Kaolinite Synthesis at 25°C

Abstract--Dissimilar fabrics, observed by scan electron micrography (SEM) on freshly broken surfaces of kaolins from weathered, water-laid material vs hydrothermally altered material in Mexico are illustrated, contrasted, and tentatively related to their respective environments of genesis. Coarse, open-textured, well-preserved books and vermiforms of kaolinite characterize the kaolin from water-laid material at Jacal, Mexico. Hydrothermal kaolins tend to have more tightly compacted crystals of either kaolinite flakes (individuals or in packets) or elongates (halloysite morphology) or mixtures of both in the same deposit. Variations in porosity of parent rock whether sedimentary or igneous, and dissimilar permeation by meteoric water and by vapor and liquids of hydrothermal fluids are deemed to be significant in the processes producing distinctive fabrics. The question is raised as to the fundamental distinction between kaolinite and halloysite and their nomenclature.

Section: Factors Influencing the Fabric Of Kaolinmentioning

confidence: 99%

Dissimilar Fabrics by Scan Electron Microscopy of Sedimentary Versus Hydrothermal Kaolins in Mexico

Keller

Hanson²

1975

“…The precipitation of kaolinite from crystalline or noncrystalline aluminosilicates in aqueous solution or under hydrothermal conditions has been discussed from many points of view, including: (1) dissolution and precipitation kinetics (Helgeson, 1971;Tsuzuki and Mizutani, 1971;Tsuzuki et aL, 1974); (2) equilibrium relations on activity diagrams (Helgeson, 1968;Helgeson et al, 1969;Kittrick, 1970;Keller et aL, 1971;Huang and Keller, 1973;Eberl and Hower, 1975;Tsuzuki, 1976;Busenberg, 1978; La Iglesia and Van OosCopyright 9 1985, The Clay Minerals Society terwyck- Tsuzuki and Suzuki, 1980;Tsuzuki and Kawabe, 1983); (3) structure and composition of starting materials (Poncelet and Brindley, 1967;De Kimpe and Fripiat, 1968;Trichet, 1969;Oberlin and Couty, 1970;Urabe et aL, 1970;Rodrique et al, 1972;De Vijnck, 1973); and (4) coordination number or polymerization state of hydrated species (De Kimpe et al, 1961;De Kimpe and Gastuche, 1964;Polzer et al, 1967;Linares and Huertas, 1971;La Iglesia and Martin Vivaldi, 1973;Hem and Lind, 1974;La Iglesia and Galan, 1975;Lind and Hem, 1975;La Iglesia et al, 1976;De Kimpe et al, 1981). A detailed review of this subject was given by Van OosterwyckGastuche and La Iglesia (1978).…”

Section: Introductionmentioning

confidence: 99%

Growth Conditions and Genesis of Spherical and Platy Kaolinite

Tomura

1985

Abstract--Spherical and platy kaolinite crystals were prepared under several hydrothermal conditions. Spherical kaolinite was produced mainly at high solid/water ratio (1/4) and at low temperatures (150 ~ 200~ Platy kaolinite predominated in products from experiments with intermediate solid/water ratios (1/256-1/16) and at high temperatures. Boehmite predominated at low solid/water ratios (1/4096) at all experimental temperatures (180"-220"C). The results indicate that the growth of the spherical kaolinite was favored at high degrees of supersaturation, whereas the growth of the platy kaolinite was favored at relatively low degrees of supersaturation.

“…There would be no difficulty in believing that the nature of sedimentary organic matter varied with changes in the biological source material, and it has been shown that organic compounds, including humic substances, can influence the crystallization of clay minerals and oxides (Linaeres and Huertas, 1971 ;Hem and Lind, 1974;Kwong and Huang, 1975;Jackson and Keller, 1970;Schwertmann, 1971;Schwertmann and Fischer, 1973;Schwertmann et al, 1968;Mackenzie, 1952;Towe and Loewnstam, 1967). We may venture to speculate, very tentatively, that the late Proterozoic peak revealed by the illite and the organic extracts represents the appearance and early expansion of eucaryotic algae followed by a decline in algal populations resulting from the emergence of protozoans and metazoans at the onset of Paleozoic time (Jackson, 1973 and.…”

Section: Discussionmentioning

confidence: 99%

A Relationship Between Crystallographic Properties of Illite and Chemical Properties of Extractable Organic Matter in Pre-Phanerozoic and Phanerozoic Sediments

Jackson¹

1977

Abstrael~Crystallographic properties of illite and chemical properties of organic matter in various mudstones ranging in age from Archean to Miocene were investigated. The breadth of the (001) X-ray powder diffraction peak of illite correlates significantly with the ratio of aliphatic to condensed.-aromatic components and the degree of condensation of aromatic rings of the polar ("humic') fraction of extractable bituminous organic matter. The broader the diffraction peak, the less highly condensed and aromatic (i.e. less highly humified) is the organic matter associated with the illite. Breadth of illite diffraction peak and degree of humification of polar organic matter vary in a complex and apparently systematic way through geologic time. All of the three different suites of mudstones investigated ("calcareous," "non-calcareous," and "glacial" mudstones) gave similar patterns of secular variation. In addition, the ratio of diffraction intensities for the (002) and (001) reflections (loo2/lool) of illite in calcareous mudstones and limestones showed a strong negative correlation with geologic age, indicating that the illites in the older rocks are enriched in magnesium with respect to aluminum.The correlation between crystal structure of illite and degree of humification of its associated organic matter could, by itself, be interpreted as an effect of post-depositional maturation processes, whereby "crystallinity" and degree of humification both increased as functions of heat and pressure. However, the patterns of secular variation suggest that the observed variations are primary, or were pre-determined by primary characteristics of the sample materials. The possibility that the original structure and composition of the organic matter influenced post-depositional changes in the crystallographic properties of sedimentary clay minerals, or post-depositional genesis of clay, would seem to merit consideration. The demonstrated relationship between crystallographic properties of iUite and the nature of the "humic" matter constitutes evidence that most of the extractable organic matter is truly indigenous to the rock in which it occurs. The results also imply that molecular structure of extractable organic matter can be used in place of the breadth of the (001) diffraction peak of illite as an index of incipient metamorphism within a single formation or stratigraphic sequence, provided the primary characteristics of the organic matter are nearly the same in all samples. This method would have the advantage of being applicable to all sediments, not just those containing illite (specifically, aluminum-rich illite).The secular variation of the Ioo2/Iool ratio of illite in calcareous sediments is provisionally ascribed to diagenetic processes whereby magnesium is abstracted from pore water and groundwater and is gradually assimilated into the crystal structure.