Quartz derivatives

It is very notable that the curves for the common mineral assemblages at elevated temperatures (calcite-albite-sericite-K feldspar-quartz (mnjCOj = 10 ) and wairakite-albite-sericite-K-feldspar-quartz assemblage) are close to curve 2 in position. To the contrary, the curve for the mineral assemblage, albite-sericite-Na-montmorillonite-quartz, derived from the Na-K-Ca relationship obtained by Fournier and Truesdell (1973) is quite different in position from the other curves calculated and the Ca + concentration under high salinity conditions. 

Partial resolution of racemates has been achieved by the use of finely powdered quartz (derived from crystals of identical chirality). One method is to shake an aqueous solution of the racemate with the powder and then filter the solution before measuring the rotational change. Colunms of powdered quartz have also been employed. It would seem that lactose is the more effective of the two in bringing about resolutions for further details see Dwyer and Mellor (1964). 

The ability of a force field to reproduce vibrational spectra is often used as another criterion of quality. Table 14 compares observed and calculated vibrational spectra of a-quartz derived from various potential functions. This table shows that the molecular mechanics force field of de Vos Burchart is clearly superior to both Tsuneyuki s and Vessal s ion pair potentials. 

In a -SiAlON, partial replacement of Si4+ by Al3+ occurs if, at the same time, charge compensation is effected by the accommodation of other ions, M = Li+, Ca2+, y3+ or other rare earth ions, in the two interstitial sites (x) in the unit cell [8], x (<2) is determined by the valence of the M ion. The structural principle is similar to that in the formation of the "stuffed" quartz derivatives in which Al3+ replaces Si4+ and valency charge balance is maintained by stuffing" Li+ or Mg2+ into the interstitial sites. As with P , Y2O3 is often used as a densification aid and to provide the for stabilization of a . 

The addition of 2,2, 4,4, 6-pentanitro-6 -methyldiphenylamine [64653-47-0] to seawater precipitates potassium (38). Aromatic amines, especially aminotetrahydronaphthalenes and their A[-aryl derivatives, are efficient flotation agents for quartz. The use of DPA for image formation in films has been patented (39,40). Diarylamines are used as intermediates (41) for azo, sulfur, oxidative base, triaryhnethane, oxazine, nitro, and safranine dyes (see Dyes and DYE INTERLffiDIATES). 

Fig. 4.1.5 The time course of aequorin luminescence measured with various concentrations of Ca2+. Calcium acetate solution (5 ml) was added to 10 pi of aequorin solution to give the final Ca2+ concentrations of 10 2 M (A), 10-4 M (B), 10-5 M (C), 10 6 M (D), and 10 7 M (E) at 25°C. The dashed line (F) represents the light emitted following the addition of deionized distilled water that had been redistilled in quartz. The concentration of EDTA derived from the aequorin sample was 10 7 M (final cone.). From Shimomura et al., 1963b, with permission from John Wiley Sons Ltd.

It was attempted to derive the relationships in the precipitated amounts of barite and quartz, flow rate and precipitation rate using the coupled fluid flow-precipitation... 

Morishita (1993) showed based on carbon isotopic composition of carbonates that carbon of carbonates in the gold-bearing quartz vein in southern Kyushu was derived from the Shimanto Supergroup shale. Imai et al. (1998) considered that hydrogen in the ore fluids was derived from the Shimanto Supergroup shale based on 5D (—60%o to — 100%c) of inclusion fluids in quartz and adularia of the Hishikari veins. These isotopic... 

This equation shows that activity of Ca + is related to pH, concentration of H2CO3 and temperature. Because pH is related to the concentration of Cl for the equilibrium curves 1 and 2 in Fig. 2.14, the relationship between the concentrations of Ca " " and Cl" can be derived for calcite-albite-sericite-K-feldspar-quartz equilibrium (curves 4 and 7 in Fig. 2.14) and calcite-albite-sericite-Na-montmorillonite-quartz equilibrium (curves 5 and 8 in Fig. 2.14) with constant w2h2C03- The range of zh2C03 in the solution in equilibrium with calcite is assumed to be 10 to 10 . The other equilibrium curves for the assemblage including Ca minerals are also drawn (Fig. 2.14). These assemblages are wairakite-albite-sericite-K-feldspar-quartz (curve 3), Ca-montmotillonite-albite-sericite-Na-montmorillonite-quartz (curve 6), Ca-montmorillonite-albite-sericite-K-feldspar-quartz (curve 9) and anhydrite (curve 10). The effect of solid solution on the equilibrium curves is not considered because of the lack of thermochemical data of solid solution. 

Shikazono (1978) theoretically derived that the concentrations of alkali and alkali earth elements in chloride-rich hydrothermal solution are nearly in equilibrium with hydrothermal alteration minerals such as albite, K-feldspar, K-mica, quartz, calcite, wairakite, and Mg-chlorite. If we use 500 mmol/kg H2O as the average Cl concentration of hydrothermal solution from the back-arc basin, which is in equilibrium with... 

The composition of the particles is related to that of the source rocks. Quartz sand [composed of silica (silicon dioxide)], which makes up the most common variety of silica sand, is derived from quartz rocks. Pure quartz is usually almost free of impurities and therefore almost colorless (white). The coloration of some silica sand is due to chemical impurities within the structure of the quartz. The common buff, brown, or gray, for example, is caused by small amounts of metallic oxides iron oxide makes the sand buff or brown, whereas manganese dioxide makes it gray. Other minerals that often also occur as sand are calcite, feldspar and obsidian Calcite (composed of calcium carbonate), is generally derived from weathered limestone or broken shells or coral feldspar is an igneous rock of complex composition, and obsidian is a natural glass derived from the lava erupting from volcanoes see Chapter 2. 

Clays occur naturally either in a relatively pure condition or mixed with other materials and they are therefore classified into one of two large groups primary and secondary clays. Primary clays are quite pure, uncontaminated by other materials, and have a rather uniform composition. Secondary clays are mixtures of clay with other minerals such as quartz, talc, mica, iron oxides, and even organic matter (the latter derived from the decay of dead plants and animals) the particles of most of the contaminating materials are generally of similar size to those of the clay (Kingery et al. 1976). 

Perhaps the most important components of reactor solids are those that are generated during processing rather than those that are derived from inert minerals (quartz, clays) and macerals (fu-sinites, etc.) in the feed coal (74). The retention of these formed materials is more difficult to predict from the characteristics of the feed and, hence, control in liquefaction processes. 

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