Illite association

Ylagan RF, Altaner SP, Pozzuoli A (2000) Reaction mechanisms of smectite illitization associated with hydrothermal alteration from Ponza Island, Italy. Clays Clay Minerals 48 610-631 Zhoukhlistov AP, Zvyagin BB, Lazarenko EK, Pavlishin VI (1977) Refinement of the crystal stracture of ferrous seladonite. Sov Phys Ciystallogr 22 284-288... 

Copper oxide gold ores. Although this ore type is not abundant, they are of significant value because they contain gold. Only a few deposits in Brazil and Australia are known. The copper in these ores is represented by cuprite, native copper, antlerite and tenorite. The gold is associated with cuprite, as an auricupride and several sulphosalts. The major problem associated with treatment of this ore type is the presence of large amounts of clay slimes in the form of iron hydroxide and illite. 

The effect of mineral and organic soil constituents on the mineralisation of LAS, AE, stearyl trimethylammonium chloride (STAC) and sodium stearate (main soap component) in soils was studied by Knaebel and co-workers [38]. The four 14C-labelled compounds were aseptically adsorbed to montmorillonite, kaolinite, illite, sand and humic acids and subsequently mixed with soil yielding surfactant concentrations of about 50 jig kg-1. The CO2 formation in the serum bottle respirometers was monitored over a period of 2 months indicating that the mineralisation extent was highest for LAS (49-75%). Somewhat lower amounts of produced CO2 were reported for AE and the stearate ranging from 34-58% and 29-47%, respectively. The mineralisation extent of the cationic surfactant did not exceed 21% (kaolinite) and achieved only 7% in the montmorillonite-modified soil. Associating the mineral type with the mineralisation kinetics showed that sand... 

Ca-Rb equilibria. The increasing number of high energy sites (table VI) is associated with the formation of collapsed (10 A) illite layers, which were observed (102-104) with increasing number of H.D. cycles. 

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. 

Clay speciation analysis, dominated by the use of short-wave infrared techniques, highlights variations in the clay alteration associated with these deposits. The presence of a key species, such as illite, may be locally significant, but absolute amounts of each clay relative to alteration intensity are typically unattainable from these types of analyses. 

Studies of hydrothermal alteration products associated with ore mineralization in acidic rocks have established the general propensity for the original minerals to be replaced by illite, sericite or hydromica in the innermost zone near the source of hydrothermal fluids and by kaolinite or expandable minerals further from the vein or center of fluid emanation. The newly-formed "mica" can be 2M, 1M, or lMd in polymorph and range compositionally from muscovite to a low potassium, silicic species which can be assimilated in the term illite (Lowell and Guilbert, 1970 Schoen and White, 1966, 1965 Kelly and Kerr, 1957 Bonorino, 1959 Tomita, e al., 1969 Yoder and Eugster, 1955 Meyer and Hemley, 1959, among many authors). 

The two series of phase relations deduced above result in, at a first approximation, two "facies" for the expandable dioctahedral minerals— that of low temperature where fully expandable minerals exist and where the tie-line or association beidellite-montmorillonite persists. More elevated conditions produce a kaolinite-illite tie-line characteristic of sequences of buried rocks. 

Figure 29. Possible general phase relations for illite and associated phyllosilicates as a function of varying P-T conditions. Ill = illite, either predominantly IMd or 2M in polymorph I = illite, 2M mica ID = k layer ordered mixed layered phase MLSS = mixed layered 3 or 2 layer ordering giving a superstructure reflection ML0 = mixed layered, ordered structure with no superstructure MLr = mixed layered non-ordered M, = fully expandable montmorillonite Chi = chlorite Kaol = kaolinite Exp 3 " expanding chlorite and/or corrensite.

The major aluminous clay minerals, alkali zeolites and feldspars which are most commonly associated in nature can be considered as the phases present in a simplified chemical system. Zeolites can be chemiographically aligned between natrolite (Na) and phillipsite (K) at the silica-poor, and mordenite-clinoptilolite at the silica-rich end of the compositional series. Potassium mica (illite), montmorillonite, kaolinite, gibbsite and opal or amorphous silica are the other phases which can be expected in... 

Clay minerals are the most common inorganic constituents of coal and of the strata associated with coal seams. Many different clay minerals have been reported within and associated with coals, but the most common clay minerals are kaolinite and mixed-layer illite-montmorillonite. Kaolinite-rich clay is commonly found within and associated with coals in most of the coal basins of the world. They are generally called either tonstein or kaolin-tonstein. 

K is obtained from associated K-feldspars and micas. The layer charge is increased by the reduction of iron in the octahedral sheet and incorporation of Al, entering through the ditrigonal holes in the basal oxygen plane, into the tetrahedral sheets (Weaver and Beck, 1971a Pollard, 1971). Weaver and Beck have presented evidence that indicates mixed-layer clays formed in this manner contain 20—30% chloritic layers and are actually mixed-layer illite-chlorite-montmorillonite clays. 

Fire clays, ball clays, flint clays are kaolinite-rich clays, usually of the 6-axis disordered variety, which contain a relatively high impurity content. Illite, montmoril-lonite, diaspore, boehmite, quartz, and organic material are the minerals usually associated with these deposits. Few, if any, of the kaolinite minerals in these clays have been concentrated enough to afford meaningful chemical data. 

Clay colloids provide a good example of the kinds of structures that can be formed upon flocculation. The association of plate-like clay particles is complicated by the fact that minerals such as montmorillonite, illite, and kaolinite can exhibit different surface charges at different particle surfaces. 

Estimates of deformation conditions during crustal deformation from studies of quartz microstructures. Blenkinsop and Drury (1988) studied the microstructures in quartzites associated with the development of a fault that forms part of a thrust belt in the Cantabrian Mountains of northwest Spain. The thickness of the overlying sediments suggests that the deformation occurred at shallow depths in the upper crust at pressures of 60-100 MPa. The deformation temperature was estimated to be 150 -250°C from the illite crystallinity. 

This study has shown that the sample of Devonian shale is composed primarily of silicates with much lower amounts of carbonate minerals. Here, as with the Green River shale sample, the silicate minerals were associated primarily with the organic-rich areas of the shale, and when present, the carbonate minerals were found mainly in the organic-poor areas. The siliceous minerals of this Devonian shale sample were found to be quartz, illite, and muscovite, with trace amounts of kaolinite. Calcite, dolomite, Fe-rich dolomite or magnesite, and siderite were observed in the carbonate regions of the Devonian shale. However, the... 

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