natural glass vs quartz

natural glass and quartz both are nouns.

Word	Noun	Adjective	Verb	Adverb
natural glass	Yes	No	No	No
quartz	Yes	No	No	No

As nouns, quartz is a hyponym of natural glass; that is, quartz is a word with a more specific, narrower meaning than natural glass:

Other hyponyms of natural glass include crystal, lechatelierite, quartz glass, vitreous silica, tektite.

natural glass (noun)	quartz (noun)
magma of any composition that cooled very rapidly	a hard glossy mineral consisting of silicon dioxide in crystal form; present in most rocks (especially sandstone and granite); yellow sand is quartz with iron oxide impurities
	colorless glass made of almost pure silica