Like labradorite and anorthite, it is a common constituent of basic igneous rocks, such as gabbro and basalt.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary"] Reference

In chemical composition and in optical and other physical characters it is thus much nearer to the anorthite end of the series than to albite.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary"] Reference

The name was afterwards applied by G. Tschermak to those plagioclase felspars which lie between labradorite and anorthite; and this has been generally adopted by petrologists.    From Wordnik.com.  [Encyclopaedia Britannica, 11th Edition, Volume 4, Part 4 "Bulgaria" to "Calgary"] Reference

The minerals anorthite, albite, and orthoclase named in this figure are all feldspars; sylvite and halite are chlorides of potash and soda.    From Wordnik.com.  [The Economic Aspect of Geology] Reference

This young scientist, too, cherished loving thoughts about Angelina, thoughts of a more earthly and volcanic tinge; certain definite projects which made him forget, at times, his preoccupation with biotite, perlite, magnetite, anorthite, and pyroxene.    From Wordnik.com.  [South Wind] Reference