Introduction to Optical Mineralogy and Petrography

ISBN: 9781332238170 出版年：2016 页码：198 M G Edwards Forgotten Books

Following Iddings, Winchell, and other American petrographers, the symbols X, Y, and Z, are here em ployed in referring to the axes of ether elasticity, instead of the German a, b, and c, used in many text and refer ence books. This is done to avoid confusion, especially in conversation or discussion, with the crystallographic axes.