Book•
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.
Citations
More filters
TL;DR: In this article, the influence of hydrolysis on the polycondensation of aluminium alkoxides was studied and two mechanisms of hydroxylation were proposed for this process.
Abstract: The influence of hydrolysis on the hydrolytic polycondensation of aluminium alkoxides was studied. Two mechanisms of hydrolysis which give two different products are proposed for this process. Structural transformations of the resultant condensates, i.e. boehmite, (γ-AlOOH), the product of hot-water hydrolysis, and gibbsite Al (OH)3, the product of cold water hydrolysis, have been investigated in temperature range 20–1300 °C. An explanation was offered for the variations in the a-Al2O3 transformations of the condensate produced by room temperature hydrolysis.
30 citations
TL;DR: The first appearance of green biotite in the Haast Schist terrane of eastern Otago was reported by Mather and Brown as discussed by the authors, who used a 1 #m scale.
Abstract: Green biotite-like material occurring in Haast Schist at Brighton, eastern Otago, consists of biotite and a kaolin-group mineral interlayered on a 1 #m scale. Electron probe analyses of composite grains show K20 contents of 4.4 to 8.5 wt. %, in part reflecting the kaolin content, and in part, leaching of K § ions. Phengitic muscovite shows similar but less extreme effects. Kaolin, siderite, calcite, and titanium oxides have formed in the rock during hydrothermal alteration of epidote, sphene, and biotite by carbonated waters. Potas- sium leaching due to surficial weathering processes appears to be widespread in biotites from the schists of eastern Otago, and biotites (hydrobiotites?) with K20 as low as 4 wt. % are reported. Similar material with 0.8 to 2.4% K20 and with Na20 about 1% is thought to be more highly degraded biotite. Microprobe analyses of kaolin and chlorites from associated rocks are given in addition to those of 'biotite' and phengitic muscovite. Analyses of sheet biotite and sheet muscovite from the Mataketake Range pegrnatites in the highest grade parts of the Haast Schist terrane are presented for comparison. The study shows that biotite is more widespread in eastern Otago than was previously thought, and that almandine-rich garnet is not confirmed down-grade of the first appearance of biotite in eastern Otago. THE Otago schists, which form part of the New Zealand Haast Schist terrane, have been commonly regarded as forming an unusually large tract within the chlorite zone of the greenschist facies. Neverthe- less Turner and Hutton (1941) noted greenish- brown biotite and small garnets in porphyroblastic albite schists from the South Branch of the Waikouaiti River (fig. 1), and Hutton (1940) described biotite in schists from western Otago. Following Tilley (1925) sporadic occurrences of green or greenish-brown biotite, particularly in greenschists, have commonly been disregarded in mapping a biotite isograd, but more recently authors such as Mather (1970) and Brown (1971, 1975) place such assemblages within the lower- grade part of the biotite zone. Brown distinguishes a 'lower biotite zone' in which the assemblages muscovite-stilpn omelane and muscovite-actino lite
30 citations
TL;DR: This formulation consists of a mucoadhesive oral film with incorporated nanocomposite biomaterial that is able to release the drug directly at the target area and inhibited the growth of Staphylococcus and Candida; the effect was prolonged for tens of hours.
Abstract: Infectious stomatitis represents the most common oral cavity ailments. Current therapy is insufficiently effective because of the short residence time of topical liquid or semisolid medical formulations. An innovative application form based on bioadhesive polymers featuring prolonged residence time on the oral mucosa may be a solution to this challenge. This formulation consists of a mucoadhesive oral film with incorporated nanocomposite biomaterial that is able to release the drug directly at the target area. This study describes the unique approach of preparing mucoadhesive oral films from carmellose with incorporating a nanotechnologically modified clay mineral intercalated with chlorhexidine. The multivariate data analysis was employed to evaluate the influence of the formulation and process variables on the properties of the medical preparation. This evaluation was complemented by testing the antimicrobial and antimycotic activity of prepared films with the aim of finding the most suitable composition for clinical application. Generally, the best results were obtained with sample containing 20 mg of chlorhexidine diacetate carried by vermiculite, with carmellose in the form of nonwoven textile in its structure. In addition to its promising physicomechanical, chemical, and mucoadhesive properties, the formulation inhibited the growth of Staphylococcus and Candida; the effect was prolonged for tens of hours.
30 citations
TL;DR: In this article, the authors investigated the role of layer silicates and feldspars in the formation and transformation of clay minerals in eight types of loess-soils, two recent chernozems and braunerden (brown forest soils), one syrosem of young Wurm age, one syrosm of synsedimentary origin, one chernoisem of older Wurmmage, one braunerde of the last interglacial period, and one earthy braunlehm of the Middle Pleistocene Period, were investigated
30 citations
TL;DR: In this paper, a grid pattern from the north of the Jordan Valley was used for geochemical, mineralogical, and textural analyses of soil samples and the results showed that the soil of the study area can be considered to be characterized by medium texture and moderately coarse and coarse texture.
Abstract: Thirty-nine soil samples were collected on a grid pattern from the north of the Jordan Valley These samples were subjected to geochemical, mineralogical and textural analyses The investigated soil is characterized by medium texture and to a less extent moderately coarse and coarse texture The value of TDS shows a slight increase in the southern part of the study area toward the Dead Sea due to the increase in temperature and decrease of the amount of precipitation The organic matter content and P 2 O 5 values show significant variations that coincide with agricultural activity and application of fertilizers and pesticides in the investigated area In the samples collected, CEC values are slightly decreased from north to south parts of the study area where the abundance of organic matter and clay minerals are low The study found that the enrichment factors of the measured heavy metals Pb, Cd, As and Hg are 28, 119, 20 and 17 respectively Accordingly, the soil of the study area can be considered mod
29 citations