Measuring quartz solubility by in situ weight-loss determination using a hydrothermal diamond cell

摘要

The solubility of quartz was determined using a hydrothermal diamond anvil cell (HDAC) within the temperature and pressure ranges of 126 to 490degreesC and up to 8.9 kbar. respectively. A novel approach has been used to measure the amount of dissolved silica. The quartz was abraded into spheres which have a diameter of similar to40 mum. The spheres were then placed in pure water inside the diamond anvil cell and heated externally. Because the transparency of the diamonds allows direct observation of the sample chamber during the experiment. we were able to estimate the amount of quartz dissolved in the water at various stages of the dissolution process by measuring the decrease in the sphere's diameter over time. Experiments were performed along isochores between 0.92 and 0.99 g/cm(3). The maximum solubility measured was 0.165 molal. The experimental solubility data were limited to 370degreesC because of overestimation of solubilities above this temperature. Reprecipitation of silica inside the HDAC sample chamber and the refaceting of the spheres to trigonal form at temperatures above 350degreesC are major contributors to the overestimation. Copyright (C) 2004 Elsevier Ltd.