The two small garnets in these images are partly mantled by chlorite.  In plane polarized light (A), garnet appear as irregularly shaped, high-relief regions (pale pink) surrounded by lower relief green chlorite.  Under crossed nicols the isotropic garnets appear black and the chlorite rims have very low birefringence (black to anomalous blue-grey).  Garnet may represent the peak metamorphic grade that this rock experienced, but the chlorite has formed at the expense of the garnet during retrograde metamorphism.  Sample is of a garnet-mica schist from an unknown location.  Views are 2.2 mm across. A ppl, B x-nicols.