Violation of any of the terms or conditions of any lease or of the regulations pertaining thereto shall subject the lease to cancellation by the Secretary of the Interior, or the lessee to a fine of not exceeding $500 per day for each and every day the terms of the lease or of the regulations are violated, or the orders of the superintendent in reference thereto are not complied with, or to both such fine and cancellation in the discretion of the Secretary of the Interior: Provided, That the lessee shall be entitled to notice and hearing with respect to the terms of the lease or of the regulations violated, which hearing shall be held by the superintendent, whose findings shall be conclusive unless an appeal be taken to the Secretary of the Interior within 30 days after notice of the superintendent's decision, and the decision of the Secretary of the Interior upon appeal shall be conclusive.