The Collaborative International Dictionary
Anorthosite \A*nor"tho*site\, n. [F. anorthose triclinic feldspar (fr. Gr. ? priv. + ? straight) + -ite.] (Petrol.) A granular igneous rock composed almost exclusively of a soda-lime feldspar, usually labradorite. [Webster 1913 Suppl.] ||
Wiktionary
n. (context geology English) A phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar.
Wikipedia
Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar (90–100%), and a minimal mafic component (0–10%). Pyroxene, ilmenite, magnetite, and olivine are the mafic minerals most commonly present.
Anorthosite on Earth can be divided into two types: Proterozoic anorthosite (also known as massif or massif-type anorthosite) and Archean anorthosite. These two types of anorthosite have different modes of occurrence, appear to be restricted to different periods in Earth's history, and are thought to have had different origins.
Lunar anorthosites constitute the light-coloured areas of the Moon's surface and have been the subject of much research.
Usage examples of "anorthosite".
This was lunar bedrock, anorthosite, buried beyond even the probings and pulverizing of the great impactors.
This was lunar bedrock, anorthosite, buried beyond even the probings and pulverizing of the great impactors.
The main components of anorthosites, you see, like plagioclase, are light.