Hi Abdullah,

I have not used a gypsum wedge to look at quartz fabrics but I can tell you that it wont give you anything quantifiable relating to the quartz fabrics. I do like to use a full wavelength plate as a quick check to see which thin sections are likely to yield good CPO fabrics when analysed by EBSD, U-stage or fabric analyser, when looking at a thin section cut in the XZ plane (parallel to lineation, perpendicular to foliation). If the thin section has a strong quartz CPO then rotating it under XPL with a full wavelength plate will show that all or most quartz grains appear blue in when rotated in one direction and yellow/orange in the other direction. This is a useful first pass for determining which samples to analyse for CPO measurements.

Andy

Hi,

This reference could be useful for you: Koeneman, F. 1986. A universal stage method for a very fine-grained crystal aggregates. Journal of Structural Geology, Vol 8, Nº 8, pp 942.