orthoclase feldspar meaning
orthoclase. n. 1. (Minerals) a white to pale yellow, red, or green mineral of the feldspar group, found in igneous, sedimentary, and metamorphic rocks.It is used in the manufacture of glass and ceramics. Composition: potassium aluminium silicate.Formula: KAlSi3O8.rÂ·thoÂ·clase. A type of feldspar consisting of potassium aluminum silicate. Orthoclase is typically white, pink, yellow, or brown, but it can also be colorless. It is especially common in igneous rocks.