anorthite

From Ancient Greek αν- (an-, “not”) + ὀρθός (orthós, “straight”) "not perpendicular; less than straight", in reference to its odd.

English Wikipedia has an article on:

anorthite

Wikipedia

anorthite (countable and uncountable, plural anorthites)

1. (mineralogy) A variety of plagioclase feldspar, the calcium endmember of that series.

• anorthitic

• David Barthelmy (1997–2025) “Anorthite”, in Webmineral Mineralogy Database.
• “anorthite”, in Mindat.org‎^[1], Hudson Institute of Mineralogy, 2000–2025.