anorthosite
noun
an·or·tho·site ə-ˈnȯr-thə-ˌsīt 
: a granular plutonic igneous rock composed almost exclusively of a soda-lime feldspar (such as labradorite)
anorthositic
ə-ˌnȯr-thə-ˈsi-tik
adjective 
Example Sentences
Recent Examples on the Web The light-colored highlands are composed of anorthosite, an igneous rock believed to be the remains of the primordial crust of the Moon, and are dated to 4.5 to 3.9 billion years. 
David Bressan, Forbes, 10 Oct. 2021 At the moment, only two mines in Greenland are active, one producing rubies and the other anorthosite, used in paints, plastic coatings and special varieties of glass. New York Times, 1 Oct. 2021 Astronauts on Apollo 15 collected a 4 x 2-inch chunk of crystal anorthosite over 4 billion years old. Michael O’donnell, WSJ, 2 July 2021 The chunks of anorthosite weren’t deposited there by nature — they were trucked in from the mountains around Pasadena. Los Angeles Times, 19 July 2019 The chunks of anorthosite weren’t deposited there by nature — they were trucked in from the mountains around Pasadena. Los Angeles Times, 19 July 2019
David Bressan, Forbes, 10 Oct. 2021 At the moment, only two mines in Greenland are active, one producing rubies and the other anorthosite, used in paints, plastic coatings and special varieties of glass. New York Times, 1 Oct. 2021 Astronauts on Apollo 15 collected a 4 x 2-inch chunk of crystal anorthosite over 4 billion years old. Michael O’donnell, WSJ, 2 July 2021 The chunks of anorthosite weren’t deposited there by nature — they were trucked in from the mountains around Pasadena. Los Angeles Times, 19 July 2019 The chunks of anorthosite weren’t deposited there by nature — they were trucked in from the mountains around Pasadena. Los Angeles Times, 19 July 2019 Word History
Etymology
French anorthose, a feldspar, from a- + Greek orthos — more at orth-
First Known Use
1863, in the meaning defined above