Abstract
Acidic volcanic rocks (Whitianga Group) in the Hahei area consist of breccia, lapilli breccia and tuff (Coroglen Subgroup) overlain by rhyolite lava domes (Minden Rhyolite Subgroup). The remnants of three or more domes are preserved, composed of biotite, biotite-hornblende, and pyroxene rhyolite.