Quantitative Clay Mineralogical Analysis of Soils and Sediments

Abstract

A B S T R A C TT H E objective of this paper is to present flow sheets for a system of quantitative mineralogical analysis of clays of soils and sediments and to show representative results. Selective dissolution analysis by the Na2S207-HCl-NaOH procedure yields the quartz and feldspar contents (0 to 63%) and differentiates feldspar K from mica K. The NaOHthermal system of selective dissolution yields the allophane plus gibbsite, kaolinite plus halloysite, and dickite contents (0 to 84% for the sediments; 1 to 2 5 % for soil clays) Mica contents (0 to 92% for the rock specimens, 7 to 4 3 % for soil clays) are determined by nonfeldspathic K (and Na). Vermiculite contents (1 to 9 7 % of specimens; 3 to 2 1 % for soil clays) are measured by blocking of interlayer CEC by drying at 110°C while K saturated and replacing with NH4CI. Montmorillonite (and palygorskite) contents (0 to 85% of specimens; 3 to 36% of soil clays) are determined by the CEC not blocked by the K and NH4 sequence for vermiculite. Chlorite contents (0 to 8 5 % for specimens; 0 to 37% for soil clays) are determined by thermal gravimetric analysis, after allocation of OH water lost between 300 and 950°C to other hydrous minerals determined.The best evidence of the accuracy of the system of analysis lies in the consistent total recovery of 24 standard mineral samples averaging 100.4 i 1·3 ( ± standard error of means) and of 22 soil clay samples averaging 99.5 i 0.8. The different constituents were present in widely different proportions in the various samples, and were determined by independent methods. The complementary total of near 100% (maximum range 95 to 105% for specimens; 95 to 103% for soil clays) for the analyses is a significant measure of the specificity of the several determinations.

Quantitative Clay Mineral Analysis Using Simultaneous Linear Equations

“…Best available values are obtained from a search of the literature or from laboratory measurements. Estimates E for 9( may be derived by any appropriate technique such as X-ray powder diffraction, differential thermal analysis, and/or the procedures of Alexiades and Jackson (1966). The dot product A.E does not equal B, but is an estimate of it.…”

“…In the quantitative clay analysis of Alexiades and Jackson (1966) each component in a sample is quantitatively evaluated on the basis of a single, measurable chemical or physical property. Chlorite and smectite contents, for example, are estimated from the following properties:…”

“…Attempts to obtain quantitative data have led to the development of methods that depend on the chemical and physical properties of clay (Alexiades and Jackson, 1966). In this approach, a chemical or physical property unique to or a dominant function of a single component is used as a quantitative measure.…”

“…The reliability of the data is generally estimated by measuring how closely the component sum approaches 100%. McNeal and Sansoterra (1964), using methods similar to that of Alexiades and Jackson (1966), developed a set of simultaneous equations for the determination ofmontmorillonite, vermiculite, and chlorite. Pearson (1978) used total silicate-analysis data in simultaneous equations for the quantitative clay mineral analysis of fine-grained sedimentary rocks.…”

Characterization of a Toposequence With Fragipan: The Leeds–ste. Marie–brompton Series of Soils, Province of Quebec

“…Mineralogical analyses of the clay fraction were carried out by X-ray diffraction, differential thermal analysis (DTA) and thermogravimetric analysis (TGA) and quantitative determinations, following the selective procedure of Alexiades and Jackson (1966).…”