Curves for the Quantification of Mica/Smectite and Chlorite/Smectite Interstratifications by X-ray Powder Diffraction

Katsutoshi Tomita and Hidewo Takahashi
Institute of Earth Sciences, Faculty of Science, Kagoshima University Kagoshima, 890, Japan
Department of Geology, Faculty of Education, Kagoshima University Kagoshima, 890, Japan

Abstract: X-ray powder diffraction intensities for many interstratified structures of mica/smectite and chlorite/smectite were calculated by changing combinations of probabilities and transition probabilities of two component layers, respectively. The calculated d-values were plotted with PMS and PSM as the axes of coordinates for mica/smectites (where M is a mica layer and S is a smectite layer). These d-values were then linked into equal d-value curves on a graph. Three equal d-value diagrams ranging from 32.5 to 24.5 Å, from 15.4 to 10.25 Å, and from 3.365 to 3.08 Å were constructed for mica/smectites. Several diagrams were also constructed for mica/glycolated-smectites and chlorite/smectites using the same techniques. PMS and PSM values of mica/smectite producing 26.8- and 12.6-Å reflections in its X-ray powder diffraction pattern were obtained from the coordinates of the intersection of the 26.8-Å line of the first diagram and the 12.6-Å line of the second diagram. The components and stacking parameters of mica/smectites and chlorite/smectites were estimated easily using these diagrams. Interstratified mica/smectites were quantified in the air-dry and glycolated states, and chlorite/smectites in the glycolated state. Stacking parameters obtained by this method agreed well with those obtained by MacEwan's method. Stacking parameters for Reichweite (R=0) and (R= 1) structures were obtained.

Key Words: Chlorite/smectite • Ethylene glycol • Interstratification • Mica/smectite • Mixed layer quantification • X-ray powder diffraction

Clays and Clay Minerals; October 1985 v. 33; no. 5; p. 379-390; DOI: 10.1346/CCMN.1985.0330502
© 1985, The Clay Minerals Society
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