Plagioclase

[pleidʒiәkleis]

(noun.) any of a series of triclinic feldspars that form rocks.

Typed by Andy--From WordNet

(n.) A general term used of any triclinic feldspar. See the Note under Feldspar.

Edited by Eva

n. a group of triclinic feldspars whose cleavage planes are not at right angles to each other.—adj. Plagioclas′tic.

Edited by Ian