Plagioclase
WordNet
noun
(1) Any of a series of triclinic feldspars that form rocks
WiktionaryText
Noun
plagioclase
- A group of feldspar minerals that form a solid solution series from albite (sodium aluminum silicate) to anorthite (calcium aluminum silicate). The plagioclase feldspars are found in igneous, plutonic, and metamorphic rocks. They all have the triclinic-pinacoidal crystal habit, but only Albite commonly occurs in well crystallized specimens.