blueschist

rock

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June 22, 2026

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Blueschist is a type of metamorphic rock formed under conditions of high pressure and low temperature. This specific type of metamorphism, known as regional metamorphism, typically occurs along continental margins where an oceanic plate is being subducted beneath a continental plate.123

The characteristic blue mineral glaucophane gives blueschists their name. Other minerals found in blueschists include garnet, jadeite, and lawsonite, all of which indicate formation under high pressure. These rocks are often found in seismically and volcanically active regions, such as along the Pacific margin. Blueschists are significant because their study provides insights into plate tectonics and the processes occurring deep within the Earth's crust and mantle.1423

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amphibole
Regional metamorphic rocks
…high-pressure, low-temperature metamorphic rocks called blueschists, which have a blue colour imparted by the glaucophane. Blueschists have basaltic bulk compositions and may also contain riebeckite. The latter also may occur in regional metamorphic schists. Tremolite-actinolite and the sheet-silicate chlorite are the principal minerals in the low-to-moderate temperature and pressure greenschist…
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…high-pressure, low-temperature metamorphic rocks called blueschists, which have a blue colour imparted by the glaucophane. Blueschists have basaltic bulk compositions and may also contain riebeckite. The latter also may occur in regional metamorphic schists. Tremolite-actinolite and the sheet-silicate chlorite are the principal minerals in the low-to-moderate temperature and pressure greenschist…
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metamorphic rock
Metamorphic facies
…coloration, such samples are called blueschists. The same rock type metamorphosed at more moderate pressures and temperatures in the range of 400–500 °C (752–932 °F) would contain abundant chlorite and actinolite, minerals that are green both in hand sample and under the microscope, and would be referred to as a…
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…coloration, such samples are called blueschists. The same rock type metamorphosed at more moderate pressures and temperatures in the range of 400–500 °C (752–932 °F) would contain abundant chlorite and actinolite, minerals that are green both in hand sample and under the microscope, and would be referred to as a…
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Precambrian
Distinctive features
Blueschist, which contains the blue mineral glaucophane, forms in subduction zones under high pressures and low temperatures, and its rare occurrence in Precambrian rocks may indicate that temperatures in early subduction zones were too high for its formation.
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Blueschist, which contains the blue mineral glaucophane, forms in subduction zones under high pressures and low temperatures, and its rare occurrence in Precambrian rocks may indicate that temperatures in early subduction zones were too high for its formation.
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