Crystallization and Recrystallization of Quartz in a Simple Piston-Cylinder Device

Abstract

Artificial quartzites were produced in a non-hydrostatic stress field from a variety of materials in a piston and cylinder device operated in a simple squeezer. Quartz was crystallized in a hydrous environment from silicic acid, colloidal silica, and opal at a range of temperatures from 250° to 900° C. at piston pressures from 3 to 10 kb. Recrystallization of quartz from flint in the presence of $H_{2}O$ was accomplished at temperatures of 500°-775° C. in 1-4 days. In most of the experiments, particularly those of longer duration (up to 10 days), the quartz crystallized or recrystallized with a preferential orientation of the c-axes at high angles to the compression direction. Although the quartz generally was too fine-grained for universal-stage measurement of its orientation, qualitative estimates of the fabric were carried out. The c-axis fabrics were shown to be symmetrical with respect to the compression direction. The quartz is considered to have been preferentially oriented with respect to the pr...