Determination of white K-mica polytype ratios; comparison of different XRD methods

Abstract

Six different X-ray diffraction (XRD) methods for determining the relative amounts ofM 1 and 1M white K-mica polytypes were compared. Unoriented samples of different concentrations of the two polytypes were prepared using the technique described by Handschin & Stern (1989) and Stern (1991). An evaluation of different XRD techniques reported in the literature revealed that the method proposed by Cailiere et al. (1982) is the most accurate. The main reasons are the use of the 1M 112 and 2M 1 025 reflections with relatively strong intensities, showing no superposition with feldspar reflections, and being only slightly affected by sample preparation effects