Mont. Code Ann. § 15-37-201

Every person engaged in or carrying on the business of working or operating any mine or mining property in the state from which vermiculite, perlite, kerrite, maconite, or any other micaceous minerals are mined, extracted, or produced must pay to the department of revenue for the exclusive use and benefit of the state a license tax for engaging in and carrying on such business in an amount equal to 5 cents per ton for each and every ton of concentrates mined, extracted, or produced by such person during such year.