Mont. Code Ann. § 82-2-401

A person, association, or corporation engaged in the business of buying or sampling or smelting for hire ores of gold, silver, copper, lead, zinc, iron, or other valuable metal shall maintain a sampling room or house to which the ore shippers or their agents or representatives must have access at all times during the sampling of ores or while the sampling is being carried on and in which must be maintained samples of all ores that the person, association, or corporation may buy or smelt.