Tetrahedrite, bornite, chalcopyrite, cinnabar, galena, sphalerite, celestite, and barite occur in fractured and faulted Triassic and Cretaceous formations on the flanks of the Oroz-Betelu anticline in northern Spain. The oldest formations exposed in the anticline are Devonian karstic limestone and clastics, intensely folded by the Hercynian orogeny and truncated by an erosion surface. Lower Triassic clastics rest upon the erosion surface, and are surrounded by a peripheral zone of upper Cretaceous limestone and dolomite outcrops. Late Cretaceous and Paleocene flysch, in turn, surround the older formations of the anticline. Cinnabar was deposited with quartz and chalcedony after copper mineralization, and does not occur in the tetrahedrite.