any of a group of hard rock-forming minerals consisting of aluminium silicates of potassium, sodium, calcium, or barium: the principal constituents of igneous rocks. The group includes orthoclase, microcline, and the plagioclase minerals
[C18: from German feldspat(h), from feld field + spat(h) spar³]
felsparorfelspar
—n
[C18: from German feldspat(h), from feld field + spat(h) spar³]