THE CRYSTALLINITY INDEX OF QUARTZ BY XRD, ITS SUSCEPTIBILITY FOR ASR, AND A BRIEF METHODOLOGICAL REVIEW

摘要

This paper reports results from the assessment by XRD of powdered quartz from non-metamorphic Dutch cherts, low-grade metamorphic Ohio cherts, and comparatively high-grade metamorphic Norwegian mylonites, to determine crystallinity indices (CI) conform the popular method introduced by Murata & Norman in 1976. Results cover the entire range from < 1 to 10 and over. Data are compared with existing data on the same sample material acquired by DTA, LOI, and accelerated expansion testing. A straight-forward correlation appears absent. The CI_(XRD) method by Murata & Norman is critically reviewed and compared with two alternative methods that use DTA and FT-IR. It is unclear which crystal structural features that do affect the solubility of quartz also affect the CI by any of the methods.