METALLICA guitarist Kirk Hammett says that the material the band has been writing for its forthcoming album "is a little bit more progressive" than the song "Lords Of Summer", which was performed for the first time more than a year ago at the opening show of METALLICA's South American tour.

During an appearance yesterday (Tuesday, April 14) on SiriusXM's Liquid Metal, Hammett spoke about the progress of the songwriting sessions for the follow-up to METALLICA's 2008 album, "Death Magnetic". He said: "I would say some of the stuff [we have written] is similar to 'Lords Of Summer'. 'Lords Of Summer' is pretty accessible, because I think it's one of the more accessible-sounding riffs and there's a really cool melody. A lot of the other material is a little bit more progressive — kind of along the lines of what 'Death Magnetic' turned out to be."

He continued: "I would say that there's some really, really hooky stuff coming through — really, really catchy stuff — and I'm really, really psyched on the direction of how things are sounding. If I could compare it to anything, maybe it might be remotely similar to the approach we took on [1988's] '…And Justice For All' [album], but it doesn't sound like '…And Justice For All' sonically — it doesn't have that sound that '…And Justice For All' had, which I thought was very unique at the time."

Hammett added: "I listen to a lot of metal bands today, and there are bands that really like that '…And Justice For All' sound and strive for that. And cool, man. I mean, they're actually doing it better than we did, 'cause you can hear the bass."

Kirk also talked about how he goes about finding the inspiration and motivation to record a new METALLICA album these days. He said: "It's what always do. I always go back to the stuff that influenced me when I was younger and first starting out, 'cause that stuff is still inspiring. And then I look around and see what's going on present day, and what bands are sounding like these days, 'cause I'm always curious."

He continued: "What I do is I like to see what's going on and I like to see how our sound fits in with what's going on. It's really just a day-to-day thing. I'll throw on the radio and start hitting the stations. And if I hear a piece of music that I think is particularly interesting, I'll listen to it and maybe I'll listen and catch something and think, 'Wow! That's a pretty good melody. Maybe I should apply that to this solo section.' And it could be any type of music — it could be rock, it could be heavy metal, reggae… anything. And I'll use that as maybe a little starting point for me to maybe create something different."

Hammett told Billboard.com in a recent interview that the band is "at the 25 percent point, maybe 30 percent point" in the making of its tenth studio album. Although Hammett said that the band has over a dozen songs ready, there is still a lot of writing to go. "We have a lot of good songs," he said. "The songs are ever-changing. Nothing is etched in stone. We still have a lot of material we have to sift through still, so it's hard to say at what point we actually are in the project. I don't think we hit the middle point yet. But I mean, we are working on it and there are songs and, you know, we're making plans to write more songs and record."

Hammett admitted that getting a new METALLICA album into production these days is a huge undertaking, explaining, "It does take on monstrous proportions. It takes up a lot of space in our lives."

The band members have steadfastly refused to say when fans might get to hear the follow-up to "Death Magnetic", although a 2015 release date is starting to look less likely at this point.

Drummer Lars Ulrich told Rolling Stone recently that the band was "pretty close" to entering the recording studio, adding that the band doesn't want to record in a way that feels "labored over and overthought."

METALLICA was recently announced as one of the headliners of this year's edition of Lollapalooza, along with Paul McCartney. The festival will take place at Grant Park in Chicago, on July 31, August 1 and August 2.

The band will play another dozen or so dates between early May and mid-September, including the inaugural Rock In Rio USA festival in Las Vegas on May 9.