Miss. Code Ann. § 27-31-41

There is hereby exempted from all ad valorem taxes becoming a lien on or after January 1, 1989, each drilling rig for which there has been procured a privilege license (as required in Section 27-17-423) in exploring for, attempting to obtain, or obtaining production of oil, gas, sulphur, salt or any other minerals whether such operation is continued from year to year or not. This exemption shall not apply to material or equipment in supply depots or yards or to additional equipment not utilized as a necessary part of the drilling rig which has been operated in Mississippi under a local privilege license properly procured.