A Chlorite-Like Mineral in Indiana Soils1
- M. G. Klages and
- J. L. White2
A clay mineral with basal spacing of approximately 14Å is a constituent of many Indiana soils. The properties of a sample of this mineral separated from Crosby silt loam were studied.
During the weathering of the soil profile, the pH decreased and the 14Å mineral replaced illite as the dominant clay mineral. In similar size fractions of clay, the potassium content decreased from the C to the A horizon, while the cation-exchange capacity remained practically unchanged.
X-ray diffraction and other procedures were used to determine the properties of the 14Å mineral and the effect of various treatments on these properties. Many of its characteristics were found to be similar to those reported for dioctahedral vermiculite. Several of the reactions suggested positively charged, partially hydrated aluminum hydroxide rather than hydrated exchangeable aluminum ions as the interlaying material.
It was concluded that during weathering of illite, aluminum can replace potassium between the clay plates. The form of this interlayer aluminum is probably influenced by soil pH. A suggested general formula is: where x varies with soil pH. Dioctahedral vermiculite and dioctahedral chlorite could thus form a continuous series.
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