Muscovite micas

Fig. V-7. f potential of muscovite mica versus electrolyte concentration at pH 5.8 0.3. (From Ref. 76.)...

Erlandsson R, Hadzioannou G, Mate M, McClelland G and Chiang S 1988 Atomic scale friction between the muscovite mica cleavage plane and a tungsten tip J. Chem. Phys. 89 5190... 

Muscovite mica Muscular weakness Mushroom Mushrooms... 

Muscovite mica formed as a primary mineral in pegmatites and granodiorite differs in physical properties compared to muscovite mica formed by secondary alteration (mica schist) (Table 2). The main differences are in flexibiUty and abiUty to be delaminated. Primary muscovite is not as brittle and delaminates much easier than muscovite formed as a secondary mineral. Mineralogical properties of the principal natural micas are shown in Table 3. The make-up of muscovite, phlogopite, and biotite are as follows ... 

Flake mica is also produced from mica schist which normally contains from 30—60% recrysta11i2ed muscovite mica along with quart2 and iron minerals. The quart2 is usually not suitable for glass sand or high purity material, however. 

Table 5. Chemical Analysis of Ground Muscovite Mica ...

Pacer Corp. Custer, S.D. flake 70% muscovite mica for oil-weU use... 

Mica [12001 -26-2]—Cl Pigment White 20, Cl No. 77019. A white powder obtained from the naturally occurring mineral muscovite mica, consisting predominantly of a potassium aluminum siHcate, [1327-44-2] H2KAl2(Si0 2- Mica may be identified and semiquantitatively determined by its characteristic x-ray diffraction pattern and by its optical properties. 

Figure 9.12 Schematic representation of the structures of muscovite mica, (K2Al4(Si6Ali)02o(OH)4], hydrated montmorillonite, [Al4Sig02o(OH)4].xH20 and chlorite, (MgioAl2(Si6Al2)02o(6H)i6], see text.

Stimulated by these observations, Odelius et al. [73] performed molecular dynamic (MD) simulations of water adsorption at the surface of muscovite mica. They found that at monolayer coverage, water forms a fully connected two-dimensional hydrogen-bonded network in epitaxy with the mica lattice, which is stable at room temperature. A model of the calculated structure is shown in Figure 26. The icelike monolayer (actually a warped molecular bilayer) corresponds to what we have called phase-I. The model is in line with the observed hexagonal shape of the boundaries between phase-I and phase-II. Another result of the MD simulations is that no free OH bonds stick out of the surface and that on average the dipole moment of the water molecules points downward toward the surface, giving a ferroelectric character to the water bilayer. 

Muscovite mica naturally contains ions on its cleavage surface. A fraction of these ions become solvated and mobile in humid enviromnents. Experiments were per-... 

Muscovite mica may be cleaved to provide thin ( -2 pm) sheets that are molecularly smooth on both sides and which can be used as substrates in studying surface forces (8). Figure 1 shows schematically the essential features of the apparatus (10)... 

Muruntau Mountain lode, 72 686 Musa textilis, 77 295 Muscles, 3 723-724 Muscopyridine, 2 76 Muscovado sugar, 23 482 Muscovite, in coal, 6 718 Muscovite mica, as filler, 77 313 Musculoskelatal disorders (MSDs), in the workplace, 27 593... 

Potassium feldspar (orthoclase) Muscovite mica Quartz Felsic (rhyolite granite)... 

Blencoe J. G. (1977). Molal volumes of synthetic paragonite-muscovite micas. Amer. Mineral, 62 1200-1215. 

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... 

The LB monolayers of dimethyldioctyadecylammonium ions on molecularly smooth muscovite mica surfaces were investigated. Direct measurements of the interaction between such surfaces were carried out using the surface force apparatus. A long-range attractive force considerably stronger than the expected van der Waals force was measured. Studies on the electrolyte dependence of this force indicate that it does not have an electrostatic origin but that the water molecules were involved in this. 

Only a few materials can be successfully studied in this way. One of them is the layered natural aluminosilicate crystal, muscovite mica, which is available in large crystals and can be cleaved in a controlled manner to produce two molecularly smooth new surfaces. 

Figure 1.46 The structure of muscovite (mica), a sheet silicate. Reprinted, by permission, from L. G. Berry, B. Mason, and R. V. Dietrich, Mineralogy concepts, descriptions, determinations, p. 431, 2nd ed. Copyright 1983 by Freeman Publishing, Inc.

Polytypism in layered silicates has been well characterized. There are as many as 19 polytypes known among micas. The repeat unit in muscovite mica, [KAl2(OH)2(Si3Al)0 o], for instance, consists of a sheet of octahedrally coordinated aluminium ions sandwiched between two identical sheets of (Si, AOO tetrahedra, the large ions being located in interlayer positions. Surface oxygens of the tetrahedra in... 

Titanium Dioxide - Mica (Fig. 77). The first multilayer pigments were marketed in the 1960s as Ti02-coated muscovite micas [5.193], [5.201]. Two different processes are used for coating mica in aqueous suspension on a commercial basis ... 

Figure 5.6 Molecular structure of muscovite mica (KAl2Si3A10io(OH)2) in side view. A unit cell is indicated by the dashed line. The number of atoms of a certain species in a layer for two unit cells is indicated at the top right. As an average in the third molecular layer from the top one silicon atom is replaced by an aluminium atom.

The tendency of mica to cleave easily along the (100) crystallographic plane results in smooth,clean reproducible surfaces. This property, coupled with good thermal stability, has led to its wide use as a substrate in surface chemical studies (2). Indeed, the ability of Muscovite mica to be cleaved to give atomically smooth surfaces over areas of several square centimeters... 

To exploit this latter alternative, mica sheets were cleaved from larger crystals of Muscovite mica until a thickness of the order of 1-5 pm was reached as judged by the brightness and color of the fringes seen under room light. Actual film thickness was determined from the infrared fringe spacing. Mica at these thicknesses is delicate but can be handled if care is taken it is possible to cleave mica to thicknesses below 1 pm but at these thicknesses the mica becomes too delicate to use unsupported. The cleaved mica sheets were mounted in standard transmission holders constructed from Teflon. 

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