8 articles
Amphibolite
Amphibolite is a coarse-grained metamorphic rock composed mainly of hornblende and plagioclase, formed from basalt or gabbro, and quarried for highway aggregate and as dimension stone sold as black granite.
Eclogite
Eclogite is a dense metamorphic rock composed of red garnet and green omphacite, formed when basalt or gabbro is buried deep during subduction of oceanic crust.
Granulite
Granulite is a high-grade metamorphic rock with an even granular texture and hydroxyl-free minerals, also naming the granulite facies formed at 700 to 1100 °C.
Greenschist
Greenschist is a schistose metamorphic rock whose green color comes from chlorite, epidote, or actinolite; it forms by low-grade regional metamorphism of shale or basalt.
Migmatite
Migmatite is a composite metamorphic rock with two or more distinct parts, at least one formed by partial melting, named by Jakob Johannes Sederholm in 1907 from the Greek for mixture.
Mylonite
Mylonite is a fine-grained, cohesive, foliated fault rock formed by ductile deformation in shear zones, coined by Charles Lapworth in 1885 along Scotland's Moine Thrust.
Phyllite
Phyllite is a fine-grained, foliated metamorphic rock intermediate in grade between slate and schist, whose tiny mica crystals give its cleavage surfaces a silky sheen.
Skarn
Skarn is a coarse-grained metamorphic rock rich in garnet, pyroxene, and other calc-silicate minerals, formed where magma intrudes and alters carbonate rocks such as limestone.