A mineral which is the common form of potash feldspar; = orthoclase, n.

A potassium-rich alkali feldspar which occurs widely in rocks and as free crystals, typically white or pink. Also more fully orthoclase feldspar.

= potassium feldspar n. at potassium, n. compounds 2.

a feldspar rich in potassium; spec. each of the three minerals orthoclase, microcline, and sanidine, which have the formula KAlSi3O8; these…