Journal article

Atomic-resolution transmission electron microscope evidence for the mechanism by which chlorite weathers to 1 : 1 semi-regular chlorite-vermiculite

JF Banfield, T Murakami

AMERICAN MINERALOGIST | MINERALOGICAL SOC AMER | Published : 1998

Abstract

Atomic-resolution transmission electron microscope (TEM) images reveal that IIbb (β = 97°) Mg,Al,Fe-chlorite from Koongarra, Australia, transforms to vermiculite via a range of intermediate chemical and structural states. Semi-quantitative analysis of contrast in atomic-resolution images of layer silicates with ∼1.4 nm basal spacings indicate that the interlayers range from brucite-like to having ∼0.3-0.6 interlayer cations per formula unit. Octahedral cations (predominantly Mg and Fe) tend to be removed from every second interlayer, leading to semi-regular 1:1 interstratifications of chlorite-vermiculite. Further loss of interlayer cations is accompanied by partial to complete interlayer co..

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