Teflon, Wear Metals, and Emery
Transmitted Circular Polarized Light with Reflected Darkfield Illumination

The large, bright, birefringent particle in this view is abraded Teflon. There are some adhering wear metals and a large emery particle stuck in one side (lower right). This emery particle may have been responsible for carving the Teflon ribbon from the Teflon gasket used in this system.