The maps so delivered to the state geologist shall be the property of the state and shall remain in the custody of the state geologist. They shall be kept at the office of the Iowa geological survey and be open to examination by all persons interested in the maps; but such examination shall only be made in the presence of the state geologist or a designee, and the state geologist shall not permit any copies of the maps to be made without the written consent of the operator or the owner of the property, except as provided in section 456.11 or if the mine has been abandoned for at least five years.