Illite/smectite clays

Lindgreen H, Drits VA, Sakharov BA, Salyn AL, Dainyak LG (2000) lllite-smectite structural changes during metamorphism in black Cambrian Alum shales from the Baltic area. Am Mineral 85 1223-1238 Lindgreen H, Jacobsen H, Jacobsen HJ (1991) Diagenetic structural transformations in North Sea Jurassic illite/smectite. Clays Clay Minerals 39 54-69... 

Polastro RM (1985) Mineralogical and morphological evidence for the formation of illite at the expense of illite-smectite. Clays and Clay Minerals 33 265-274 Polastro RM (1993) Considerations and applications of the illite/smectite geothermometer in hydrocarbon bearing rocks of Miocene to Mississippian age. Clays and Clay Miner 41 119-133... 

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). 

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. 

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... 

The molar ratio of Al Si in clay minerals is variable, kaolinite (0.85), mica-illite (0.61), and smectitic clays (0.35) (McCarthy et al. 1987). Bituminous coal tends to have higher concentrations of kaolinite, while lignite and subbituminous coals contain mica-illite or smectitic clays. McCarthy et al. (1987) predicted that the higher the Al Si ratio of the clay minerals the... 

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 ... 

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. 

Lindgreen H. (1994) Ammonium fixation during illite-smectite diagenesis in upper Jurassic shale. North Sea. Clay Min. 29, 527-537. 

Pearson M. J. and Small J. S. (1988) Illite-smectite diagenesis and paleotemperature in northern North Sea Quaternary to Mesozoic shale sequence. Clay Min. 23, 109-132. 

The most widespread of the secondary minerals formed during the development of a laterite weathering profile are iron and aluminium ses-quioxides (Table 3.1). These may form either directly from the alteration of primary minerals, or else via a series of pathways involving the formation of intermediary sheet silicate minerals and clays (e.g. chlorite, illite, smectite, vermiculite and halloysite), which are then themselves broken down, stripped of their mobile ions and silica, and eventually converted to alumina and ferric oxyhydroxide residua (Figure 3.9). It is not possible to describe these mineral transformations in detail, but the key issue is that under tropical-type weathering conditions these transformation pathways lead to... 

Clay minerals consist primarily of a mixed layer illite/smectite. 

The similar structure of illite and smectite allows mixing or interstratification of 2 1 units to form mixed-layer clays. Most illites and smectites are interstrati-fied to a small degree, but they are not classified as such until detectable by X-ray diffraction. As one might expect, illite-smectite mixed-layer clays have intermediate cation exchange capacity between the end-member compositions. 

Smectite clay catalysts are potential alternative adsorbents, although some modifications of the natural mineral are necessary. Interlayer sites in smectite dehydrate at temperatures above 200°C, collapsing to an illitic structure. Since the ion-exchange capacity of smectite centres on the interlayer site, collapse must be prevented if clay catalysts are to be used in thermal treatments of chemical organic toxins. The intercalation of thermally stable cations, which act as molecular props or pillars, is one... 

Because they are the dominant mineral in shales, illites, and illite-smectites (see below) are the most abundant of all the clays. Illites are defined as micalike materials less than 2 yttm in size, which, like the micas, have a basal spacing of 10 A (Drever 1988). Most illites are dioctahedral and structurally similar to muscovite, although some are trioctahedral like biotite. Illites contain less and Al and more Si than muscovite. They also usually contain some Mg + and Fe, The irregularity of occurrence of interlayer K+ makes bonding between the layers weaker than in muscovite. Illitic clays... 

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