"Mineral" is either a noun or an adjective. Example as a noun: Calcite is a mineral. Example as an adjective: "Still in matters vegetable, animal, or mineral, I am the very model of a modern major general" (from The Pirates of Penzance).
part of speech
The part of speech for this particular word is a noun.
The part of speech for "answer" is a noun.
adverb
what part of speech is beneath
The part of speech for "explicit" is an adjective.
The part of speech for "twirl" is a verb.
The part of speech for "unfamiliar" is an adjective.
The part of speech of "came" is a verb.
The part of speech for "lecturer" is a noun.
The part of speech for "indefinite" is an adjective.
The part of speech for "buried" is a verb.