This article presents a translation of the so-called Virunum album (found near Klagenfurt, Austria), a bronze plaque commemorating two important moments in the life of local Mithraic community and also registering names of its members. This monument, although not very spectacular at first sight, provides us with some important insights into Mithraic cultic life and its social structure: (a) it seems to support the former views about the importance of solstices in Mithraic eschatology; (b) it raises the possibility that Mithraic grades were transferable from one community to another; (c) it proves (with some degree of certainty) that a Mithraic community, when its members became too numerous, split and a new cell was founded.