Chlorites and hydroxy-interlayered vermiculite and smectite

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.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/5A8715FD71CA51CA3617D2C4386A3530/S0009855800001965a.pdf/div-class-title-weathering-of-the-primary-rock-forming-minerals-processes-products-and-rates-div.pdf

Weathering of the primary rock-forming minerals: processes, products and rates

This paper reviews the synthesis of smectites and porous pillared clay catalysts. Synthetic as well as natural smectites serve as precursors for the synthesis of Al, Zr, Ti, Fe, Cr, Ga, V, Si, and other pillared clays as well as mixed Fe/Al, Ga/Al, Si/Al, Zr/Al and other mixed metal/Al pillared clays. The use of these pillared clays in some catalytic reactions is also briefly reviewed.

Synthesis of Smectites and Porous Pillared Clay Catalysts: A Review

One of the first subjects introduced to students of environmental chemistry is the aqueous chemistry of aluminum. This metal is the third most abundant element in the shallow Earth, where it hydrolyzes in water to produce a rich array of solute molecules and solids, including clays and aluminum hydroxide phases. Although these materials are ubiquitous, we are just beginning to understand the kinetic properties of their surfaces at the molecular scale. The problem is experimental sthe solids are too unwieldy, even as colloids, for detailed spectroscopy. One recent approach has been to use 1 -2 nm aqueous Al(III) molecules as experimental models to determine reaction rates and pathways at a fundamental level. The 1 -2nm-sized clusters are useful because they expose functional groups that resemble those found on the minerals, yet reactions at these functional groups can be studied at the molecular scale using relatively simple methods of solution spectroscopy, such as NMR. The 1 -2 nm ions are sufficiently small that reactions can then be simulated at a high * E-mail: whcasey@ucdavis.edu. Phone: 530-752-3211. William Casey (born 1955) received his Ph.D. degree in Mineralogy and Geochemistry from The Pennsylvania State University in 1986 under the direction of Prof. Antonio Lasaga. After graduating, he worked as a research geochemist at Sandia National Laboratories in Albuquerque, New Mexico, for several years and jointed the faculty of the University of California in 1991. He has published over 130 scientific articles on subjects relating to aqueous solution chemistry of natural waters, mineral surface chemistry, and reaction kinetics. Volume 106, Number 1

Large aqueous aluminum hydroxide molecules.

The origin and formation of soil clay minerals, namely micas, vermiculites, smectites, chlorites and interlayered minerals, interstratified minerals and kaolin minerals, are broadly reviewed in the context of research over the past half century. In particular, the pioneer overviews of Millot, Pedro and Duchaufour in France and of Jackson in the USA, are considered in the light of selected examples from the huge volume of work that has since taken place on this topic. It is concluded that these early overviews may still be regarded as being generally valid, although it may be that too much emphasis has been placed upon transformation mechanisms and not enough upon neoformation processes. This review also highlights some of the many problems pertaining to the origin and formation of soil clays that remain to be resolved.

The origin and formation of clay minerals in soils: past, present and future perspectives

Characterization of Hydroxy‐Aluminum Solutions by Aluminum‐27 Nuclear Magnetic Resonance Spectroscopy

Speciation of Hydroxy-Aluminum Solutions by Wet Chemical and Aluminum-27 NMR Methods1

Surface mined prime farmland may be reclaimed by adding organic wastes and lime to subsoil thus improving conditions in root zone. In this study, sewage sludge, poultry manure, horse bedding, and lime were applied to subsoil (15-30 cm) during reclamation. Soil properties and plant growth were measured over two years. All organic amendments tended to lower the subsoil bulk density and increase organic matter and total nitrogen. Liming raised exchangeable calcium, slightly increased pH, but decreased exchangeable magnesium and potassium. Corn ear-leaf and forage tissue nitrogen, yields, and nitrogen removal increased in treatments amended with sewage sludge and poultry manure, but not horse bedding. Subsoil application of sewage sludge or poultry manure seems like a promising method in the reclamation of surface mined prime farmland based on the improvements observed in the root zone environment.

http://www.asmr.us/Publications/Conference%20Proceedings/1996/0740-Zhai.pdf

A reclamation approach for mined prime farmland by adding organic wastes and lime to the subsoil

Because the soils that frequently overlie eastern U.S. oil shale outcrops and near-surface deposits are relatively shallow, acidic, and infertile, use of toposoil substitutes and supplemental materials are anticipated to achieve satisfactory reclamation during surface mining. This study was conducted to determine the effectss of weathering on selected overburden strata (the Borden and Bedford Shales) in terms of particle-size distribution, moisture retention character, reactivity, and macronutrient availability (...)

Richard I. Barnhisel

Papers

Chlorites and hydroxy-interlayered vermiculite and smectite

Characterization of Hydroxy‐Aluminum Solutions by Aluminum‐27 Nuclear Magnetic Resonance Spectroscopy

Speciation of Hydroxy-Aluminum Solutions by Wet Chemical and Aluminum-27 NMR Methods1

A reclamation approach for mined prime farmland by adding organic wastes and lime to the subsoil

Physical and chemical properties of potential topsoil substitutes in Kentucky oil shale mining reclamation