Metamorphic rocks are formed from the alteration of existing rocks (igneous, sedimentary, or other metamorphic rocks) under conditions of high pressure, high temperature, and/or chemically active fluids. Here are some examples of metamorphic rocks:
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Schist - Characterized by its schistosity, schist is a highly foliated metamorphic rock that contains large, flat minerals, such as mica, that give it a shiny appearance.
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Gneiss - A banded metamorphic rock that typically contains alternating layers of light and dark minerals. It forms under high-grade metamorphic conditions.
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Marble - Formed from the metamorphism of limestone, marble is composed mainly of calcite and is known for its use in sculpture and architecture, often having a crystalline texture.
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Quartzite - This rock is formed from the metamorphism of sandstone and is composed primarily of quartz grains. It is known for its hardness and resistance to weathering.
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Slate - A fine-grained metamorphic rock that forms from shale. It exhibits excellent fissility (the ability to be split into thin sheets) and is often used for roofing and flooring.
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Phyllite - A metamorphic rock that is between slate and schist in terms of its degree of metamorphism. It has a glossy sheen and a well-defined foliation.
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Hornfels - A fine-grained metamorphic rock that forms by contact metamorphism, typically adjacent to igneous intrusions. It does not exhibit foliation and can be composed of various minerals.
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Amphibolite - A metamorphic rock that is primarily composed of amphibole minerals and plagioclase feldspar. It is usually dark in color and forms under high-grade metamorphic conditions.
These rocks exemplify the diverse forms and compositions that can arise through the processes of metamorphism.