Montana Title 39. Labor § 39-4-103. Underground miners and smelter workers

(1) The period of employment of workers in all underground mines or workings, including railroad or other tunnels, may not exceed 8 hours a day unless the employer and employee agree to a workday of more than 8 hours:

(2) The period of employment of workers in smelters, stamp mills, sampling works, concentrators, and all other institutions for the reduction of ores and refining of ores or metals may not exceed 8 hours a day unless the employer and employee agree to a workday of more than 8 hours:

(3) A person, corporation, agent, manager, or employer who violates any of the provisions of this section is guilty of a misdemeanor and upon conviction for each offense is subject to a fine of not less than $100 or more than $600 or by imprisonment in the county jail for a period of not more than 6 months, or both.