D.J. Morgan E.V. Eslinger D. D. Eberl M.R. Karlinger J. Srodon 1986 <p><span>Chemical data from three different series of diagenetic illite/smectites (I/S), analyzed statistically by two regresion techniques, indicate that the content of fixed-K per illite layer is not constant, but ranges from ∼0.55 per O</span>₁₀<span>(OH)</span>₂<span><span>&nbsp;</span>for illite layers in randomly interstratified I/S (R=0; &gt; 50% smectite layers) to ∼1.0 per O</span>₁₀<span>(OH)</span>₂<span><span>&nbsp;</span>for illite layers formed in ordered I/S (R&gt;0; &lt;50% smectite layers). By extrapolation of the experimental data, the following chemical characteristics were obtained for end-member illite derived from the alteration of smectite in bentonite: average fixed-K per illite layer = 0.75 per O</span>₁₀<span>(OH)</span>₂<span>; total charge = about −0.8; cation-exchange capacity = 15 meq/100 g; surface area (EGME) = 150 m</span>²<span>/g.</span></p> application/pdf 10.1346/CCMN.1986.0340403 en The Clay Minerals Society Chemistry of illite/smectite and end-member illite article