Moonstone

n.

1.

(Min.) A nearly pellucid variety of feldspar, showing pearly or opaline reflections from within. It is used as a gem. The best specimens come from Ceylon.

Noun

1.

moonstone - a transparent or translucent gemstone with a pearly luster; some specimens are orthoclase feldspar and others are plagioclase feldspar

feldspar, felspar, transparent gem