Mont. Code Ann. § 77-3-308

The department may withhold from public inspection any information obtained from a coal mining lessee or permittee under this part if the information relates to the geology of the mining lease or permit. The withholding is effective for as long as the department considers it necessary either to protect the lessee's or permittee's economic interest in the geologic information against unwarranted injury or to protect the public's best interest.