Mo. Rev. Stat. § 293.460
Any person desiring to perform the work of a coal miner and for himself to conduct room, entry or other underground mining in coal mines of this state, shall, before being permitted to engage in such work, produce evidence of a satisfactory nature that he has for one year worked in coal mines with or as a practical miner; such applicant to furnish evidence of his experience and qualifications to the director of the division of mine inspection, or to the person designated by said director to pass upon the competency of such applicant, and until said applicant shall have fully satisfied the director or the party designated by the said director at the mine, wherein such employment is sought of his fitness to perform the duties as above mentioned, he shall not be permitted to mine coal unless associated with a practical miner for such length of time as will qualify said applicant to safely for himself and others perform underground work; and any owner, agent or operator of any coal mine in this state who shall knowingly violate any of the provisions of this section shall be deemed guilty of a misdemeanor, and, upon conviction, shall be punished by a fine of not less than fifty dollars nor more than two hundred dollars for each and every offense, or by imprisonment in the county jail for a period of not less than thirty days nor more than sixty days, or both such fine and imprisonment, proceedings to be instituted by any court having competent jurisdiction.
§ 293.460, RSMo