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Grain growth rates for novaculite, flint and jasper have been determined between 1000° and 800°C and 15 to 2 kb water pressure. A pre-treatment established an equilibrium microstructure and a nearly uniform mean grain diameter (D₀). At 1000°C and 15 kb the grain growth data are linear on a log (D-D₀) vs. log time plot, and there is no significant difference between the three samples although the jasper contained 5-10 vol % iron oxide. At lower pressures and temperatures the growth curves are approximately parallel to the 1000°C and 15 kb data, but growth is slower and that for jasper is slower than for the other two. The growth rate is strongly dependent on the solubility of quartz in the intergranular fluid, and the activation energy is about 11 kcal/mole. The data are used to estimate the growth rate of quartz at metamorphic conditions and to help evaluate the conditions where growth of dynamically recrystallized grains may be significant. The growth rate of calcite grains (Solnhofen limestone) is faster than that for quartz; however, it is considerably slower than that for loose calcite grains.
Tullis et al. (Sat,) studied this question.