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The structure of vermiculite and some interstratifications

Published online by Cambridge University Press:  14 March 2018

Bibhuti Mukherjee
Bibhuti Mukherjee*
Affiliation:
Geological Survey of India, Calcutta, India
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Abstract

The inference of Gruner that unsatisfactory powder photographs of vermiculite resulted from distortion of the structural planes by grinding has not been substantiated. The unit cell parameters of a true vermiculite were found to be ao = 5·24± 0·02Å, bo = 9·17 ± 0·02Å, co = 28·60±0·05Å, β = 94° 36′ ± 24′, while the structural formula worked out as (Mg2·37, Fe3+0·37 X0·26) (Al1·28, Si2·72)O9 (OH)3·4H2O, where X represents the remaining octahedral cations. The determined density of the thin flakes was 2·28 g/cm3 and taking this value along with the volume of the unit cell (1370Å3) and the “molecular weight” calculated from the above formula, the number of formula units per unit cell worked out as Z=4·03. Some ‘vermiculite’ samples contain small groups of mica layers, but the non-basal mica reflections are not observable. The structures of these interstratifications and also of interstratifications containing chlorite are considered. Electron micrographs of vermiculite and the interstratified minerals are presented.

Type
Research Article
Information
Clay Minerals Bulletin , Volume 5 , Issue 29 , July 1963 , pp. 194 - 202
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1963

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References

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