anorthosite

[an-awr-thuh-sahyt]

noun

Petrology.

1. a granular plutonic rock composed largely of labradorite or a more calcic feldspar.

anorthosite

/ ænˈɔːθəˌsaɪt /

noun

1. a coarse-grained plutonic igneous rock consisting almost entirely of plagioclase feldspar

anorthosite

1. An igneous rock consisting almost entirely of plagioclase feldspar, especially the labradorite variety. Anorthosites have been identified among rock samples collected from the Moon.

Other Word Forms

• anorthositic adjective

Word History and Origins

Origin of anorthosite¹

1860–65; < French anorthose anorthoclase ( an- an- ¹ + Greek orthós straight) + -ite ¹

Word History and Origins

Origin of anorthosite¹

C19: from French anorthose (see _an- , _ortho- ) + _-ite ¹

Example Sentences

Scientists think that when the Moon formed 4.5 billion years ago, it began to cool and a lighter mineral called ferroan anorthosite floated to the surface.

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This ferroan anorthosite - or molten rock - formed the moon’s surface.

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The team behind the new findings found evidence of ferroan anorthosite in the south pole.

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Tarduno and his team used innovative strategies and techniques to examine the strength of the magnetic field by studying magnetism locked in ancient feldspar and pyroxene crystals from the rock anorthosite.

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On the second of their three days exploring Descartes, Young picked up a four-pound chunk of bright white stone that turned out to be anorthosite, a remnant of the moon’s original crust.

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