Mont. Code Ann. § 15-23-501 — Taxation Of Mines

15-23-501 . Taxation of mines. (1) All mines and mining claims, both placer and rock in place, containing or bearing gold, silver, copper, lead, coal, or other valuable mineral deposits, after purchase of the mines and mining claims from the United States, are taxed as all other land is taxed. All machinery, equipment, and other personal property used in mining or appurtenant to mines and mining claims that have a value separate and independent of the mines or mining claims and, except as provided in subsection (2), the annual net proceeds of all mines and mining claims are taxed as other personal property. Surface improvements upon or appurtenant to mines and mining claims that have a value separate and independent of the mines or mining claims are taxed as other improvements.
(2) Bentonite produced from mines and mining claims is not subject to net proceeds taxation and is taxed as provided in Title 15, chapter 39, part 1.