Experimental study on crystallization kinetics of alkali feldspar under high T-P conditions

In the granite-NaF-H2O system, there exists a nucleation lag in the course of alkali feldspar crystallization indicated by experiments on crystallizat ion kinetics. The nucleation lag time is about 18 h at 700 degreesC and abo ut 6 h at 650 degreesC. Meanwhile, both nucleation rate and crystal-growth rate of alkali feldspar are not constant during the crystallization process , but vary with crystallization time. Here we suggest that the lag time sho uld be taken into account in the calculation formula of nucleation rate and crystal-growth rate to obtain more reliable parameters.