“Reflected light digital image in plane polarized light of fine-grained covellite (blue), which shows a network of shrinking cracks, in association with chalcopyrite (yellow) in interstices of subhedral krut'aite-penroseite solid solution crystals (bright creme). For further explanations see reference: Origin of the El Dragón Selenium Mineralization, Quijarro Province, Potosí, Bolivia. Günter Grundmann and Hans-Jürgen Förster, published in: Minerals 2017, 7, 68; doi:10.3390/min7050068”