopy, electron microprobe, inductively coupled plasma-atomic emission spectroscopy, and thermogravimetric analysis. The unit-cell parameters of the orthorhombic cell are: a = 5.18, b = 8.96, and c = 12.54/~. The cation-exchange capacity was determined to be 70 meq/100 g. A maximum of 40 wt. % water was present and reversibly lost by heating to about 55"C. The loss of water caused a decrease of the basal spacing to 9.98/~. At temperatures >600"C, the Na-beidellite started to dehydroxylate, reaching its maximum in the range 600"-630"C. At 1100*C the remaining solid recrystallized to A16Si20~a (mullite) and SiO2 (cristobalite).
62 citations
Cites background or result from "The x-ray identification and crysta..."
...0106 Weir and Greene-Kelly (1962), Brown (1961) l 5....
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...50 ~ (Weir and Greene-Kelly, 1962; Brindley and Brown, 1980). Indexing based on the calculated lattice parameters revealed that an 024 index for the peak at 3.15 /~ reported by Weir and Greene-Kelly (1962) is incorrect....
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...2 Brown (1961); Weir and Greene-Kelly (1962). 3 002 not given by Brown (1961), Weir and Greene-Kelly (1962). 4 004 instead of 024 as given by Weir and Greene-Kelly (1962)....
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...for Na-beideUite from Brindley and Brown (I 980) and for Ca-beidellite from Weir and Greene-Kelly (1962) in Table 3....
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...50 ~ (Weir and Greene-Kelly, 1962; Brindley and Brown, 1980). Indexing based on the calculated lattice parameters revealed that an 024 index for the peak at 3.15 /~ reported by Weir and Greene-Kelly (1962) is incorrect. An assignment of 004 is more consistent with the other reflections. The indexing given here is in accord with the data given by Nadeau et al. (1985) for the Unterrupsroth beidellite....
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TL;DR: In this paper, the authors investigated the expandibility of tubular and non-tubular kaolinite in lateritic weathering profiles on dolerite and granite in Western Australia.
Abstract: The kaolin minerals in lateritic weathering profiles on dolerite and granite in Western Australia have been characterized by intercalation tests for halloysites, and also by their particle morphologies. Towards the surface of the profiles there is a decrease in both total kaolin mineral content, and in the expandibility of those minerals to intercalation. Tubular kaolinite that is non-expandible by any of the intercalation tests for halloysite was identified in the upper few metres of both profiles. Hydrated halloysite is most common at the base of both profiles. Formamide expands some anhydrous kaolin minerals while the sequence of hydrazine/water/glycerol (HWG) expands more of these minerals. Non-tubular (subhedral to sub-hexagonal platy) kaolinite is also present. Hydrated tubular halloysite apparently alters to tubular kaolinite via dehydrated halloysite that is expandible by formamide and a tubular ‘kaolin’ that is expandible by HWG but not by formamide.
62 citations
TL;DR: The infrared spectrum of nordstrandite, which is probably the stable polymorph in alkaline solution, shows evidence of strongly polarized hydroxyl ions similar to gibbsite as mentioned in this paper.
Abstract: Infrared absorption spectra of the precipitated solids separated from aluminium-hydroxide solutions below the pH of minimum solubility of Al(OH)3 demonstrate the slow ageing of polymeric Al complexes to gibbsite. On comparison with the spectra of natural gibbsites, shifts in absorption frequency during crystal growth are interpreted in terms of changes in hydrogen bonding as a consequence of deprotonation and stacking of aluminium hydroxide layers to form gibbsite. In alkaline solutions the bayerite polymorph precipitates and IR frequencies are compatible with protonation as aluminate ions associate with the bayerite crystal having a lower crystal energy than its low pH polymorph. The infrared spectrum of nordstrandite, which is probably the stable polymorph in alkaline solution, shows evidence of strongly polarized hydroxyl ions similar to gibbsite.
62 citations
TL;DR: Palabora as discussed by the authors represents an interstratified vermiculite-biotite containing less than 50% vermiculate, and was prepared by immersion in saturated brine at ambient conditions.
62 citations
TL;DR: The environmental dynamics of pesticides are influenced largely by the various factors operating in the environment and the physicochemical and biological properties of pesticides.
Abstract: The environmental dynamics of pesticides are influenced largely by the various factors operating in the environment and the physicochemical and biological properties of pesticides. In the broad sense, the environment is divided into four major components, namely, atmosphere (air), hydrosphere (water), lithosphere (soil), and biosphere (biota), each possessing its own physical and chemical and/ or biological properties. The biotic and abiotic elements in each component influence the dynamics of pesticides. The environmental dynamics of pesticides are further influenced by the physicochemical properties of pesticides. Such properties of pesticides as hydro- or lipo-philicity, partition coefficients, adsorption or chemiosorption, vapor pressure, and volatility determine the ultimate fate of pesticides in the living and nonliving portions of the sytems.
61 citations