Quartz

Quartz sounds like the exact moment heavy rock shed its psychedelic skin and became something leaner and more dangerous. Coming out of Birmingham, their music carries that specific industrial weight, but they play it with a frantic energy that predates the speed of the 1980s. It is the sound of denim, leather, and overdriven tube amps in a room that smells like stale cigarettes and ambition.

What sets them apart is the pedigree of their production and the tightness of their rhythm section. Having Tony Iommi behind the boards for their debut gave them a massive, dark guitar tone that most of their contemporaries couldn't touch. They managed to be 'heavy' without being 'plodding,' incorporating the swing of hard rock into the aggressive templates that would soon define the New Wave of British Heavy Metal.

Start with their self-titled debut album. It is a masterclass in the transition from the 70s to the 80s, featuring guest spots from rock royalty and a collection of riffs that feel like they were forged in a furnace. It is essential listening for anyone trying to understand where the DNA of modern metal actually comes from.