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A CRYSTALLINITY INDEX FOR SOIL KAOLINS AND ITS RELATION TO PARENT ROCK, CLIMATE AND SOIL MATURITY
Author(s) -
HUGHES J. C.,
BROWN G.
Publication year - 1979
Publication title -
journal of soil science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.244
H-Index - 111
eISSN - 1365-2389
pISSN - 0022-4588
DOI - 10.1111/j.1365-2389.1979.tb01009.x
Subject(s) - halloysite , crystallinity , kaolinite , triclinic crystal system , soil water , mineralogy , index (typography) , geology , materials science , geochemistry , soil science , chemistry , composite material , crystallography , crystal structure , world wide web , computer science
Summary To sub‐divide the large group of kaolinitic soil clays a new empirical index of crystallinity was obtained from the X‐ray diffraction patterns of eight standard kaolins. The index used is the ratio of the intensity above background of the peak at 4.46Å to the intensity above background at about 2.43Å (43.2° 2θ CoKα) and ranges from 4.8 for halloysite to 83 for a well‐ordered triclinic kaolinite. For the kaolins from a group of soils from S.W. Nigeria, the ratio lies between 4.3 and 13.7 and can be tentatively related to the presence of weatherable minerals in the soil and/or the length of the dry season.