“New insights into the fine-grained, opaque selenide veinlets of the Brummerjahn Mine, Zorge. Photo 21. Eucairite (greenish-crème) in association with umangite (purple), and tiemannite (light-gray), in calcite matrix (dark-gray). Polished section, plane polarized reflected light digital image, width 0.2 mm. Ore microscopy illuminates the darkness of the opaque "gray ugly" with true reflectance colors! G. Grundmann collection and photo. ”