To study the effect of different extractants on clay mineral
and soil carbonate dissolution (due to the importance of carbonates in the studied soils), the contents of Ca, Mg, Al and K extracted by Ca[Cl.sub.2], HC1, citric acid and oxalic acid solutions were determined during the short- and long-term experiments (Table 3).
Bauxite is a mixture of minerals such as gibbsite, boehmite and diaspore, iron oxides such as goethite and hematite, clay mineral
kaolinite and some amounts of anatase.
Studies on acid contaminated soils indicated that dissolution of aluminosilicate of clay mineral
with subsequent mineral formations leads to volume changes in soils (Sokolovich 1995; Mal'tsev 1998; Sivapullaiah et al.
The sample preparation for XRD tests of the relative clay mineral
content is as follows: (1) the air-dried sample is crushed to a particle size of less than 1 mm, the crushed power is placed into the beaker, and then the sample is soaked with distilled water and dispersed by the ultrasonic treatment.
However, the potential impact of various factors (e.g., clay mineral
composition, water content, grain gradation, and confining pressure) has not yet been reported.
The chemical modification of clay mineral
through the use of cationic surfactant to generate organoclays  has applications in environmental remediation .
In soil mineralogy, VNIR can be used to characterize various soil mineralogic properties such as clay mineral
composition, clay content, and mineral weathering/alteration degree, although quartz and feldspar have weak/nonexistent absorption in the VNIR range [22-24].
Essentially, the clay mineral
can be modified in two ways: in the interlayer space in pursuance of swelling and cation exchange and on the surface due to an adsorption process.
Based on the formula, feldspar dissolution can provide the large amounts of [Al.sup.3+] and Si[O.sub.2] needed for clay mineral
and authigenic quartz precipitation .
As a chloritic clay mineral
of unusual type, corrensite in a natural system was documented from the Triassic in England (Stephen and MacEwan, 1951).
In order to determine the clay mineral
associations, the XRD patterns of oriented air-dried preparations of clay fraction ([less than or equal to]2 [micro]m) were analysed.