plagioclase

The name given by Breithaupt to the group of triclinie feldspars the two prominent cleavagedirections in which are oblique to each other.

A general term used of any triclinic feldspar. See the Note under feldspar.

Any of a group of aluminum silicate feldspathic minerals ranging in their ratio of calcium to sodium.

any of a series of triclinic feldspars that form rocks