Everyone’s excited about Black Sabbath playing a handful of shows this summer, but in recent months the members of the legendary metal outfit have been holed up writing material for their highly anticipated new album.

Singer Ozzy Osbourne tells NME that the group have written 15 new tracks for the disc and that things are moving along with Rick Rubin lending his producing expertise. The vocalist says, “We’ve written about 15 songs so far, whether they’ll get on an album [I don't know]…You just keep on writing. I was trying to work out, where would we be musically if we’d have stayed together?” Osbourne says they’re still some way away from completing a disc, but adds, “Next year, 2013, is a good clue of what we’ll call the album.”

Speaking about Rubin’s influence on the record, bassist Geezer Butler added, “He sat us down, put the first album on and said, ‘Listen to this. Imagine it’s 1969, you’ve just done that, what would you do next?’”

Black Sabbath were expected to play a full slate of shows this summer, but Tony Iommi‘s recuperation from cancer treatments led the band to scale back their schedule. Aside from August’s headlining appearance at Lollapalooza, the group’s only other upcoming date is their Download appearance June 10. However, Ozzy Osbourne and Butler are honoring a number of the other proposed shows by playing “Ozzy and Friends” sets in Europe.