Kyanite

For a variety of minerals listed in table 4.2, Fe2+ — Fe3 IVCT transitions have been assigned to a range of energies spanning 9,700 cm-1 to 18,500 cm-1. These data enable two widely held beliefs to be examined first, that the charge transfer energies should decrease with decreasing separation between the inter- 

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Figure Bl.12.13. MAS NMR spectra from kyanite (a) at 17.55 T along with the complete simulation and the individual components, (b) simulation of centreband lineshapes of kyanite as a fiinction of applied magnetic field, and tire satellite transitions showing (c) the complete spiimmg sideband manifold and (d) an expansion of individual sidebands and their simulation.

Figure Bl.12.14. (a) A1 DOR NMR spectrum of kyanite at 11.7 T at various spiiming speeds and (b) the MQ MAS NMR spectnim of kyanite at 9.4 T (top) along with the isotropic projections at 11.7 and 18.8 T. (The MQ MAS NMR data are taken from [38] with the pennission of Academic Press.)...

Sillimanite Minerals. This group includes sillimanite, andalusite [12183-80-17, and kyanite [1302-76-7]. AH have the formula AI2O2 Si02. 

A U.S. Bureau of Mines survey covering 202 froth flotation plants in the United States showed that 198 million tons of material were treated by flotation in 1960 to recover 20 million tons of concentrates which contained approximately 1 billion in recoverable products. Most of the worlds copper, lead, zinc, molybdenum, and nickel are produced from ores that are concentrated first by flotation. In addition, flotation is commonly used for the recoveiy of fine coal and for the concentration of a wide range of mineral commodities including fluorspar, barite, glass sand, iron oxide, pyrite, manganese ore, clay, feldspar, mica, sponumene, bastnaesite, calcite, garnet, kyanite, and talc. 

A number of nonmetallic mineral deposits are formed during metamorphism as a result of recrystallisation. Important among these are graphite, asbestos, talc, soapstone and pyrophyllite, kyanite, sillimanite, and semi precious stones like garnet and emery. 

Troup, G.J. and Hutton, D.R. 1964. Paramagnetic resonance of Fe3+ in kyanite. British Journal of Applied Physics 15 1493-1499. 

Table 1.4 The enthalpy of formation of the three polymorphs of AI2Si()5, kyanite, andalu-site and sillimanite at 298.15 K [3].

Table 1.5 The enthalpy of formation of kyanite, andalusite and sillimanite from the binary constituent oxides [3]. The enthalpy of transition between the different polymorphs is also given. All enthalpies are given for T = 298.15 K.

Figure 1.10 The standard Gibbs energy of formation from the binary constitutent oxides of the kyanite, sillimanite and andalusite modifications of A SiOs as a function of pressure at 800 K. Data are taken from [3]. All three oxides are treated as incompressible.

ArV is not necessarily positive, and to compare the relative stability of the different modifications of a ternary compound like AGSiOs the volume of formation of the ternary oxide from the binary constituent oxides is considered for convenience. The pressure dependence of the Gibbs energies of formation from the binary constituent oxides of kyanite, sillimanite and andalusite polymorphs of A SiOs are shown in Figure 1.10. Whereas sillimanite and andalusite have positive volumes of formation and are destabilized by pressure relative to the binary oxides, kyanite has a negative volume of formation and becomes the stable high-pressure phase. The thermodynamic data used in the calculations are given in Table 1.7 [3].1... 

Table 1.7 Thermodynamic properties of the kyanite, sillimanite and andalusite polymorphs of Al2SiC>5 at 800 K [3].

Kuhni contacters, 10 778 Kujimycins, 15 280 Kunster marrow needle, 3 743 Kurnakov test, 19 656 Kurrol s salts, 13 848 Kuruma shrimp, common and scientific names, 3 188t K X rays, 21 311 KX zeolite. See Zeolite KX Kyanite, 2 345t in clays, 6 685 in coal, 6 718 Kynarflex, 7 641 Kynar SL, 7 641 Kynol fibers, 13 797 Kyoto Protocol, 11 721 KY zeolite. See Zeolite KY... 

Kossel model, 34 208, 223 low-energy Kossel structure, 34 223 Kyanite, 33 255... 

If we now recall the phase rule, it is evident that, at the P-T conditions represented by point D in figure 2.5, slight variations in the P or T values will not induce any change in the structural state of the phase (there are one phase and one component the variance is 2). At point A in the same figure, any change in one of the two intensive variables will induce a phase transition. To maintain the coexistence of kyanite and andalusite, a dP increment consistent with the slope of the univariant curve (there are two phases and one component the variance... 

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