Mont. Code § 15-23-506
If any report required by this part contains any willfully false or fraudulent statements as to the gross amount received by any person engaged in mining for any mine's product, then the department shall compute the gross value of such mine's product based upon the average quotations of the price of such mine's product in New York City or the relative market value at the point of delivery as evidenced by some established authority or market report. If any such person has sold or otherwise disposed of any of its mine's product at a price substantially below the true market price of such product at the time and place of such sale or disposal, then the department shall compute the gross value of such portion of the mine's product so sold or disposed of substantially below the market price, which gross value shall be based upon the quotations of the price of such mine's product in New York City or the relative market value at the point of delivery at the time such portion of the product was so sold or otherwise disposed of as evidenced by some established authority or market report. Should there be no quotation covering any particular product, then the department shall fix the value of such gross product or such portion thereof as shall have been sold or otherwise disposed of at a price substantially below the true market price at the time and place of such sale or disposal in such a manner as may seem to be equitable.
§ 15-23-506, MCA