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

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

n. 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.

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

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

"The moonstone is another example of this peculiar feature which is possessed in a more or less degree by all the stones in the class of pellucid jewels, but no stone or gem can in any way even rival the curious mixture of opaqueness, translucency, silkiness, milkiness, fire, and the steadfast changeable and prismatic brilliance of colour of the precious opal."

transparent gem    feldspar    felspar   

carnelian    topaz    beryl    chrysolite    malachite