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Randomly Interstratified Serpentine/Chlorite: Its Detection and Quantification by Powder X-ray Diffraction Methods

Published online by Cambridge University Press:  28 February 2024

R. C. Reynolds Jr. ,
M. P. DiStefano  and
R. W. Lahann
R. C. Reynolds Jr.
Affiliation:
Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire 03755
M. P. DiStefano
Affiliation:
Exploration Research Division, Conoco Inc., P.O. Box 1267, Ponca City, Oklahoma 74603
R. W. Lahann
Affiliation:
Exploration Research Division, Conoco Inc., P.O. Box 1267, Ponca City, Oklahoma 74603
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Abstract

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X-ray diffraction studies of the pore-lining chloritic mineral from the Tuscaloosa Formation disclose a marked pattern of odd-order line broadening for the 001 to the 00,16 reflections. The odd-order peaks are approximately twice as broad as the even orders after correction for instrumental broadening effects. These results are consistent with a randomly interstratified 7-Å/14-Å structure, which is most likely serpentine/chlorite. Quantitative analysis of line broadening and model calculations indicate that the serpentine/chlorite contains 7% serpentine layers.

A simplified method is proposed for quantifying randomly interstratified serpentine/chlorite. Residual line broadening (βr) is obtained from the half-height widths of uncorrected diffraction profiles for the 004 and 005 “chlorite” reflections by means of the following:

βr=(β0051.25−β0041.25)11.25.
Percent serpentine in the random interstratification is computed from the empirical expression
%S=−0.51+24.27βr,
 which is valid from about 1 to 20 percent serpentine.

Keywords

InterstratificationMixed-layeredSerpentine/chloriteTuscaloosaX-ray diffraction line broadening
Type
Research Article
Information
Clays and Clay Minerals , Volume 40 , Issue 3 , June 1992 , pp. 262 - 267
Copyright
Copyright © 1992, The Clay Minerals Society

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