mining vs salt working

mining and salt working both are nouns.

Word	Noun	Adjective	Verb	Adverb
mining	Yes	No	No	No
salt working	Yes	No	No	No

As nouns, salt working is a hyponym of mining; that is, salt working is a word with a more specific, narrower meaning than mining:

Other hyponyms of mining include placer mining, opencast mining, strip mining, fracking, salt-working.

mining (noun)	salt working (noun)
the act of extracting ores or coal etc from the earth	The manufacture of salt.
laying explosive mines in concealed places to destroy enemy personnel and equipment