Definify.com

Webster 1913 Edition

Noun.

[Gr.

ἀν

priv. +

ὀρθόσ

straight (

ὀρθή

sc.

γωνία

right angle); not in a right angle.]

A mineral of the feldspar family, commonly occurring in small glassy crystals, also a constituent of some igneous rocks. It is a lime feldspar. See

anorthite ‎(plural anorthites)

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

mineral