Rock variety is a broad term that encompasses many different types of rocks. Gneiss (6 letters) is a metamorphic rock that is composed of alternating bands of light and dark minerals. GRUNGE (6 letters) is a type of rock music that originated in the Pacific Northwest in the late 1980s and early 1990s. ACID (4 letters) rock is a type of rock music characterized by distorted guitars, heavy drums, and psychedelic lyrics. METAL (5 letters) is a genre of rock music that is characterized by aggressive and distorted guitar riffs, powerful drumming, and often dark lyrics. Quartzite (9 letters) is a type of metamorphic rock that is composed of quartz grains that have been cemented together.