Abstract
The 16-8-, 8-5-, 5-2-, 2-1-, 1-0.5-, 0.5-0.3-, 0.3-0.1-, and <0.1-μm size fractions were centrifuged from a Georgia (U.S.A.) sedimentary kaolin and a hydrothermal kaolin from the Sasso mine (Italy) and analyzed by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), infrared spectroscopy (IR), differential thermal analysis (DTA) and thermogravimetry (TGA) together with the corresponding whole rocks. All size fractions of the Georgia sample consisted dominantly of well-crystallized, fine-grained kaolinite, associated with minor quantities of smectite. Some halloysite-like elongate particles were noted by SEM in the intermediate size fractions, minor amounts of quartz were identified in the coarsest size fractions, and < 1% noncrystalline material and traces of organic material were suspected in the finest size fraction. The crystallinity of the kaolinite as measured by XRD and IR varied moderately with size. IR suggested that nacrite-like stacking disorder increased with decreasing size for particles < 5 μm in size.
In the Sasso sample kaolinite dominated all size fractions and was accompanied by dickite in the coarse and by halloysite in the fine size fractions. Regular mixed-layer illite/smectite (I/S) was present in all size fractions and dominated in the finest. Abundant quartz and traces of alunite were identified in the whole rock and coarsest size fractions. The kaolinite in this sample showed marked variation in stacking order and crystallinity, as shown by changes in XRD, IR, and DTA patterns.
The observed compositional and structural variations in the size fractions of the Georgia sedimentary kaolin are small, as expected from formational environment, which was characterized by low temperatures and relative stable genetic conditions. The much more marked differences in composition within the size fractions of the Sasso hydrothermal kaolin are likely a result of the broad range of temperatures and fluid chemistry of its formational environment. The sequence dickite-well-crystallized kaolinite-kaolinite-halloysite is probably temperature-dependent.
Similar content being viewed by others
References
Bramão, L., Cady, J. G., Hendricks, S. B., and Swerdlow, M. (1952) Characterization of kaolin minerals: Soil Sci. 73, 273–287.
Brindley, G. W., de Souza Santos, P., and de Souza Santos, H. L. (1963) Mineralogical studies of kaolinite-halloysite clays: Part I. Identification problems: Amer. Mineral. 48, 897–910.
Byström-Asklund, A. M. (1966) Sample cups and a technique for sideward packing of X-ray diffractometer specimens: Amer. Mineral. 51, 1233–1237.
Farmer, V. C. (1974) The layer silicates: in The Infrared Spectra of Minerals, V. C. Farmer, ed., Mineralogical Society, London, 331–363.
Farmer, V. C. and Russell, J. D. (1966) Effects of particle size and structure on the vibrational frequencies of layer silicates: Spectrochim. Acta 22, 389–398.
Field, C. and Lombardi, G. (1972) Sulfur isotopic evidence for the supergene origin of alunite deposits, Tolfa district, Italy: Miner. Deposita 7, 113–125.
Galan, E., Mattias, P. P., and Galvan, J. (1977) Correlacion entre cristalinidad, tamafio, genesis y edad de algunas ca-olinitas espafiolas: in Proc. 8th Int. Kaolin Symp. and Meet, on Alunite, Madrid-Rome, 1977, E. Galan, ed., Ministerio de Industria y Energia, Madrid, 8 pp.
Grim, R. E. (1972) Technical properties and application of clays and clay minerals: in Proc. Int. Clay Conf, Madrid, 1972, J. M. Serratosa, ed., Consejo Superior de Investiga-ciones Cientificas CSIC, Madrid, 719–721.
Hassanipak, A. A. and Eslinger, E. (1985) Mineralogy, crys-tallinity, δO18/016, and D/H of Georgia kaolins: Clays & Clay Minerals 33, 99–106.
Hinckley, D. N. (1961) Mineralogical and chemical variations in the kaolin deposits of the Coastal Plain of Georgia and South Carolina: Ph.D. thesis, the Pennsylvania State University, University Park, Pennsylvania, 206 pp.
Hinckley, D. N. (1963) Variability in “crystallinity” values among the kaolin deposits of the Coastal Plain of Georgia and South Carolina: in Clays and Clay Minerals, Proc. 11th Natl. Conf., Ottawa, Ontario, Canada, 1962, W. F. Bradley, ed., Pergamon Press, New York, 229–235.
Hinckley, D. N. (1965) Mineralogical and chemical variations in the kaolin deposits of the Coastal Plain of Georgia and South Carolina: Amer. Mineral. 50, 1865–1883.
Holdridge, D. A. and Vaughan, F. (1957) The kaolin minerals (kandites): in The Differential Thermal Analysis of Clays, R. C. Mackenzie, ed., Mineralogical Society, London, 98–139.
Hurst, V. J., ed. (1979) Field Conference on Kaolin, Bauxite and Fuller’s Earth: Clay Minerals Society Annual Meeting, Macon, Georgia, 1979, 107 pp.
Keller, W. D. (1977) Scan electron micrographs of kaolins collected from diverse environments of origin—IV. Georgia kaolin and kaolinizing source rocks: Clays & Clay Minerals 25, 311–345.
Keller, W. D. and Haenni, R. P. (1978) Effects of micro-sized mixtures of clay minerals on properties of kaolinites: Clays & Clay Minerals 26, 384–396.
Keller, W. D., Galan, E., and Mattias, P. P. (1977) Scan electron micrographs of clays from field-trip localities of the VIII International Kaolin Symposium, Spain and Italy, 1977: in Proc. 8th Int. Kaolin Symp. and Meet, on Alunite, Madrid-Rome, 1977, E. Galan, ed., Ministerio de Industria y Energia, Madrid, 10 pp.
Kocsardy, E. and Heydemann, A. (1980) Characterization of kaolin minerals of different origin: Acta Miner. Petr. Saged Suppl. 24, 91–99.
Kodama, H. and Oinuma, K. (1963) Identification of kaolin minerals in the presence of chlorite by X-ray diffraction and infrared absorption spectra: in Clay and Clay Minerals, Proc. 11th Natl. Conf, Ottawa, Ontario, 1962, Ada Swineford, ed., Pergamon Press, New York, 236–249.
Lombardi, G. and Mattias, P. (1979) Petrology and mineralogy of the kaolin and alunite mineralizations of Latium (Italy): Geol. Romana 18, 157–214.
Lombardi, G. and Sheppard, S. M. F. (1977) Petrographic and isotopic studies of the altered acid volcanics of the Tolfa-Cerite area, Italy. The genesis of the clays: Clay Miner. 12, 147–162.
Mattias, P. and Caneva, C. (1979) Mineralogia del giacimento di caolino di M. Sughereto (Santa Severa, Roma): Rend. Soc. It. Miner. Petr. 35, 721–753.
Murray, H. H. (1976) The Georgia sedimentary kaolins: in Proc. 7th Symp. Genesis of Kaolin, Int. Geol. Correlation Program, Committee on Correlation of Age and Genesis of Kaolin, Tokyo, Japan, 1976, H. Minato, ed., 114–125.
Olivier, J. P. and Sennett, P. (1972) Particle size-shape relationships in Georgia sedimentary kaolins—II: in 1972 Int. Clay Conf. Kaolin Symp. Proc, J. M. Serratosa, ed., Consejo Sup. de Investigaciones Cientificas, CSIC, Madrid, 171–173.
Parker, T. W. (1969) Classification of kaolinites by infrared spectroscopy: Clay Miner. 8, 135–141.
Smykatz-Kloss, W. (1974a) The determination of the degree of (dis-)order of kaolinites by means of DTA: Chemie der Erde 33, 358–366.
Smykatz-Kloss, W. (1974b) Differential Thermal Analysis. Applications and Results in Mineralogy: Springer-Verlag, Berlin, 188 pp.
Srodon, J. (1980) Precise identification of illite/smectite interstratification by X-ray powder diffraction: Clays & Clay Minerals 28, 401–411.
Tanner, C. B. and Jackson, M. L. (1947) Nomographs of sedimentation times for soil particles under gravity or centrifugal acceleration: Soil Sci. Soc. Amer. Proc. 11, 60–65.
Van der Marel, H. W. and Beutelspacher, H. (1976) Atlas of Infrared Spectroscopy of Clay Minerals and Their Admixtures: Elsevier, Amsterdam, 396 pp.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lombardi, G., Russell, J.D. & Keller, W.D. Compositional and Structural Variations in the Size Fractions of a Sedimentary and a Hydrothermal Kaolin. Clays Clay Miner. 35, 321–335 (1987). https://doi.org/10.1346/CCMN.1987.0350501
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1346/CCMN.1987.0350501