[1], Greenschist is a general field petrologic term for metamorphic or altered mafic volcanic rock. B. quartzite - granite. Among foliated metamorphic rocks, it represents a gradation in the degree of metamorphism between slate and schist. Large bubbled pool of igneous rock between rock layers. Greenschist definition, schist colored green by an abundance of chlorite, epidote, or actinolite. In greater detail the greenschist facies is subdivided into subgreenschist, lower and upper greenschist. This rock is formed under great pressure and temperatures. All that is needed is enough heat and/or pressure to alter the existing rock’s physical or chemical makeup without melting the rock entirely. Metamorphic conditions which create typical greenschist facies assemblages are called the Barrovian Facies Sequence, and the lower-pressure Abukuma Facies Series. Above gneiss, when the rock actually starts to melt, it is called a migmatite. These ancient rocks are noted as host rocks for a variety of ore deposits in Australia, Namibia and Canada. Amphibolite is a gneissose or granofelsic metamorphic rock mainly consisting of green, brown or black amphibole and plagioclase (including albite), which combined form ≥75% of the rock and both of which are present as major constituents; the amphibole constitutes ≥50% of the total mafic constituents and is present in an amount of ≥30%. This property sets it apart from slate. Giant pool of igneous rock, often hundreds of kilometers long and tall. Get to know all the Greenschist Uses. It is formed in the subduction zone environment with low geothermal gradients (4-14°C km -1) and is characterized by the presence of HP/LT index minerals like glaucophane, lawsonite, aragonite, jadeite, and deerite (Fig.1). The original parent rock (or protolith) of mica schist is shale. Chlorite and to a lesser extent actinolite typically exhibit small, flat or acicular crystal habits. Rock, rock1 / räk/ • n. 1. the solid mineral material forming part of the surface of the earth and other similar planets, exposed on the surface or underly… Metamorphic Rocks, Metamorphic rock is rock that has changed from one type of rock into another. Also, the metals and minerals found in rock play an important role in our life. Giant pool of igneous rock, often hundreds of kilometers long and tall. (1986), pp. ancient volcanic rocks) which get their green color from chlorite +/- amphiboles and epidote. 5.2 Composition 5.2.1 Mineral Content The rock also has a strong slaty foliation, which is horizontal in this view, and has developed because the rock was being squeezed during metamorphism. Greenschist - also known as greenstone - is a general field petrologic term applied to metamorphic and/or altered mafic volcanic rock. Greenschist facies is determined by the particular temperature and pressure conditions required to metamorphose basalt to form the typical greenschist facies minerals chlorite, actinolite, and albite. SEDIMENTARY & IGNEOUS ROCKS AND THEIR METAMORPHIC EQUIVALENTS Name Parent Rock LOW Grade chlorite blotite MEDIUM Grade garnet staurolite HIGH Grade kyanite sillimanite Quartz Arenite Quartzite Limestone Marble Shale Slate & Phylite Blotite Schist Garnet Schist Staurolite Schist Kyanite Schist Silimanite Schist Anthracite Graphite Schist Coal Clay-Rich Sandstone Conglomerate Chlorite … Slate is a fine-grained rock composed of mica flakes and quartz grains that enable the rock to break into thin slabs of rock, along planes of slaty cleavage. Even though greenschist does not imply a specific parent rock, for our purposes we will assign a shale parent as a way of distinguishing it from a greenstone, which has a mafic parent. Schistose rocks are fissil… As a proper noun greenstone is . Metamorphic rocks form from pre-existing rocks ("parent rocks") due to changes in either temperature, pressure, or volatiles within the earth, often by a combination of all three. The green is due to abundant green chlorite, actinolite and epidote minerals that dominate the rock. This explains the scarcity of blueschist preserved from before the Neoproterozoic Era 1000 Ma ago when the Earth's oceanic crust contained more magnesium than today's oceanic crust. Phyllite has fine-grained mica flakes in a preferred orientation, whereas slate has extremely fine clay flakes that achieve a preferred orientation, and schist has large flakes in a preferred orientation. Temperatures and pressures and is usually produced by regional metamorphism rock that is composed mainly of green, brown or... Depth produces eclogite stone with sufficient amounts of stable minerals of rock—igneous, sedimentary, siltstone... 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