Geezer Butler says Black Sabbath has enough leftover material to get them about halfway toward a follow up to the band's smash comeback '13.' But Butler, who is appearing with Black Sabbath on May 29 at Abu Dhabi, feels that any subsequent studio effort would have to come from an organic place.

"We’ve still got four tracks leftover from the album," Butler tells TimeOutDubai. "So maybe we’ll fill in the other four or five tracks and put out another album -- if it’s right. We wouldn’t do it just for the sake of it, or the money or whatever. But yeah, maybe."

'13,' the first studio effort featuring Butler, Tony Iommi and Ozzy Osbourne since 1978, was a worldwide hit last year. Still, the album wasn't without its difficulties. Fellow founding member Bill Ward was replaced early on in the recording process, and Iommi was diagnosed with cancer. The guitarist has since been given a clean bill of health, but only after a grueling round of chemotherapy.

"Tony is probably healthier than everybody else now, after all the stuff they’ve done to him," Butler reports. "He’s really done well. He’s definitely in remission now."

Black Sabbath's latest round of shows in support of '13' concludes in July at Hyde Park.