strip mine vs surface-mine

strip mine is a noun but surface-mine is not a noun.

Word	Noun	Adjective	Verb	Adverb
strip mine	Yes	No	Yes	No
surface-mine	No	No	Yes	No

As verbs, strip mine and surface-mine are synonyms defined as:

Other synonyms of strip mine include surface mine.

strip mine (noun)	surface-mine (noun)
an open mine (usually for coal) where the seams run close to the surface

strip mine (verb)	surface-mine (verb)
extract (ore) from a strip-mine	extract (ore) from a strip-mine