Muscovite clay minerals

Silicates with layer. structures include some of the most familiar and important minerals known to man, partieularly the clay minerals [such as kaolinite (china clay), montmorillonite (bentonite, fuller s earth), and vermiculite], the micas (e.g. muscovite, phlogopite, and biotite), and others such as chrysotile (white asbestos). 

Reichenbach, H.G. and Rich, C.J. (1968) Potassium release from muscovite as influenced by particle size. Clays Clay Mineral, 17, 23-29. 

In a further test of the clustering procedure, analyses of particles of standard clay minerals, ripidolite, montmorillonite, nontronite as well as muscovite mica, were clustered. The procedure easily identified the different minerals, giving rise to well... 

MgOn(OH)j -] units (Fig. 7.5), and the illite type in which the octahedral sheet is sandwiched between two layers of tetrahedra (cf. micas such as muscovite, Fig. 7.4). Many important clay minerals such as vermiculite, biotite, and smectites (notably montmorillonite and beidellite, the princi-... 

This has been confirmed in the present study for chlorites from six rocks from the Belt series in northern Montana (Harrison and Jobin, 1963) and three samples from the outer zones in the Alpine chain. From these analyses, it is apparent that metamorphic chlorites which have crystallized with muscovite have low silica contents and a rather limited alumina content (27 3% A1 ions). The relatively large variation in chlorite Fe-Mg ratio from rock to rock suggests that bulk rock composition is more important in determining the chlorite composition than is the case of chlorites from clay mineral facies. 

The stability conditions of corrensite then cover the low grade clay mineral facies (near 100°C) and extend well into the calcium zeolite-prehnite, muscovite-chlorite facies. In pelitic rocks the upper limit will be somewhat lower near the illite-chlorite zone. It is evident that composition of a rock governs the occurrence of corrensite. It can be... 

RICH (C. I.) and OBERSHAIN (S.S.), 1955. Chemical and clay mineral properties of a red-yellow podzolic soil derived from a muscovite schist. Soil Sci. Ame. Proc. jL9, 334-9. 

The Hostrock and Backfill Material. Most crystalline igneous rocks, including granite and gneiss, are composed of a comparatively small number of rock forming silicate minerals like quartz, feldspars (albite, microcline, anorthite etc.) micas (biotite, muscovite) and sometimes pyroxenes, amphiboles, olivine and others. Besides, there is a rather limited number of common accessory minerals like magnetite, hematite, pyrite, fluorite, apatite, cal cite and others. Moreover, the weathering and alteration products (clay minerals etc.) from these major constituents of the rock would be present, especially on water exposed surfaces in cracks and fissures. 

Velde, B., 1964. Mixed-layer mineral associations in muscovite-celadonite and muscovite. Clays Clay Miner., Proc., 13 29-32. 

Weaver, C. E., 1958. The effects and geologic significance of potassium fixation" by expandable clay minerals derived from muscovite, biotite, chlorite, and volcanic material. Am. Mineralogist, 43 839-861. 

Knurr, R.A. and Bailey, S.W. (1986) Refinement of Mn-subsfituted muscovite and phlogophite. Clays and Clay Minerals, 34, 7-16. 

IHite/Smectite. Another common intergrowth of sheet silicates is the mixed-layering of illite and smectite. As discussed above, illite and smectite are clay minerals whose basic structures resemble the mica muscovite. Their compositions may differ significantly from muscovite, but they generally have a lower occupancy of the interlayer sites than mica. Numerous other compositional differences are possible for smectite however, this discussion will be restricted to a dioctahedral illite and a dioctahedral smectite containing potassium and vacancies in the interlayer sites as given above. 

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 main feature of clay minerals and micas is the layered crystallographic structure. Muscovite is a 2 1 [tetrahedral-octahedral-tetrahedral(T O-T)] phyllosilicate. In an ideal structure, aluminum exists in the octahedral sheet (=0) between two tetrahedral sheets ( = T), whose cations are composed of 25% Al and 75% Si. Interlayer K + cations balance the resulting negative charge (see schematic representation in Fig. 12, below). 

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