A band doesn't always fit into a specific musical category even though it's associated with one by default. Burn Sand Burn (due on Thursday, August 20, at the hi-dive) often plays with metal bands, but anyone able to listen honestly can hear that these guys do not bother to play within strict boundaries. Sure, there's the melodic, anthemic hard rock in the songwriting, but at that same core of the act's sound is an urgency and desperation more akin to punk rock. And yet Burn is not purely about volume and aggression, either. Inside each of the songs are moments of surf rock's blurry edges, an amped psychedelic flavoring and a tinge of the blues. While those elements could result in an unholy dilettante-ish mess, this foursome has forged it into something refreshingly original in the heavy-rock underground.