emery rock vs emery stone

emery rock and emery stone both are nouns.

Word	Noun	Adjective	Verb	Adverb
emery rock	Yes	No	No	No
emery stone	Yes	No	No	No

As nouns, emery rock and emery stone are synonyms defined as:

emery rock and emery stone: a mixture of emery dust and a binder; can be molded into grindstones

emery rock (noun)	emery stone (noun)
a mixture of emery dust and a binder; can be molded into grindstones	a mixture of emery dust and a binder; can be molded into grindstones