mercury vs mercurial

mercury is a noun but mercurial is not a noun.

Word	Noun	Adjective	Verb	Adverb
mercury	Yes	No	No	No
mercurial	No	Yes	No	No

mercury (noun)	mercurial (noun)
temperature measured by a mercury thermometer
a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures

mercury (adjective)	mercurial (adjective)
	relating to or containing or caused by mercury
	liable to sudden unpredictable change