Mixed-layer clay mineral

Mixed layer clay mineral (sericite/smectite) is found in Kuroko ore bodies and altered dacitic rocks underlying the ore. This mineral is thought to have formed by the... 

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 eomparison, the Te-type deposits contain fine-grained quartz, chalcedonic quartz, sericite, barite, adularia, ehlorite/smectite interstratified mixed layer clay mineral and rarely anatase. Carbonates and Mn-minerals are very poor in the Te-type deposits and they do not coexist with Te-minerals. Carbonates are abundant and barite is absent in the Se-type deposits. The grain size of quartz in the Te-type deposits is very fine, while large quartz crystals are common in the Se-type deposits although they formed in a late stage and do not coexist with Au-Ag minerals. 

Principal gangue minerals in base-metal vein-type deposits are quartz, chlorite, Mn-carbonates, calcite, siderite and sericite (Shikazono, 1985b). Barite is sometimes found. K-feldspar, Mn-silicates, interstratified mixed layer clay minerals (chlorite/smectite, sericite/smectite) are absent. Vuggy, comb, cockade, banding and brecciated textures are commonly observed in these veins. 

Zeolite minerals (wairakite, laumontite etc.), mixed-layer clay minerals and sme-cite occur in the upper part of the propylitically altered rocks (e.g., Seigoshi, Fuke, Kushikino), but they are sometimes poor in amounts. Generally carbonates are more abundant in the mine area as in the Toyoha district. Temporal relationship between the formation of high temperature propylitic alteration minerals (epidote, actinolite, prehnite) and low temperature propylitic alteration minerals) (wairakite, laumontite, chlorite/smectite, smectite) in these areas (Seigoshi, Fuke, Kushikino) is uncertain. 

Seigoshi argentite electrum, pearceite, polybasite, pyrargyrite, stephanite, chalcopyrite, fahore, galena, sphalerite quartz, adularia, inesite, xonotlite, chlorite, mixed layer clay mineral, sericite. calcite, rhodochrosite... 

This information is reported as the percentage that each of the clay mineral type contributes to total identifiable clay mineral content of the noncarbonate clay-sized fraction of the surface sediments. These percentages were determined by x-ray diffraction, which is luiable to identify noncrystalline solids. Using this technique, clay minerals were found to comprise about 60% of the mass of carbonate-free fine-grained fraction. Most of the noncrystalline soUds are probably mixed-layer clay minerals. Carbonate was removed to facilitate the x-ray diffraction characterization of the clay minerals. In some cases, roimd off errors cause the sum of the percentages of kaolinite, illite, montmorillonite, and chlorite to deviate slightly from 100%. 

Those chlorites associated with mixed layered clay minerals are most silica-rich and have the greatest compositional variations for grains in a single thin section they tend to be iron-rich and aluminous. One chlorite vein was found to transect a glauconite pellet. This chlorite was quite iron-poor indicating attainment of a local chemical equilibrium between chlorite and iron mica upon its crystallization. 

IIYAKA (J.T.) and ROY (R.), 1963. Controlled synthesis of heteropolytypic (mixed-layered) clay minerals. Clays and Clay Min. 10, 4-22. 

Grim. R.E., Droste, J.B. and Bradley, W.F., 1961. A mixed-layer clay mineral associated with an evaporite. Clays Clay Miner., Proc, Natl. Conf. Clays Clay Miner., 8<1959) 228—236. 

Heckroodt, R.O. and Roering, C., 1965. A high-alluminous chlorite-swelling chlorite regular mixed-layer clay mineral. Clay Miner., 6 83-89. 

Two sediments from the bituminous subunit (NR-10, 151 and 170 m) are almost free of carbonate. Opal and quartz are dominant in these samples and are accompanied by mixed-layer clay minerals, kaolinite and illite. In the most organic-carbon-rich sediment (NR-10, 170.5 m 25.5% C ) opal is present as amorphous opal A and not as opal CT like in the other sample. Furthermore, the carbonate signals in the X-ray diffractogram are extremely broad. This indicates that the minerals in this sediment are diagenetically less altered than those in the other samples studied. 

The most widespread fill material is reddish brown (2.5 YR 4/4, 5 YR 4/4) loam with a minor admixture of relatively large oolitic bauxite pebbles (derived from the Late Triassic - Camian - beds) and coarse clasts of black chert. Pilot X-ray diffraction analysis revealed mostly muscovite/illite, plus mixed-layer clay minerals of illite/montmorillonite type, chlorite plus mixed-layer clay minerals of chlorite/montmorillonite type, calcium montmorillonite, and diaspore plus gibbsite, or just traces of bauxite minerals (Misic, 2000). The mineral composition is not as uniform as might be expected, and further research, intended for application of factorial analysis, is in progress. A potential sediment source area in the present Cerkniscica River basin (Fig. 1) appears obvious at first glance, but similar outcrops of bauxite and chert do also appear at other sites that are not much more remote. 

The suite of minerals occurring as impurities in U.S. coals of commercial quality is moderately consistent this suite includes quartz, calcite, pyrite, various clay minerals including kaolinite, illite, and varieties of illite-smectite mixed-layer clay minerals. The weathering of pyrite produces some sulfate minerals in many coals. Several other minerals are present in most coals in trace amounts. 

The determination of the mixed-layer clay minerals is done by the NATMIX module, which makes decisions based on the comparison of the three states — dried, heated, and solvated. The comparison is based on rules that allow predictions to be made for the different types of mineral layers due to the different behavior in the three states. The system also proposes adding additional specific experiments that further refine the characterization of the layer composition. The system covers the entire family of mixed-layer clay minerals and determines their nature. 

For samples taken up-dip of the Setif and Medjounes areas the values range from +2.9 to -5.8%o (Tables 7.2,7.3 Fig. 7.2). The light carbon makes itself felt in the carbonates where we find traces of recrystallization or of other mineralogical neoformations and in particular the appearance of mixed-layer clay minerals with perfectly ordered crystal structures. In the same samples microfissures are filled by secondary calcite or dolomite with detrital carbonate cement frequently being present between the crystals. In other cases we observe entire fields of neoformed minerals (dolomite... 

Corrensite, a mixed-layer mineral of the chlorite-montmorillonite type with an ordered structure, occurs at several levels within the Triassic Basin and in particular in the area of the Hassi R Mel deposit (Plate 15). Corrensite is a highly useful geothermal indicator in sediments (Porrenga 1967 Kiibler 1973)- In the area mentioned it starts to appear at a depth of 2.1 km and remains stable down to 2.3 km. The maximum temperatures reached were reconstructed on the basis of the appearance or disappearance of allevardite, kalkbergite and corrensite mixed-layer minerals (Fig. 8.2). Min-eralogical and crystallochemical analyses of mixed-layer clay minerals reveal the pro-... 

J. B. Droste, and W. F. Bradley, 1960. A mixed-layer clay mineral associated with an evaporite. 

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