adamant vs adamantine

adamant is a noun but adamantine is not a noun.

Word	Noun	Adjective	Verb	Adverb
adamant	Yes	Yes	No	No
adamantine	No	Yes	No	No

As adjectives, adamant and adamantine are synonyms defined as:

adamant and adamantine: impervious to pleas, persuasion, requests, reason

Other synonyms of adamant include inexorable, intransigent.

adamant (noun)	adamantine (noun)
very hard native crystalline carbon valued as a gem

adamant (adjective)	adamantine (adjective)
impervious to pleas, persuasion, requests, reason	consisting of or having the hardness of adamant
	having the hardness of a diamond
	impervious to pleas, persuasion, requests, reason