W. D. Keller

Bio: W. D. Keller is an academic researcher. The author has contributed to research in topics: Ball clay & Texture (geology). The author has an hindex of 1, co-authored 1 publications receiving 112 citations.

Scan electron micrographs of kaolins collected from diverse environments of origin; I

Abstract: Scan electron micrographs (SEM) show the textures of ball clay, plastic refractory clay, flint clay, and of kaolins from Cornwall, U.K., and Brittany, France. The texture of ball clay is a swirl and ragged-flake pattern. Plastic refractory clay shows a transition in texture from ball clay to plastic, semi-plastic, to semi-flint, and flint-clay. Flint-clay texture exhibits a matrix of tiny, compactly interlocked clay grains in which may be interspersed small, tight books and sheaves of kaolinite. The plastic to flint clays are interpreted to be sequential components of the flint-clay facies. In one sense they represent elements in clay diagenesis. Kaolins from the Cornwall district, U.K., and Brittany, France, show more similarity than dissimilarity in texture. Evidence from texture suggests that while hydrothermal action at Cornwall initiated alteration of the granite, the last significant process of kaolinization there was weathering.

Determinants of Clay and Shale Microfabric Signatures: Processes and Mechanisms

Abstract: The energy sources that result in sediment particle associations, reorientation, and disaggregation are presented in terms of processes and mechanisms Based on electron microscopy observations and theoretical considerations, the observed and modeled microfabric forms and signatures are associated with processes and mechanisms operating in various micro- and macroenvironments The interplay of geological, chemical, and biological processes and mechanisms during transport, deposition, and burial of particulate material largely controls and ultimately determines the physical nature, properties, and observable micro- and macro-characteristics of soft sediments and their indurated equivalents Discrete events such as suspended sediment transport, flocculation, and slumping may be identified and/or observed in the field or laboratory More often, the sedimentary material is studied to understand and infer processes and mechanisms responsible for its fundamental properties, origin, significance, and stratigraphic position in the geological record The particle-to-particle development and ultimate nature of a sedimentary deposit and its variability in time and space depend on multiple processes that include some important mechanisms that occur extremely fast and others that progress over eons

Dissolution of pyroxenes and amphiboles during weathering.

Abstract: Augite, hypersthene, diopside, and hornblende all undergo dissolution during weathering by means of the formation, growth, and coalescence of distinctive, parallel, lens-shaped etch pits. Similar etch features can be produced if these minerals are treated in the laboratory with concentrated hydrofluoric acid plus hydrochloric acid. These pits most likely form at dislocation outcrops, and their shape and orientation are controlled primarily by the crystallography of the underlying mineral. The results are similar to those found for soil feldspars and suggest that silicate weathering, in general, takes place by selective etching and not by general attack of the surface with consequent rounding as necessiated by bulk diffusion-type weathering theories.

Classification of Kaolins Exemplified by Their Textures in Scan Electron Micrographs

Abstract: Varieties of kaolin, a rock, may be classified geologically, mineralogically, crystallographically, genetically, texturally, morphologically, by industrial use, and in other ways which are desired. In this paper, the first-order of classification used is geological, i.e., transported and residual, after which other categories are used as subdivisions.