Metallica are working on an ambitious album that will take a little time to nurture. The band describes their latest pieces of work as the "Riff Bank," and hopefully all these guitar hooks and crunches will be worth the wait. Fans expecting a quick turnaround for new material, however, will be disappointed.

The news was divulged in an MTV News interview with Kirk Hammett. "The Riff Bank keeps getting bigger and bigger, still, to this day," says the guitarist, whose group staged the Orion Music + More Festival in Detroit over the weekend. "I'm writing stuff, Rob's [Trujillo] writing stuff, James [Hetfield] is writing stuff, Lars [Ulrich] is writing stuff, continually expanding the Riff Bank. So, it doesn't look like we're going to be putting out an album any time soon this year, it would be an amazing stroke of luck and grace if our album came out next year. I think it's a more sober statement to say that the album will probably come out in 2015."

Once released, the album will constitute of the first pure Metallica work since the well-received 2008 effort 'Death Magnetic.' Their team-up with Lou Reed for the 2011 project 'Lulu' received a lukewarm reception, and it's heartening news that, according to Hammett, the band are making their latest batch of music as "heavy and as high energy as possible."

The group's dedication to immersing fans with their muscular wall of metal sound was evident at the Orion festival, as they performed under the secret moniker Dehaan (named after actor Dane Dehaan, who stars in their 3D concert film 'Metallica Through the Never' that's due in September). The band performed their entire album 'Kill 'Em All' for the fans as they ripped through songs like 'The Four Horseman,' 'Whiplash' and 'Seek and Destroy.'