The shape of sand‐sized crushed quartz particles

Abstract

The platy nature of sand‐sized quartz particles reported by Wellendorf & Krinsley (1980) is corroborated by the results of an exercise given in my optical crystallography course. In order to bridge the gap between the immersion oils technique and thin‐section work, the exercise asks the students to determine the sieve mesh‐size interval of crushed quartz particles that best corresponds to the standard thin‐section thickness of 0·03 mm, by determining the sieve interval which has the largest percentage of straw‐yellow interference colours. Consistently, this interval has been found to be the −140 to +170 mesh interval (0·10‐0·09 mm).