felspar vs moonstone

felspar and moonstone both are nouns.

Word	Noun	Adjective	Verb	Adverb
felspar	Yes	No	No	No
moonstone	Yes	No	No	No

As nouns, moonstone is a hyponym of felspar; that is, moonstone is a word with a more specific, narrower meaning than felspar:

felspar: any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium
moonstone: a transparent or translucent gemstone with a pearly luster; some specimens are orthoclase feldspar and others are plagioclase feldspar

Other hyponyms of felspar include orthoclase, oligoclase, plagioclase.

felspar (noun)	moonstone (noun)
any of a group of hard crystalline minerals that consist of aluminum silicates of potassium or sodium or calcium or barium	a transparent or translucent gemstone with a pearly luster; some specimens are orthoclase feldspar and others are plagioclase feldspar