Oregon Revised Statutes Mortgages and Liens § 87.352

(1) A person has a lien upon a mine or an improvement to secure payment for labor performed or materials furnished if that person:

(2) For purposes of this section, when two or more mines are owned or claimed by the same person and worked through a common excavation, or over one tram, or at one mill or other reduction works, then all the mines so worked, and all excavations and improvements used or owned in connection therewith shall be deemed one mine.