anorthosite

American  

[an-awr-thuh-sahyt] / ænˈɔr θəˌsaɪt /

noun

Petrology.

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

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anorthosite British  

/ ænˈɔːθəˌsaɪt /

noun

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

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anorthosite Scientific  

/ ăn-ôr′thə-sīt′ /

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.

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Other Word Forms

Derived Forms

• anorthositic
  adjective

Etymology

Origin of anorthosite

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

Example Sentences

There are currently only two operational mines on the island -- one gold mine in the south, and one for anorthosite, a rock containing titanium, on the west coast.

From Barron's • Feb. 14, 2026

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.

From BBC • Aug. 21, 2024

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.

From Science Daily • May 3, 2024

It was a breccia containing a nugget of anorthosite that apparently crystallized 4.46 billion years ago.

From Washington Post • Apr. 21, 2022

Segregations of iron ores, such as ilmenite, usually with pyroxene or olivine, occur in association with some gabbro and anorthosite masses.

From Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 4 "G" to "Gaskell, Elizabeth" by Various