Illite-smectite

Main gangue minerals of the Se-type deposits comprise quartz, adularia, illite/ smectite interstratified mixed layer clay mineral, chlorite/smectite interstratified mixed layer clay mineral, smectite, calcite, Mn-carbonates, manganoan caleite, rhodoehrosite, Mn-silicates (inesite, johannsenite) and Ca-silicates (xonotlite, truscottite). 

Gangue minerals Quartz (fine-large grained), adularia, illite/smectite, chlorite/smectite, calcite, rhodochrosite Quartz (very fine-grained), barite, illite, kaolinite, adularia... 

In the Se-type gangue minerals comprise quartz, adularia, illite/smectite inter-stratified mixed layer clay mineral, smectite, calcite, Mn carbonates (manganoan calcite, rhodochrosite), Mn silicates (inesite, johansenite) and Ca silicates (xonotlite, truscottite). In comparison, the Te-type contains fine-grained, chalcedonic quartz, sericite, barite, adularia and chlorite/smectite interstratified mixed layer clay mineral. Carbonates and Mn minerals are very poor in the Te-type and they do not coexist with Te minerals. Carbonates are abundant and barite is absent in the Se-type. Grain size of quartz in the Te-type is very fine, while large quartz crystals are common in the Se-type. 

Figure 2. Plot of XRD peak positions (CuK radiation ethylene glycol-solvated samples) for Kinney smectite treated with 0.05 N Na + K exchange solutions. Experimental points are labeled with percentages of K in solution. The graph, used to determine percentage illite layers and glycol-spacing for illite/smectites having crystallite thickness of 1-14 layers, is from (42).

Figure 9. Percentage illite layers versus equivalents of fixed interlayer cations per illite layer [based on 010(OH)2] for RO illite/smectites formed by diagenesis in bentonites. Calculated from data in (53).

Equation 11.162 cannot be extended to other OH-bearing phases such as serpentine, chlorite, and clay minerals (illite, smectite). Concerning serpentine, the experiments conducted by Sakai and Tsutsumi (1978) on clinochrysotile at 2... 

Three MER diagrams (Figs. 2, 3, 4) collectively illustrate the mineralogical controls observed in each of the Meguma Supergroup formations. Because these metamorphosed rocks derive from proximal and distal flysch sediments, they likely once contained quartz, K-feldspar, albite, muscovite, illite, smectite (montmorillonite-beidellite), chlorite... 

Formation has compositionally distinct upper and lower members. Both can be explained by illite-smectite mixtures, but Lower Cunard slates also contain quartz. Like the Lower Cunard rocks, the Feltzen Formation has compositions explained by mixtures of illite, smectite and quartz. 

Alteration assemblages may include primary chlorite, illite, smectites, and/or kaolinite, and various primary and secondary iron oxides, carbonates, and sulfides (Fig.1), any one of which may serve as indicators of fluid composition. Lithologic geochemical surveys rely on an understanding of these patterns to vector towards uranium deposits. The interpretation of hydromorphic geochemical surveys, including lake and stream sediment, and soil, depends on the mobility of uranium and associated elements in the surface and near surface environment. 

Feng X., Faiia A.M., Gabriel G.W., Aronson J.L., Poage M.A., and Ghamberlain C.P. (1999) Oxygen isotope studies of illite/smectite and clinoptilolite from Yucca Mountain implications for paleohydrologic conditions. Earth Planet. Sci. Eett. 171, 95-106. 

Figure 17. Proposed phase relations where K is a mobile component and Al, Fe are immobile components at about 20°C and several atmosphere water pressure for aluminous and ferric-ferrous mica-smectite minerals. Symbols are as follows I illite G = non-expanding glauconite Ox = iron oxide Kaol = kaolinlte Mo montmorillonite smectite N nontronitic smectite MLAL aluminous illite-smectite interlayered minerals Mlpe = iron-rich glauconite mica-smectite interlayered mineral. Dashed lines 1, 2, and 3 indicate the path three different starting materials might take during the process of glauconitization. The process involves increase of potassium content and the attainment of an iron-rich octahedral layer in a mica structure.

The differences in cation compositions are probably due to the fact that phases containing these ions (illite, smectite, etc.) have sufficient time to form in natural systems but did not form in the experimental system. The high HCO3 content of the experimental system is due to contact with an infinite reservoir of CO2 having a partial pressure of 0.1 atmosphere. 

Suspended solid surfaces (particles or colloids) in waters play a prominent role in controlling the concentration of dissolved trace elements. Most of these elements are eliminated by sedimentation after incorporation on to or into particles, generally by complexation with the surface sites. The most common inorganic particles and colloids are non-clay silicates (quartz, potash feldspar, plagioclase, opaline silica (diatoms)) clays (illite, smectite) carbonates (calcite, dolomite) Fe-Mn oxides (goethite, magnetite) phosphates (apatite) sulfides (mackinawite). Particles and colloids in a water body may be classified as a function of their origin ... 

Mineralogy. The most important mineral constituents were determined by X-ray diffraction for five samples (four of them from NR-10). Quartz and opal (mainly CT) are important components in all five samples. In a marl (NR-10, 81.5 m), calcite, kaolinite, pyrite, gypsum and illite/smectite mixed-layer minerals occur in addition to those. 

The mixed-layer structure of illite and smectite was obtained by alternating layers of illite and smectite. To allow comparison to other 1.0-nm structures, a layer spacing of exactly 1.0 nm was used for muscovite and biotite, and a layer spacing of exactly 2.0 nm was used for the 2-layer illite/smectite structure. 

Figures 10a and 10b show experimental images of a mixed-layer illite/smectite obtained with the c -axis perpendicular to the electron beam Figure 10a was obtained with the objective lens near Scherzer focus, and Figure 10b was obtained from the same area with...

Figure 10. Experimental HRTEM image of illite/smectite. Smectite interlayers are arrowed, a) Scherzer focus, b) +50 nm overfocus.

Figure 12. Computer-simulated image of Rl-ordered illite/smectite for a JEOL 100C operated at a defocus of -135 nm (see 12 for details). Smectite layers appear thicker than illite layers however, the model structure assumed a 1.0-nm basal spacing for both.

Missana, T., M. Garcia-Gutierrez, and U. Alonso. 2008. Sorption of strontium onto illite/ smectite mixed clays. Phys. Chem. Earth, Parts A/B/C 33 S156-S162. 

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