Journal Article•
Vermiculite and its relation to biotite as revealed by base exchange reactions, x-ray analyses, differential thermal curves, and water content
About: This article is published in American Mineralogist.The article was published on 1948-12-01 and is currently open access. It has received 135 citations till now. The article focuses on the topics: Vermiculite.
Citations
More filters
TL;DR: In this paper, a review of the literature concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed.
Abstract: Investigations concerning selective sorption and fixation of K and similar cations by clay minerals and soil clays and the mechanisms of these reactions are reviewed. In particular, recent observations on selective sorption of these ions in dilute solutions by weathered micas and vermiculite in relation to the interlayer structures are discussed in detail. Also, implications of the resistance to weathering of small mica particles to cation selectivity by soils are described. Despite the increased understanding of sorption and fixation reactions, the following aspects remain unclear. First, the mechanism of the collapse of alternate layers in vermiculite on K or Cs sorption has not been unequivocally established. Second, factors that impart stability to the central core of mica particles so that K extraction becomes progressively difficult are not known. Third, inability of Ca or Mg ions to expand interlayers of Cs-saturated vermiculite in contrast to K-saturated vermiculite is not completely understood.
602 citations
01 Jan 1986
440 citations
TL;DR: In this article, the authors describe the ways in which the major rock-forming primary minerals (olivine, pyroxenes, amphiboles, feldspars, micas and chlorites) break down during weathering, the products that develop during this breakdown and the rates at which this breakdown occurs.
Abstract: This paper describes the ways in which the major rock-forming primary minerals (olivine, pyroxenes, amphiboles, feldspars, micas and chlorites) break down during weathering, the products that develop during this breakdown and the rates at which this breakdown occurs. The perspective chosen to illustrate this vast topic is that of the residual soil weathering profile. Different physical and chemical conditions characterize the various parts of such a profile. Thus, in the slightly weathered rock at the base of the profile, mineral weathering will take place in microfissures and narrow solution channels and the capillary water in such spatially restricted volumes may be expected to be close to equilibrium with the primary mineral. In these circumstances, the weathering product formed may be closely related to the primary mineral both compositionally and structurally. The saprolite higher up in the weathering profile may or may not retain the fabric and structure of the original parent rock, but in either case the close relationship observed between primary mineral and weathering product in the slightly weathered rock may be lost. This part of the profile will usually be affected by freely flowing drainage waters, the composition of which will be far from equilibrium with specific primary minerals. Weathering products which do form are likely to reflect the interaction between bulk water and bulk parent material. In the soil profile, the situation will be further complicated by organic ligands derived from decomposing organic matter or from the direct activities of soil microbes or plant roots. Thus, biological weathering will assume a much greater significance in this part of the profile compared with the mainly inorganic processes dominating in the saprolite and the slightly weathered rock. The general nature of any particular weathering profile will reflect the interactions between climate, topography, parent material, soil biota and time and superimposed upon this complexity, when considering how individual primary minerals break down in detail, will be factors related to the nature of the mineral itself. Particularly important in this respect is the inherent susceptibility of the mineral to weathering, which is related to overall chemical composition and structure, as well as the distribution and density of defects, dislocations and exsolution features, which often control the progress of the weathering reaction.
417 citations
01 Jan 1985
398 citations
TL;DR: This chapter reviews important papers of research in the field of mineralization of organic nitrogen in soil, beginning with the years preceding World War II.
Abstract: Publisher Summary This chapter reviews important papers of research in the field of mineralization of organic nitrogen in soil, beginning with the years preceding World War II. Although mineralization of nitrogen must consequently be recognized as a very old problem—even the overestimation of the importance of humus for plant nutrition by Albrecht Thaer at the beginning of the 19th century was a result of the conviction of mineralization of organic compounds in soil—it still occupies a prominent position in studies about plant nutrition. The general character of the nitrogen balance in grassland has been investigated long ago, but the spectacular ability of perennial grass to absorb even very high amounts of applied nitrogen and to retain nearly all mineralized and added nitrogen in organically bound form is still considered surprising. Consequently, much attention is paid to this characteristic of grassland and the whole problem of nitrogen mineralization in grassland remains unsolved. Investigations on nitrogen mineralization in uncultivated virgin bogs are very scarce. Cyplenkin and Schilin showed NO3-N formation in the waterlogged peaty soil of the tundra only locally on some hill crests and southbound slopes. Ammonification is much more common in the tundra soil, but is still very slow compared to well-drained neutral soils. Michniewicz determined the rate of nitrogen mineralization and the number of nitrifying organisms in the upper layers of the forest floor and of peat bogs.
375 citations