moonstone

A variety of feldspar valued as a gem for its pearly translucence.

A variety of feldspar which by reflected light presents a delicate pearly play of color not unlike that of the moon.

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.

A translucent gemstone, an orthoclase feldspar, that has a pearly lustre.

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