Sparenga, S.
The importance of polarized light microscopy in the analytical setting.  Microscopy and Microanalysis 14: 1032-1033 (2008).

The polarized light microscope can provide information about virtually any type of sample. It may be used to determine whether two products have the same chemical composition, it allows for the identification of hazardous substances, and it can also be used in contaminant analysis for quality control. These are just a few of the ways the polarized light microscope can aid in analysis as illustrated by the following examples.