blueschist

noun

blue·​schist ˈblü-ˌshist 

plural blueschists

geology : a metamorphic rock that is formed under high pressure and low temperature and is characterized by the presence of glaucophane

Also radiometric ages of blueschists from the same regions cluster around 400-500 Myr.

—T. Nakajima et al., Nature, 19 July 1990

At this depth, where the pressure is 15 to 20 kilobars and temperatures reach about 500 degrees C, rocks called blueschists and eclogites form.

—Ian Anderson, New Scientist, 29 Mar. 1997

Word History

First Known Use

1789, in the meaning defined above

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