Sabbath keep serving up bluesy sweat on Seventh Star, their second record with vocalist Glenn Hughes. His soulful grit comes out on “Turn to Stone,” a speeding jam anchored by Eric Singer’s metronome-like drums, and “Heart Like a Wheel,” a ballad that ditches metal altogether for the kind of blues rock Hughes originally dished out with Deep Purple. Tony Iommi proves stunningly adaptable, his gracefully powerful melodicism on “Danger Zone” light years removed from Sabbath’s ’70s-era crunch.