Amphibolite

Amphibolite ( /æmˈfɪbəlaɪt/) is the name given to a metamorphic rock consisting mainly of amphibole, especially the species hornblende and actinolite. A holocrystalline plutonic igneous rock composed primarily of hornblende amphibole is called a hornblendite, which are usually crystal cumulates. Rocks with >90% amphiboles which have a feldspar groundmass may be a lamprophyre.