Regression analysis of high-precision structural and chemical data on trioctahedral and dioctahedral micas yielded interrelationships between unit-cell parameters, chemical composition and structural details. Regression equations relating b and c sin β parameters of micas to composition were used for estimating composition from cell data in order to analyse P-T conditions of rock formation. Algorithms for computing atomic coordinates for 2M 1 37' and 1M dioctahedral micas having either centrosymmetric or non-centrosymmetric layers and 1M trioctahedral micas are presented. Deviations of computed atomic coordinates from experimental values are, on average, 0·002 Å for octahedral cations and 0·005-0·010 Å for other atoms. Discrepancies between calculated and experimental individual interatomic distances seldom exceed 0·01 Å. Computed atomic coordinates were used to calculate X-ray diffraction patterns for glauconite and illite. Results indicate a close fit between the calculated and experimental patterns. The local structure around an octahedral cation of interest can be determined.
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B. B. Smoliar-Zviagin (1993) studied this question.