In this paper, we've extracted the typical color palette of metal album artworks. We show that metal artwork designers make an extensive use of dark colors. Black is overwhelming in metal artworks and other frequently used colors include grey shades and brown tones. This palette is very different from what is used in the design of album belonging to other musical genres. We also highlight specific color choices in some metal subgenres (black, drone, crossover, groove metal). Interestingly, these dark colors have been associated in the past to emotions such as agitation and anger, but also to musical characteristics such as distortion, loudness and heaviness. This perfectly depicts most metal music pieces and support the well-known associations between music and colors on one hand, and between the musical content of an album and its artwork on the other hand.