Wollastonite minerals

Typical fillers wood flour, glass fiber, carbon fiber, mica, wollastonite, mineral wool, talc, magnesium hydroxide, graphite, molybdenum sulfide, carbon black, cashew shell particles, alumina, chromium oxide, brass and copper powder, iron particles, steel fiber, ceramic powder, rubber particles, aramid, wollastonite, cellulosic fiber, lignin... 

SYNONYMS calcium hydrosilicate, calcium metasilicate, calcium monosilicate, calcium polysilicate, calcium salt of silicic acid, wollastonite (mineral). 

Cesium carbonate Cesium chloride Cesium sulfate Magnesium sulfate anhydrous mineral wool Wollastonite mineral, pharmaceuticals Calcium gluceptate mineral, trace animal feeds Zinc carbonate Zinc chloride mineral, trace food supplements Zinc carbonate Zinc chloride minerals, testing Hydrazine sulfate mines... 

Wollastonite (mineral) (Ca silicate) High thermal stability Not reproduced Jingjiang et al., 1990... 

The interacting ions with their mass and charges is presented in Table 3.1, and the potential energy function parameters for adsorbed molecules is presented in Table 3.2. Table 3.3 shows the respective potential parameters used for quartz and wollastonite mineral systems. 

RESULTS AND DISCUSSION 3.3.1 Quartz-Wollastonite Mineral System... 

Law KM, Blnndy JD, Wood BJ, Ragnarsdottir KV (2000) Trace element partitioning between wollastonite and carbonate-silicate melt. Mineral Mag 64 155-165... 

This reaction is similar to Eq. 21.8. Wollastonite is an example of a calcium silicate mineral produced by the metamorphosis of detrital biogenic calcium carbonate and BSi. 

Greenwood H. J. (1967). Wollastonite Stability in H2O-CO2 mixtures and occurrence in a contact metamorphic aureole near Salmo, British Columbia, Canada. Amer. Mineral, 52 1669-1680. 

Fig. 2.1 Configurations of the tetrahedral units and chain, double chain, and sheet structures in the silicate and aluminosilicate minerals. (A) Two-dimensional representation of a single silicate tetrahedron. (A ) Two-dimensional representation of an extended silicate chain. (B) Three-dimensional representations of single tetra-hedra in two orientations. The apexes of the tetrahedra point above or below the plane of the paper. (B ) Three-dimensional representations of extended silicate chains showing different orientations of the tetrahedra in two of the many possible configurations. Single chain pyroxenes (C), wollastonite (D), rhodonite (E). Double chains amphiboles (F). Sheets as found in the serpentines, micas, and clays (G).

Another pyroxenoid, bustamite, [(Mn,Ca,)3Si309], whose stmcture closely approximates that of wollastonite, has also been identified in fibrous form, but no detailed examination has been undertaken to check the possibility that a structural segregation similar to wollastonite exists in this mineral, and might contribute to the formation of fibers. 

Chain silicate minerals with MgSiOg (En), FeSiOg (Fs), and CaSiOg (Wo) as the major components, where En is enstatite, Fs is ferrosilite, and Wo is wollastonite. 

There is an interesting analogy between cyclosiloxanes and the cyclic metasilicates [Si 03 ] " n = 3-6), e.g. (Me2SiO)3 (10.42) and [SisOg] " (10.43) the methyl groups in the dimethylsiloxanes are replaced by the formally iso-electronic in the silicates. Cyclic metasilicates occur naturally in certain minerals. For example, the trimer (n = 3) is found in CasSisOg (a-wollastonite), whereas the hexamer (n = 6) is a constituent of Be3Al2Si60ig (beryl). 

Murphy, W. M. Helgeson, H. C. (1987) Thermodynamic and kinetic constraints on reaction rates among minerals and aqueous solution. III. Activated complexes and the pH-dependence of the rates of feldspar, pyroxene, wollastonite, and olivine hydrolysis. Geochim. Cosmochim. Acta, 51, 3137-53. 

Monoclinic minerals have an inclined angle of extinction. Orthorhombic minerals have parallel extinction. Chrysotile can be monoclinic or orthorhombic depending upon whether it is the ortho or clino variety. The b axis of the clino variety is so close to 90° (93°), (25) that the fibers will appear to have parallel extinction unless this is carefully measured. Anthophyllite, an orthorhombic mineral, has parallel extinction that is, the angle of extinction is zero degrees. All amphibole asbestos minerals except anthophyllite are monoclinic. Although wollastonite is a triclinic mineral, its extinction is parallel, or nearly parallel. The angle of extinction of some asbestos minerals is shown in table I (26, 27). 

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