Quartz solubility

Dissolved silica is one of the most troublesome products of liquid-dominated high-T geothermal fields. In the reservoir, aqueous silica concentrations are controlled by quartz solubility according to reaction (2) above (Mahon 1966 Fournier Rowe 1966 Arnorsson 1975). Boiling of high-71 water, which lowers its T and... 

Rimstidt, J. D. 1997. Quartz solubility at low temperatures. Geochimica et Cosmochimica Acta, 61, 2553-2558. 

Elias B. P. and Hajash A., Jr. (1992) Changes in quartz solubility and porosity due to effective stress an experimental investigation of pressure solution. Geology 20, 451-454. 

Newton R. C. and Manning C. E. (2000a) Quartz solubility in H20-NaCl and H2O—CO2 solutions at deep crust—upper mantle pressures and temperatures 2—15kbar and 500— 900 °C. Geochim. Cosmochim. Acta 64, 2993—3005. 

Walther J. V. and Orville P. M. (1983) The extraction-quench technique for determination of the thermodynamic properties of solute complexes. Application to quartz solubility in fluid mixtures. Am. Mineral. 68, 731-741. 

Xie Z. and Walther J. V. (1993) Quartz solubilities in NaCl solutions with and without wollastonite at elevated temperatures and pressures. Geochim. Cosmochim. Acta 57, 1947-1955. 

Figures 1 and 2 show the change in solubility of the acid-cleaned radiolarian and sponge spicule assemblages at 26° 1°C and 3° 1°C as a function of geologic age. Also shown are the estimated values of the high and low cristobalite and low quartz solubilities at these two temperatures. The open and crossed circles represent the initial leveling off of the concentration of Si (OH) 4 vs. time curves, and the dots are the...

Richer et al. (1982) present thermodynamic data for silica species equivalent to a quartz solubility of 6 ppm at 25°C, which corresponds to a concentration of 1 O " mol/kg. The same solubility is supported by Fournier, who gives log (quartz) = 0.41 - 1309/T(K) (see Nordstrom et al. 1990). We will assume a quartz solubility value of 6 ppm at 25°C in future calculations and discussions. 

As seen on fig. 5 the very rough estimations of nucleation pressure shifted to more negative than on fig. 1-4. The nucleation in CsCl solution never observed above -40 MPa and this process extended up to -200-250 MPa. Main part of the experimental points are grouping around -100 MPa as on fig. 2 for alkali solutions. It could be result of similar quartz solubility in these liquids Si02 solubility in CsCl solutions is higher than in any other chlorides solutions including even salt-in effect in wide P-T area (Shmulovich et. al., 2006). 

Better quality of inner surface of the inclusions (increasing quartz solubility in the liquid) lead to shift of nucleation to larger tension. 

Von Damm KL, Bischoff JL, Rosenbauer RJ (1991) Quartz solubility in hydrothermal seawater—an experimental study and equation describing quartz solubility for up to 0.5 M NaCl solutions. Am J Sci 291 977-1007... 

Rhoton FE, Bigham JM, Schulze DG (1993) Properties of iron-manganese nodules from a sequence of eroded fragipan soils. Soil Sci Soc Am J 57 1386-1392 Rimstidt JD (1997) Quartz solubility at low temperatures. Geochim Cosmochim Acta 61 2553-2558 Rimstidt JD, Barnes HL (1980) The kinetics of silica-water reactions. Geochim Cosmochim Acta 44 1683-... 

Let s suppose that a measurement of quartz solubility has been used to obtain the free energy of formation (standard or apparent) of H4Si04 in the ideal one molal standard state. This number can then be used (with A/G° terms for the minerals) to calculate the equilibrium constant of the albite-nepheline reaction (equation (13.11)), giving the equilibrium silica concentration in a solution that may never have been experimentally determined, or perhaps never existed, and in which quartz is not stable. Thus knowing the solubility of quartz, one could in a similar way calculate the silica concentration in fluids in contact with a variety of mineral assemblages. 

Fig. 19.1. Predicted quartz solubilities as a function of pH, temperature and total sodium concentration. After Crerar and Anderson (1971)...

In the calculation results (Fig. 20.5), silica concentration increases as the fluid flows downward, reflecting the increase in quartz solubility with depth, and then decreases as fluid moves back toward the surface. In calculations in which the reaction time exceeds about ten years, the fluid remains close to equilibrium with... 

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